Patent Publication Number: US-2017373916-A1

Title: Broadcast signal transmission apparatus, broadcast signal reception apparatus, broadcast signal transmission method, and broadcast signal reception method

Description:
TECHNICAL FIELD 
     The present invention relates to a broadcast signal transmission apparatus, a broadcast signal receiving apparatus, and a broadcast signal transceiving method. 
     BACKGROUND ART 
     As analog broadcast signal transmission is terminated, various technologies for transmitting and receiving a digital broadcast signal have been developed. A digital broadcast signal is capable of containing a larger amount of video/audio data than an analog broadcast signal and further containing various types of additional data as well as video/audio data. 
     DISCLOSURE 
     Technical Problem 
     That is, a digital broadcast system may provide a high definition (HD) image, multi-channel audio, and various additional services. However, for digital broadcast, network flexibility obtained by considering data transmission efficiency for a large amount of data transmission, robustness of a transceiving network, and a mobile receiving apparatus needs to be enhanced. 
     Technical Solution 
     The present invention proposes a system and a related signaling method for effectively supporting future broadcast services in environments supporting future hybrid broadcast using terrestrial broadcast networks and the Internet as included and described herein according to the object of the present invention. 
     Advantageous Effects 
     The present invention can control quality of service (QoS) of each service or service component by processing data depending on service characteristics to provide various broadcast services. 
     The present invention can transmit various broadcast services through the same radio frequency (RF) signal bandwidth to accomplish transmission flexibility. 
     According to the present invention, it is possible to provide broadcast signal transmission and reception methods and apparatuses capable of receiving digital broadcast signals without error even when a mobile reception apparatus is used or in indoor environments. 
     The present invention can effectively support future broadcast services in environments supporting future hybrid broadcast using terrestrial broadcast networks and the Internet. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
         FIG. 1  illustrates a structure of an apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention; 
         FIG. 2  illustrates an input formatting block according to one embodiment of the present invention; 
         FIG. 3  illustrates an input formatting block according to another embodiment of the present invention; 
         FIG. 4  illustrates a BICM block according to an embodiment of the present invention; 
         FIG. 5  illustrates a BICM block according to another embodiment of the present invention; 
         FIG. 6  illustrates a frame building block according to one embodiment of the present invention; 
         FIG. 7  illustrates an OFDM generation block according to an embodiment of the present invention; 
         FIG. 8  illustrates a structure of an apparatus for receiving broadcast signals for future broadcast services according to an embodiment of the present invention; 
         FIG. 9  illustrates a frame structure according to an embodiment of the present invention; 
         FIG. 10  illustrates a signaling hierarchy structure of the frame according to an embodiment of the present invention; 
         FIG. 11  illustrates preamble signaling data according to an embodiment of the present invention; 
         FIG. 12  illustrates PLS1 data according to an embodiment of the present invention; 
         FIG. 13  illustrates PLS2 data according to an embodiment of the present invention; 
         FIG. 14  illustrates PLS2 data according to another embodiment of the present invention; 
         FIG. 15  illustrates a logical structure of a frame according to an embodiment of the present invention; 
         FIG. 16  illustrates PLS mapping according to an embodiment of the present invention; 
         FIG. 17  illustrates EAC mapping according to an embodiment of the present invention; 
         FIG. 18  illustrates FIC mapping according to an embodiment of the present invention; 
         FIG. 19  illustrates an FEC structure according to an embodiment of the present invention; 
         FIG. 20  illustrates time interleaving according to an embodiment of the present invention; 
         FIG. 21  illustrates the basic operation of a twisted row-column block interleaver according to an embodiment of the present invention; 
         FIG. 22  illustrates an operation of a twisted row-column block interleaver according to another embodiment of the present invention; 
         FIG. 23  illustrates a diagonal-wise reading pattern of a twisted row-column block interleaver according to an embodiment of the present invention; 
         FIG. 24  illustrates interleaved XFECBLOCKs from each interleaving array according to an embodiment of the present invention; 
         FIG. 25  illustrates signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention; 
         FIG. 26  illustrates FI schemes of FSS in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention; 
         FIG. 27  illustrates operation of a reset mode in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention; 
         FIG. 28  illustrates equations indicating input and output of the frequency interleaver in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention; 
         FIG. 29  illustrates equations of a logical operation mechanism of frequency interleaving based on FI scheme #1 and FI scheme #2 in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention; 
         FIG. 30  illustrates an example in which the number of symbols is an even number in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention; 
         FIG. 31  illustrates an example in which the number of symbols is an even number in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention; 
         FIG. 32  illustrates an example in which the number of symbols is an odd number in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention; 
         FIG. 33  illustrates an example in which the number of symbols is an odd number in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention; 
         FIG. 34  illustrates operation of the frequency deinterleaver in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention; 
         FIG. 35  illustrates the concept of a variable bit-rate system according to an embodiment of the present invention; 
         FIG. 36  illustrates writing and reading operations of block interleaving according to an embodiment of the present invention; 
         FIG. 37  shows equations representing block interleaving according to an embodiment of the present invention; 
         FIG. 38  illustrates virtual FEC blocks according to an embodiment of the present invention; 
         FIG. 39  shows equations representing reading operation after insertion of virtual FEC blocks according to an embodiment of the present invention; 
         FIG. 40  is a flowchart illustrating a time interleaving process according to an embodiment of the present invention; 
         FIG. 41  shows equations representing a process of determining a shift value and a maximum TI block size according to an embodiment of the present invention; 
         FIG. 42  illustrates a writing operation according to an embodiment of the present invention; 
         FIG. 43  illustrates a reading operation according to an embodiment of the present invention; 
         FIG. 44  illustrates a result of skip operation in reading operation according to an embodiment of the present invention; 
         FIG. 45  shows a writing process of time deinterleaving according to an embodiment of the present invention; 
         FIG. 46  illustrates a writing process of time deinterleaving according to another embodiment of the present invention; 
         FIG. 47  shows equations representing reading operation of time deinterleaving according to another embodiment of the present invention; 
         FIG. 48  is a flowchart illustrating a time deinterleaving process according to an embodiment of the present invention; 
         FIG. 49  illustrates a receiver protocol stack according to an embodiment of the present invention; 
         FIG. 50  illustrates a relationship between an SLT and service layer signaling (SLS) according to an embodiment of the present invention; 
         FIG. 51  illustrates an SLT according to an embodiment of the present invention; 
         FIG. 52  illustrates SLS bootstrapping and service discovery processes according to an embodiment of the present invention; 
         FIG. 53  illustrates a USBD fragment for ROUTE/DASH according to an embodiment of the present invention; 
         FIG. 54  illustrates an S-TSID fragment for ROUTE/DASH according to an embodiment of the present invention; 
         FIG. 55  illustrates a USBD/USD fragment for an MMT according to an embodiment of the present invention; 
         FIG. 56  illustrates a link layer protocol architecture according to an embodiment of the present invention; 
         FIG. 57  illustrates a base header structure of a link layer packet according to an embodiment of the present invention; 
         FIG. 58  illustrates an additional header structure of a link layer packet according to an embodiment of the present invention; 
         FIG. 59  illustrates an additional header structure of a link layer packet according to another embodiment of the present invention; 
         FIG. 60  illustrates a link layer packet header structure for an MPEG-2 TS packet and a process of encapsulating the same according to an embodiment of the present invention; 
         FIG. 61  illustrates an embodiment of adaptation modes in IP header compression according to an embodiment of the present invention (transmission side); 
         FIG. 62  illustrates a link mapping table (LMT) and a ROHC-U description table according to an embodiment of the present invention; 
         FIG. 63  illustrates a link layer structure at the side of a transmitter according to an embodiment of the present invention; 
         FIG. 64  illustrates a link layer structure at the side of a receiver according to an embodiment of the present invention; 
         FIG. 65  illustrates a signaling transmission structure through a link layer according to an embodiment of the present invention (transmission/reception sides); 
         FIG. 66  illustrates a protocol stack for a future broadcast system according to an embodiment of the present invention; 
         FIG. 67  illustrates a receiver of a future broadcast system according to an embodiment of the present invention; 
         FIG. 68  illustrates a timeline component for synchronization between a transport stream of a broadcast network and a transport stream of the Internet (hybrid network) according to an embodiment of the present invention; 
         FIG. 69  shows a broadcast transport stream according to an embodiment of the present invention; 
         FIG. 70  shows a broadcast transport stream according to another embodiment of the present invention; 
         FIG. 71  shows a structure of a transport stream carrying a broadcast service according to an embodiment of the present invention; 
         FIG. 72  shows values available for a network_protocol field included in a transport packet carrying a broadcast service according to an embodiment of the present invention; 
         FIG. 73  shows signaling of a broadcast service and a broadcast service transmission path through a broadcast service signaling table and broadcast service transmission path signaling information according to an embodiment of the present invention; 
         FIG. 74  shows a broadcast service signaling table according to an embodiment of the present invention; 
         FIG. 75  shows values available for a service_category field included in a broadcast service signaling table according to an embodiment of the present invention; 
         FIG. 76  shows a broadcast service signaling table according to another embodiment of the present invention; 
         FIG. 77  shows a stream identifier descriptor according to an embodiment of the present invention; 
         FIG. 78  shows an operation of a broadcast transmission apparatus to transmit a broadcast packet according to an embodiment of the present invention; 
         FIG. 79  shows an operation of a broadcast reception apparatus to receive a broadcast packet according to an embodiment of the present invention; 
         FIG. 80  shows a packet configuration according to an embodiment of the present invention; 
         FIG. 81  shows a structure of a real-time transport protocol (RTP) packet according to an embodiment of the present invention; 
         FIG. 82  illustrates a media file format based on an ISO base media file format (BMFF) according to an embodiment of the present invention; 
         FIG. 83  illustrates a payload header configuration of a packet payload according to an embodiment of the present invention; 
         FIGS. 84 and 85  illustrate payload configurations of a transport packet obtained by packetizing one piece of media data into one packet; 
         FIGS. 86 and 87  illustrate payload configurations of a transport packet obtained by packetizing different pieces of media data into one packet; 
         FIG. 88  illustrates a payload configuration of transport packets (referred to as fragmented packets) obtained by packetizing one piece of media data into multiple transport packets; 
         FIG. 89  illustrates another embodiment of a payload configuration of a fragmented packet; 
         FIG. 90  shows that a broadcast transmission apparatus fragments an ISO BMFF based media file into multiple packets according to an embodiment of the present invention; 
         FIG. 91  shows a specific embodiment of first fragmentation unit data packetized by the broadcast transmission apparatus of  FIG. 90 ; 
         FIGS. 92 to 94  shows embodiments of a fragmentation unit including remaining data other than start data of fragmentation unit data; 
         FIG. 95  shows a timeline signaling table of metadata according to an embodiment of the present invention; 
         FIG. 96  illustrates a configuration of payload data obtained by packetizing one piece of metadata in payload data of a transport packet; 
         FIG. 97  illustrates an embodiment when payload data of a transport packet includes metadata regarding a timeline; 
         FIG. 98  illustrates a case in which multiple pieces of metadata are packetized into one transport packet; 
         FIG. 99  illustrates a case in which one transport packet includes multiple pieces of timeline information; 
         FIG. 100  illustrates a packet payload obtained by packetizing one piece of metadata into multiple transport packets; 
         FIG. 101  illustrates another embodiment of a metadata fragment header; 
         FIG. 102  illustrates an operation of a broadcast reception apparatus to receive a broadcast packet according to an embodiment of the present invention; 
         FIG. 103  illustrates a case in which a video stream is transmitted using an RTP through a broadcast network and a video stream is transmitted using file format based media data through the Internet; 
         FIG. 104  illustrates a configuration of a transport packet according to an embodiment of the present invention; 
         FIG. 105  illustrates a configuration of a packet header according to an embodiment of the present invention; 
         FIGS. 106 and 107  illustrate header extension configurations including time information; 
         FIGS. 108 to 111  illustrate header extension configurations according to another embodiment of the present invention; 
         FIG. 112  illustrates a header extension structure for supporting mapping with different timing information according to an embodiment of the present invention; 
         FIG. 113  illustrates an operating method of a broadcast transmission apparatus according to an embodiment of the present invention; 
         FIG. 114  illustrates an operating method of a broadcast reception apparatus according to an embodiment of the present invention; 
         FIG. 115  illustrates a packet header structure including information about a transport packet configuration; 
         FIG. 116  illustrates the transport packet configuration illustrated in  FIG. 115 ; 
         FIG. 117  illustrates an operating method of a broadcast transmission apparatus according to an embodiment of the present invention; 
         FIG. 118  illustrates an operating method of a broadcast reception apparatus according to an embodiment of the present invention; 
         FIG. 119  illustrates a hybrid broadcast reception apparatus according to an embodiment of the present invention; 
         FIG. 120  is a block diagram of a hybrid broadcast receiver according to an embodiment of the present invention; 
         FIG. 121  illustrates a protocol stack of a future hybrid broadcast system according to an embodiment of the present invention; 
         FIG. 122  illustrates a structure of a transmission frame delivered to a physical layer of a future broadcast transmission system according to an embodiment of the present invention; 
         FIG. 123  illustrates a first packet structure according to an embodiment of the present invention; 
         FIG. 124  illustrates the first packet structure according to another embodiment of the present invention; 
         FIG. 125  illustrates the first packet structure according to another embodiment of the present invention; 
         FIG. 126  illustrates payload structures of a first packet according to another embodiment of the present invention; 
         FIG. 127  illustrates a header structure and a payload header structure of a second packet according to an embodiment of the present invention; 
         FIG. 128  illustrates header structures of the second packet according to another embodiment of the present invention; 
         FIG. 129  illustrates header extension structures of the second packet according to another embodiment of the present invention; 
         FIG. 130  illustrates a process of transmitting the first packet or the second packet according to an embodiment of the present invention; 
         FIG. 131  illustrates a method of transmitting a broadcast signal according to an embodiment of the present invention; 
         FIG. 132  illustrates an apparatus for transmitting a broadcast signal according to an embodiment of the present invention; 
         FIG. 133  is a table showing interleaving types applied depending on the number of PLPs; 
         FIG. 134  is a block diagram illustrating a first embodiment of the hybrid time interleaver structure; 
         FIG. 135  is a block diagram illustrating a second embodiment of the hybrid time interleaver structure; 
         FIG. 136  is a block diagram illustrating a first embodiment of a hybrid time deinterleaver structure; and 
         FIG. 137  is a block diagram illustrating a second embodiment of the hybrid time deinterleaver structure. 
     
    
    
     BEST MODE 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention, rather than to show the only embodiments that can be implemented according to the present invention. 
     Although most terms of elements in this specification have been selected from general ones widely used in the art taking into consideration functions thereof in this specification, the terms may be changed depending on the intention or convention of those skilled in the art or the introduction of new technology. Some terms have been arbitrarily selected by the applicant and their meanings are explained in the following description as needed. Thus, the terms used in this specification should be construed based on the overall content of this specification together with the actual meanings of the terms rather than their simple names or meanings. 
     The present invention provides apparatuses and methods for transmitting and receiving broadcast signals for future broadcast services. Future broadcast services according to an embodiment of the present invention include a terrestrial broadcast service, a mobile broadcast service, a UHDTV service, etc. The present invention may process broadcast signals for the future broadcast services through non-MIMO (Multiple Input Multiple Output) or MIMO according to one embodiment. A non-MIMO scheme according to an embodiment of the present invention may include a MISO (Multiple Input Single Output) scheme, a SISO (Single Input Single Output) scheme, etc. 
     While MISO or MIMO uses two antennas in the following for convenience of description, the present invention is applicable to systems using two or more antennas. The present invention may defines three physical layer (PL) profiles—base, handheld and advanced profiles—each optimized to minimize receiver complexity while attaining the performance required for a particular use case. The physical layer (PHY) profiles are subsets of all configurations that a corresponding receiver should implement. 
     The three PHY profiles share most of the functional blocks but differ slightly in specific blocks and/or parameters. Additional PHY profiles can be defined in the future. For the system evolution, future profiles can also be multiplexed with the existing profiles in a single RF channel through a future extension frame (FEF). The details of each PHY profile are described below. 
     1. Base Profile 
     The base profile represents a main use case for fixed receiving devices that are usually connected to a roof-top antenna. The base profile also includes portable devices that could be transported to a place but belong to a relatively stationary reception category. Use of the base profile could be extended to handheld devices or even vehicular by some improved implementations, but those use cases are not expected for the base profile receiver operation. 
     Target SNR range of reception is from approximately 10 to 20 dB, which includes the 15 dB SNR reception capability of the existing broadcast system (e.g. ATSC A/53). The receiver complexity and power consumption is not as critical as in the battery-operated handheld devices, which will use the handheld profile. Key system parameters for the base profile are listed in below table 1. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                 LDPC codeword length 
                 16K, 64K bits 
               
               
                 Constellation size 
                 4~10 bpcu (bits per channel use) 
               
               
                 Time de-interleaving memory size 
                 ≦2 19  data cells 
               
               
                 Pilot patterns 
                 Pilot pattern for fixed reception 
               
               
                 FFT size 
                 16K, 32K points 
               
               
                   
               
            
           
         
       
     
     2. Handheld Profile 
     The handheld profile is designed for use in handheld and vehicular devices that operate with battery power. The devices can be moving with pedestrian or vehicle speed. The power consumption as well as the receiver complexity is very important for the implementation of the devices of the handheld profile. The target SNR range of the handheld profile is approximately 0 to 10 dB, but can be configured to reach below 0 dB when intended for deeper indoor reception. 
     In addition to low SNR capability, resilience to the Doppler Effect caused by receiver mobility is the most important performance attribute of the handheld profile. Key system parameters for the handheld profile are listed in the below table 2. 
     
       
         
           
               
               
             
               
                 TABLE 2 
               
               
                   
               
             
            
               
                 LDPC codeword length 
                 16K bits 
               
               
                 Constellation size 
                 2~8 bpcu 
               
               
                 Time de-interleaving memory size 
                 ≦2 18  data cells 
               
               
                 Pilot patterns 
                 Pilot patterns for mobile and indoor 
               
               
                   
                 reception 
               
               
                 FFT size 
                 8K, 16K points 
               
               
                   
               
            
           
         
       
     
     3. Advanced Profile 
     The advanced profile provides highest channel capacity at the cost of more implementation complexity. This profile requires using MIMO transmission and reception, and UHDTV service is a target use case for which this profile is specifically designed. The increased capacity can also be used to allow an increased number of services in a given bandwidth, e.g., multiple SDTV or HDTV services. 
     The target SNR range of the advanced profile is approximately 20 to 30 dB. MIMO transmission may initially use existing elliptically-polarized transmission equipment, with extension to full-power cross-polarized transmission in the future. Key system parameters for the advanced profile are listed in below table 3. 
     
       
         
           
               
               
             
               
                 TABLE 3 
               
               
                   
               
             
            
               
                 LDPC codeword length 
                 16K, 64K bits 
               
               
                 Constellation size 
                 8~12 bpcu 
               
               
                 Time de-interleaving memory size 
                 ≦2 19  data cells 
               
               
                 Pilot patterns 
                 Pilot pattern for fixed reception 
               
               
                 FFT size 
                 16K, 32K points 
               
               
                   
               
            
           
         
       
     
     In this case, the base profile can be used as a profile for both the terrestrial broadcast service and the mobile broadcast service. That is, the base profile can be used to define a concept of a profile which includes the mobile profile. Also, the advanced profile can be divided advanced profile for a base profile with MIMO and advanced profile for a handheld profile with MIMO. Moreover, the three profiles can be changed according to intention of the designer. 
     The following terms and definitions may apply to the present invention. The following terms and definitions can be changed according to design. 
     auxiliary stream: sequence of cells carrying data of as yet undefined modulation and coding, which may be used for future extensions or as required by broadcasters or network operators 
     base data pipe: data pipe that carries service signaling data 
     baseband frame (or BBFRAME): set of Kbch bits which form the input to one FEC encoding process (BCH and LDPC encoding) 
     cell: modulation value that is carried by one carrier of the OFDM transmission 
     coded block: LDPC-encoded block of PLS1 data or one of the LDPC-encoded blocks of PLS2 data 
     data pipe: logical channel in the physical layer that carries service data or related metadata, which may carry one or multiple service(s) or service component(s). 
     data pipe unit: a basic unit for allocating data cells to a DP in a frame. 
     data symbol: OFDM symbol in a frame which is not a preamble symbol (the frame signaling symbol and frame edge symbol is included in the data symbol) 
     DP_ID: this 8-bit field identifies uniquely a DP within the system identified by the SYSTEM_ID 
     dummy cell: cell carrying a pseudo-random value used to fill the remaining capacity not used for PLS signaling, DPs or auxiliary streams 
     emergency alert channel—part of a frame that carries EAS information data 
     frame: physical layer time slot that starts with a preamble and ends with a frame edge symbol 
     frame repetition unit: a set of frames belonging to same or different physical layer profile including a FEF, which is repeated eight times in a super-frame 
     fast information channel: a logical channel in a frame that carries the mapping information between a service and the corresponding base DP 
     FECBLOCK: set of LDPC-encoded bits of a DP data 
     FFT size: nominal FFT size used for a particular mode, equal to the active symbol period Ts expressed in cycles of the elementary period T 
     frame signaling symbol: OFDM symbol with higher pilot density used at the start of a frame in certain combinations of FFT size, guard interval and scattered pilot pattern, which carries a part of the PLS data 
     frame edge symbol: OFDM symbol with higher pilot density used at the end of a frame in certain combinations of FFT size, guard interval and scattered pilot pattern 
     frame-group: the set of all the frames having the same PHY profile type in a super-frame. 
     future extension frame: physical layer time slot within the super-frame that could be used for future extension, which starts with a preamble 
     Futurecast UTB system: proposed physical layer broadcasting system, of which the input is one or more MPEG2-TS or IP or general stream(s) and of which the output is an RF signal 
     input stream: A stream of data for an ensemble of services delivered to the end users by the system. 
     normal data symbol: data symbol excluding the frame signaling symbol and the frame edge symbol 
     PHY profile: subset of all configurations that a corresponding receiver should implement 
     PLS: physical layer signaling data consisting of PLS1 and PLS2 
     PLS1: a first set of PLS data carried in the FSS symbols having a fixed size, coding and modulation, which carries basic information about the system as well as the parameters needed to decode the PLS2 
     NOTE: PLS1 data remains constant for the duration of a frame-group. 
     PLS2: a second set of PLS data transmitted in the FSS symbol, which carries more detailed PLS data about the system and the DPs 
     PLS2 dynamic data: PLS2 data that may dynamically change frame-by-frame 
     PLS2 static data: PLS2 data that remains static for the duration of a frame-group 
     preamble signaling data: signaling data carried by the preamble symbol and used to identify the basic mode of the system 
     preamble symbol: fixed-length pilot symbol that carries basic PLS data and is located in the beginning of a frame 
     NOTE: The preamble symbol is mainly used for fast initial band scan to detect the system signal, its timing, frequency offset, and FFT-size. 
     reserved for future use: not defined by the present document but may be defined in future 
     super-frame: set of eight frame repetition units 
     time interleaving block (TI block): set of cells within which time interleaving is carried out, corresponding to one use of the time interleaver memory 
     TI group: unit over which dynamic capacity allocation for a particular DP is carried out, made up of an integer, dynamically varying number of XFECBLOCKs 
     NOTE: The TI group may be mapped directly to one frame or may be mapped to multiple frames. It may contain one or more TI blocks. 
     Type 1 DP: DP of a frame where all DPs are mapped into the frame in TDM fashion 
     Type 2 DP: DP of a frame where all DPs are mapped into the frame in FDM fashion 
     XFECBLOCK: set of Ncells cells carrying all the bits of one LDPC FECBLOCK 
       FIG. 1  illustrates a structure of an apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention. 
     The apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention can include an input formatting block  1000 , a BICM (Bit interleaved coding &amp; modulation) block  1010 , a frame building block  1020 , an OFDM (Orthogonal Frequency Division Multiplexing) generation block  1030  and a signaling generation block  1040 . A description will be given of the operation of each module of the apparatus for transmitting broadcast signals. 
     IP stream/packets and MPEG2-TS are the main input formats, other stream types are handled as General Streams. In addition to these data inputs, Management Information is input to control the scheduling and allocation of the corresponding bandwidth for each input stream. One or multiple TS stream(s), IP stream(s) and/or General Stream(s) inputs are simultaneously allowed. 
     The input formatting block  1000  can demultiplex each input stream into one or multiple data pipe(s), to each of which an independent coding and modulation is applied. The data pipe (DP) is the basic unit for robustness control, thereby affecting quality-of-service (QoS). One or multiple service(s) or service component(s) can be carried by a single DP. Details of operations of the input formatting block  1000  will be described later. 
     The data pipe is a logical channel in the physical layer that carries service data or related metadata, which may carry one or multiple service(s) or service component(s). 
     Also, the data pipe unit: a basic unit for allocating data cells to a DP in a frame. 
     In the BICM block  1010 , parity data is added for error correction and the encoded bit streams are mapped to complex-value constellation symbols. The symbols are interleaved across a specific interleaving depth that is used for the corresponding DP. For the advanced profile, MIMO encoding is performed in the BICM block  1010  and the additional data path is added at the output for MIMO transmission. Details of operations of the BICM block  1010  will be described later. 
     The Frame Building block  1020  can map the data cells of the input DPs into the OFDM symbols within a frame. After mapping, the frequency interleaving is used for frequency-domain diversity, especially to combat frequency-selective fading channels. Details of operations of the Frame Building block  1020  will be described later. 
     After inserting a preamble at the beginning of each frame, the OFDM Generation block  1030  can apply conventional OFDM modulation having a cyclic prefix as guard interval. For antenna space diversity, a distributed MISO scheme is applied across the transmitters. In addition, a Peak-to-Average Power Reduction (PAPR) scheme is performed in the time domain. For flexible network planning, this proposal provides a set of various FFT sizes, guard interval lengths and corresponding pilot patterns. Details of operations of the OFDM Generation block  1030  will be described later. 
     The Signaling Generation block  1040  can create physical layer signaling information used for the operation of each functional block. This signaling information is also transmitted so that the services of interest are properly recovered at the receiver side. Details of operations of the Signaling Generation block  1040  will be described later. 
       FIGS. 2, 3 and 4  illustrate the input formatting block  1000  according to embodiments of the present invention. A description will be given of each figure. 
       FIG. 2  illustrates an input formatting block according to one embodiment of the present invention.  FIG. 2  shows an input formatting module when the input signal is a single input stream. 
     The input formatting block illustrated in  FIG. 2  corresponds to an embodiment of the input formatting block  1000  described with reference to  FIG. 1 . 
     The input to the physical layer may be composed of one or multiple data streams. Each data stream is carried by one DP. The mode adaptation modules slice the incoming data stream into data fields of the baseband frame (BBF). The system supports three types of input data streams: MPEG2-TS, Internet protocol (IP) and Generic stream (GS). MPEG2-TS is characterized by fixed length (188 byte) packets with the first byte being a sync-byte (0x47). An IP stream is composed of variable length IP datagram packets, as signaled within IP packet headers. The system supports both IPv4 and IPv6 for the IP stream. GS may be composed of variable length packets or constant length packets, signaled within encapsulation packet headers. 
     (a) shows a mode adaptation block  2000  and a stream adaptation  2010  for signal DP and (b) shows a PLS generation block  2020  and a PLS scrambler  2030  for generating and processing PLS data. A description will be given of the operation of each block. 
     The Input Stream Splitter splits the input TS, IP, GS streams into multiple service or service component (audio, video, etc.) streams. The mode adaptation module  2010  is comprised of a CRC Encoder, BB (baseband) Frame Slicer, and BB Frame Header Insertion block. 
     The CRC Encoder provides three kinds of CRC encoding for error detection at the user packet (UP) level, i.e., CRC-8, CRC-16, and CRC-32. The computed CRC bytes are appended after the UP. CRC-8 is used for TS stream and CRC-32 for IP stream. If the GS stream doesn&#39;t provide the CRC encoding, the proposed CRC encoding should be applied. 
     BB Frame Slicer maps the input into an internal logical-bit format. The first received bit is defined to be the MSB. The BB Frame Slicer allocates a number of input bits equal to the available data field capacity. To allocate a number of input bits equal to the BBF payload, the UP packet stream is sliced to fit the data field of BBF. 
     BB Frame Header Insertion block can insert fixed length BBF header of 2 bytes is inserted in front of the BB Frame. The BBF header is composed of STUFFI (1 bit), SYNCD (13 bits), and RFU (2 bits). In addition to the fixed 2-Byte BBF header, BBF can have an extension field (1 or 3 bytes) at the end of the 2-byte BBF header. 
     The stream adaptation  2010  is comprised of stuffing insertion block and BB scrambler. The stuffing insertion block can insert stuffing field into a payload of a BB frame. If the input data to the stream adaptation is sufficient to fill a BB-Frame, STUFFI is set to ‘0’ and the BBF has no stuffing field. Otherwise STUFFI is set to ‘1’ and the stuffing field is inserted immediately after the BBF header. The stuffing field comprises two bytes of the stuffing field header and a variable size of stuffing data. 
     The BB scrambler scrambles complete BBF for energy dispersal. The scrambling sequence is synchronous with the BBF. The scrambling sequence is generated by the feed-back shift register. 
     The PLS generation block  2020  can generate physical layer signaling (PLS) data. The PLS provides the receiver with a means to access physical layer DPs. The PLS data consists of PLS1 data and PLS2 data. 
     The PLS1 data is a first set of PLS data carried in the FSS symbols in the frame having a fixed size, coding and modulation, which carries basic information about the system as well as the parameters needed to decode the PLS2 data. The PLS1 data provides basic transmission parameters including parameters required to enable the reception and decoding of the PLS2 data. Also, the PLS1 data remains constant for the duration of a frame-group. 
     The PLS2 data is a second set of PLS data transmitted in the FSS symbol, which carries more detailed PLS data about the system and the DPs. The PLS2 contains parameters that provide sufficient information for the receiver to decode the desired DP. The PLS2 signaling further consists of two types of parameters, PLS2 Static data (PLS2-STAT data) and PLS2 dynamic data (PLS2-DYN data). The PLS2 Static data is PLS2 data that remains static for the duration of a frame-group and the PLS2 dynamic data is PLS2 data that may dynamically change frame-by-frame. 
     Details of the PLS data will be described later. 
     The PLS scrambler  2030  can scramble the generated PLS data for energy dispersal. 
     The above-described blocks may be omitted or replaced by blocks having similar or identical functions. 
       FIG. 3  illustrates an input formatting block according to another embodiment of the present invention. 
     The input formatting block illustrated in  FIG. 3  corresponds to an embodiment of the input formatting block  1000  described with reference to  FIG. 1 . 
       FIG. 3  shows a mode adaptation block of the input formatting block when the input signal corresponds to multiple input streams. 
     The mode adaptation block of the input formatting block for processing the multiple input streams can independently process the multiple input streams. 
     Referring to  FIG. 3 , the mode adaptation block for respectively processing the multiple input streams can include an input stream splitter  3000 , an input stream synchronizer  3010 , a compensating delay block  3020 , a null packet deletion block  3030 , a head compression block  3040 , a CRC encoder  3050 , a BB frame slicer  3060  and a BB header insertion block  3070 . Description will be given of each block of the mode adaptation block. 
     Operations of the CRC encoder  3050 , BB frame slicer  3060  and BB header insertion block  3070  correspond to those of the CRC encoder, BB frame slicer and BB header insertion block described with reference to  FIG. 2  and thus description thereof is omitted. 
     The input stream splitter  3000  can split the input TS, IP, GS streams into multiple service or service component (audio, video, etc.) streams. 
     The input stream synchronizer  3010  may be referred as ISSY. The ISSY can provide suitable means to guarantee Constant Bit Rate (CBR) and constant end-to-end transmission delay for any input data format. The ISSY is always used for the case of multiple DPs carrying TS, and optionally used for multiple DPs carrying GS streams. 
     The compensating delay block  3020  can delay the split TS packet stream following the insertion of ISSY information to allow a TS packet recombining mechanism without requiring additional memory in the receiver. 
     The null packet deletion block  3030 , is used only for the TS input stream case. Some TS input streams or split TS streams may have a large number of null-packets present in order to accommodate VBR (variable bit-rate) services in a CBR TS stream. In this case, in order to avoid unnecessary transmission overhead, null-packets can be identified and not transmitted. In the receiver, removed null-packets can be re-inserted in the exact place where they were originally by reference to a deleted null-packet (DNP) counter that is inserted in the transmission, thus guaranteeing constant bit-rate and avoiding the need for time-stamp (PCR) updating. 
     The head compression block  3040  can provide packet header compression to increase transmission efficiency for TS or IP input streams. Because the receiver can have a priori information on certain parts of the header, this known information can be deleted in the transmitter. 
     For Transport Stream, the receiver has a-priori information about the sync-byte configuration (0x47) and the packet length (188 Byte). If the input TS stream carries content that has only one PID, i.e., for only one service component (video, audio, etc.) or service sub-component (SVC base layer, SVC enhancement layer, MVC base view or MVC dependent views), TS packet header compression can be applied (optionally) to the Transport Stream. IP packet header compression is used optionally if the input steam is an IP stream. The above-described blocks may be omitted or replaced by blocks having similar or identical functions. 
       FIG. 4  illustrates a BICM block according to an embodiment of the present invention. 
     The BICM block illustrated in  FIG. 4  corresponds to an embodiment of the BICM block  1010  described with reference to  FIG. 1 . 
     As described above, the apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention can provide a terrestrial broadcast service, mobile broadcast service, UHDTV service, etc. 
     Since QoS (quality of service) depends on characteristics of a service provided by the apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention, data corresponding to respective services needs to be processed through different schemes. Accordingly, the a BICM block according to an embodiment of the present invention can independently process DPs input thereto by independently applying SISO, MISO and MIMO schemes to the data pipes respectively corresponding to data paths. Consequently, the apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention can control QoS for each service or service component transmitted through each DP. 
     (a) shows the BICM block shared by the base profile and the handheld profile and (b) shows the BICM block of the advanced profile. 
     The BICM block shared by the base profile and the handheld profile and the BICM block of the advanced profile can include plural processing blocks for processing each DP. 
     A description will be given of each processing block of the BICM block for the base profile and the handheld profile and the BICM block for the advanced profile. 
     A processing block  5000  of the BICM block for the base profile and the handheld profile can include a Data FEC encoder  5010 , a bit interleaver  5020 , a constellation mapper  5030 , an SSD (Signal Space Diversity) encoding block  5040  and a time interleaver  5050 . 
     The Data FEC encoder  5010  can perform the FEC encoding on the input BBF to generate FECBLOCK procedure using outer coding (BCH), and inner coding (LDPC). The outer coding (BCH) is optional coding method. Details of operations of the Data FEC encoder  5010  will be described later. 
     The bit interleaver  5020  can interleave outputs of the Data FEC encoder  5010  to achieve optimized performance with combination of the LDPC codes and modulation scheme while providing an efficiently implementable structure. Details of operations of the bit interleaver  5020  will be described later. 
     The constellation mapper  5030  can modulate each cell word from the bit interleaver  5020  in the base and the handheld profiles, or cell word from the Cell-word demultiplexer  5010 - 1  in the advanced profile using either QPSK, QAM-16, non-uniform QAM (NUQ-64, NUQ-256, NUQ-1024) or non-uniform constellation (NUC-16, NUC-64, NUC-256, NUC-1024) to give a power-normalized constellation point, el. This constellation mapping is applied only for DPs. Observe that QAM-16 and NUQs are square shaped, while NUCs have arbitrary shape. When each constellation is rotated by any multiple of 90 degrees, the rotated constellation exactly overlaps with its original one. This “rotation-sense” symmetric property makes the capacities and the average powers of the real and imaginary components equal to each other. Both NUQs and NUCs are defined specifically for each code rate and the particular one used is signaled by the parameter DP_MOD filed in PLS2 data. 
     The time interleaver  5050  can operates at the DP level. The parameters of time interleaving (TI) may be set differently for each DP. Details of operations of the time interleaver  5050  will be described later. 
     A processing block  5000 - 1  of the BICM block for the advanced profile can include the Data FEC encoder, bit interleaver, constellation mapper, and time interleaver. 
     However, the processing block  5000 - 1  is distinguished from the processing block  5000  further includes a cell-word demultiplexer  5010 - 1  and a MIMO encoding block  5020 - 1 . 
     Also, the operations of the Data FEC encoder, bit interleaver, constellation mapper, and time interleaver in the processing block  5000 - 1  correspond to those of the Data FEC encoder  5010 , bit interleaver  5020 , constellation mapper  5030 , and time interleaver  5050  described and thus description thereof is omitted. 
     The cell-word demultiplexer  5010 - 1  is used for the DP of the advanced profile to divide the single cell-word stream into dual cell-word streams for MIMO processing. Details of operations of the cell-word demultiplexer  5010 - 1  will be described later. 
     The MIMO encoding block  5020 - 1  can processing the output of the cell-word demultiplexer  5010 - 1  using MIMO encoding scheme. The MIMO encoding scheme was optimized for broadcasting signal transmission. The MIMO technology is a promising way to get a capacity increase but it depends on channel characteristics. Especially for broadcasting, the strong LOS component of the channel or a difference in the received signal power between two antennas caused by different signal propagation characteristics makes it difficult to get capacity gain from MIMO. The proposed MIMO encoding scheme overcomes this problem using a rotation-based pre-coding and phase randomization of one of the MIMO output signals. 
     MIMO encoding is intended for a 2×2 MIMO system requiring at least two antennas at both the transmitter and the receiver. Two MIMO encoding modes are defined in this proposal; full-rate spatial multiplexing (FR-SM) and full-rate full-diversity spatial multiplexing (FRFD-SM). The FR-SM encoding provides capacity increase with relatively small complexity increase at the receiver side while the FRFD-SM encoding provides capacity increase and additional diversity gain with a great complexity increase at the receiver side. The proposed MIMO encoding scheme has no restriction on the antenna polarity configuration. 
     MIMO processing is required for the advanced profile frame, which means all DPs in the advanced profile frame are processed by the MIMO encoder. MIMO processing is applied at DP level. Pairs of the Constellation Mapper outputs NUQ (e1,i and e2,i) are fed to the input of the MIMO Encoder. Paired MIMO Encoder output (g1,i and g2,i) is transmitted by the same carrier k and OFDM symbol 1 of their respective TX antennas. 
     The above-described blocks may be omitted or replaced by blocks having similar or identical functions. 
       FIG. 5  illustrates a BICM block according to another embodiment of the present invention. 
     The BICM block illustrated in  FIG. 6  corresponds to an embodiment of the BICM block  1010  described with reference to  FIG. 1 . 
       FIG. 5  illustrates a BICM block for protection of physical layer signaling (PLS), emergency alert channel (EAC) and fast information channel (FIC). EAC is a part of a frame that carries EAS information data and FIC is a logical channel in a frame that carries the mapping information between a service and the corresponding base DP. Details of the EAC and FIC will be described later. 
     Referring to  FIG. 6 , the BICM block for protection of PLS, EAC and FIC can include a PLS FEC encoder  6000 , a bit interleaver  6010  and a constellation mapper  6020 . 
     Also, the PLS FEC encoder  6000  can include a scrambler, BCH encoding/zero insertion block, LDPC encoding block and LDPC parity punturing block. Description will be given of each block of the BICM block. 
     The PLS FEC encoder  6000  can encode the scrambled PLS 1/2 data, EAC and FIC section. 
     The scrambler can scramble PLS1 data and PLS2 data before BCH encoding and shortened and punctured LDPC encoding. 
     The BCH encoding/zero insertion block can perform outer encoding on the scrambled PLS 1/2 data using the shortened BCH code for PLS protection and insert zero bits after the BCH encoding. For PLS1 data only, the output bits of the zero insertion may be permutted before LDPC encoding. 
     The LDPC encoding block can encode the output of the BCH encoding/zero insertion block using LDPC code. To generate a complete coded block, Cldpc, parity bits, Pldpc are encoded systematically from each zero-inserted PLS information block, Ildpc and appended after it. 
         C   ldpc   =[I   ldpc   P   ldpc   ]=[i   0   ,i   1   , . . . ,i   K     ldpc     −1   ,p   0   ,p   1   , . . . ,p   N     ldpc     −K     ldpc     −1 ]  [Equation 1]
 
     The LDPC code parameters for PLS1 and PLS2 are as following table 4. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                 Signaling 
                   
                   
                   
                 K ldpc   
                   
                   
                 code 
                   
               
               
                 Type 
                 K sig   
                 K bch   
                 N bch     —     parity   
                 (=N bch ) 
                 N ldpc   
                 N ldpc     —     parity   
                 rate 
                 Q ldpc   
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 PLS1 
                 342 
                 1020 
                 60 
                 1080 
                 4320 
                 3240 
                 1/4  
                 36 
               
               
                 PLS2 
                 &lt;1021 
               
               
                   
                 &gt;1020 
                 2100 
                   
                 2160 
                 7200 
                 5040 
                 3/10 
                 56 
               
               
                   
               
            
           
         
       
     
     The LDPC parity punturing block can perform puncturing on the PLS1 data and PLS 2 data. 
     When shortening is applied to the PLS1 data protection, some LDPC parity bits are punctured after LDPC encoding. Also, for the PLS2 data protection, the LDPC parity bits of PLS2 are punctured after LDPC encoding. These punctured bits are not transmitted. 
     The bit interleaver  6010  can interleave the each shortened and punctured PLS1 data and PLS2 data. 
     The constellation mapper  6020  can map the bit ineterlaeved PLS1 data and PLS2 data onto constellations. 
     The above-described blocks may be omitted or replaced by blocks having similar or identical functions. 
       FIG. 6  illustrates a frame building block according to one embodiment of the present invention. 
     The frame building block illustrated in  FIG. 6  corresponds to an embodiment of the frame building block  1020  described with reference to  FIG. 1 . 
     Referring to  FIG. 6 , the frame building block can include a delay compensation block  7000 , a cell mapper  7010  and a frequency interleaver  7020 . Description will be given of each block of the frame building block. 
     The delay compensation block  7000  can adjust the timing between the data pipes and the corresponding PLS data to ensure that they are co-timed at the transmitter end. The PLS data is delayed by the same amount as data pipes are by addressing the delays of data pipes caused by the Input Formatting block and BICM block. The delay of the BICM block is mainly due to the time interleaver  5050 . In-band signaling data carries information of the next TI group so that they are carried one frame ahead of the DPs to be signaled. The Delay Compensating block delays in-band signaling data accordingly. 
     The cell mapper  7010  can map PLS, EAC, FIC, DPs, auxiliary streams and dummy cells into the active carriers of the OFDM symbols in the frame. The basic function of the cell mapper  7010  is to map data cells produced by the TIs for each of the DPs, PLS cells, and EAC/FIC cells, if any, into arrays of active OFDM cells corresponding to each of the OFDM symbols within a frame. Service signaling data (such as PSI (program specific information)/SI) can be separately gathered and sent by a data pipe. The Cell Mapper operates according to the dynamic information produced by the scheduler and the configuration of the frame structure. Details of the frame will be described later. 
     The frequency interleaver  7020  can randomly interleave data cells received from the cell mapper  7010  to provide frequency diversity. Also, the frequency interleaver  7020  can operate on very OFDM symbol pair comprised of two sequential OFDM symbols using a different interleaving-seed order to get maximum interleaving gain in a single frame. 
     The above-described blocks may be omitted or replaced by blocks having similar or identical functions. 
       FIG. 7  illustrates an OFDM generation block according to an embodiment of the present invention. 
     The OFDM generation block illustrated in  FIG. 7  corresponds to an embodiment of the OFDM generation block  1030  described with reference to  FIG. 1 . 
     The OFDM generation block modulates the OFDM carriers by the cells produced by the Frame Building block, inserts the pilots, and produces the time domain signal for transmission. Also, this block subsequently inserts guard intervals, and applies PAPR (Peak-to-Average Power Radio) reduction processing to produce the final RF signal. 
     Referring to  FIG. 7 , the OFDM generation block can include a pilot and reserved tone insertion block  8000 , a 2D-eSFN encoding block  8010 , an IFFT (Inverse Fast Fourier Transform) block  8020 , a PAPR reduction block  8030 , a guard interval insertion block  8040 , a preamble insertion block  8050 , other system insertion block  8060  and a DAC block  8070 . 
     The other system insertion block  8060  can multiplex signals of a plurality of broadcast transmission/reception systems in the time domain such that data of two or more different broadcast transmission/reception systems providing broadcast services can be simultaneously transmitted in the same RF signal bandwidth. In this case, the two or more different broadcast transmission/reception systems refer to systems providing different broadcast services. The different broadcast services may refer to a terrestrial broadcast service, mobile broadcast service, etc. 
       FIG. 8  illustrates a structure of an apparatus for receiving broadcast signals for future broadcast services according to an embodiment of the present invention. 
     The apparatus for receiving broadcast signals for future broadcast services according to an embodiment of the present invention can correspond to the apparatus for transmitting broadcast signals for future broadcast services, described with reference to  FIG. 1 . 
     The apparatus for receiving broadcast signals for future broadcast services according to an embodiment of the present invention can include a synchronization &amp; demodulation module  9000 , a frame parsing module  9010 , a demapping &amp; decoding module  9020 , an output processor  9030  and a signaling decoding module  9040 . A description will be given of operation of each module of the apparatus for receiving broadcast signals. 
     The synchronization &amp; demodulation module  9000  can receive input signals through m Rx antennas, perform signal detection and synchronization with respect to a system corresponding to the apparatus for receiving broadcast signals and carry out demodulation corresponding to a reverse procedure of the procedure performed by the apparatus for transmitting broadcast signals. 
     The frame parsing module  9010  can parse input signal frames and extract data through which a service selected by a user is transmitted. If the apparatus for transmitting broadcast signals performs interleaving, the frame parsing module  9010  can carry out deinterleaving corresponding to a reverse procedure of interleaving. In this case, the positions of a signal and data that need to be extracted can be obtained by decoding data output from the signaling decoding module  9040  to restore scheduling information generated by the apparatus for transmitting broadcast signals. 
     The demapping &amp; decoding module  9020  can convert the input signals into bit domain data and then deinterleave the same as necessary. The demapping &amp; decoding module  9020  can perform demapping for mapping applied for transmission efficiency and correct an error generated on a transmission channel through decoding. In this case, the demapping &amp; decoding module  9020  can obtain transmission parameters necessary for demapping and decoding by decoding the data output from the signaling decoding module  9040 . 
     The output processor  9030  can perform reverse procedures of various compression/signal processing procedures which are applied by the apparatus for transmitting broadcast signals to improve transmission efficiency. In this case, the output processor  9030  can acquire necessary control information from data output from the signaling decoding module  9040 . The output of the output processor  8300  corresponds to a signal input to the apparatus for transmitting broadcast signals and may be MPEG-TSs, IP streams (v4 or v6) and generic streams. 
     The signaling decoding module  9040  can obtain PLS information from the signal demodulated by the synchronization &amp; demodulation module  9000 . As described above, the frame parsing module  9010 , demapping &amp; decoding module  9020  and output processor  9030  can execute functions thereof using the data output from the signaling decoding module  9040 . 
       FIG. 9  illustrates a frame structure according to an embodiment of the present invention. 
       FIG. 9  shows an example configuration of the frame types and FRUs in a super-frame. (a) shows a super frame according to an embodiment of the present invention, (b) shows FRU (Frame Repetition Unit) according to an embodiment of the present invention, (c) shows frames of variable PHY profiles in the FRU and (d) shows a structure of a frame. 
     A super-frame may be composed of eight FRUs. The FRU is a basic multiplexing unit for TDM of the frames, and is repeated eight times in a super-frame. 
     Each frame in the FRU belongs to one of the PHY profiles, (base, handheld, advanced) or FEF. The maximum allowed number of the frames in the FRU is four and a given PHY profile can appear any number of times from zero times to four times in the FRU (e.g., base, base, handheld, advanced). PHY profile definitions can be extended using reserved values of the PHY_PROFILE in the preamble, if required. 
     The FEF part is inserted at the end of the FRU, if included. When the FEF is included in the FRU, the minimum number of FEFs is 8 in a super-frame. It is not recommended that FEF parts be adjacent to each other. 
     One frame is further divided into a number of OFDM symbols and a preamble. As shown in (d), the frame comprises a preamble, one or more frame signaling symbols (FSS), normal data symbols and a frame edge symbol (FES). 
     The preamble is a special symbol that enables fast Futurecast UTB system signal detection and provides a set of basic transmission parameters for efficient transmission and reception of the signal. The detailed description of the preamble will be will be described later. 
     The main purpose of the FSS(s) is to carry the PLS data. For fast synchronization and channel estimation, and hence fast decoding of PLS data, the FSS has more dense pilot pattern than the normal data symbol. The FES has exactly the same pilots as the FSS, which enables frequency-only interpolation within the FES and temporal interpolation, without extrapolation, for symbols immediately preceding the FES. 
       FIG. 10  illustrates a signaling hierarchy structure of the frame according to an embodiment of the present invention. 
       FIG. 10  illustrates the signaling hierarchy structure, which is split into three main parts: the preamble signaling data  11000 , the PLS1 data  11010  and the PLS2 data  11020 . The purpose of the preamble, which is carried by the preamble symbol in every frame, is to indicate the transmission type and basic transmission parameters of that frame. The PLS1 enables the receiver to access and decode the PLS2 data, which contains the parameters to access the DP of interest. The PLS2 is carried in every frame and split into two main parts: PLS2-STAT data and PLS2-DYN data. The static and dynamic portion of PLS2 data is followed by padding, if necessary. 
       FIG. 11  illustrates preamble signaling data according to an embodiment of the present invention. 
     Preamble signaling data carries 21 bits of information that are needed to enable the receiver to access PLS data and trace DPs within the frame structure. Details of the preamble signaling data are as follows: 
     PHY_PROFILE: This 3-bit field indicates the PHY profile type of the current frame. The mapping of different PHY profile types is given in below table 5. 
     
       
         
           
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                 Value 
                 PHY profile 
               
               
                   
               
             
            
               
                 000 
                 Base profile 
               
               
                 001 
                 Handheld profile 
               
               
                 010 
                 Advanced profiled 
               
               
                 011~110 
                 Reserved 
               
               
                 111 
                 FEF 
               
               
                   
               
            
           
         
       
     
     FFT_SIZE: This 2 bit field indicates the FFT size of the current frame within a frame-group, as described in below table 6. 
     
       
         
           
               
               
             
               
                 TABLE 6 
               
               
                   
               
               
                 Value 
                 FFT size 
               
               
                   
               
             
            
               
                 00 
                  8K FFT 
               
               
                 01 
                 16K FFT 
               
               
                 10 
                 32K FFT 
               
               
                 11 
                 Reserved 
               
               
                   
               
            
           
         
       
     
     GI_FRACTION: This 3 bit field indicates the guard interval fraction value in the current super-frame, as described in below table 7. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 7 
               
               
                   
                   
               
               
                   
                 Value 
                 GI_FRACTION 
               
               
                   
                   
               
             
            
               
                   
                 000 
                 1/5  
               
               
                   
                 001 
                 1/10 
               
               
                   
                 010 
                 1/20 
               
               
                   
                 011 
                 1/40 
               
               
                   
                 100 
                 1/80 
               
               
                   
                 101 
                  1/160 
               
               
                   
                 110~111 
                 Reserved 
               
               
                   
                   
               
            
           
         
       
     
     EAC_FLAG: This 1 bit field indicates whether the EAC is provided in the current frame. If this field is set to ‘1’, emergency alert service (EAS) is provided in the current frame. If this field set to ‘0’, EAS is not carried in the current frame. This field can be switched dynamically within a super-frame. 
     PILOT_MODE: This 1-bit field indicates whether the pilot mode is mobile mode or fixed mode for the current frame in the current frame-group. If this field is set to ‘0’, mobile pilot mode is used. If the field is set to ‘1’, the fixed pilot mode is used. 
     PAPR_FLAG: This 1-bit field indicates whether PAPR reduction is used for the current frame in the current frame-group. If this field is set to value ‘1’, tone reservation is used for PAPR reduction. If this field is set to ‘0’, PAPR reduction is not used. 
     FRU_CONFIGURE: This 3-bit field indicates the PHY profile type configurations of the frame repetition units (FRU) that are present in the current super-frame. All profile types conveyed in the current super-frame are identified in this field in all preambles in the current super-frame. The 3-bit field has a different definition for each profile, as show in below table 8. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 8 
               
               
                   
                   
               
               
                   
                 Current 
                 Current 
                 Current 
                 Current 
               
               
                   
                 PHY_PRO- 
                 PHY_PRO- 
                 PHY_PRO- 
                 PHY_PRO- 
               
               
                   
                 FILE = 
                 FILE = 
                 FILE = 
                 FILE = 
               
               
                   
                 ‘000’ 
                 ‘001’ 
                 ‘010’ 
                 ‘111’ 
               
               
                   
                 (base) 
                 (handheld) 
                 (advanced) 
                 (FEF) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 FRU_CON- 
                 Only base 
                 Only 
                 Only 
                 Only FEF 
               
               
                 FIGURE = 
                 profile 
                 handheld 
                 advanced 
                 present 
               
               
                 000 
                 present 
                 profile 
                 profile 
               
               
                   
                   
                 present 
                 present 
               
               
                 FRU_CON- 
                 Handheld 
                 Base 
                 Base 
                 Base 
               
               
                 FIGURE = 
                 profile 
                 profile 
                 profile 
                 profile 
               
               
                 1XX 
                 present 
                 present 
                 present 
                 present 
               
               
                 FRU_CON- 
                 Advanced 
                 Advanced 
                 Handheld 
                 Handheld 
               
               
                 FIGURE = 
                 profile 
                 profile 
                 profile 
                 profile 
               
               
                 X1X 
                 present 
                 present 
                 present 
                 present 
               
               
                 FRU_CON- 
                 FEF 
                 FEF 
                 FEF 
                 Advanced 
               
               
                 FIGURE = 
                 present 
                 present 
                 present 
                 profile 
               
               
                 XX1 
                   
                   
                   
                 present 
               
               
                   
               
            
           
         
       
     
     RESERVED: This 7-bit field is reserved for future use. 
       FIG. 12  illustrates PLS1 data according to an embodiment of the present invention. 
     PLS1 data provides basic transmission parameters including parameters required to enable the reception and decoding of the PLS2. As above mentioned, the PLS1 data remain unchanged for the entire duration of one frame-group. The detailed definition of the signaling fields of the PLS1 data are as follows: 
     PREAMBLE_DATA: This 20-bit field is a copy of the preamble signaling data excluding the EAC_FLAG. 
     NUM_FRAME_FRU: This 2-bit field indicates the number of the frames per FRU. 
     PAYLOAD_TYPE: This 3-bit field indicates the format of the payload data carried in the frame-group. PAYLOAD_TYPE is signaled as shown in table 9. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 9 
               
               
                   
                   
               
               
                   
                 value 
                 Payload type 
               
               
                   
                   
               
             
            
               
                   
                 1XX 
                 TS stream is transmitted 
               
               
                   
                 X1X 
                 IP stream is transmitted 
               
               
                   
                 XX1 
                 GS stream is transmitted 
               
               
                   
                   
               
            
           
         
       
     
     NUM_FSS: This 2-bit field indicates the number of FSS symbols in the current frame. 
     SYSTEM_VERSION: This 8-bit field indicates the version of the transmitted signal format. The SYSTEM_VERSION is divided into two 4-bit fields, which are a major version and a minor version. 
     Major version: The MSB four bits of SYSTEM_VERSION field indicate major version information. A change in the major version field indicates a non-backward-compatible change. The default value is ‘0000’. For the version described in this standard, the value is set to ‘0000’. 
     Minor version: The LSB four bits of SYSTEM_VERSION field indicate minor version information. A change in the minor version field is backward-compatible. 
     CELL_ID: This is a 16-bit field which uniquely identifies a geographic cell in an ATSC network. An ATSC cell coverage area may consist of one or more frequencies, depending on the number of frequencies used per Futurecast UTB system. If the value of the CELL_ID is not known or unspecified, this field is set to ‘0’. 
     NETWORK_ID: This is a 16-bit field which uniquely identifies the current ATSC network. 
     SYSTEM_ID: This 16-bit field uniquely identifies the Futurecast UTB system within the ATSC network. The Futurecast UTB system is the terrestrial broadcast system whose input is one or more input streams (TS, IP, GS) and whose output is an RF signal. The Futurecast UTB system carries one or more PHY profiles and FEF, if any. The same Futurecast UTB system may carry different input streams and use different RF frequencies in different geographical areas, allowing local service insertion. The frame structure and scheduling is controlled in one place and is identical for all transmissions within a Futurecast UTB system. One or more Futurecast UTB systems may have the same SYSTEM_ID meaning that they all have the same physical layer structure and configuration. 
     The following loop consists of FRU_PHY_PROFILE, FRU_FRAME_LENGTH, FRU_GI_FRACTION, and RESERVED which are used to indicate the FRU configuration and the length of each frame type. The loop size is fixed so that four PHY profiles (including a FEF) are signaled within the FRU. If NUM_FRAME_FRU is less than 4, the unused fields are filled with zeros. 
     FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile type of the (i+1)th (i is the loop index) frame of the associated FRU. This field uses the same signaling format as shown in the table 8. 
     FRU_FRAME_LENGTH: This 2-bit field indicates the length of the (i+1)th frame of the associated FRU. Using FRU_FRAME_LENGTH together with FRU_GI_FRACTION, the exact value of the frame duration can be obtained. 
     FRU_GI_FRACTION: This 3-bit field indicates the guard interval fraction value of the (i+1)th frame of the associated FRU. FRU_GI_FRACTION is signaled according to the table 7. 
     RESERVED: This 4-bit field is reserved for future use. 
     The following fields provide parameters for decoding the PLS2 data. 
     PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used by the PLS2 protection. The FEC type is signaled according to table 10. The details of the LDPC codes will be described later. 
     
       
         
           
               
               
             
               
                 TABLE 10 
               
               
                   
               
               
                 Content 
                 PLS2 FEC type 
               
               
                   
               
             
            
               
                 00 
                 4K-1/4 and 7K-3/10 LDPC codes 
               
               
                 01~11 
                 Reserved 
               
               
                   
               
            
           
         
       
     
     PLS2_MOD: This 3-bit field indicates the modulation type used by the PLS2. The modulation type is signaled according to table 11. 
     
       
         
           
               
               
             
               
                 TABLE 11 
               
               
                   
               
               
                 Value 
                 PLS2_MODE 
               
               
                   
               
             
            
               
                 000 
                 BPSK 
               
               
                 001 
                 QPSK 
               
               
                 010 
                 QAM-16 
               
               
                 011 
                 NUQ-64 
               
               
                 100~111 
                 Reserved 
               
               
                   
               
            
           
         
       
     
     PLS2_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, the size (specified as the number of QAM cells) of the collection of full coded blocks for PLS2 that is carried in the current frame-group. This value is constant during the entire duration of the current frame-group. 
     PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, of the PLS2-STAT for the current frame-group. This value is constant during the entire duration of the current frame-group. 
     PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of the PLS2-DYN for the current frame-group. This value is constant during the entire duration of the current frame-group. 
     PLS2_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetition mode is used in the current frame-group. When this field is set to value ‘1’, the PLS2 repetition mode is activated. When this field is set to value ‘0’, the PLS2 repetition mode is deactivated. 
     PLS2_REP_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, the size (specified as the number of QAM cells) of the collection of partial coded blocks for PLS2 carried in every frame of the current frame-group, when PLS2 repetition is used. If repetition is not used, the value of this field is equal to 0. This value is constant during the entire duration of the current frame-group. 
     PLS2_NEXT_FEC_TYPE: This 2-bit field indicates the FEC type used for PLS2 that is carried in every frame of the next frame-group. The FEC type is signaled according to the table 10. 
     PLS2_NEXT_MOD: This 3-bit field indicates the modulation type used for PLS2 that is carried in every frame of the next frame-group. The modulation type is signaled according to the table 11. 
     PLS2_NEXT_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetition mode is used in the next frame-group. When this field is set to value ‘1’, the PLS2 repetition mode is activated. When this field is set to value ‘0’, the PLS2 repetition mode is deactivated. 
     PLS2_NEXT_REP_SIZE_CELL: This 15-bit field indicates Ctotal_full_block, The size (specified as the number of QAM cells) of the collection of full coded blocks for PLS2 that is carried in every frame of the next frame-group, when PLS2 repetition is used. If repetition is not used in the next frame-group, the value of this field is equal to 0. This value is constant during the entire duration of the current frame-group. 
     PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, of the PLS2-STAT for the next frame-group. This value is constant in the current frame-group. 
     PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of the PLS2-DYN for the next frame-group. This value is constant in the current frame-group. 
     PLS2_AP_MODE: This 2-bit field indicates whether additional parity is provided for PLS2 in the current frame-group. This value is constant during the entire duration of the current frame-group. The below table 12 gives the values of this field. When this field is set to ‘00’, additional parity is not used for the PLS2 in the current frame-group. 
     
       
         
           
               
               
             
               
                 TABLE 12 
               
               
                   
               
               
                 Value 
                 PLS2-AP mode 
               
               
                   
               
             
            
               
                 00 
                 AP is not provided 
               
               
                 01 
                 AP1 mode 
               
               
                 10~11 
                 Reserved 
               
               
                   
               
            
           
         
       
     
     PLS2_AP_SIZE_CELL: This 15-bit field indicates the size (specified as the number of QAM cells) of the additional parity bits of the PLS2. This value is constant during the entire duration of the current frame-group. 
     PLS2_NEXT_AP_MODE: This 2-bit field indicates whether additional parity is provided for PLS2 signaling in every frame of next frame-group. This value is constant during the entire duration of the current frame-group. The table 12 defines the values of this field 
     PLS2_NEXT_AP_SIZE_CELL: This 15-bit field indicates the size (specified as the number of QAM cells) of the additional parity bits of the PLS2 in every frame of the next frame-group. This value is constant during the entire duration of the current frame-group. 
     RESERVED: This 32-bit field is reserved for future use. 
     CRC_32: A 32-bit error detection code, which is applied to the entire PLS1 signaling. 
       FIG. 13  illustrates PLS2 data according to an embodiment of the present invention. 
       FIG. 13  illustrates PLS2-STAT data of the PLS2 data. The PLS2-STAT data are the same within a frame-group, while the PLS2-DYN data provide information that is specific for the current frame. 
     The details of fields of the PLS2-STAT data are as follows: 
     FIC_FLAG: This 1-bit field indicates whether the FIC is used in the current frame-group. If this field is set to ‘1’, the FIC is provided in the current frame. If this field set to ‘0’, the FIC is not carried in the current frame. This value is constant during the entire duration of the current frame-group. 
     AUX_FLAG: This 1-bit field indicates whether the auxiliary stream(s) is used in the current frame-group. If this field is set to ‘1’, the auxiliary stream is provided in the current frame. If this field set to ‘0’, the auxiliary stream is not carried in the current frame. This value is constant during the entire duration of current frame-group. 
     NUM_DP: This 6-bit field indicates the number of DPs carried within the current frame. The value of this field ranges from 1 to 64, and the number of DPs is NUM_DP+1. 
     DP_ID: This 6-bit field identifies uniquely a DP within a PHY profile. 
     DP_TYPE: This 3-bit field indicates the type of the DP. This is signaled according to the below table 13. 
     
       
         
           
               
               
             
               
                 TABLE 13 
               
               
                   
               
               
                 Value 
                 DP Type 
               
               
                   
               
             
            
               
                 000 
                 DP Type 1 
               
               
                 001 
                 DP Type 2 
               
               
                 010~111 
                 reserved 
               
               
                   
               
            
           
         
       
     
     DP_GROUP_ID: This 8-bit field identifies the DP group with which the current DP is associated. This can be used by a receiver to access the DPs of the service components associated with a particular service, which will have the same DP_GROUP_ID. 
     BASE_DP_ID: This 6-bit field indicates the DP carrying service signaling data (such as PSI/SI) used in the Management layer. The DP indicated by BASE_DP_ID may be either a normal DP carrying the service signaling data along with the service data or a dedicated DP carrying only the service signaling data 
     DP_FEC_TYPE: This 2-bit field indicates the FEC type used by the associated DP. The FEC type is signaled according to the below table 14. 
     
       
         
           
               
               
             
               
                 TABLE 14 
               
               
                   
               
               
                 Value 
                 FEC_TYPE 
               
               
                   
               
             
            
               
                 00 
                 16K LDPC 
               
               
                 01 
                 64K LDPC 
               
               
                 10~11 
                 Reserved 
               
               
                   
               
            
           
         
       
     
     DP_COD: This 4-bit field indicates the code rate used by the associated DP. The code rate is signaled according to the below table 15. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 15 
               
               
                   
                   
               
               
                   
                 Value 
                 Code rate 
               
               
                   
                   
               
             
            
               
                   
                 0000 
                 5/15 
               
               
                   
                 0001 
                 6/15 
               
               
                   
                 0010 
                 7/15 
               
               
                   
                 0011 
                 8/15 
               
               
                   
                 0100 
                 9/15 
               
               
                   
                 0101 
                 10/15  
               
               
                   
                 0110 
                 11/15  
               
               
                   
                 0111 
                 12/15  
               
               
                   
                 1000 
                 13/15  
               
               
                   
                 1001~1111 
                 Reserved 
               
               
                   
                   
               
            
           
         
       
     
     DP_MOD: This 4-bit field indicates the modulation used by the associated DP. The modulation is signaled according to the below table 16. 
     
       
         
           
               
               
             
               
                 TABLE 16 
               
               
                   
               
               
                 Value 
                 Modulation 
               
               
                   
               
             
            
               
                 0000 
                 QPSK 
               
               
                 0001 
                 QAM-16 
               
               
                 0010 
                 NUQ-64 
               
               
                 0011 
                 NUQ-256 
               
               
                 0100 
                 NUQ-1024 
               
               
                 0101 
                 NUC-16 
               
               
                 0110 
                 NUC-64 
               
               
                 0111 
                 NUC-256 
               
               
                 1000 
                 NUC-1024 
               
               
                 1001~1111 
                 reserved 
               
               
                   
               
            
           
         
       
     
     DP_SSD_FLAG: This 1-bit field indicates whether the SSD mode is used in the associated DP. If this field is set to value ‘1’, SSD is used. If this field is set to value ‘0’, SSD is not used. 
     The following field appears only if PHY_PROFILE is equal to ‘010’, which indicates the advanced profile: 
     DP_MIMO: This 3-bit field indicates which type of MIMO encoding process is applied to the associated DP. The type of MIMO encoding process is signaled according to the table 17. 
     
       
         
           
               
               
             
               
                 TABLE 17 
               
               
                   
               
               
                 Value 
                 MIMO encoding 
               
               
                   
               
             
            
               
                 000 
                 FR-SM 
               
               
                 001 
                 FRFD-SM 
               
               
                 010~111 
                 reserved 
               
               
                   
               
            
           
         
       
     
     DP_TI_TYPE: This 1-bit field indicates the type of time-interleaving. A value of ‘0’ indicates that one TI group corresponds to one frame and contains one or more TI-blocks. A value of ‘1’ indicates that one TI group is carried in more than one frame and contains only one TI-block. 
     DP_TI_LENGTH: The use of this 2-bit field (the allowed values are only 1, 2, 4, 8) is determined by the values set within the DP_TI_TYPE field as follows: 
     If the DP_TI_TYPE is set to the value ‘1’, this field indicates PI, the number of the frames to which each TI group is mapped, and there is one TI-block per TI group (NTI=1). The allowed PI values with 2-bit field are defined in the below table 18. 
     If the DP_TI_TYPE is set to the value ‘0’, this field indicates the number of TI-blocks NTI per TI group, and there is one TI group per frame (PI=1). The allowed PI values with 2-bit field are defined in the below table 18. 
     
       
         
           
               
               
               
             
               
                 TABLE 18 
               
               
                   
               
               
                 2-bit field 
                 P I   
                 N TI   
               
               
                   
               
             
            
               
                 00 
                 1 
                 1 
               
               
                 01 
                 2 
                 2 
               
               
                 10 
                 4 
                 3 
               
               
                 11 
                 8 
                 4 
               
               
                   
               
            
           
         
       
     
     DP_FRAME_INTERVAL: This 2-bit field indicates the frame interval (HUMP) within the frame-group for the associated DP and the allowed values are 1, 2, 4, 8 (the corresponding 2-bit field is ‘00’, ‘01’, ‘10’, or ‘11’, respectively). For DPs that do not appear every frame of the frame-group, the value of this field is equal to the interval between successive frames. For example, if a DP appears on the frames 1, 5, 9, 13, etc., this field is set to ‘4’. For DPs that appear in every frame, this field is set to ‘1’. 
     DP_TI_BYPASS: This 1-bit field determines the availability of time interleaver  5050 . If time interleaving is not used for a DP, it is set to ‘1’. Whereas if time interleaving is used it is set to ‘0’. 
     DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of the first frame of the super-frame in which the current DP occurs. The value of DP_FIRST_FRAME_IDX ranges from 0 to 31 
     DP_NUM_BLOCK_MAX: This 10-bit field indicates the maximum value of DP_NUM_BLOCKS for this DP. The value of this field has the same range as DP_NUM_BLOCKS. 
     DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the payload data carried by the given DP. DP_PAYLOAD_TYPE is signaled according to the below table 19. 
     
       
         
           
               
               
             
               
                 TABLE 19 
               
               
                   
               
               
                 Value 
                 Payload Type 
               
               
                   
               
             
            
               
                 00 
                 TS. 
               
               
                 01 
                 IP 
               
               
                 10 
                 GS 
               
               
                 11 
                 reserved 
               
               
                   
               
            
           
         
       
     
     DP_INBAND_MODE: This 2-bit field indicates whether the current DP carries in-band signaling information. The in-band signaling type is signaled according to the below table 20. 
     
       
         
           
               
               
             
               
                 TABLE 20 
               
               
                   
               
               
                 Value 
                 In-band mode 
               
               
                   
               
             
            
               
                 00 
                 In-band signaling is not carried. 
               
               
                 01 
                 INBAND-PLS is carried only 
               
               
                 10 
                 INBAND-ISSY is carried only 
               
               
                 11 
                 INBAND-PLS and INBAND-ISSY are carried 
               
               
                   
               
            
           
         
       
     
     DP_PROTOCOL_TYPE: This 2-bit field indicates the protocol type of the payload carried by the given DP. It is signaled according to the below table 21 when input payload types are selected. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 21 
               
               
                   
               
               
                   
                 If 
                 If 
                 If 
               
               
                   
                 DP_PAY- 
                 DP_PAY- 
                 DP_PAY- 
               
               
                   
                 LOAD_TYPE 
                 LOAD_TYPE 
                 LOAD_TYPE 
               
               
                 Value 
                 Is TS 
                 Is IP 
                 Is GS 
               
               
                   
               
             
            
               
                 00 
                 MPEG2-TS 
                 IPv4 
                 (Note) 
               
               
                 01 
                 Reserved 
                 IPv6 
                 Reserved 
               
               
                 10 
                 Reserved 
                 Reserved 
                 Reserved 
               
               
                 11 
                 Reserved 
                 Reserved 
                 Reserved 
               
               
                   
               
            
           
         
       
     
     DP_CRC_MODE: This 2-bit field indicates whether CRC encoding is used in the Input Formatting block. The CRC mode is signaled according to the below table 22. 
     
       
         
           
               
               
             
               
                 TABLE 22 
               
               
                   
               
               
                 Value 
                 CRC mode 
               
               
                   
               
             
            
               
                 00 
                 Not used 
               
               
                 01 
                 CRC-8 
               
               
                 10 
                 CRC-16 
               
               
                 11 
                 CRC-32 
               
               
                   
               
            
           
         
       
     
     DNP_MODE: This 2-bit field indicates the null-packet deletion mode used by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). DNP_MODE is signaled according to the below table 23. If DP_PAYLOAD_TYPE is not TS (‘00’), DNP_MODE is set to the value ‘00’. 
     
       
         
           
               
               
             
               
                 TABLE 23 
               
               
                   
               
               
                 Value 
                 Null-packet deletion mode 
               
               
                   
               
             
            
               
                 00 
                 Not used 
               
               
                 01 
                 DNP-NORMAL 
               
               
                 10 
                 DNP-OFFSET 
               
               
                 11 
                 reserved 
               
               
                   
               
            
           
         
       
     
     ISSY_MODE: This 2-bit field indicates the ISSY mode used by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). The ISSY_MODE is signaled according to the below table 24 If DP_PAYLOAD_TYPE is not TS (‘00’), ISSY_MODE is set to the value ‘00’. 
     
       
         
           
               
               
             
               
                 TABLE 24 
               
               
                   
               
               
                 Value 
                 ISSY mode 
               
               
                   
               
             
            
               
                 00 
                 Not used 
               
               
                 01 
                 ISSY-UP 
               
               
                 10 
                 ISSY-BBF 
               
               
                 11 
                 reserved 
               
               
                   
               
            
           
         
       
     
     HC_MODE_TS: This 2-bit field indicates the TS header compression mode used by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). The HC_MODE_TS is signaled according to the below table 25. 
     
       
         
           
               
               
             
               
                 TABLE 25 
               
               
                   
               
               
                 Value 
                 Header compression mode 
               
               
                   
               
             
            
               
                 00 
                 HC_MODE_TS 1 
               
               
                 01 
                 HC_MODE_TS 2 
               
               
                 10 
                 HC_MODE_TS 3 
               
               
                 11 
                 HC_MODE_TS 4 
               
               
                   
               
            
           
         
       
     
     HC_MODE_IP: This 2-bit field indicates the IP header compression mode when DP_PAYLOAD_TYPE is set to IP (‘01’). The HC_MODE_IP is signaled according to the below table 26. 
     
       
         
           
               
               
             
               
                 TABLE 26 
               
               
                   
               
               
                 Value 
                 Header compression mode 
               
               
                   
               
             
            
               
                 00 
                 No compression 
               
               
                 01 
                 HC_MODE_IP 1 
               
               
                 10~11 
                 reserved 
               
               
                   
               
            
           
         
       
     
     PID: This 13-bit field indicates the PID number for TS header compression when DP_PAYLOAD_TYPE is set to TS (‘00’) and HC_MODE_TS is set to ‘01’ or ‘10’. 
     RESERVED: This 8-bit field is reserved for future use. 
     The following field appears only if FIC_FLAG is equal to ‘1’: 
     FIC_VERSION: This 8-bit field indicates the version number of the FIC. 
     FIC_LENGTH_BYTE: This 13-bit field indicates the length, in bytes, of the FIC. 
     RESERVED: This 8-bit field is reserved for future use. 
     The following field appears only if AUX_FLAG is equal to ‘1’: 
     NUM_AUX: This 4-bit field indicates the number of auxiliary streams. Zero means no auxiliary streams are used. 
     AUX_CONFIG_RFU: This 8-bit field is reserved for future use. 
     AUX_STREAM_TYPE: This 4-bit is reserved for future use for indicating the type of the current auxiliary stream. 
     AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future use for signaling auxiliary streams. 
       FIG. 14  illustrates PLS2 data according to another embodiment of the present invention. 
       FIG. 14  illustrates PLS2-DYN data of the PLS2 data. The values of the PLS2-DYN data may change during the duration of one frame-group, while the size of fields remains constant. 
     The details of fields of the PLS2-DYN data are as follows: 
     FRAME_INDEX: This 5-bit field indicates the frame index of the current frame within the super-frame. The index of the first frame of the super-frame is set to ‘0’. 
     PLS_CHANGE_COUNTER: This 4-bit field indicates the number of super-frames ahead where the configuration will change. The next super-frame with changes in the configuration is indicated by the value signaled within this field. If this field is set to the value ‘0000’, it means that no scheduled change is foreseen: e.g., value ‘1’ indicates that there is a change in the next super-frame. 
     FIC_CHANGE_COUNTER: This 4-bit field indicates the number of super-frames ahead where the configuration (i.e., the contents of the FIC) will change. The next super-frame with changes in the configuration is indicated by the value signaled within this field. If this field is set to the value ‘0000’, it means that no scheduled change is foreseen: e.g. value ‘0001’ indicates that there is a change in the next super-frame. 
     RESERVED: This 16-bit field is reserved for future use. 
     The following fields appear in the loop over NUM_DP, which describe the parameters associated with the DP carried in the current frame. 
     DP_ID: This 6-bit field indicates uniquely the DP within a PHY profile. 
     DP_START: This 15-bit (or 13-bit) field indicates the start position of the first of the DPs using the DPU addressing scheme. The DP_START field has differing length according to the PHY profile and FFT size as shown in the below table 27. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 27 
               
             
            
               
                   
                   
               
               
                   
                 DP_START field size 
                   
               
            
           
           
               
               
               
               
            
               
                   
                 PHY profile 
                 64K 
                 16K 
               
               
                   
                   
               
               
                   
                 Base 
                 13 bit 
                 15 bit 
               
               
                   
                 Handheld 
                 — 
                 13 bit 
               
               
                   
                 Advanced 
                 13 bit 
                 15 bit 
               
               
                   
                   
               
            
           
         
       
     
     DP_NUM_BLOCK: This 10-bit field indicates the number of FEC blocks in the current TI group for the current DP. The value of DP_NUM_BLOCK ranges from 0 to 1023 
     RESERVED: This 8-bit field is reserved for future use. 
     The following fields indicate the FIC parameters associated with the EAC. 
     EAC_FLAG: This 1-bit field indicates the existence of the EAC in the current frame. This bit is the same value as the EAC_FLAG in the preamble. 
     EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the version number of a wake-up indication. 
     If the EAC_FLAG field is equal to ‘1’, the following 12 bits are allocated for EAC_LENGTH_BYTE field. If the EAC_FLAG field is equal to ‘0’, the following 12 bits are allocated for EAC_COUNTER. 
     EAC_LENGTH_BYTE: This 12-bit field indicates the length, in byte, of the EAC. 
     EAC_COUNTER: This 12-bit field indicates the number of the frames before the frame where the EAC arrives. 
     The following field appears only if the AUX_FLAG field is equal to ‘1’: 
     AUX_PRIVATE_DYN: This 48-bit field is reserved for future use for signaling auxiliary streams. The meaning of this field depends on the value of AUX_STREAM_TYPE in the configurable PLS2-STAT. 
     CRC_32: A 32-bit error detection code, which is applied to the entire PLS2. 
       FIG. 15  illustrates a logical structure of a frame according to an embodiment of the present invention. 
     As above mentioned, the PLS, EAC, FIC, DPs, auxiliary streams and dummy cells are mapped into the active carriers of the OFDM symbols in the frame. The PLS1 and PLS2 are first mapped into one or more FSS(s). After that, EAC cells, if any, are mapped immediately following the PLS field, followed next by FIC cells, if any. The DPs are mapped next after the PLS or EAC, FIC, if any. Type 1 DPs follows first, and Type 2 DPs next. The details of a type of the DP will be described later. In some case, DPs may carry some special data for EAS or service signaling data. The auxiliary stream or streams, if any, follow the DPs, which in turn are followed by dummy cells. Mapping them all together in the above mentioned order, i.e. PLS, EAC, FIC, DPs, auxiliary streams and dummy data cells exactly fill the cell capacity in the frame. 
       FIG. 16  illustrates PLS mapping according to an embodiment of the present invention. 
     PLS cells are mapped to the active carriers of FSS(s). Depending on the number of cells occupied by PLS, one or more symbols are designated as FSS(s), and the number of FSS(s) NFSS is signaled by NUM_FSS in PLS1. The FSS is a special symbol for carrying PLS cells. Since robustness and latency are critical issues in the PLS, the FSS(s) has higher density of pilots allowing fast synchronization and frequency-only interpolation within the FSS. 
     PLS cells are mapped to active carriers of the NFSS FSS(s) in a top-down manner as shown in an example in  FIG. 16 . The PLS1 cells are mapped first from the first cell of the first FSS in an increasing order of the cell index. The PLS2 cells follow immediately after the last cell of the PLS1 and mapping continues downward until the last cell index of the first FSS. If the total number of required PLS cells exceeds the number of active carriers of one FSS, mapping proceeds to the next FSS and continues in exactly the same manner as the first FSS. 
     After PLS mapping is completed, DPs are carried next. If EAC, FIC or both are present in the current frame, they are placed between PLS and “normal” DPs. 
       FIG. 17  illustrates EAC mapping according to an embodiment of the present invention. 
     EAC is a dedicated channel for carrying EAS messages and links to the DPs for EAS. EAS support is provided but EAC itself may or may not be present in every frame. EAC, if any, is mapped immediately after the PLS2 cells. EAC is not preceded by any of the FIC, DPs, auxiliary streams or dummy cells other than the PLS cells. The procedure of mapping the EAC cells is exactly the same as that of the PLS. 
     The EAC cells are mapped from the next cell of the PLS2 in increasing order of the cell index as shown in the example in  FIG. 17 . Depending on the EAS message size, EAC cells may occupy a few symbols, as shown in  FIG. 17 . 
     EAC cells follow immediately after the last cell of the PLS2, and mapping continues downward until the last cell index of the last FSS. If the total number of required EAC cells exceeds the number of remaining active carriers of the last FSS mapping proceeds to the next symbol and continues in exactly the same manner as FSS(s). The next symbol for mapping in this case is the normal data symbol, which has more active carriers than a FSS. 
     After EAC mapping is completed, the FIC is carried next, if any exists. If FIC is not transmitted (as signaled in the PLS2 field), DPs follow immediately after the last cell of the EAC. 
       FIG. 18  illustrates FIC mapping according to an embodiment of the present invention. 
     (a) shows an example mapping of FIC cell without EAC and (b) shows an example mapping of FIC cell with EAC. 
     FIC is a dedicated channel for carrying cross-layer information to enable fast service acquisition and channel scanning. This information primarily includes channel binding information between DPs and the services of each broadcaster. For fast scan, a receiver can decode FIC and obtain information such as broadcaster ID, number of services, and BASE_DP_ID. For fast service acquisition, in addition to FIC, base DP can be decoded using BASE_DP_ID. Other than the content it carries, a base DP is encoded and mapped to a frame in exactly the same way as a normal DP. Therefore, no additional description is required for a base DP. The FIC data is generated and consumed in the Management Layer. The content of FIC data is as described in the Management Layer specification. 
     The FIC data is optional and the use of FIC is signaled by the FIC_FLAG parameter in the static part of the PLS2. If FIC is used, FIC_FLAG is set to ‘1’ and the signaling field for FIC is defined in the static part of PLS2. Signaled in this field are FIC_VERSION, and FIC_LENGTH_BYTE. FIC uses the same modulation, coding and time interleaving parameters as PLS2. FIC shares the same signaling parameters such as PLS2_MOD and PLS2_FEC. FIC data, if any, is mapped immediately after PLS2 or EAC if any. FIC is not preceded by any normal DPs, auxiliary streams or dummy cells. The method of mapping FIC cells is exactly the same as that of EAC which is again the same as PLS. 
     Without EAC after PLS, FIC cells are mapped from the next cell of the PLS2 in an increasing order of the cell index as shown in an example in (a). Depending on the FIC data size, FIC cells may be mapped over a few symbols, as shown in (b). 
     FIC cells follow immediately after the last cell of the PLS2, and mapping continues downward until the last cell index of the last FSS. If the total number of required FIC cells exceeds the number of remaining active carriers of the last FSS, mapping proceeds to the next symbol and continues in exactly the same manner as FSS(s). The next symbol for mapping in this case is the normal data symbol which has more active carriers than a FSS. 
     If EAS messages are transmitted in the current frame, EAC precedes FIC, and FIC cells are mapped from the next cell of the EAC in an increasing order of the cell index as shown in (b). 
     After FIC mapping is completed, one or more DPs are mapped, followed by auxiliary streams, if any, and dummy cells. 
       FIG. 19  illustrates an FEC structure according to an embodiment of the present invention. 
       FIG. 19  illustrates an FEC structure according to an embodiment of the present invention before bit interleaving. As above mentioned, Data FEC encoder may perform the FEC encoding on the input BBF to generate FECBLOCK procedure using outer coding (BCH), and inner coding (LDPC). The illustrated FEC structure corresponds to the FECBLOCK. Also, the FECBLOCK and the FEC structure have same value corresponding to a length of LDPC codeword. 
     The BCH encoding is applied to each BBF (K bch  bits), and then LDPC encoding is applied to BCH-encoded BBF (K ldpc , bits=N bch  bits) as illustrated in  FIG. 22 . 
     The value of N ldpc  is either 64800 bits (long FECBLOCK) or 16200 bits (short FECBLOCK). 
     The below table 28 and table 29 show FEC encoding parameters for a long FECBLOCK and a short FECBLOCK, respectively. 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 28 
               
               
                   
               
               
                   
                   
                   
                   
                 BCH error 
                   
               
               
                 LDPC 
                   
                   
                   
                 correction 
               
               
                 Rate 
                 N ldpc   
                 K ldpc   
                 K bch   
                 capability 
                 N bch  − K bch   
               
               
                   
               
             
            
               
                 5/15 
                 64800 
                 21600 
                 21408 
                 12 
                 192 
               
               
                 6/15 
                   
                 25920 
                 25728 
               
               
                 7/15 
                   
                 30240 
                 30048 
               
               
                 8/15 
                   
                 34560 
                 34368 
               
               
                 9/15 
                   
                 38880 
                 38688 
               
               
                 10/15  
                   
                 43200 
                 43008 
               
               
                 11/15  
                   
                 47520 
                 47328 
               
               
                 12/15  
                   
                 51840 
                 51648 
               
               
                 13/15  
                   
                 56160 
                 55968 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 29 
               
               
                   
               
               
                   
                   
                   
                   
                 BCH error 
                   
               
               
                 LDPC 
                   
                   
                   
                 correction 
               
               
                 Rate 
                 N ldpc   
                 K ldpc   
                 K bch   
                 capability 
                 N bch  − K bch   
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 5/15 
                 16200 
                 5400 
                 5232 
                 12 
                 168 
               
               
                 6/15 
                   
                 6480 
                 6312 
               
               
                 7/15 
                   
                 7560 
                 7392 
               
               
                 8/15 
                   
                 8640 
                 8472 
               
               
                 9/15 
                   
                 9720 
                 9552 
               
               
                 10/15  
                   
                 10800 
                 10632 
               
               
                 11/15  
                   
                 11880 
                 11712 
               
               
                 12/15  
                   
                 12960 
                 12792 
               
               
                 13/15  
                   
                 14040 
                 13872 
               
               
                   
               
            
           
         
       
     
     The details of operations of the BCH encoding and LDPC encoding are as follows: 
     A 12-error correcting BCH code is used for outer encoding of the BBF. The BCH generator polynomial for short FECBLOCK and long FECBLOCK are obtained by multiplying together all polynomials. 
     LDPC code is used to encode the output of the outer BCH encoding. To generate a completed Bldpc (FECBLOCK), Pldpc (parity bits) is encoded systematically from each Ildpc (BCH-encoded BBF), and appended to Ildpc. The completed Bldpc (FECBLOCK) are expressed as follow equation. 
         B   ldpc   =[I   ldpc   P   ldpc   ]=[i   0   ,i   1   , . . . ,i   K     ldpc     −1   ,p   0   ,p   1   , . . . ,p   N     ldpc     −K     ldpc     −1 ]  [Equation 2]
 
     The parameters for long FECBLOCK and short FECBLOCK are given in the above table 28 and 29, respectively. 
     The detailed procedure to calculate Nldpc−Kldpc parity bits for long FECBLOCK, is as follows: 
     1) Initialize the parity bits, 
         P   0   =P   1   =P   2   = . . . =P   N     ldpc     −K     ldpc     −1 =0  [Equation 3]
 
     2) Accumulate the first information bit—i0, at parity bit addresses specified in the first row of an addresses of parity check matrix. The details of addresses of parity check matrix will be described later. For example, for rate 13/15: 
     
       
      
       p 
       983 
       =p 
       983 
       ⊕i 
       0  
       p 
       2815 
       =p 
       2815 
       ⊕i 
       0  
      
     
     
       
      
       p 
       4837 
       =p 
       4837 
       ⊕i 
       0  
       p 
       4989 
       =p 
       4989 
       ⊕i 
       0  
      
     
     
       
      
       p 
       6138 
       =p 
       6138 
       ⊕i 
       0  
       p 
       6458 
       =p 
       6458 
       ⊕i 
       0  
      
     
     
       
      
       p 
       6921 
       =p 
       6921 
       ⊕i 
       0  
       p 
       6974 
       =p 
       6974 
       ⊕i 
       0  
      
     
     
       
      
       p 
       7572 
       =p 
       7572 
       ⊕i 
       0  
       p 
       8260 
       =p 
       8260 
       ⊕i 
       0  
      
     
         p   8496   =p   8496   ⊕i   0   [Equation 4]
 
     3) For the next 359 information bits, is, s=1, 2, . . . , 359 accumulate is at parity bit addresses using following equation. 
       { x +( s  mod 360)× Q   ldpc } mod( N   ldpc   −K   ldpc )  [Equation 5]
 
     where x denotes the address of the parity bit accumulator corresponding to the first bit i0, and Qldpc is a code rate dependent constant specified in the addresses of parity check matrix. Continuing with the example, Qldpc=24 for rate 13/15, so for information bit i1, the following operations are performed: 
     
       
      
       p 
       1007 
       =p 
       1007 
       ⊕i 
       1  
       p 
       2839 
       =p 
       2839 
       ⊕i 
       1  
      
     
     
       
      
       p 
       4861 
       =p 
       4861 
       ⊕i 
       1  
       p 
       5013 
       =p 
       5013 
       ⊕i 
       1  
      
     
     
       
      
       p 
       6161 
       =p 
       6162 
       ⊕i 
       1  
       p 
       6482 
       =p 
       6482 
       ⊕i 
       1  
      
     
     
       
      
       p 
       6945 
       =p 
       6945 
       ⊕i 
       1  
       p 
       6998 
       =p 
       6998 
       ⊕i 
       1  
      
     
     
       
      
       p 
       7596 
       =p 
       7596 
       ⊕i 
       1  
       p 
       8284 
       =p 
       8284 
       ⊕i 
       1  
      
     
         p   8520   =p   8520   ⊕i   1   [Equation 6]
 
     4) For the 361st information bit i360, the addresses of the parity bit accumulators are given in the second row of the addresses of parity check matrix. In a similar manner the addresses of the parity bit accumulators for the following 359 information bits is, s=361, 362, . . . , 719 are obtained using the equation 6, where x denotes the address of the parity bit accumulator corresponding to the information bit i360, i.e., the entries in the second row of the addresses of parity check matrix. 
     5) In a similar manner, for every group of 360 new information bits, a new row from addresses of parity check matrixes used to find the addresses of the parity bit accumulators. 
     After all of the information bits are exhausted, the final parity bits are obtained as follows: 
     6) Sequentially perform the following operations starting with i=1 
         p   i   =p   i   ⊕p   i−1   , i= 1,2, . . . , N   ldpc   −K   ldpc −1  [Equation 7]
 
     where final content of pi, i=0, 1, . . . Nldpc−Kldpc−1 is equal to the parity bit pi. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 30 
               
               
                   
                   
               
               
                   
                 Code Rate 
                 Q ldpc   
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 5/15 
                 120 
               
               
                   
                 6/15 
                 108 
               
               
                   
                 7/15 
                 96 
               
               
                   
                 8/15 
                 84 
               
               
                   
                 9/15 
                 72 
               
               
                   
                 10/15  
                 60 
               
               
                   
                 11/15  
                 48 
               
               
                   
                 12/15  
                 36 
               
               
                   
                 13/15  
                 24 
               
               
                   
                   
               
            
           
         
       
     
     This LDPC encoding procedure for a short FECBLOCK is in accordance with the LDPC encoding procedure for the long FECBLOCK, except replacing the table 30 with table 31, and replacing the addresses of parity check matrix for the long FECBLOCK with the addresses of parity check matrix for the short FECBLOCK. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 31 
               
               
                   
                   
               
               
                   
                 Code Rate 
                 Q ldpc   
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 5/15 
                 30 
               
               
                   
                 6/15 
                 27 
               
               
                   
                 7/15 
                 24 
               
               
                   
                 8/15 
                 21 
               
               
                   
                 9/15 
                 18 
               
               
                   
                 10/15  
                 15 
               
               
                   
                 11/15  
                 12 
               
               
                   
                 12/15  
                 9 
               
               
                   
                 13/15  
                 6 
               
               
                   
                   
               
            
           
         
       
     
       FIG. 20  illustrates a time interleaving according to an embodiment of the present invention. 
     (a) to (c) show examples of TI mode. 
     The time interleaver operates at the DP level. The parameters of time interleaving (TI) may be set differently for each DP. 
     The following parameters, which appear in part of the PLS2-STAT data, configure the TI: 
     DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode; ‘0’ indicates the mode with multiple TI blocks (more than one TI block) per TI group. In this case, one TI group is directly mapped to one frame (no inter-frame interleaving). ‘1’ indicates the mode with only one TI block per TI group. In this case, the TI block may be spread over more than one frame (inter-frame interleaving). 
     DP_TI_LENGTH: If DP_TI_TYPE=‘0’, this parameter is the number of TI blocks NTI per TI group. For DP_TI_TYPE=‘1’, this parameter is the number of frames PI spread from one TI group. 
     DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the maximum number of XFECBLOCKs per TI group. 
     DP_FRAME_INTERVAL (allowed values: 1, 2, 4, 8): Represents the number of the frames HUMP between two successive frames carrying the same DP of a given PHY profile. 
     DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving is not used for a DP, this parameter is set to ‘1’. It is set to ‘0’ if time interleaving is used. 
     Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN data is used to represent the number of XFECBLOCKs carried by one TI group of the DP. 
     When time interleaving is not used for a DP, the following TI group, time interleaving operation, and TI mode are not considered. However, the Delay Compensation block for the dynamic configuration information from the scheduler will still be required. In each DP, the XFECBLOCKs received from the SSD/MIMO encoding are grouped into TI groups. That is, each TI group is a set of an integer number of XFECBLOCKs and will contain a dynamically variable number of XFECBLOCKs. The number of XFECBLOCKs in the TI group of index n is denoted by NxBLOCK_Group(n) and is signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note that NxBLOCK_Group(n) may vary from the minimum value of 0 to the maximum value NxBLOCK_Group_MAX (corresponding to DP_NUM_BLOCK_MAX) of which the largest value is 1023. 
     Each TI group is either mapped directly onto one frame or spread over PI frames. Each TI group is also divided into more than one TI blocks (NTI), where each TI block corresponds to one usage of time interleaver memory. The TI blocks within the TI group may contain slightly different numbers of XFECBLOCKs. If the TI group is divided into multiple TI blocks, it is directly mapped to only one frame. There are three options for time interleaving (except the extra option of skipping the time interleaving) as shown in the below table 32. 
     
       
         
           
               
               
             
               
                 TABLE 32 
               
               
                   
               
               
                 Modes 
                 Descriptions 
               
               
                   
               
             
            
               
                 Option-1 
                 Each TI group contains one TI block and is mapped directly to 
               
               
                   
                 one frame as shown in (a). This option is signaled in the 
               
               
                   
                 PLS2-STAT by DP_TI_TYPE = ‘0’ and 
               
               
                   
                 DP_TI_LENGTH = ‘1’(N TI  = 1). 
               
               
                 Option-2 
                 Each TI group contains one TI block and is mapped to more 
               
               
                   
                 than one frame, (b) shows an example, where one TI group is 
               
               
                   
                 mapped to two frames, i.e., DP_TI_LENGTH = ‘2’ (P I  = 2) 
               
               
                   
                 and DP_FRAME_INTERVAL (I JUMP  = 2). This provides 
               
               
                   
                 greater time diversity for low data-rate services. This option is 
               
               
                   
                 signaled in the PLS2-STAT by DP_TI_TYPE = ‘1’. 
               
               
                 Option-3 
                 Each TI group is divided into multiple TI blocks and is 
               
               
                   
                 mapped directly to one frame as shown in (c). Each TI block 
               
               
                   
                 may use full TI memory, so as to provide the maximum bit- 
               
               
                   
                 rate for a DP. This option is signaled in the PLS2-STAT 
               
               
                   
                 signaling by DP_TI_TYPE = ‘0’ and 
               
               
                   
                 DP_TI_LENGTH = N TI , while P I  = 1. 
               
               
                   
               
            
           
         
       
     
     Typically, the time interleaver will also act as a buffer for DP data prior to the process of frame building. This is achieved by means of two memory banks for each DP. The first TI-block is written to the first bank. The second TI-block is written to the second bank while the first bank is being read from and so on. 
     The TI is a twisted row-column block interleaver. For the sth TI block of the nth TI group, the number of rows N r  of a TI memory is equal to the number of cells N cells , i.e., N r =N cell , while the number of columns N c  is equal to the number N xBLOCK   _   TI (n,s) 
       FIG. 21  illustrates the basic operation of a twisted row-column block interleaver according to an embodiment of the present invention. 
       FIG. 21 ( a )  shows a writing operation in the time interleaver and  FIG. 21( b )  shows a reading operation in the time interleaver. The first XFECBLOCK is written column-wise into the first column of the TI memory, and the second XFECBLOCK is written into the next column, and so on as shown in (a). Then, in the interleaving array, cells are read out diagonal-wise. During diagonal-wise reading from the first row (rightwards along the row beginning with the left-most column) to the last row, N r  cells are read out as shown in (b). In detail, assuming z n,s,i  (i=0, . . . , N r N c ) as the TI memory cell position to be read sequentially, the reading process in such an interleaving array is performed by calculating the row index R n,s,i , the column index C n,s,i , and the associated twisting parameter T n,s,i  as follows equation. 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 GENERATE (R n,s,i , C n,s,i ) = 
                 [Equation 8] 
               
               
                   
                 { 
                   
               
               
                   
                 R n,s,i  = mod(i, N r ), 
                   
               
               
                   
                 T n,s,i  = mod(S shift  × R n,s,i , N c ), 
                   
               
               
                   
                   
               
               
                   
                 
                   
                     
                       
                         
                           C 
                           
                             n 
                             , 
                             s 
                             , 
                             i 
                           
                         
                         = 
                         
                           mod 
                            
                           
                             ( 
                             
                               
                                 
                                   T 
                                   
                                     n 
                                     , 
                                     s 
                                     , 
                                     i 
                                   
                                 
                                 + 
                                 
                                   ⌊ 
                                   
                                     i 
                                     
                                       N 
                                       r 
                                     
                                   
                                   ⌋ 
                                 
                               
                               , 
                               
                                 N 
                                 
                                   c 
                                    
                                   
                                       
                                   
                                 
                               
                             
                             ) 
                           
                         
                       
                     
                   
                 
                   
               
               
                   
                   
               
               
                   
                 } 
               
               
                   
                   
               
            
           
         
       
     
     where S shift  is a common shift value for the diagonal-wise reading process regardless of N xBLOCK   _   TI (n,s), and it is determined by N xBLOCE   _   TI   _   MAX  given in the PLS2-STAT as follows equation. 
     
       
         
           
             
               
                 
                   for 
                    
                   
                     { 
                     
                       
                         
                           
                             
                               
                                 
                                   
                                     
                                       N 
                                       
                                         xBLOCK 
                                          
                                         
                                             
                                         
                                          
                                         _ 
                                          
                                         
                                             
                                         
                                          
                                         TI 
                                          
                                         
                                             
                                         
                                          
                                         _ 
                                          
                                         
                                             
                                         
                                          
                                         MA 
                                          
                                         
                                             
                                         
                                          
                                         X 
                                       
                                       ′ 
                                     
                                     = 
                                   
                                 
                               
                               
                                 
                                   
                                     
                                       
                                         N 
                                         
                                           xBLOCK 
                                            
                                           
                                               
                                           
                                            
                                           _ 
                                            
                                           
                                               
                                           
                                            
                                           TI 
                                            
                                           
                                               
                                           
                                            
                                           _ 
                                            
                                           
                                               
                                           
                                            
                                           MA 
                                            
                                           
                                               
                                           
                                            
                                           X 
                                         
                                       
                                       + 
                                       1 
                                     
                                     , 
                                   
                                 
                               
                             
                           
                           
                             
                               
                                 if 
                                  
                                 
                                     
                                 
                                  
                                 
                                   N 
                                   
                                     xBLOCK 
                                      
                                     
                                         
                                     
                                      
                                     _ 
                                      
                                     
                                         
                                     
                                      
                                     TI 
                                      
                                     
                                         
                                     
                                      
                                     _ 
                                      
                                     
                                         
                                     
                                      
                                     MA 
                                      
                                     
                                         
                                     
                                      
                                     X 
                                   
                                 
                                  
                                 mod 
                                  
                                 
                                     
                                 
                                  
                                 2 
                               
                               = 
                               0 
                             
                           
                         
                         
                           
                             
                               
                                 
                                   
                                     
                                       N 
                                       
                                         xBLOCK 
                                          
                                         
                                             
                                         
                                          
                                         _ 
                                          
                                         
                                             
                                         
                                          
                                         TI 
                                          
                                         
                                             
                                         
                                          
                                         _ 
                                          
                                         
                                             
                                         
                                          
                                         MA 
                                          
                                         
                                             
                                         
                                          
                                         X 
                                       
                                       ′ 
                                     
                                     = 
                                   
                                 
                               
                               
                                 
                                   
                                     
                                       N 
                                       
                                         xBLOCK 
                                          
                                         
                                             
                                         
                                          
                                         _ 
                                          
                                         
                                             
                                         
                                          
                                         TI 
                                          
                                         
                                             
                                         
                                          
                                         _ 
                                          
                                         
                                             
                                         
                                          
                                         MA 
                                          
                                         
                                             
                                         
                                          
                                         X 
                                       
                                     
                                     , 
                                   
                                 
                               
                             
                           
                           
                             
                               
                                 if 
                                  
                                 
                                     
                                 
                                  
                                 
                                   N 
                                   
                                     xBLOCK 
                                      
                                     
                                         
                                     
                                      
                                     _ 
                                      
                                     
                                         
                                     
                                      
                                     TI 
                                      
                                     
                                         
                                     
                                      
                                     _ 
                                      
                                     
                                         
                                     
                                      
                                     MA 
                                      
                                     
                                         
                                     
                                      
                                     X 
                                   
                                 
                                  
                                 mod 
                                  
                                 
                                     
                                 
                                  
                                 2 
                               
                               = 
                               1 
                             
                           
                         
                       
                       , 
                       
                         
 
                       
                        
                       
                         
                           S 
                           shift 
                         
                         = 
                         
                           
                             
                               N 
                               
                                 xBLOCK 
                                  
                                 
                                     
                                 
                                  
                                 _ 
                                  
                                 
                                     
                                 
                                  
                                 TI 
                                  
                                 
                                     
                                 
                                  
                                 _ 
                                  
                                 
                                     
                                 
                                  
                                 MA 
                                  
                                 
                                     
                                 
                                  
                                 X 
                               
                               ′ 
                             
                             - 
                             1 
                           
                           2 
                         
                       
                     
                   
                 
               
               
                 
                   [ 
                   
                     Equation 
                      
                     
                         
                     
                      
                     9 
                   
                   ] 
                 
               
             
           
         
       
     
     As a result, the cell positions to be read are calculated by a coordinate as z n,s,i =N r C n,s,i +R n,s,i . 
       FIG. 22  illustrates an operation of a twisted row-column block interleaver according to another embodiment of the present invention. 
     More specifically,  FIG. 22  illustrates the interleaving array in the TI memory for each TI group, including virtual XFECBLOCKs when N xBLOCK   _   TI (0,0)=3, N xBLOCK   _   TI (1,0)=6, N xBLOCK   _   TI (2,0)=5. 
     The variable number N xrBLOCK   _   TI (n,s)=N r  will be less than or equal to N xBLOCK   _   TI   _   MAX ′. Thus, in order to achieve a single-memory deinterleaving at the receiver side, regardless of N xBLOCK   _   TI (n,s), the interleaving array for use in a twisted row-column block interleaver is set to the size of N r ×N c =N cells ×N xBLOCK   _   TI   _   MAX ′ by inserting the virtual XFECBLOCKs into the TI memory and the reading process is accomplished as follow equation. 
     
       
         
           
               
             
               
                   
               
             
            
               
                 [Equation10] 
               
            
           
           
               
               
            
               
                   
                 p = 0; 
               
               
                   
                 for i = 0;i &lt; N cells N′ xBLOCK     —     TI     —     MAX ;i = i + 1 
               
               
                   
                 {GENERATE (R n,s,i ,C n,s,i ); 
               
               
                   
                 V i  = N r C n,s,j  + R n,s,j   
               
               
                   
                  if V i  &lt; N cells N xBLOCK     —     TI (n,s) 
               
               
                   
                  { 
               
               
                   
                   Z n,s,p  = V i ; p = p + 1; 
               
               
                   
                   } 
               
               
                   
                 } 
               
               
                   
                   
               
            
           
         
       
     
     The number of TI groups is set to 3. The option of time interleaver is signaled in the PLS2-STAT data by DP_TI_TYPE=‘0’, DP_FRAME_INTERVAL=‘1’, and DP_TI_LENGTH=‘1’, i.e., NTI=1, IJUMP=1, and PI=1. The number of XFECBLOCKs, each of which has Ncells=30 cells, per TI group is signaled in the PLS2-DYN data by NxBLOCK_TI(0,0)=3, NxBLOCK_TI(1,0)=6, and NxBLOCK_TI(2,0)=5, respectively. The maximum number of XFECBLOCK is signaled in the PLS2-STAT data by NxBLOCK_Group_MAX, which leads to └N xBLOCK   _   Group   _   MAX /N TI ┘=N xBLOCK   _   TI   _   MAX =6. 
       FIG. 23  illustrates a diagonal-wise reading pattern of a twisted row-column block interleaver according to an embodiment of the present invention. 
     More specifically  FIG. 23  shows a diagonal-wise reading pattern from each interleaving array with parameters of N xBLOCK   _   TI   _   MAX ′=7 and Sshift=(7−1)/2=3. Note that in the reading process shown as pseudocode above, if V i ≧N cells N xBLOCK   _   TI (n,s), the value of Vi is skipped and the next calculated value of Vi is used. 
       FIG. 24  illustrates interleaved XFECBLOCKs from each interleaving array according to an embodiment of the present invention. 
       FIG. 24  illustrates the interleaved XFECBLOCKs from each interleaving array with parameters of N xBLOCK   _   TI   _   MAX ′=7 and Sshift=3. 
       FIG. 25  illustrates signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention. 
     As described above, the frequency interleaver according to the present invention performs interleaving using different interleaving sequences in a plurality of OFDM symbols, but the frequency deinterleaver may perform single-memory deinterleaving on the received OFDM symbols. 
     The present invention proposes a method for performing single-memory deinterleaving by the frequency deinterleaver irrespective of whether the number of OFDM symbols in one frame is an even number or an odd number. To this end, the above-described architecture of the frequency interleaver may operate differently depending on whether the number of OFDM symbols is an even number or an odd number. Furthermore, signaling information related thereto may be additionally defined in the above-described preamble and/or the physical layer signal (PLS). As such, single-memory deinterleaving is not limited to a case in which the number of OFDM symbols is an even number, and may always be enabled. 
     Here, the PLS may be transmitted in a frame starting symbol (FSS) of every frame. Alternatively, according to another embodiment, the PLS may be transmitted in the first OFDM symbol. Otherwise, based on whether the PLS is present, signaling information corresponding to the PLS may be completely transmitted in the preamble. Or, signaling information corresponding to the preamble and/or the PLS may be transmitted in bootstrap information. The bootstrap information may be an information part located in front of the preamble. 
     Information about, for example, a processing operation used by the frequency interleaver of the transmitter may include an FI_mode field and an N_sym field. 
     The FI_mode field may be a 1-bit field which can be located in the preamble. The FI_mode field may indicate an interleaving scheme used in the FSS or the first OFDM symbol of every frame. 
     The interleaving scheme indicated as the FI_mode field may include FI scheme #1 and FI scheme #2. 
     FI scheme #1 can indicate that the frequency interleaver of the transmitter performs random writing operation and then linear reading operation on the FSS. This case may correspond to a case in which the FI_mode field value is 0. The random writing or linear reading operation may be performed in or from memory using a value generated by an arbitrary random sequence generator using, for example, a pseudo-random binary sequence (PRBS). Here, linear reading may refer to sequentially reading operation. 
     FI scheme #2 can indicate that the transmitter performs linear writing operation and then random reading operation on the FSS. This case may correspond to a case in which the FI_mode field value is 1. Likewise, the linear writing or random reading operation may be performed in or from memory using a value generated by an arbitrary random sequence generator using, for example, PRBS. Here, linear writing may refer to a sequentially writing operation. 
     In addition, the FI_mode field may indicate an interleaving scheme used in a frame edge symbol (FES) or the last OFDM symbol of every frame. The interleaving scheme applied to the FES may be indicated differently from the value of the N_sym field transmitted by the PLS. That is, the interleaving scheme indicated as the FI_mode field may differ depending on whether the number of OFDM symbols is an odd number or an even number. Mapping information between the two fields may be predefined as a table by the transmitter and the receiver. 
     The FI_mode field may be defined and transmitted in a part of the frame other than the preamble according to another embodiment. 
     The N_sym field may be a field which can be located in the PLS part. The number of bits of the N_sym field is variable according to embodiments. The N_sym field may indicate number of OFDM symbols included in one frame. As such, the receiver can acquire information about whether the number of OFDM symbols is an even number or an odd number. 
     Operation of the frequency deinterleaver corresponding to the frequency interleaver irrespective of the number of OFDM symbols in one frame is as described below. This frequency deinterleaver may perform single-memory deinterleaving by utilizing the proposed signaling fields irrespective of whether the number of OFDM symbols is an even number or an odd number. 
     Initially, the frequency deinterleaver may perform frequency deinterleaving on the FSS using information of the FI_mode field of the preamble because the frequency interleaving scheme used in the FSS is indicated as the FI_mode. 
     The frequency deinterleaver may perform frequency deinterleaving on the FES using signaling information of the FI_mode field and signaling information of the N_sym field of the PLS. In this case, the mapping information between the two fields may be acquired using the predefined table. A description of the predefined table will be given below. 
     Overall deinterleaving operation on the other symbols may be performed inversely from the interleaving operation of the transmitter. That is, on a pair of contiguously input OFDM symbols, the frequency deinterleaver may perform deinterleaving using one interleaving sequence. Here, the interleaving sequence may be an interleaving sequence used by the frequency interleaver for reading &amp; writing. The frequency deinterleaver may perform reading &amp; writing operation inversely using the interleaving sequence. 
     However, the frequency deinterleaver according to the present invention may not use a ping pong architecture using double memories. The frequency deinterleaver may perform deinterleaving on contiguously input OFDM symbols using a single memory. As such, the efficiency of using memory by the frequency deinterleaver may be increased. 
       FIG. 26  illustrates FI schemes of FSS in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention. 
     An interleaving scheme applied to frequency interleaving operation may be determined using the above-described FI_mode field and the N_sym field. 
     In the case of FSS, when the number of OFDM symbols indicated as the N_sym field is an even number, FI scheme #1 may be performed on the FSS irrespective of the FI_mode field value. 
     When the number of OFDM symbols indicated as the N_sym field is an odd number, FI scheme #1 may be applied to the FSS if the FI_mode field has a value of 0, and FI scheme #2 may be applied to the FSS if the FI_mode field has a value of 1. That is, when the number of OFDM symbols is an odd number, FI schemes #1 and #2 may be alternately applied to the FSS symbols for frequency interleaving. 
       FIG. 27  illustrates operation of a reset mode in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention. 
     For frequency interleaving on FES, the above-described symbol offset generator may adopt a reset mode as a new concept. The reset mode may refer to a mode in which a symbol offset value generated by the symbol offset generator is ‘0’. 
     For frequency interleaving on FES, whether to use the reset mode may be determined using the above-described FI_mode field and the N_sym field. 
     When the number of OFDM symbols indicated as the N_sym field is an even number, the reset mode of the symbol offset generator may not operate (off) irrespective of the value of the FI_mode field. 
     When the number of OFDM symbols indicated as the N_sym field is an odd number, if the value of the FI_mode field is 0, the symbol offset generator may operate in the reset mode (on). Otherwise, if the value of the FI_mode field is 1, the reset mode of the symbol offset generator may not operate (off). That is, when the number of OFDM symbols is an odd number, the reset mode may be alternately turned on and off for frequency interleaving. 
       FIG. 28  illustrates equations indicating input and output of the frequency interleaver in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention. 
     As described above, OFDM symbol pairs of memory bank-A and memory bank-B may be processed through the above-described interleaving operation. As described above, for interleaving, a variety of different interleaving seeds generated by cyclically shifting one main interleaving seed may be used. Here, the interleaving seed may also be called an interleaving sequence. Alternatively, the interleaving seed may also be called an interleaving address value, an address value, or an interleaving address. Here, the term “interleaving address value(s)” can be used for referring plural address values, or for referring a interleaving seed which is a singular. That is, depending on embodiments, interleaving address value(s) can mean H(p) itself, or each addresses belong to H(p). 
     Input of frequency interleaving to be interleaved within one OFDM symbol may be indicated as Om,1 (t 50010 ). Here, data cells may be indicated as xm,1, 0, . . . xm,1,Ndata−1. Meanwhile, p may indicate a cell index, 1 may indicate an OFDM symbol index, and m may indicate a frame index. That is, xm,1,p may indicate a p-th data cell of an 1-th OFDM symbol of an m-th frame. Ndata may indicate the number of data cells. Nsym may indicate the number of symbols (frame signaling symbols, normal data symbols, or frame edge symbols). 
     Data cells which are interleaved based on the above-described operation may be indicated as Pm,1 (t 50020 ). The interleaved data cells may be indicated as vm,1, 0, . . . vm,1,Ndata−1. Meanwhile, p, 1, and m may have the above-described index values. 
       FIG. 29  illustrates equations of a logical operation mechanism of frequency interleaving based on FI scheme #1 and FI scheme #2 in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention. 
     A description is now given of frequency interleaving based on FI scheme #1. As described above, frequency interleaving may be performed using an interleaving sequence (interleaving address) of each memory bank. 
     Interleaving operation on an even symbol (j mod 2=0) may be mathematically expressed as given by equation t 51010 . On input data x, frequency interleaving may be performed using the interleaving sequence (interleaving address) to acquire output v. Here, p-th input data x may be permuted to be identical to H(p)-th output data v. 
     That is, on an even symbol (the first symbol), random writing operation may be performed using the interleaving sequence, and then linear reading operation for sequentially reading data may be performed. Here, the interleaving sequence (interleaving address) may be a value generated by an arbitrary random sequence generator using, for example, PRBS. 
     Interleaving operation on an odd symbol (j mod 2=1) may be mathematically expressed as given by equation t 51020 . On input data x, frequency interleaving may be performed using the interleaving sequence (interleaving address) to acquire output v. Here, H(p)-th input data x may be permuted to be identical to p-th output data v. That is, compared to the interleaving process performed on the even symbol, the interleaving sequence (interleaving address) may be applied inversely. 
     That is, on an odd symbol (the second symbol), a linear writing operation for sequentially writing data in memory may be performed, and then random reading operation for randomly reading the data using the interleaving sequence may be performed. Likewise, the interleaving sequence (interleaving address) may be a value generated by an arbitrary random sequence generator using, for example, PRBS. 
     A description is now given of frequency interleaving based on FI scheme #2. 
     In the case of frequency interleaving based on FI scheme #2, operation on an even/odd symbol may be performed inversely from the operation based on FI scheme #1. 
     That is, on the even symbol, linear writing operation may be performed and then random reading operation may be performed as given by equation t 51020 . In addition, on the odd symbol, random writing operation may be performed and then linear reading operation may be performed as given by equation t 51010 . A detailed description thereof is the same as that given above in relation to FI scheme #1. 
     The symbol index 1 may be indicated as 0, 1, . . . , N sym −1, and the cell index p may be indicated as 0, 1, . . . , N data −1. According to another embodiment, the frequency interleaving scheme on an even symbol and the frequency interleaving scheme on an odd symbol may be switched. In addition, according to another embodiment, the frequency interleaving scheme based on FI scheme #1 and the frequency interleaving scheme based on FI scheme #2 may be switched. 
       FIG. 30  illustrates an example in which the number of symbols is an even number in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention. 
     In the current embodiment, the N_sym field may indicate that the number of OFDM symbols in one frame is an even number. The current embodiment assumes that one frame includes one preamble and eight OFDM symbols. According to another embodiment, bootstrap information may be further included in front of the preamble. The bootstrap information is not illustrated. 
     In the current embodiment, one frame may include one FSS and one FES. Here, it is assumed that the FSS and the FES have the same length. In addition, since information of the N_sym field is transmitted in the PLS part, the frequency deinterleaver may acquire the corresponding information after decoding the FSS. Furthermore, the current embodiment assumes that the N_sym field is completely decoded before operation on the FES is performed. 
     In the FSS of each frame, the value of the symbol offset generator may be reset to 0. Accordingly, the first and second symbols may be processed using the same interleaving sequence. In addition, sequence #0 may be used for operation whenever each frame starts. After that, sequences #1 and #2 may be sequentially used for operation of the frequency interleaver/deinterleaver. 
       FIG. 31  illustrates an example in which the number of symbols is an even number in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention. 
     In the first frame, information about an interleaving scheme of the FSS may be acquired from the FI_mode field of the preamble. In the current embodiment, since the number of OFDM symbols is an even number, only FI scheme #1 may be used. 
     Then, the FSS may be decoded and thus N_sym information may be acquired. The N_sym information indicates that the number of symbols in the current frame is an even number. After that, the acquired FI_mode information and the N_sym information may be used when the frequency deinterleaver decodes the FES. Since the number of symbols is an even number, the symbol offset generator does not operate in the above-described reset mode. That is, the reset mode may be in an off state. 
     Subsequently, even in another frame, since an even number of OFDM symbols are included, the frequency deinterleaver may operate in the same manner. That is, the FI scheme to be used in the FSS is FI scheme #1, and the reset mode to be used in the FES may be in an off state. 
       FIG. 32  illustrates an example in which the number of symbols is an odd number in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention. 
     In the current embodiment, the N_sym field may indicate that the number of OFDM symbols in one frame is an odd number. The current embodiment assumes that one frame includes one preamble and seven OFDM symbols. According to another embodiment, bootstrap information may be further included in front of the preamble. The bootstrap information is not illustrated. 
     In the current embodiment, like the case in which the number of symbols is an even number, one frame may include one FSS and one FES. Here, it is assumed that the FSS and the FES have the same length. In addition, since information of the N_sym field is transmitted in the PLS part, the frequency deinterleaver may acquire the corresponding information after decoding the FSS. Furthermore, the current embodiment assumes that the N_sym field is completely decoded before operation on the FES is performed. 
     In the FSS of each frame, the value of the symbol offset generator may be reset to 0. Furthermore, in the FES of an arbitrary frame, the symbol offset generator may operate in a reset mode based on the values of the FI_mode field and the N_sym field. Accordingly, in the FES of the arbitrary frame, the value of the symbol offset generator may be reset or not reset to 0. These reset operations may be alternately performed on frames. 
     The symbol offset generator may be reset in the last symbol of the first frame, i.e., the FES. Accordingly, the interleaving sequence may be reset to sequence #0. As such, the frequency interleaver/deinterleaver may process the corresponding FES based on sequence #0 (t 54010 ). 
     In the FSS of a subsequent frame, the symbol offset generator may be reset again and thus sequence #0 may be used (t 54010 ). The symbol offset generator may not be reset in the FES of the second frame (frame #1), and may be reset again in the FES of the third frame (frame #2). 
       FIG. 33  illustrates an example in which the number of symbols is an odd number in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention. 
     In the first frame, information about an interleaving scheme of the FSS may be acquired from the FI_mode field of the preamble. Since the number of OFDM symbols is an odd number, FI scheme #1 and FI scheme #2 may be used. In the current embodiment, FI scheme #1 is used in the first frame. 
     Then, the FSS may be decoded and thus N_sym information may be acquired. The N_sym information indicates that the number of symbols in the current frame is an odd number. After that, the acquired FI_mode information and the N_sym information may be used when the frequency deinterleaver decodes the FES. Since the number of symbols is an odd number and FI scheme #1 is used, the FI_mode field value is 0. Since the FI_mode is 0, the symbol offset generator may operate in the above-described reset mode. That is, the reset mode may be in an on state. 
     The symbol offset generator may operate in the reset mode and thus may be reset to 0. Since the FI_mode field value is 1 in the second frame, this indicates that the FSS is processed based on FI scheme #2. The N_sym field indicates that the number of symbols is an odd number. In the second frame, since the FI_mode field value is 1 and the number of symbols is an odd number, the symbol offset generator may not operate in the reset mode. 
     In this manner, the FI scheme to be used in the FSS may be alternately set to FI schemes #1 and #2. Furthermore, the reset mode to be used in the FES may be alternately set to be on and off. According to another embodiment, the settings may not be changed every frame. 
       FIG. 34  illustrates operation of the frequency deinterleaver in signaling for single-memory deinterleaving irrespective of the number of symbols in a frame according to an embodiment of the present invention. 
     The frequency deinterleaver may perform frequency deinterleaving using information of the predefined FI_mode field and/or the N_sym field. As described above, the frequency deinterleaver may operate using a single memory. Basically, frequency deinterleaving may be inverse operation of the frequency interleaving operation performed by the transmitter, to restore the order of data. 
     As described above, frequency deinterleaving on the FSS may be performed based on information about the FI scheme which is acquired from the FI_mode field and the N_sym field of the preamble. Frequency deinterleaving on the FES may be performed based on information indicating whether to the reset mode operates, which is acquired using the FI_mode field and the N_sym field. 
     That is, on a pair of input OFDM symbols, the frequency deinterleaver may perform inverse operation of the reading/writing operation of the frequency interleaver. One interleaving sequence may be used in this operation. 
     However, as described above, the frequency interleaver follows the ping pong architecture using double memories, but the frequency deinterleaver may perform deinterleaving using a single memory. This single-memory frequency deinterleaving operation may be performed using information of the FI_mode field and the N_sym field. This information may allow single-memory frequency deinterleaving even on a frame having an odd number of OFDM symbols irrespective of the number of OFDM symbols. 
     The frequency interleaver according to the present invention may perform frequency interleaving on all data cells of the OFDM symbols. The frequency interleaver may map the data cells to available data carriers of the symbols. 
     The frequency interleaver according to the present invention may operate in different interleaving modes based on FFT size. For example, when the FFT size is 32K, the frequency interleaver may perform random writing/linear reading operation on an even symbol and perform linear writing/random reading operation on an odd symbol as in FI scheme #1 described above. Alternatively, when the FFT size is 16K or 8K, the frequency interleaver may perform linear reading/random writing operation on all symbols irrespective of an even/odd number. 
     The FFT size, which determines whether to switch the interleaving modes, may vary according to embodiments. That is, interleaving as in FI scheme #1 may be performed in the case of 32K and 16K, and interleaving irrespective of an even/odd number may be performed in the case of 8K. Alternatively, interleaving as in FI scheme #1 may be performed for all FFT sizes, or interleaving irrespective of an even/odd number may be performed for all FFT sizes. Otherwise, according to another embodiment, interleaving as in FI scheme #2 may be performed for a specific FFT size. 
     This frequency interleaving operation may be performed using the above-described interleaving sequence (interleaving address). The interleaving sequence may be variously generated using an offset value as described above. Alternatively, address check may be performed to generate various interleaving sequences. 
       FIG. 35  illustrates the concept of a variable bit-rate system according to an embodiment of the present invention. 
     Specifically, a transport superframe, shown in  FIG. 35 , is composed of NTI_NUM TI groups and each TI group can include N BLOCK_TI FEC blocks. In this case, TI groups may respectively include different numbers of FEC blocks. The TI group according to an embodiment of the present invention can be defined as a block for performing time interleaving and can be used in the same meaning as the aforementioned TI block or IF. That is, one IF can include at least one TI block and the number of FEC blocks in the TI block is variable. 
     When TI groups include different numbers of FEC blocks, the present invention performs interleaving on the TI groups using one twisted row-column block interleaving rule in an embodiment. Accordingly, the receiver can perform deinterleaving using a single memory. A description will be given of an input FEC block memory arrangement method and reading operation of the time interleaver in consideration of variable bit-rate (VBR) transmission in which the number of FEC blocks can be changed per TI group. 
       FIG. 36  illustrates writing and reading operations of block interleaving according to an embodiment of the present invention. Detailed descriptions about this figure was described before. 
       FIG. 37  shows equations representing block interleaving according to an embodiment of the present invention. 
     The equations shown in the figure represent block interleaving applied per TI group. As expressed by the equations, shift values can be respectively calculated in a case in which the number of FEC blocks included in a TI group is an odd number and a case in which the number of FEC blocks included in a TI group is an even number. That is, block interleaving according to an embodiment of the present invention can calculate a shift value after making the number of FEC blocks be an odd-number. 
     A time interleaver according to an embodiment of the present invention can determine parameters related to interleaving on the basis of a TI group having a maximum number of FEC blocks in the corresponding superframe. Accordingly, the receiver can perform deinterleaving using a single memory. Here, for a TI group having a smaller number of FEC blocks than the maximum number of FEC blocks, virtual FEC blocks corresponding to a difference between the number of FEC blocks and the maximum number of FEC blocks can be added. 
     Virtual FEC blocks according to an embodiment of the present invention can be inserted before actual FEC blocks. Subsequently, the time interleaver according to an embodiment of the present invention can perform interleaving on the TI groups using one twisted row-column block interleaving rule in consideration of the virtual FEC blocks. In addition, the time interleaver according to an embodiment of the present invention can perform the aforementioned skip operation when a memory-index corresponding to virtual FEC blocks is generated during reading operation. In the following writing operation, the number of FEC blocks of input TI groups is matched to the number of FEC blocks of output TI groups. Consequently, according to time interleaving according to an embodiment of the present invention, loss of data rate of data actually transmitted may be prevented through skip operation even if virtual FEC blocks are inserted in order to perform efficient single-memory deinterleaving in the receiver. 
       FIG. 38  illustrates virtual FEC blocks according to an embodiment of the present invention. 
     The left side of the figure shows parameters indicating a maximum number of FEC blocks in a TI group, the actual number of FEC blocks included in a TI group and a difference between the maximum number of FEC blocks and the actual number of FEC blocks, and equations for deriving the number of virtual FEC blocks. 
     The right side of the figure shows an embodiment of inserting virtual FEC blocks into a TI group. In this case, the virtual FEC blocks can be inserted before actual FEC blocks, as described above. 
       FIG. 39  shows equations representing reading operation after insertion of virtual FEC blocks according to an embodiment of the present invention. 
     Skip operation illustrated in the figure can skip virtual FEC blocks in reading operation. 
       FIG. 40  is a flowchart illustrating a time interleaving process according to an embodiment of the present invention. 
     A time interleaver according to an embodiment of the present invention can setup initial values (S 67000 ). 
     Then, the time interleaver according to an embodiment of the present invention can perform writing operation on actual FEC blocks in consideration of virtual FEC blocks (S 67100 ). 
     The time interleaver according to an embodiment of the present invention can generate a temporal TI address (S 67200 ). 
     Subsequently, the time interleaver according to an embodiment of the present invention can evaluate the availability of the generated TI reading address (S 67300 ). Then, the time interleaver according to an embodiment of the present invention can generate a final TI reading address (S 67400 ). 
     The time interleaver according to an embodiment of the present invention can read the actual FEC blocks (S 67500 ). 
       FIG. 41  shows equations representing a process of determining a shift value and a maximum TI block size according to an embodiment of the present invention. 
     The figure shows an embodiment in which the number of TI groups is 2, the number of cells in a TI group is 30, the number of FEC blocks included in the first TI group is 5 and the number of FEC blocks included in the second TI block is 6. While a maximum number of FEC blocks is 6, 6 is an even number. Accordingly, a maximum number of FEC blocks, which is adjusted in order to obtain the shift value, can be 7 and the shift value can be calculated as 4. 
       FIGS. 42 to 44  illustrate a TI process of the embodiment described before. 
       FIG. 42  illustrates writing operation according to an embodiment of the present invention. 
       FIG. 42  shows writing operation for the two TI groups described before. 
     A block shown in the left side of the figure represents a TI memory address array and blocks shown in the right side of the figure illustrate writing operation when two virtual FEC blocks and one virtual FEC block are respectively inserted into two continuous TI groups. Since the adjusted maximum number of FEC blocks is 7, as described above, two virtual FEC blocks are inserted into the first TI group and one virtual FEC block is inserted into the second TI group. 
       FIG. 43  illustrates reading operation according to an embodiment of the present invention. 
     A block shown in the left side of the figure represents a TI memory address array and blocks shown in the right side of the figure illustrate reading operation when two virtual FEC blocks and one virtual FEC block are respectively inserted into two continuous TI groups. In this case, reading operation can be performed on the virtual FEC blocks in the same manner as the reading operation performed on actual FEC blocks. 
       FIG. 44  illustrates a result of skip operation in reading operation according to an embodiment of the present invention. 
     As shown in the figure, virtual FEC blocks can be skipped in two TI groups. 
       FIGS. 45 to 46  illustrate time deinterleaving corresponding to a reverse of TI described before. 
     Specifically,  FIG. 47  illustrates time deinterleaving for the first TI group and  FIG. 48  illustrates time deinterleaving for the second TI group. 
       FIG. 45  shows a writing process of time deinterleaving according to an embodiment of the present invention. 
     A left block in the figure shows a TI memory address array, a middle block shows the first TI group input to a time deinterleaver and a right block shows a writing process performed in consideration of virtual FEC blocks that are skipped with respect to the first TI group. 
     As shown in the figure, two virtual FEC blocks skipped during TI can be restored for correct reading operation in the writing process. In this case, the positions and quantity of the skipped two virtual FEC blocks can be estimated through an arbitrary algorithm. 
       FIG. 46  illustrates a writing process of time deinterleaving according to another embodiment of the present invention. 
     A left block in the figure shows a TI memory address array, a middle block shows the second TI group input to the time deinterleaver and a right block shows a writing process performed in consideration of virtual FEC blocks that are skipped with respect to the second TI group. 
     As shown in the figure, one virtual FEC block skipped during TI can be restored for correct reading operation in the writing process. In this case, the position and quantity of the skipped one virtual FEC block can be estimated through an arbitrary algorithm. 
       FIG. 47  shows equations representing reading operation of time deinterleaving according to another embodiment of the present invention. 
     A TDI shift value used in the receiver can be determined by a shift value used in the transmitter, and skip operation can skip virtual FEC blocks in reading operation, similarly to skip operation performed in the transmitter. 
       FIG. 48  is a flowchart illustrating a time deinterleaving process according to an embodiment of the present invention. 
     A time deinterleaver according to an embodiment of the present invention can setup initial values (S 75000 ). 
     Then, the time deinterleaver according to an embodiment of the present invention can perform writing operation on actual FEC blocks in consideration of virtual FEC blocks (S 75100 ). 
     Subsequently, the time deinterleaver according to an embodiment of the present invention can generate a temporal TDI reading address (S 75200 ). 
     The time deinterleaver according to an embodiment of the present invention can evaluate the availability of the generated TDI reading address (S 75300 ). Then, the time deinterleaver according to an embodiment of the present invention can generate a final TDI reading address (S 75400 ). 
     Subsequently, the time deinterleaver according to an embodiment of the present invention can read the actual FEC blocks (S 75500 ). 
       FIG. 49  illustrates a receiver protocol stack according to an embodiment of the present invention. 
     Two schemes may be used in broadcast service delivery through a broadcast network. 
     In a first scheme, media processing units (MPUs) are transmitted using an MMT protocol (MMTP) based on MPEG media transport (MMT). In a second scheme, dynamic adaptive streaming over HTTP (DASH) segments may be transmitted using real time object delivery over unidirectional transport (ROUTE) based on MPEG DASH. 
     Non-timed content including NRT media, EPG data, and other files is delivered with ROUTE. Signaling may be delivered over MMTP and/or ROUTE, while bootstrap signaling information is provided by the means of the Service List Table (SLT). 
     In hybrid service delivery, MPEG DASH over HTTP/TCP/IP is used on the broadband side. Media files in ISO Base Media File Format (BMFF) are used as the delivery, media encapsulation and synchronization format for both broadcast and broadband delivery. Here, hybrid service delivery may refer to a case in which one or more program elements are delivered through a broadband path. 
     Services are delivered using three functional layers. These are the physical layer, the delivery layer and the service management layer. The physical layer provides the mechanism by which signaling, service announcement and IP packet streams are transported over the broadcast physical layer and/or broadband physical layer. The delivery layer provides object and object flow transport functionality. It is enabled by the MMTP or the ROUTE protocol, operating on a UDP/IP multicast over the broadcast physical layer, and enabled by the HTTP protocol on a TCP/IP unicast over the broadband physical layer. The service management layer enables any type of service, such as linear TV or HTML5 application service, to be carried by the underlying delivery and physical layers. 
     In this figure, a protocol stack part on a broadcast side may be divided into a part transmitted through the SLT and the MMTP, and a part transmitted through ROUTE. 
     The SLT may be encapsulated through UDP and IP layers. Here, the SLT will be described below. The MMTP may transmit data formatted in an MPU format defined in MMT, and signaling information according to the MMTP. The data may be encapsulated through the UDP and IP layers. ROUTE may transmit data formatted in a DASH segment form, signaling information, and non-timed data such as NRT data, etc. The data may be encapsulated through the UDP and IP layers. According to a given embodiment, some or all processing according to the UDP and IP layers may be omitted. Here, the illustrated signaling information may be signaling information related to a service. 
     The part transmitted through the SLT and the MMTP and the part transmitted through ROUTE may be processed in the UDP and IP layers, and then encapsulated again in a data link layer. The link layer will be described below. Broadcast data processed in the link layer may be multicast as a broadcast signal through processes such as encoding/interleaving, etc. in the physical layer. 
     In this figure, a protocol stack part on a broadband side may be transmitted through HTTP as described above. Data formatted in a DASH segment form, signaling information, NRT information, etc. may be transmitted through HTTP. Here, the illustrated signaling information may be signaling information related to a service. The data may be processed through the TCP layer and the IP layer, and then encapsulated into the link layer. According to a given embodiment, some or all of the TCP, the IP, and the link layer may be omitted. Broadband data processed thereafter may be transmitted by unicast in the broadband through a process for transmission in the physical layer. 
     Service can be a collection of media components presented to the user in aggregate; components can be of multiple media types; a Service can be either continuous or intermittent; a Service can be Real Time or Non-Real Time; Real Time Service can consist of a sequence of TV programs. 
       FIG. 50  illustrates a relation between the SLT and SLS according to an embodiment of the present invention. 
     Service signaling provides service discovery and description information, and comprises two functional components: Bootstrap signaling via the Service List Table (SLT) and the Service Layer Signaling (SLS). These represent the information which is necessary to discover and acquire user services. The SLT enables the receiver to build a basic service list, and bootstrap the discovery of the SLS for each service. 
     The SLT can enable very rapid acquisition of basic service information. The SLS enables the receiver to discover and access services and their content components. Details of the SLT and SLS will be described below. 
     As described in the foregoing, the SLT may be transmitted through UDP/IP. In this instance, according to a given embodiment, data corresponding to the SLT may be delivered through the most robust scheme in this transmission. 
     The SLT may have access information for accessing SLS delivered by the ROUTE protocol. In other words, the SLT may be bootstrapped into SLS according to the ROUTE protocol. The SLS is signaling information positioned in an upper layer of ROUTE in the above-described protocol stack, and may be delivered through ROUTE/UDP/IP. The SLS may be transmitted through one of LCT sessions included in a ROUTE session. It is possible to access a service component corresponding to a desired service using the SLS. 
     In addition, the SLT may have access information for accessing an MMT signaling component delivered by MMTP. In other words, the SLT may be bootstrapped into SLS according to the MMTP. The SLS may be delivered by an MMTP signaling message defined in MMT. It is possible to access a streaming service component (MPU) corresponding to a desired service using the SLS. As described in the foregoing, in the present invention, an NRT service component is delivered through the ROUTE protocol, and the SLS according to the MMTP may include information for accessing the ROUTE protocol. In broadband delivery, the SLS is carried over HTTP(S)/TCP/IP. 
       FIG. 51  illustrates an SLT according to an embodiment of the present invention. 
     First, a description will be given of a relation among respective logical entities of service management, delivery, and a physical layer. 
     Services may be signaled as being one of two basic types. First type is a linear audio/video or audio-only service that may have an app-based enhancement. Second type is a service whose presentation and composition is controlled by a downloaded application that is executed upon acquisition of the service. The latter can be called an “app-based” service. 
     The rules regarding presence of ROUTE/LCT sessions and/or MMTP sessions for carrying the content components of a service may be as follows. 
     For broadcast delivery of a linear service without app-based enhancement, the service&#39;s content components can be carried by either (but not both): (1) one or more ROUTE/LCT sessions, or (2) one or more MMTP sessions. 
     For broadcast delivery of a linear service with app-based enhancement, the service&#39;s content components can be carried by: (1) one or more ROUTE/LCT sessions, and (2) zero or more MMTP sessions. 
     In certain embodiments, use of both MMTP and ROUTE for streaming media components in the same service may not be allowed. 
     For broadcast delivery of an app-based service, the service&#39;s content components can be carried by one or more ROUTE/LCT sessions. 
     Each ROUTE session comprises one or more LCT sessions which carry as a whole, or in part, the content components that make up the service. In streaming services delivery, an LCT session may carry an individual component of a user service such as an audio, video or closed caption stream. Streaming media is formatted as DASH Segments. 
     Each MMTP session comprises one or more MMTP packet flows which carry MMT signaling messages or as a whole, or in part, the content component. An MMTP packet flow may carry MMT signaling messages or components formatted as MPUs. 
     For the delivery of NRT User Services or system metadata, an LCT session carries file-based content items. These content files may consist of continuous (time-based) or discrete (non-time-based) media components of an NRT service, or metadata such as Service Signaling or ESG fragments. Delivery of system metadata such as service signaling or ESG fragments may also be achieved through the signaling message mode of MMTP. 
     A broadcast stream is the abstraction for an RF channel, which is defined in terms of a carrier frequency centered within a specified bandwidth. It is identified by the pair [geographic area, frequency]. A physical layer pipe (PLP) corresponds to a portion of the RF channel Each PLP has certain modulation and coding parameters. It is identified by a PLP identifier (PLPID), which is unique within the broadcast stream it belongs to. Here, PLP can be referred to as DP (data pipe). 
     Each service is identified by two forms of service identifier: a compact form that is used in the SLT and is unique only within the broadcast area; and a globally unique form that is used in the SLS and the ESG. A ROUTE session is identified by a source IP address, destination IP address and destination port number. An LCT session (associated with the service component(s) it carries) is identified by a transport session identifier (TSI) which is unique within the scope of the parent ROUTE session. Properties common to the LCT sessions, and certain properties unique to individual LCT sessions, are given in a ROUTE signaling structure called a service-based transport session instance description (S-TSID), which is part of the service layer signaling. Each LCT session is carried over a single physical layer pipe. According to a given embodiment, one LCT session may be transmitted through a plurality of PLPs. Different LCT sessions of a ROUTE session may or may not be contained in different physical layer pipes. Here, the ROUTE session may be delivered through a plurality of PLPs. The properties described in the S-TSID include the TSI value and PLPID for each LCT session, descriptors for the delivery objects/files, and application layer FEC parameters. 
     A MMTP session is identified by destination IP address and destination port number. An MMTP packet flow (associated with the service component(s) it carries) is identified by a packet_id which is unique within the scope of the parent MMTP session. Properties common to each MMTP packet flow, and certain properties of MMTP packet flows, are given in the SLT. Properties for each MMTP session are given by MMT signaling messages, which may be carried within the MMTP session. Different MMTP packet flows of a MMTP session may or may not be contained in different physical layer pipes. Here, the MMTP session may be delivered through a plurality of PLPs. The properties described in the MMT signaling messages include the packet_id value and PLPID for each MMTP packet flow. Here, the MMT signaling messages may have a form defined in MMT, or have a deformed form according to embodiments to be described below. 
     Hereinafter, a description will be given of low level signaling (LLS). 
     Signaling information which is carried in the payload of IP packets with a well-known address/port dedicated to this function is referred to as low level signaling (LLS). The IP address and the port number may be differently configured depending on embodiments. In one embodiment, LLS can be transported in IP packets with address 224.0.23.60 and destination port 4937/udp. LLS may be positioned in a portion expressed by “SLT” on the above-described protocol stack. However, according to a given embodiment, the LLS may be transmitted through a separate physical channel (dedicated channel) in a signal frame without being subjected to processing of the UDP/IP layer. 
     UDP/IP packets that deliver LLS data may be formatted in a form referred to as an LLS table. A first byte of each UDP/IP packet that delivers the LLS data may correspond to a start of the LLS table. The maximum length of any LLS table is limited by the largest IP packet that can be delivered from the PHY layer, 65,507 bytes. 
     The LLS table may include an LLS table ID field that identifies a type of the LLS table, and an LLS table version field that identifies a version of the LLS table. According to a value indicated by the LLS table ID field, the LLS table may include the above-described SLT or a rating region table (RRT). The RRT may have information about content advisory rating. 
     Hereinafter, the SLT will be described. LLS can be signaling information which supports rapid channel scans and bootstrapping of service acquisition by the receiver, and SLT can be a table of signaling information which is used to build a basic service listing and provide bootstrap discovery of SLS. 
     The function of the SLT is similar to that of the program association table (PAT) in MPEG-2 Systems, and the fast information channel (FIC) found in ATSC Systems. For a receiver first encountering the broadcast emission, this is the place to start. SLT supports a rapid channel scan which allows a receiver to build a list of all the services it can receive, with their channel name, channel number, etc., and SLT provides bootstrap information that allows a receiver to discover the SLS for each service. For ROUTE/DASH-delivered services, the bootstrap information includes the destination IP address and destination port of the LCT session that carries the SLS. For MMT/MPU-delivered services, the bootstrap information includes the destination IP address and destination port of the MMTP session carrying the SLS. 
     The SLT supports rapid channel scans and service acquisition by including the following information about each service in the broadcast stream. First, the SLT can include information necessary to allow the presentation of a service list that is meaningful to viewers and that can support initial service selection via channel number or up/down selection. Second, the SLT can include information necessary to locate the service layer signaling for each service listed. That is, the SLT may include access information related to a location at which the SLS is delivered. 
     The illustrated SLT according to the present embodiment is expressed as an XML document having an SLT root element. According to a given embodiment, the SLT may be expressed in a binary format or an XML document. 
     The SLT root element of the SLT illustrated in the figure may include @bsid, @ sltSectionVersion, @ sltSectionNumber, @ totalSltSectionNumbers, @ language, @capabilities, InetSigLoc and/or Service. According to a given embodiment, the SLT root element may further include @providerld. According to a given embodiment, the SLT root element may not include @language. 
     The service element may include @serviceId, @SLTserviceSeqNumber, @protected, @ majorChannelNo, @minorChannelNo, @serviceCategory, @ shortServiceName, @hidden, @ slsProtocolType, BroadcastSignaling, @ slsPlpId, @ slsDestinationIpAddress, @ slsDestinationUdpPort, @ slsSourceIpAddress, @ slsMajorProtocolVersion, @ SlsMinorProtocolVersion, @ serviceLanguage, @broadbandAccessRequired, @capabilities and/or InetSigLoc. 
     According to a given embodiment, an attribute or an element of the SLT may be added/changed/deleted. Each element included in the SLT may additionally have a separate attribute or element, and some attribute or elements according to the present embodiment may be omitted. Here, a field which is marked with @ may correspond to an attribute, and a field which is not marked with @ may correspond to an element. 
     @bsid is an identifier of the whole broadcast stream. The value of BSID may be unique on a regional level. 
     @providerld can be an index of broadcaster that is using part or all of this broadcast stream. This is an optional attribute. When it&#39;s not present, it means that this broadcast stream is being used by one broadcaster. @providerld is not illustrated in the figure. 
     @sltSectionVersion can be a version number of the SLT section. The sltSectionVersion can be incremented by 1 when a change in the information carried within the slt occurs. When it reaches maximum value, it wraps around to 0. 
     @sltSectionNumber can be the number, counting from 1, of this section of the SLT. In other words, @sltSectionNumber may correspond to a section number of the SLT section. When this field is not used, @sltSectionNumber may be set to a default value of 1. 
     @totalSltSectionNumbers can be the total number of sections (that is, the section with the highest sltSectionNumber) of the SLT of which this section is part. sltSectionNumber and totalSltSectionNumbers together can be considered to indicate “Part M of N” of one portion of the SLT when it is sent in fragments. In other words, when the SLT is transmitted, transmission through fragmentation may be supported. When this field is not used, @totalSltSectionNumbers may be set to a default value of 1. A case in which this field is not used may correspond to a case in which the SLT is not transmitted by being fragmented. 
     @language can indicate primary language of the services included in this slt instance. According to a given embodiment, a value of this field may have be a three-character language code defined in the ISO. This field may be omitted. 
     @capabilities can indicate required capabilities for decoding and meaningfully presenting the content for all the services in this slt instance. 
     InetSigLoc can provide a URL telling the receiver where it can acquire any requested type of data from external server(s) via broadband. This element may include @urlType as a lower field. According to a value of the @urlType field, a type of a URL provided by InetSigLoc may be indicated. According to a given embodiment, when the @urlType field has a value of 0, InetSigLoc may provide a URL of a signaling server. When the @urlType field has a value of 1, InetSigLoc may provide a URL of an ESG server. When the @urlType field has other values, the field may be reserved for future use. 
     The service field is an element having information about each service, and may correspond to a service entry. Service element fields corresponding to the number of services indicated by the SLT may be present. Hereinafter, a description will be given of a lower attribute/element of the service field. 
     @serviceId can be an integer number that uniquely identify this service within the scope of this broadcast area. According to a given embodiment, a scope of @serviceId may be changed. @ SLTserviceSeqNumber can be an integer number that indicates the sequence number of the SLT service information with service ID equal to the serviceId attribute above. SLTserviceSeqNumber value can start at 0 for each service and can be incremented by 1 every time any attribute in this service element is changed. If no attribute values are changed compared to the previous Service element with a particular value of ServiceID then SLTserviceSeqNumber would not be incremented. The SLTserviceSeqNumber field wraps back to 0 after reaching the maximum value. 
     @protected is flag information which may indicate whether one or more components for significant reproduction of the service are in a protected state. When set to “1” (true), that one or more components necessary for meaningful presentation is protected. When set to “0” (false), this flag indicates that no components necessary for meaningful presentation of the service are protected. Default value is false. 
     @majorChannelNo is an integer number representing the “major” channel number of the service. An example of the field may have a range of 1 to 999. 
     @minorChannelNo is an integer number representing the “minor” channel number of the service. An example of the field may have a range of 1 to 999. 
     @serviceCategory can indicate the category of this service. This field may indicate a type that varies depending on embodiments. According to a given embodiment, when this field has values of 1, 2, and 3, the values may correspond to a linear A/V service, a linear audio only service, and an app-based service, respectively. When this field has a value of 0, the value may correspond to a service of an undefined category. When this field has other values except for 1, 2, and 3, the field may be reserved for future use. @ shortServiceName can be a short string name of the Service. 
     @hidden can be boolean value that when present and set to “true” indicates that the service is intended for testing or proprietary use, and is not to be selected by ordinary TV receivers. The default value is “false” when not present. 
     @ slsProtocolType can be an attribute indicating the type of protocol of Service Layer Signaling used by this service. This field may indicate a type that varies depending on embodiments. According to a given embodiment, when this field has values of 1 and 2, protocols of SLS used by respective corresponding services may be ROUTE and MMTP, respectively. When this field has other values except for 0, the field may be reserved for future use. This field may be referred to as @ slsProtocol. 
     BroadcastSignaling and lower attributes/elements thereof may provide information related to broadcast signaling. When the BroadcastSignaling element is not present, the child element InetSigLoc of the parent service element can be present and its attribute urlType includes URL_type 0x00 (URL to signaling server). In this case attribute url supports the query parameter svc=&lt;service_id&gt; where service_id corresponds to the serviceId attribute for the parent service element. 
     Alternatively when the BroadcastSignaling element is not present, the element InetSigLoc can be present as a child element of the slt root element and the attribute urlType of that InetSigLoc element includes URL_type 0x00 (URL to signaling server). In this case, attribute url for URL_type 0x00 supports the query parameter svc=&lt;service_Id&gt; where service_id corresponds to the serviceId attribute for the parent Service element. 
     @slsPlpId can be a string representing an integer number indicating the PLP ID of the physical layer pipe carrying the SLS for this service. 
     @slsDestinationIpAddress can be a string containing the dotted-IPv4 destination address of the packets carrying SLS data for this service. 
     @ slsDestinationUdpPort can be a string containing the port number of the packets carrying SLS data for this service. As described in the foregoing, SLS bootstrapping may be performed by destination IP/UDP information. 
     @slsSourceIpAddress can be a string containing the dotted-IPv4 source address of the packets carrying SLS data for this service. 
     @ slsMajorProtocolVersion can be major version number of the protocol used to deliver the service layer signaling for this service. Default value is 1. 
     @SlsMinorProtocolVersion can be minor version number of the protocol used to deliver the service layer signaling for this service. Default value is 0. 
     @serviceLanguage can be a three-character language code indicating the primary language of the service. A value of this field may have a form that varies depending on embodiments. 
     @broadbandAccessRequired can be a Boolean indicating that broadband access is required for a receiver to make a meaningful presentation of the service. Default value is false. When this field has a value of True, the receiver needs to access a broadband for significant service reproduction, which may correspond to a case of hybrid service delivery. 
     @capabilities can represent required capabilities for decoding and meaningfully presenting the content for the service with service ID equal to the service Id attribute above. 
     InetSigLoc can provide a URL for access to signaling or announcement information via broadband, if available. Its data type can be an extension of the any URL data type, adding an @urlType attribute that indicates what the URL gives access to. An @urlType field of this field may indicate the same meaning as that of the @urlType field of InetSigLoc described above. When an InetSigLoc element of attribute URL_type 0x00 is present as an element of the SLT, it can be used to make HTTP requests for signaling metadata. The HTTP POST message body may include a service term. When the InetSigLoc element appears at the section level, the service term is used to indicate the service to which the requested signaling metadata objects apply. If the service term is not present, then the signaling metadata objects for all services in the section are requested. When the InetSigLoc appears at the service level, then no service term is needed to designate the desired service. When an InetSigLoc element of attribute URL_type 0x01 is provided, it can be used to retrieve ESG data via broadband. If the element appears as a child element of the service element, then the URL can be used to retrieve ESG data for that service. If the element appears as a child element of the SLT element, then the URL can be used to retrieve ESG data for all services in that section. 
     In another example of the SLT, @ sltSectionVersion, @ sltSectionNumber, @totalSltSectionNumbers and/or @language fields of the SLT may be omitted 
     In addition, the above-described InetSigLoc field may be replaced by @sltInetSigUri and/or @sltInetEsgUri field. The two fields may include the URI of the signaling server and URI information of the ESG server, respectively. The InetSigLoc field corresponding to a lower field of the SLT and the InetSigLoc field corresponding to a lower field of the service field may be replaced in a similar manner 
     The suggested default values may vary depending on embodiments. An illustrated “use” column relates to the respective fields. Here, “1” may indicate that a corresponding field is an essential field, and “0 . . . 1” may indicate that a corresponding field is an optional field. 
       FIG. 52  illustrates SLS bootstrapping and a service discovery process according to an embodiment of the present invention. 
     Hereinafter, SLS will be described. 
     SLS can be signaling which provides information for discovery and acquisition of services and their content components. 
     For ROUTE/DASH, the SLS for each service describes characteristics of the service, such as a list of its components and where to acquire them, and the receiver capabilities required to make a meaningful presentation of the service. In the ROUTE/DASH system, the SLS includes the user service bundle description (USBD), the S-TSID and the DASH media presentation description (MPD). Here, USBD or user service description (USD) is one of SLS XML fragments, and may function as a signaling herb that describes specific descriptive information. USBD/USD may be extended beyond 3GPP MBMS. Details of USBD/USD will be described below. 
     The service signaling focuses on basic attributes of the service itself, especially those attributes needed to acquire the service. Properties of the service and programming that are intended for viewers appear as service announcement, or ESG data. 
     Having separate Service Signaling for each service permits a receiver to acquire the appropriate SLS for a service of interest without the need to parse the entire SLS carried within a broadcast stream. 
     For optional broadband delivery of Service Signaling, the SLT can include HTTP URLs where the Service Signaling files can be obtained, as described above. 
     LLS is used for bootstrapping SLS acquisition, and subsequently, the SLS is used to acquire service components delivered on either ROUTE sessions or MMTP sessions. The described figure illustrates the following signaling sequences. Receiver starts acquiring the SLT described above. Each service identified by service_id delivered over ROUTE sessions provides SLS bootstrapping information: PLPID(#1), source IP address (sIP1), destination IP address (dIP1), and destination port number (dPort1). Each service identified by service_id delivered over MMTP sessions provides SLS bootstrapping information: PLPID(#2), destination IP address (dIP2), and destination port number (dPort2). 
     For streaming services delivery using ROUTE, the receiver can acquire SLS fragments carried over the IP/UDP/LCT session and PLP; whereas for streaming services delivery using MMTP, the receiver can acquire SLS fragments carried over an MMTP session and PLP. For service delivery using ROUTE, these SLS fragments include USBD/USD fragments, S-TSID fragments, and MPD fragments. They are relevant to one service. USBD/USD fragments describe service layer properties and provide URI references to S-TSID fragments and URI references to MPD fragments. In other words, the USBD/USD may refer to S-TSID and MPD. For service delivery using MMTP, the USBD references the MMT signaling&#39;s MPT message, the MP Table of which provides identification of package ID and location information for assets belonging to the service. Here, an asset is a multimedia data entity, and may refer to a data entity which is combined into one unique ID and is used to generate one multimedia presentation. The asset may correspond to a service component included in one service. The MPT message is a message having the MP table of MMT. Here, the MP table may be an MMT package table having information about content and an MMT asset. Details may be similar to a definition in MMT. Here, media presentation may correspond to a collection of data that establishes bounded/unbounded presentation of media content. 
     The S-TSID fragment provides component acquisition information associated with one service and mapping between DASH Representations found in the MPD and in the TSI corresponding to the component of the service. The S-TSID can provide component acquisition information in the form of a TSI and the associated DASH representation identifier, and PLPID carrying DASH segments associated with the DASH representation. By the PLPID and TSI values, the receiver collects the audio/video components from the service and begins buffering DASH media segments then applies the appropriate decoding processes. 
     For USBD listing service components delivered on MMTP sessions, as illustrated by “Service #2” in the described figure, the receiver also acquires an MPT message with matching MMT_package_id to complete the SLS. An MPT message provides the full list of service components comprising a service and the acquisition information for each component. Component acquisition information includes MMTP session information, the PLPID carrying the session and the packet_id within that session. 
     According to a given embodiment, for example, in ROUTE, two or more S-TSID fragments may be used. Each fragment may provide access information related to LCT sessions delivering content of each service. 
     In ROUTE, S-TSID, USBD/USD, MPD, or an LCT session delivering S-TSID, USBD/USD or MPD may be referred to as a service signaling channel. In MMTP, USBD/UD, an MMT signaling message, or a packet flow delivering the MMTP or USBD/UD may be referred to as a service signaling channel 
     Unlike the illustrated example, one ROUTE or MMTP session may be delivered through a plurality of PLPs. In other words, one service may be delivered through one or more PLPs. As described in the foregoing, one LCT session may be delivered through one PLP. Unlike the figure, according to a given embodiment, components included in one service may be delivered through different ROUTE sessions. In addition, according to a given embodiment, components included in one service may be delivered through different MMTP sessions. According to a given embodiment, components included in one service may be delivered separately through a ROUTE session and an MMTP session. Although not illustrated, components included in one service may be delivered via broadband (hybrid delivery). 
       FIG. 53  illustrates a USBD fragment for ROUTE/DASH according to an embodiment of the present invention. 
     Hereinafter, a description will be given of SLS in delivery based on ROUTE. 
     SLS provides detailed technical information to the receiver to enable the discovery and access of services and their content components. It can include a set of XML-encoded metadata fragments carried over a dedicated LCT session. That LCT session can be acquired using the bootstrap information contained in the SLT as described above. The SLS is defined on a per-service level, and it describes the characteristics and access information of the service, such as a list of its content components and how to acquire them, and the receiver capabilities required to make a meaningful presentation of the service. In the ROUTE/DASH system, for linear services delivery, the SLS consists of the following metadata fragments: USBD, S-TSID and the DASH MPD. The SLS fragments can be delivered on a dedicated LCT transport session with TSI=0. According to a given embodiment, a TSI of a particular LCT session (dedicated LCT session) in which an SLS fragment is delivered may have a different value. According to a given embodiment, an LCT session in which an SLS fragment is delivered may be signaled using the SLT or another scheme. 
     ROUTE/DASH SLS can include the user service bundle description (USBD) and service-based transport session instance description (S-TSID) metadata fragments. These service signaling fragments are applicable to both linear and application-based services. The USBD fragment contains service identification, device capabilities information, references to other SLS fragments required to access the service and constituent media components, and metadata to enable the receiver to determine the transport mode (broadcast and/or broadband) of service components. The S-TSID fragment, referenced by the USBD, provides transport session descriptions for the one or more ROUTE/LCT sessions in which the media content components of a service are delivered, and descriptions of the delivery objects carried in those LCT sessions. The USBD and S-TSID will be described below. 
     In streaming content signaling in ROUTE-based delivery, a streaming content signaling component of SLS corresponds to an MPD fragment. The MPD is typically associated with linear services for the delivery of DASH Segments as streaming content. The MPD provides the resource identifiers for individual media components of the linear/streaming service in the form of Segment URLs, and the context of the identified resources within the Media Presentation. Details of the MPD will be described below. 
     In app-based enhancement signaling in ROUTE-based delivery, app-based enhancement signaling pertains to the delivery of app-based enhancement components, such as an application logic file, locally-cached media files, an network content items, or a notification stream. An application can also retrieve locally-cached data over a broadband connection when available. 
     Hereinafter, a description will be given of details of USBD/USD illustrated in the figure. 
     The top level or entry point SLS fragment is the USBD fragment. An illustrated USBD fragment is an example of the present invention, basic fields of the USBD fragment not illustrated in the figure may be additionally provided according to a given embodiment. As described in the foregoing, the illustrated USBD fragment has an extended form, and may have fields added to a basic configuration. 
     The illustrated USBD may have a bundleDescription root element. The bundleDescription root element may have a userServiceDescription element. The userServiceDescription element may correspond to an instance for one service. 
     The userServiceDescription element may include @serviceld, @atsc:serviceld, @atsc:serviceStatus, @atsc:fullMPDUri, @atsc:sTSIDUri, name, serviceLanguage, atsc:capabilityCode and/or deliveryMethod. 
     @serviceld can be a globally unique URI that identifies a service, unique within the scope of the BSID. This parameter can be used to link to ESG data (Service@globalServiceID). 
     @atsc:serviceld is a reference to corresponding service entry in LLS(SLT). The value of this attribute is the same value of serviceld assigned to the entry. 
     @atsc:serviceStatus can specify the status of this service. The value indicates whether this service is active or inactive. When set to “1” (true), that indicates service is active. When this field is not used, @atsc:serviceStatus may be set to a default value of 1. 
     @ atsc:fullMPDUri can reference an MPD fragment which contains descriptions for contents components of the service delivered over broadcast and optionally, also over broadband. 
     @ atsc:sTSIDUri can reference the S-TSID fragment which provides access related parameters to the Transport sessions carrying contents of this service. 
     name can indicate name of the service as given by the lang attribute. name element can include lang attribute, which indicating language of the service name. The language can be specified according to XML data types. 
     serviceLanguage can represent available languages of the service. The language can be specified according to XML data types. 
     atsc:capabilityCode can specify the capabilities required in the receiver to be able to create a meaningful presentation of the content of this service. According to a given embodiment, this field may specify a predefined capability group. Here, the capability group may be a group of capability attribute values for significant presentation. This field may be omitted according to a given embodiment. 
     deliveryMethod can be a container of transport related information pertaining to the contents of the service over broadcast and (optionally) broadband modes of access. Referring to data included in the service, when the number of the data is N, delivery schemes for respective data may be described by this element. The deliveryMethod may include an r12:broadcastAppService element and an r12:unicastAppService element. Each lower element may include a basePattern element as a lower element. 
     r12:broadcastAppService can be a DASH Representation delivered over broadcast, in multiplexed or non-multiplexed form, containing the corresponding media component(s) belonging to the service, across all Periods of the affiliated media presentation. In other words, each of the fields may indicate DASH representation delivered through the broadcast network. 
     r12:unicastAppService can be a DASH Representation delivered over broadband, in multiplexed or non-multiplexed form, containing the constituent media content component(s) belonging to the service, across all periods of the affiliated media presentation. In other words, each of the fields may indicate DASH representation delivered via broadband. 
     basePattern can be a character pattern for use by the the receiver to match against any portion of the segment URL used by the DASH client to request media segments of a parent representation under its containing period. A match implies that the corresponding requested media segment is carried over broadcast transport. In a URL address for receiving DASH representation expressed by each of the r12:broadcastAppService element and the r12:unicastAppService element, a part of the URL, etc. may have a particular pattern. The pattern may be described by this field. Some data may be distinguished using this information. The proposed default values may vary depending on embodiments. The “use” column illustrated in the figure relates to each field. Here, M may denote an essential field, O may denote an optional field, OD may denote an optional field having a default value, and CM may denote a conditional essential field. 0 . . . 1 to 0 . . . N may indicate the number of available fields. 
       FIG. 54  illustrates an S-TSID fragment for ROUTE/DASH according to an embodiment of the present invention. 
     Hereinafter, a description will be given of the S-TSID illustrated in the figure in detail. 
     S-TSID can be an SLS XML fragment which provides the overall session description information for transport session(s) which carry the content components of a service. The S-TSID is the SLS metadata fragment that contains the overall transport session description information for the zero or more ROUTE sessions and constituent LCT sessions in which the media content components of a service are delivered. The S-TSID also includes file metadata for the delivery object or object flow carried in the LCT sessions of the service, as well as additional information on the payload formats and content components carried in those LCT sessions. 
     Each instance of the S-TSID fragment is referenced in the USBD fragment by the @atsc:sTSIDUri attribute of the userServiceDescription element. The illustrated S-TSID according to the present embodiment is expressed as an XML document. According to a given embodiment, the S-TSID may be expressed in a binary format or as an XML document. 
     The illustrated S-TSID may have an S-TSID root element. The S-TSID root element may include @ serviceId and/or RS. 
     @serviceID can be a reference corresponding service element in the USD. The value of this attribute can reference a service with a corresponding value of service_id. 
     The RS element may have information about a ROUTE session for delivering the service data. Service data or service components may be delivered through a plurality of ROUTE sessions, and thus the number of RS elements may be 1 to N. 
     The RS element may include @bsid, @sIpAddr, @dIpAddr, @dport, @PLPID and/or LS. 
     @bsid can be an identifier of the broadcast stream within which the content component(s) of the broadcastAppService are carried. When this attribute is absent, the default broadcast stream is the one whose PLPs carry SLS fragments for this service. Its value can be identical to that of the broadcast_stream_id in the SLT. 
     @sIpAddr can indicate source IP address. Here, the source IP address may be a source IP address of a ROUTE session for delivering a service component included in the service. As described in the foregoing, service components of one service may be delivered through a plurality of ROUTE sessions. Thus, the service components may be transmitted using another ROUTE session other than the ROUTE session for delivering the S-TSID. Therefore, this field may be used to indicate the source IP address of the ROUTE session. A default value of this field may be a source IP address of a current ROUTE session. When a service component is delivered through another ROUTE session, and thus the ROUTE session needs to be indicated, a value of this field may be a value of a source IP address of the ROUTE session. In this case, this field may correspond to M, that is, an essential field. 
     @dIpAddr can indicate destination IP address. Here, a destination IP address may be a destination IP address of a ROUTE session that delivers a service component included in a service. For a similar case to the above description of @ sIpAddr, this field may indicate a destination IP address of a ROUTE session that delivers a service component. A default value of this field may be a destination IP address of a current ROUTE session. When a service component is delivered through another ROUTE session, and thus the ROUTE session needs to be indicated, a value of this field may be a value of a destination IP address of the ROUTE session. In this case, this field may correspond to M, that is, an essential field. 
     @dport can indicate destination port. Here, a destination port may be a destination port of a ROUTE session that delivers a service component included in a service. For a similar case to the above description of @ sIpAddr, this field may indicate a destination port of a ROUTE session that delivers a service component. A default value of this field may be a destination port number of a current ROUTE session. When a service component is delivered through another ROUTE session, and thus the ROUTE session needs to be indicated, a value of this field may be a destination port number value of the ROUTE session. In this case, this field may correspond to M, that is, an essential field. 
     @PLPID may be an ID of a PLP for a ROUTE session expressed by an RS. A default value may be an ID of a PLP of an LCT session including a current S-TSID. According to a given embodiment, this field may have an ID value of a PLP for an LCT session for delivering an S-TSID in the ROUTE session, and may have ID values of all PLPs for the ROUTE session. 
     An LS element may have information about an LCT session for delivering a service data. Service data or service components may be delivered through a plurality of LCT sessions, and thus the number of LS elements may be 1 to N. 
     The LS element may include @tsi, @PLPID, @bw, @startTime, @endTime, SrcFlow and/or RprFlow. 
     @tsi may indicate a TSI value of an LCT session for delivering a service component of a service. 
     @PLPID may have ID information of a PLP for the LCT session. This value may be overwritten on a basic ROUTE session value. 
     @bw may indicate a maximum bandwidth value. @startTime may indicate a start time of the LCT session. @endTime may indicate an end time of the LCT session. A SrcFlow element may describe a source flow of ROUTE. A RprFlow element may describe a repair flow of ROUTE. 
     The proposed default values may be varied according to an embodiment. The “use” column illustrated in the figure relates to each field. Here, M may denote an essential field, O may denote an optional field, OD may denote an optional field having a default value, and CM may denote a conditional essential field. 0 . . . 1 to 0 . . . N may indicate the number of available fields. 
     Hereinafter, a description will be given of MPD for ROUTE/DASH. 
     The MPD is an SLS metadata fragment which contains a formalized description of a DASH Media Presentation, corresponding to a linear service of a given duration defined by the broadcaster (for example a single TV program, or the set of contiguous linear TV programs over a period of time). The contents of the MPD provide the resource identifiers for Segments and the context for the identified resources within the Media Presentation. The data structure and semantics of the MPD fragment can be according to the MPD defined by MPEG DASH. 
     One or more of the DASH Representations conveyed in the MPD can be carried over broadcast. The MPD may describe additional Representations delivered over broadband, e.g. in the case of a hybrid service, or to support service continuity in handoff from broadcast to broadcast due to broadcast signal degradation (e.g. driving through a tunnel). 
       FIG. 55  illustrates a USBD/USD fragment for MMT according to an embodiment of the present invention. 
     MMT SLS for linear services comprises the USBD fragment and the MMT Package (MP) table. The MP table is as described above. The USBD fragment contains service identification, device capabilities information, references to other SLS information required to access the service and constituent media components, and the metadata to enable the receiver to determine the transport mode (broadcast and/or broadband) of the service components. The MP table for MPU components, referenced by the USBD, provides transport session descriptions for the MMTP sessions in which the media content components of a service are delivered and the descriptions of the Assets carried in those MMTP sessions. 
     The streaming content signaling component of the SLS for MPU components corresponds to the MP table defined in MMT. The MP table provides a list of MMT assets where each asset corresponds to a single service component and the description of the location information for this component. 
     USBD fragments may also contain references to the S-TSID and the MPD as described above, for service components delivered by the ROUTE protocol and the broadband, respectively. According to a given embodiment, in delivery through MMT, a service component delivered through the ROUTE protocol is NRT data, etc. Thus, in this case, MPD may be unnecessary. In addition, in delivery through MMT, information about an LCT session for delivering a service component, which is delivered via broadband, is unnecessary, and thus an S-TSID may be unnecessary. Here, an MMT package may be a logical collection of media data delivered using MMT. Here, an MMTP packet may refer to a formatted unit of media data delivered using MMT. An MPU may refer to a generic container of independently decodable timed/non-timed data. Here, data in the MPU is media codec agnostic. 
     Hereinafter, a description will be given of details of the USBD/USD illustrated in the figure. 
     The illustrated USBD fragment is an example of the present invention, and basic fields of the USBD fragment may be additionally provided according to an embodiment. As described in the foregoing, the illustrated USBD fragment has an extended form, and may have fields added to a basic structure. 
     The illustrated USBD according to an embodiment of the present invention is expressed as an XML document. According to a given embodiment, the USBD may be expressed in a binary format or as an XML document. 
     The illustrated USBD may have a bundleDescription root element. The bundleDescription root element may have a userServiceDescription element. The userServiceDescription element may be an instance for one service. 
     The userServiceDescription element may include @serviceld, @atsc:serviceld, name, serviceLanguage, atsc:capabilityCode, atsc:Channel, atsc:mpuComponent, atsc:routeComponent, atsc:broadbandComponent and/or atsc:ComponentInfo. 
     Here, @ serviceId, @ atsc:serviceId, name, serviceLanguage, and atsc:capabilityCode may be as described above. The lang field below the name field may be as described above. atsc:capabilityCode may be omitted according to a given embodiment. 
     The userServiceDescription element may further include an atsc:contentAdvisoryRating element according to an embodiment. This element may be an optional element. atsc:contentAdvisoryRating can specify the content advisory rating. This field is not illustrated in the figure. 
     atsc:Channel may have information about a channel of a service. The atsc:Channel element may include @atsc:majorChannelNo, @atsc:minorChannelNo, @ atsc:serviceLang, @ atsc:serviceGenre, @ atsc:serviceIcon and/or atsc:ServiceDescription. @atsc:majorChannelNo, @atsc:minorChannelNo, and @atsc:serviceLang may be omitted according to a given embodiment. 
     @atsc:majorChannelNo is an attribute that indicates the major channel number of the service. 
     @atsc:minorChannelNo is an attribute that indicates the minor channel number of the service. 
     @atsc:serviceLang is an attribute that indicates the primary language used in the service. 
     @atsc:serviceGenre is an attribute that indicates primary genre of the service. 
     @atsc:serviceIcon is an attribute that indicates the Uniform Resource Locator (URL) for the icon used to represent this service. 
     atsc:ServiceDescription includes service description, possibly in multiple languages. atsc:ServiceDescription includes can include @atsc:serviceDescrText and/or @ atsc:serviceDescrLang. 
     @atsc:serviceDescrText is an attribute that indicates description of the service. 
     @atsc:serviceDescrLang is an attribute that indicates the language of the serviceDescrText attribute above. 
     atsc:mpuComponent may have information about a content component of a service delivered in a form of an MPU. atsc:mpuComponent may include @ atsc:mmtPackageId and/or @ atsc: nextMmtPackageId. 
     @atsc:mmtPackageId can reference a MMT Package for content components of the service delivered as MPUs. 
     @atsc:nextMmtPackageId can reference a MMT Package to be used after the one referenced by @atsc:mmtPackageId in time for content components of the service delivered as MPUs. 
     atsc:routeComponent may have information about a content component of a service delivered through ROUTE. atsc:routeComponent may include @atsc:sTSIDUri, @sTSIDPlpId, @ sTSIDDestinationIpAddress, @sTSIDDestinationUdpPort, @sTSIDSourceIpAddress, @ sTSIDMajorProtocolVersion and/or @sTSIDMinorProtocolVersion. 
     @atsc:sTSIDUri can be a reference to the S-TSID fragment which provides access related parameters to the Transport sessions carrying contents of this service. This field may be the same as a URI for referring to an S-TSID in USBD for ROUTE described above. As described in the foregoing, in service delivery by the MMTP, service components, which are delivered through NRT, etc., may be delivered by ROUTE. This field may be used to refer to the S-TSID therefor. 
     @sTSIDPlpId can be a string representing an integer number indicating the PLP ID of the physical layer pipe carrying the S-TSID for this service. (default: current physical layer pipe). 
     @sTSIDDestinationIpAddress can be a string containing the dotted-IPv4 destination address of the packets carrying S-TSID for this service. (default: current MMTP session&#39;s source IP address) 
     @ sTSIDDestinationUdpPort can be a string containing the port number of the packets carrying S-TSID for this service. 
     @sTSIDSourceIpAddress can be a string containing the dotted-IPv4 source address of the packets carrying S-TSID for this service. 
     @sTSIDMajorProtocolVersion can indicate major version number of the protocol used to deliver the S-TSID for this service. Default value is 1. 
     @sTSIDMinorProtocolVersion can indicate minor version number of the protocol used to deliver the S-TSID for this service. Default value is 0. 
     atsc:broadbandComponent may have information about a content component of a service delivered via broadband. In other words, atsc:broadbandComponent may be a field on the assumption of hybrid delivery. atsc:broadbandComponent may further include @ atsc:fullfMPDUri. 
     @atsc:fullfMPDUri can be a reference to an MPD fragment which contains descriptions for contents components of the service delivered over broadband. 
     An atsc:ComponentInfo field may have information about an available component of a service. The atsc:Componentlnfo field may have information about a type, a role, a name, etc. of each component. The number of atsc:Componentlnfo fields may correspond to the number (N) of respective components. The atsc:Componentlnfo field may include @atsc:componentType, @atsc:componentRole, @ atsc:componentProtectedFlag, @ atsc:componentId and/or @ atsc:componentName. 
     @atsc:componentType is an attribute that indicates the type of this component. Value of 0 indicates an audio component. Value of 1 indicates a video component. Value of 2 indicated a closed caption component. Value of 3 indicates an application component. Values 4 to 7 are reserved. A meaning of a value of this field may be differently set depending on embodiments. 
     @atsc:componentRole is an attribute that indicates the role or kind of this component. 
     For audio (when componentType attribute above is equal to 0): values of componentRole attribute are as follows: 0=Complete main, 1=Music and Effects, 2=Dialog, 3=Commentary, 4=Visually Impaired, 5=Hearing Impaired, 6=Voice-Over, 7-254=reserved, 255=unknown. 
     For video (when componentType attribute above is equal to 1) values of componentRole attribute are as follows: 0=Primary video, 1=Alternative camera view, 2=Other alternative video component, 3=Sign language inset, 4=Follow subject video, 5=3D video left view, 6=3D video right view, 7=3D video depth information, 8=Part of video array &lt;x,y&gt; of &lt;n,m&gt;, 9=Follow-Subject metadata, 10-254=reserved, 255=unknown. 
     For Closed Caption component (when componentType attribute above is equal to 2) values of componentRole attribute are as follows: 0=Normal, 1=Easy reader, 2-254=reserved, 255=unknown. 
     When componentType attribute above is between 3 to 7, inclusive, the componentRole can be equal to 255. A meaning of a value of this field may be differently set depending on embodiments. 
     @atsc:componentProtectedFlag is an attribute that indicates if this component is protected (e.g. encrypted). When this flag is set to a value of 1 this component is protected (e.g. encrypted). When this flag is set to a value of 0 this component is not protected (e.g. encrypted). When not present the value of componentProtectedFlag attribute is inferred to be equal to 0. A meaning of a value of this field may be differently set depending on embodiments. 
     @atsc:componentId is an attribute that indicates the identifier of this component. The value of this attribute can be the same as the asset_id in the MP table corresponding to this component. 
     @atsc:componentName is an attribute that indicates the human readable name of this component. 
     The proposed default values may vary depending on embodiments. The “use” column illustrated in the figure relates to each field. Here, M may denote an essential field, O may denote an optional field, OD may denote an optional field having a default value, and CM may denote a conditional essential field. 0 . . . 1 to 0 . . . N may indicate the number of available fields. 
     Hereinafter, a description will be given of MPD for MMT. 
     The Media Presentation Description is an SLS metadata fragment corresponding to a linear service of a given duration defined by the broadcaster (for example a single TV program, or the set of contiguous linear TV programs over a period of time). The contents of the MPD provide the resource identifiers for segments and the context for the identified resources within the media presentation. The data structure and semantics of the MPD can be according to the MPD defined by MPEG DASH. 
     In the present embodiment, an MPD delivered by an MMTP session describes Representations delivered over broadband, e.g. in the case of a hybrid service, or to support service continuity in handoff from broadcast to broadband due to broadcast signal degradation (e.g. driving under a mountain or through a tunnel). 
     Hereinafter, a description will be given of an MMT signaling message for MMT. 
     When MMTP sessions are used to carry a streaming service, MMT signaling messages defined by MMT are delivered by MMTP packets according to signaling message mode defined by MMT. The value of the packet_id field of MMTP packets carrying service layer signaling is set to ‘00’ except for MMTP packets carrying MMT signaling messages specific to an asset, which can be set to the same packet_id value as the MMTP packets carrying the asset. Identifiers referencing the appropriate package for each service are signaled by the USBD fragment as described above. MMT Package Table (MPT) messages with matching MMT_package_id can be delivered on the MMTP session signaled in the SLT. Each MMTP session carries MMT signaling messages specific to its session or each asset delivered by the MMTP session. 
     In other words, it is possible to access USBD of the MMTP session by specifying an IP destination address/port number, etc. of a packet having the SLS for a particular service in the SLT. As described in the foregoing, a packet ID of an MMTP packet carrying the SLS may be designated as a particular value such as 00, etc. It is possible to access an MPT message having a matched packet ID using the above-described package IP information of USBD. As described below, the MPT message may be used to access each service component/asset. 
     The following MMTP messages can be delivered by the MMTP session signaled in the SLT. 
     MMT Package Table (MPT) message: This message carries an MP (MMT Package) table which contains the list of all Assets and their location information as defined by MMT. If an Asset is delivered by a PLP different from the current PLP delivering the MP table, the identifier of the PLP carrying the asset can be provided in the MP table using physical layer pipe identifier descriptor. The physical layer pipe identifier descriptor will be described below. 
     MMT ATSC3 (MA3) message mmt_atsc3_message( ): This message carries system metadata specific for services including service layer signaling as described above. mmt_atsc3_message( ) will be described below. 
     The following MMTP messages can be delivered by the MMTP session signaled in the SLT, if required. 
     Media Presentation Information (MPI) message: This message carries an MPI table which contains the whole document or a subset of a document of presentation information. An MP table associated with the MPI table also can be delivered by this message. 
     Clock Relation Information (CRI) message: This message carries a CRI table which contains clock related information for the mapping between the NTP timestamp and the MPEG-2 STC. According to a given embodiment, the CRI message may not be delivered through the MMTP session. 
     The following MMTP messages can be delivered by each MMTP session carrying streaming content. 
     Hypothetical Receiver Buffer Model message: This message carries information required by the receiver to manage its buffer. 
     Hypothetical Receiver Buffer Model Removal message: This message carries information required by the receiver to manage its MMT de-capsulation buffer. 
     Hereinafter, a description will be given of mmt_atsc3_message( ) corresponding to one of MMT signaling messages. An MMT Signaling message mmt_atsc3_message( ) is defined to deliver information specific to services according to the present invention described above. The signaling message may include message ID, version, and/or length fields corresponding to basic fields of the MMT signaling message. A payload of the signaling message may include service ID information, content type information, content version information, content compression information and/or URI information. The content type information may indicate a type of data included in the payload of the signaling message. The content version information may indicate a version of data included in the payload, and the content compression information may indicate a type of compression applied to the data. The URI information may have URI information related to content delivered by the message. 
     Hereinafter, a description will be given of the physical layer pipe identifier descriptor. 
     The physical layer pipe identifier descriptor is a descriptor that can be used as one of descriptors of the MP table described above. The physical layer pipe identifier descriptor provides information about the PLP carrying an asset. If an asset is delivered by a PLP different from the current PLP delivering the MP table, the physical layer pipe identifier descriptor can be used as an asset descriptor in the associated MP table to identify the PLP carrying the asset. The physical layer pipe identifier descriptor may further include BSID information in addition to PLP ID information. The BSID may be an ID of a broadcast stream that delivers an MMTP packet for an asset described by the descriptor. 
       FIG. 56  illustrates a link layer protocol architecture according to an embodiment of the present invention. 
     Hereinafter, a link layer will be described. 
     The link layer is the layer between the physical layer and the network layer, and transports the data from the network layer to the physical layer at the sending side and transports the data from the physical layer to the network layer at the receiving side. The purpose of the link layer includes abstracting all input packet types into a single format for processing by the physical layer, ensuring flexibility and future extensibility for as yet undefined input types. In addition, processing within the link layer ensures that the input data can be transmitted in an efficient manner, for example by providing options to compress redundant information in the headers of input packets. The operations of encapsulation, compression and so on are referred to as the link layer protocol and packets created using this protocol are called link layer packets. The link layer may perform functions such as packet encapsulation, overhead reduction and/or signaling transmission, etc. 
     Hereinafter, packet encapsulation will be described. Link layer protocol allows encapsulation of any type of packet, including ones such as IP packets and MPEG-2 TS. Using link layer protocol, the physical layer need only process one single packet format, independent of the network layer protocol type (here we consider MPEG-2 TS packet as a kind of network layer packet.) Each network layer packet or input packet is transformed into the payload of a generic link layer packet. Additionally, concatenation and segmentation can be performed in order to use the physical layer resources efficiently when the input packet sizes are particularly small or large. 
     As described in the foregoing, segmentation may be used in packet encapsulation. When the network layer packet is too large to process easily in the physical layer, the network layer packet is divided into two or more segments. The link layer packet header includes protocol fields to perform segmentation on the sending side and reassembly on the receiving side. When the network layer packet is segmented, each segment can be encapsulated to link layer packet in the same order as original position in the network layer packet. Also each link layer packet which includes a segment of network layer packet can be transported to PHY layer consequently. 
     As described in the foregoing, concatenation may be used in packet encapsulation. When the network layer packet is small enough for the payload of a link layer packet to include several network layer packets, the link layer packet header includes protocol fields to perform concatenation. The concatenation is combining of multiple small sized network layer packets into one payload. When the network layer packets are concatenated, each network layer packet can be concatenated to payload of link layer packet in the same order as original input order. Also each packet which constructs a payload of link layer packet can be whole packet, not a segment of packet. 
     Hereinafter, overhead reduction will be described. Use of the link layer protocol can result in significant reduction in overhead for transport of data on the physical layer. The link layer protocol according to the present invention may provide IP overhead reduction and/or MPEG-2 TS overhead reduction. In IP overhead reduction, IP packets have a fixed header format, however some of the information which is needed in a communication environment may be redundant in a broadcast environment. Link layer protocol provides mechanisms to reduce the broadcast overhead by compressing headers of IP packets. In MPEG-2 TS overhead reduction, link layer protocol provides sync byte removal, null packet deletion and/or common header removal (compression). First, sync byte removal provides an overhead reduction of one byte per TS packet, secondly a null packet deletion mechanism removes the 188 byte null TS packets in a manner that they can be re-inserted at the receiver and finally a common header removal mechanism. 
     For signaling transmission, in the link layer protocol, a particular format for the signaling packet may be provided for link layer signaling, which will be described below. 
     In the illustrated link layer protocol architecture according to an embodiment of the present invention, link layer protocol takes as input network layer packets such as IPv4, MPEG-2 TS and so on as input packets. Future extension indicates other packet types and protocol which is also possible to be input in link layer. Link layer protocol also specifies the format and signaling for any link layer signaling, including information about mapping to specific channel to the physical layer. Figure also shows how ALP incorporates mechanisms to improve the efficiency of transmission, via various header compression and deletion algorithms. In addition, the link layer protocol may basically encapsulate input packets. 
       FIG. 57  illustrates a structure of a base header of a link layer packet according to an embodiment of the present invention. Hereinafter, the structure of the header will be described. 
     A link layer packet can include a header followed by the data payload. The header of a link layer packet can include a base header, and may include an additional header depending on the control fields of the base header. The presence of an optional header is indicated from flag fields of the additional header. According to a given embodiment, a field indicating the presence of an additional header and an optional header may be positioned in the base header. 
     Hereinafter, the structure of the base header will be described. The base header for link layer packet encapsulation has a hierarchical structure. The base header can be two bytes in length and is the minimum length of the link layer packet header. 
     The illustrated base header according to the present embodiment may include a Packet_Type field, a PC field and/or a length field. According to a given embodiment, the base header may further include an HM field or an S/C field. 
     Packet_Type field can be a 3-bit field that indicates the original protocol or packet type of the input data before encapsulation into a link layer packet. An IPv4 packet, a compressed IP packet, a link layer signaling packet, and other types of packets may have the base header structure and may be encapsulated. However, according to a given embodiment, the MPEG-2 TS packet may have a different particular structure, and may be encapsulated. When the value of Packet_Type is “000”, “001” “100” or “111”, that is the original data type of an ALP packet is one of an IPv4 packet, a compressed IP packet, link layer signaling or extension packet. When the MPEG-2 TS packet is encapsulated, the value of Packet_Type can be “010”. Other values of the Packet_Type field may be reserved for future use. 
     Payload_Configuration (PC) field can be a 1-bit field that indicates the configuration of the payload. A value of 0 can indicate that the link layer packet carries a single, whole input packet and the following field is the Header_Mode field. A value of 1 can indicate that the link layer packet carries more than one input packet (concatenation) or a part of a large input packet (segmentation) and the following field is the Segmentation_Concatenation field. 
     Header_Mode (HM) field can be a 1-bit field, when set to 0, that can indicate there is no additional header, and that the length of the payload of the link layer packet is less than 2048 bytes. This value may be varied depending on embodiments. A value of 1 can indicate that an additional header for single packet defined below is present following the Length field. In this case, the length of the payload is larger than 2047 bytes and/or optional features can be used (sub stream identification, header extension, etc.). This value may be varied depending on embodiments. This field can be present only when Payload_Configuration field of the link layer packet has a value of 0. 
     Segmentation_Concatenation (S/C) field can be a 1-bit field, when set to 0, that can indicate that the payload carries a segment of an input packet and an additional header for segmentation defined below is present following the Length field. A value of 1 can indicate that the payload carries more than one complete input packet and an additional header for concatenation defined below is present following the Length field. This field can be present only when the value of Payload_Configuration field of the ALP packet is 1. 
     Length field can be a 11-bit field that indicates the 11 least significant bits (LSBs) of the length in bytes of payload carried by the link layer packet. When there is a Length_MSB field in the following additional header, the length field is concatenated with the Length_MSB field, and is the LSB to provide the actual total length of the payload. The number of bits of the length field may be changed to another value rather than 11 bits. 
     Following types of packet configuration are thus possible: a single packet without any additional header, a single packet with an additional header, a segmented packet and a concatenated packet. According to a given embodiment, more packet configurations may be made through a combination of each additional header, an optional header, an additional header for signaling information to be described below, and an additional header for time extension. 
       FIG. 58  illustrates a structure of an additional header of a link layer packet according to an embodiment of the present invention. 
     Various types of additional headers may be present. Hereinafter, a description will be given of an additional header for a single packet. 
     This additional header for single packet can be present when Header_Mode (HM)=“1”. The Header_Mode (HM) can be set to 1 when the length of the payload of the link layer packet is larger than 2047 bytes or when the optional fields are used. The additional header for single packet is shown in Figure (tsib 10010 ). 
     Length_MSB field can be a 5-bit field that can indicate the most significant bits (MSBs) of the total payload length in bytes in the current link layer packet, and is concatenated with the Length field containing the 11 least significant bits (LSBs) to obtain the total payload length. The maximum length of the payload that can be signaled is therefore 65535 bytes. The number of bits of the length field may be changed to another value rather than 11 bits. In addition, the number of bits of the Length_MSB field may be changed, and thus a maximum expressible payload length may be changed. According to a given embodiment, each length field may indicate a length of a whole link layer packet rather than a payload. 
     SIF (Sub stream Identifier Flag) field can be a 1-bit field that can indicate whether the sub stream ID (SID) is present after the HEF field or not. When there is no SID in this link layer packet, SIF field can be set to 0. When there is a SID after HEF field in the link layer packet, SIF can be set to 1. The detail of SID is described below. 
     HEF (Header Extension Flag) field can be a 1-bit field that can indicate, when set to 1 additional header is present for future extension. A value of 0 can indicate that this extension header is not present. 
     Hereinafter, a description will be given of an additional header when segmentation is used. 
     This additional header (tsib 10020 ) can be present when Segmentation_Concatenation (S/C)=“0”. Segment_Sequence_Number can be a 5-bit unsigned integer that can indicate the order of the corresponding segment carried by the link layer packet. For the link layer packet which carries the first segment of an input packet, the value of this field can be set to 0x0. This field can be incremented by one with each additional segment belonging to the segmented input packet. 
     Last_Segment_Indicator (LSI) can be a 1-bit field that can indicate, when set to 1, that the segment in this payload is the last one of input packet. A value of 0, can indicate that it is not last segment. 
     SIF (Sub stream Identifier Flag) can be a 1-bit field that can indicate whether the SID is present after the HEF field or not. When there is no SID in the link layer packet, SIF field can be set to 0. When there is a SID after the HEF field in the link layer packet, SIF can be set to 1. 
     HEF (Header Extension Flag) can be a This 1-bit field that can indicate, when set to 1, that the optional header extension is present after the additional header for future extensions of the link layer header. A value of 0 can indicate that optional header extension is not present. 
     According to a given embodiment, a packet ID field may be additionally provided to indicate that each segment is generated from the same input packet. This field may be unnecessary and thus be omitted when segments are transmitted in order. 
     Hereinafter, a description will be given of an additional header when concatenation is used. 
     This additional header (tsib 10030 ) can be present when Segmentation_Concatenation (S/C)=“1”. 
     Length_MSB can be a 4-bit field that can indicate MSB bits of the payload length in bytes in this link layer packet. The maximum length of the payload is 32767 bytes for concatenation. As described in the foregoing, a specific numeric value may be changed. 
     Count can be a field that can indicate the number of the packets included in the link layer packet. The number of the packets included in the link layer packet, 2 can be set to this field. So, its maximum value of concatenated packets in a link layer packet is 9. A scheme in which the count field indicates the number may be varied depending on embodiments. That is, the numbers from 1 to 8 may be indicated. 
     HEF (Header Extension Flag) can be a 1-bit field that can indicate, when set to 1 the optional header extension is present after the additional header for future extensions of the link layer header. A value of 0, can indicate extension header is not present. 
     Component_Length can be a 12-bit length field that can indicate the length in byte of each packet. Component_Length fields are included in the same order as the packets present in the payload except last component packet. The number of length field can be indicated by (Count+1). According to a given embodiment, length fields, the number of which is the same as a value of the count field, may be present. When a link layer header consists of an odd number of Component_Length, four stuffing bits can follow after the last Component_Length field. These bits can be set to 0. According to a given embodiment, a Component_length field indicating a length of a last concatenated input packet may not be present. In this case, the length of the last concatenated input packet may correspond to a length obtained by subtracting a sum of values indicated by respective Component_length fields from a whole payload length. 
     Hereinafter, the optional header will be described. 
     As described in the foregoing, the optional header may be added to a rear of the additional header. The optional header field can contain SID and/or header extension. The SID is used to filter out specific packet stream in the link layer level. One example of SID is the role of service identifier in a link layer stream carrying multiple services. The mapping information between a service and the SID value corresponding to the service can be provided in the SLT, if applicable. The header extension contains extended field for future use. Receivers can ignore any header extensions which they do not understand. 
     SID (Sub stream Identifier) can be a 8-bit field that can indicate the sub stream identifier for the link layer packet. If there is optional header extension, SID present between additional header and optional header extension. 
     Header_Extension( ) can include the fields defined below. 
     Extension_Type can be an 8-bit field that can indicate the type of the Header_Extension ( ). 
     Extension_Length can be a 8-bit field that can indicate the length of the Header Extension ( ) in bytes counting from the next byte to the last byte of the Header_Extension ( ). 
     Extension_Byte can be a byte representing the value of the Header_Extension ( ). 
       FIG. 59  illustrates a structure of an additional header of a link layer packet according to another embodiment of the present invention. 
     Hereinafter, a description will be given of an additional header for signaling information. 
     How link layer signaling is incorporated into link layer packets are as follows. Signaling packets are identified by when the Packet_Type field of the base header is equal to 100. 
     Figure (tsib 11010 ) shows the structure of the link layer packets containing additional header for signaling information. In addition to the link layer header, the link layer packet can consist of two additional parts, additional header for signaling information and the actual signaling data itself. The total length of the link layer signaling packet is shown in the link layer packet header. 
     The additional header for signaling information can include following fields. According to a given embodiment, some fields may be omitted. 
     Signaling_Type can be an 8-bit field that can indicate the type of signaling. 
     Signaling_Type_Extension can be a 16-bit filed that can indicate the attribute of the signaling. Detail of this field can be defined in signaling specification. 
     Signaling_Version can be an 8-bit field that can indicate the version of signaling. 
     Signaling_Format can be a 2-bit field that can indicate the data format of the signaling data. Here, a signaling format may refer to a data format such as a binary format, an XML format, etc. 
     Signaling_Encoding can be a 2-bit field that can specify the encoding/compression format. This field may indicate whether compression is not performed and which type of compression is performed. 
     Hereinafter, a description will be given of an additional header for packet type extension. 
     In order to provide a mechanism to allow an almost unlimited number of additional protocol and packet types to be carried by link layer in the future, the additional header is defined. Packet type extension can be used when Packet_type is 111 in the base header as described above. Figure (tsib 11020 ) shows the structure of the link layer packets containing additional header for type extension. 
     The additional header for type extension can include following fields. According to a given embodiment, some fields may be omitted. 
     extended_type can be a 16-bit field that can indicate the protocol or packet type of the input encapsulated in the link layer packet as payload. This field cannot be used for any protocol or packet type already defined by Packet_Type field. 
       FIG. 60  illustrates a header structure of a link layer packet for an MPEG-2 TS packet and an encapsulation process thereof according to an embodiment of the present invention. 
     Hereinafter, a description will be given of a format of the link layer packet when the MPEG-2 TS packet is input as an input packet. 
     In this case, the Packet_Type field of the base header is equal to 010. Multiple TS packets can be encapsulated within each link layer packet. The number of TS packets is signaled via the NUMTS field. In this case, as described in the foregoing, a particular link layer packet header format may be used. 
     Link layer provides overhead reduction mechanisms for MPEG-2 TS to enhance the transmission efficiency. The sync byte (0x47) of each TS packet can be deleted. The option to delete NULL packets and similar TS headers is also provided. 
     In order to avoid unnecessary transmission overhead, TS null packets (PID=0x1FFF) may be removed. Deleted null packets can be recovered in receiver side using DNP field. The DNP field indicates the count of deleted null packets. Null packet deletion mechanism using DNP field is described below. 
     In order to achieve more transmission efficiency, similar header of MPEG-2 TS packets can be removed. When two or more successive TS packets have sequentially increased continuity counter fields and other header fields are the same, the header is sent once at the first packet and the other headers are deleted. HDM field can indicate whether the header deletion is performed or not. Detailed procedure of common TS header deletion is described below. 
     When all three overhead reduction mechanisms are performed, overhead reduction can be performed in sequence of sync removal, null packet deletion, and common header deletion. According to a given embodiment, a performance order of respective mechanisms may be changed. In addition, some mechanisms may be omitted according to a given embodiment. 
     The overall structure of the link layer packet header when using MPEG-2 TS packet encapsulation is depicted in Figure (tsib 12010 ). 
     Hereinafter, a description will be given of each illustrated field. Packet_Type can be a 3-bit field that can indicate the protocol type of input packet as describe above. For MPEG-2 TS packet encapsulation, this field can always be set to 010. 
     NUMTS (Number of TS packets) can be a 4-bit field that can indicate the number of TS packets in the payload of this link layer packet. A maximum of 16 TS packets can be supported in one link layer packet. The value of NUMTS=0 can indicate that 16 TS packets are carried by the payload of the link layer packet. For all other values of NUMTS, the same number of TS packets are recognized, e.g. NUMTS=0001 means one TS packet is carried. 
     AHF (Additional Header Flag) can be a field that can indicate whether the additional header is present of not. A value of 0 indicates that there is no additional header. A value of 1 indicates that an additional header of length 1-byte is present following the base header. If null TS packets are deleted or TS header compression is applied this field can be set to 1. The additional header for TS packet encapsulation consists of the following two fields and is present only when the value of AHF in this link layer packet is set to 1. 
     HDM (Header Deletion Mode) can be a 1-bit field that indicates whether TS header deletion can be applied to this link layer packet. A value of 1 indicates that TS header deletion can be applied. A value of “0” indicates that the TS header deletion method is not applied to this link layer packet. 
     DNP (Deleted Null Packets) can be a 7-bit field that indicates the number of deleted null TS packets prior to this link layer packet. A maximum of 128 null TS packets can be deleted. When HDM=0 the value of DNP=0 can indicate that 128 null packets are deleted. When HDM=1 the value of DNP=0 can indicate that no null packets are deleted. For all other values of DNP, the same number of null packets are recognized, e.g. DNP=5 means 5 null packets are deleted. 
     The number of bits of each field described above may be changed. According to the changed number of bits, a minimum/maximum value of a value indicated by the field may be changed. These numbers may be changed by a designer. 
     Hereinafter, SYNC byte removal will be described. 
     When encapsulating TS packets into the payload of a link layer packet, the SYNC byte (0x47) from the start of each TS packet can be deleted. Hence the length of the MPEG2-TS packet encapsulated in the payload of the link layer packet is always of length 187 bytes (instead of 188 bytes originally). 
     Hereinafter, null packet deletion will be described. 
     Transport Stream rules require that bit rates at the output of a transmitter&#39;s multiplexer and at the input of the receiver&#39;s de-multiplexer are constant in time and the end-to-end delay is also constant. For some Transport Stream input signals, null packets may be present in order to accommodate variable bitrate services in a constant bitrate stream. In this case, in order to avoid unnecessary transmission overhead, TS null packets (that is TS packets with PID=0x1FFF) may be removed. The process is carried-out in a way that the removed null packets can be re-inserted in the receiver in the exact place where they were originally, thus guaranteeing constant bitrate and avoiding the need for PCR time stamp updating. 
     Before generation of a link layer packet, a counter called DNP (Deleted Null-Packets) can first be reset to zero and then incremented for each deleted null packet preceding the first non-null TS packet to be encapsulated into the payload of the current link layer packet. Then a group of consecutive useful TS packets is encapsulated into the payload of the current link layer packet and the value of each field in its header can be determined. After the generated link layer packet is injected to the physical layer, the DNP is reset to zero. When DNP reaches its maximum allowed value, if the next packet is also a null packet, this null packet is kept as a useful packet and encapsulated into the payload of the next link layer packet. Each link layer packet can contain at least one useful TS packet in its payload. 
     Hereinafter, TS packet header deletion will be described. TS packet header deletion may be referred to as TS packet header compression. 
     When two or more successive TS packets have sequentially increased continuity counter fields and other header fields are the same, the header is sent once at the first packet and the other headers are deleted. When the duplicated MPEG-2 TS packets are included in two or more successive TS packets, header deletion cannot be applied in transmitter side. HDM field can indicate whether the header deletion is performed or not. When TS header deletion is performed, HDM can be set to 1. In the receiver side, using the first packet header, the deleted packet headers are recovered, and the continuity counter is restored by increasing it in order from that of the first header. 
     An example tsib 12020  illustrated in the figure is an example of a process in which an input stream of a TS packet is encapsulated into a link layer packet. First, a TS stream including TS packets having SYNC byte (0x47) may be input. First, sync bytes may be deleted through a sync byte deletion process. In this example, it is presumed that null packet deletion is not performed. 
     Here, it is presumed that packet headers of eight TS packets have the same field values except for CC, that is, a continuity counter field value. In this case, TS packet deletion/compression may be performed. Seven remaining TS packet headers are deleted except for a first TS packet header corresponding to CC=1. The processed TS packets may be encapsulated into a payload of the link layer packet. 
     In a completed link layer packet, a Packet_Type field corresponds to a case in which TS packets are input, and thus may have a value of 010. A NUMTS field may indicate the number of encapsulated TS packets. An AHF field may be set to 1 to indicate the presence of an additional header since packet header deletion is performed. An HDM field may be set to 1 since header deletion is performed. DNP may be set to 0 since null packet deletion is not performed. 
       FIG. 61  illustrates an example of adaptation modes in IP header compression according to an embodiment of the present invention (transmitting side). 
     Hereinafter, IP header compression will be described. 
     In the link layer, IP header compression/decompression scheme can be provided. IP header compression can include two parts: header compressor/decompressor and adaptation module. The header compression scheme can be based on the Robust Header Compression (RoHC). In addition, for broadcasting usage, adaptation function is added. 
     In the transmitter side, ROHC compressor reduces the size of header for each packet. Then, adaptation module extracts context information and builds signaling information from each packet stream. In the receiver side, adaptation module parses the signaling information associated with the received packet stream and attaches context information to the received packet stream. ROHC decompressor reconstructs the original IP packet by recovering the packet header. 
     The header compression scheme can be based on the RoHC as described above. In particular, in the present system, an RoHC framework can operate in a unidirctional mode (U mode) of the RoHC. In addition, in the present system, it is possible to use an RoHC UDP header compression profile which is identified by a profile identifier of 0x0002. 
     Hereinafter, adaptation will be described. 
     In case of transmission through the unidirectional link, if a receiver has no information of context, decompressor cannot recover the received packet header until receiving full context. This may cause channel change delay and turn on delay. For this reason, context information and configuration parameters between compressor and decompressor can be always sent with packet flow. 
     The Adaptation function provides out-of-band transmission of the configuration parameters and context information. Out-of-band transmission can be done through the link layer signaling. Therefore, the adaptation function is used to reduce the channel change delay and decompression error due to loss of context information. 
     Hereinafter, extraction of context information will be described. 
     Context information may be extracted using various schemes according to adaptation mode. In the present invention, three examples will be described below. The scope of the present invention is not restricted to the examples of the adaptation mode to be described below. Here, the adaptation mode may be referred to as a context extraction mode. 
     Adaptation Mode 1 (not illustrated) may be a mode in which no additional operation is applied to a basic RoHC packet stream. In other words, the adaptation module may operate as a buffer in this mode. Therefore, in this mode, context information may not be included in link layer signaling 
     In Adaptation Mode 2 (tsib 13010 ), the adaptation module can detect the IR packet from ROHC packet flow and extract the context information (static chain). After extracting the context information, each IR packet can be converted to an IR-DYN packet. The converted IR-DYN packet can be included and transmitted inside the ROHC packet flow in the same order as IR packet, replacing the original packet. 
     In Adaptation Mode 3 (tsib 13020 ), the adaptation module can detect the IR and IR-DYN packet from ROHC packet flow and extract the context information. The static chain and dynamic chain can be extracted from IR packet and dynamic chain can be extracted from IR-DYN packet. After extracting the context information, each IR and IR-DYN packet can be converted to a compressed packet. The compressed packet format can be the same with the next packet of IR or IR-DYN packet. The converted compressed packet can be included and transmitted inside the ROHC packet flow in the same order as IR or IR-DYN packet, replacing the original packet. 
     Signaling (context) information can be encapsulated based on transmission structure. For example, context information can be encapsulated to the link layer signaling. In this case, the packet type value can be set to “100”. 
     In the above-described Adaptation Modes 2 and 3, a link layer packet for context information may have a packet type field value of 100. In addition, a link layer packet for compressed IP packets may have a packet type field value of 001. The values indicate that each of the signaling information and the compressed IP packets are included in the link layer packet as described above. 
     Hereinafter, a description will be given of a method of transmitting the extracted context information. 
     The extracted context information can be transmitted separately from ROHC packet flow, with signaling data through specific physical data path. The transmission of context depends on the configuration of the physical layer path. The context information can be sent with other link layer signaling through the signaling data pipe. 
     In other words, the link layer packet having the context information may be transmitted through a signaling PLP together with link layer packets having other link layer signaling information (Packet_Type=100). Compressed IP packets from which context information is extracted may be transmitted through a general PLP (Packet_Type=001). Here, depending on embodiments, the signaling PLP may refer to an L1 signaling path. In addition, depending on embodiments, the signaling PLP may not be separated from the general PLP, and may refer to a particular and general PLP through which the signaling information is transmitted. 
     At a receiving side, prior to reception of a packet stream, a receiver may need to acquire signaling information. When receiver decodes initial PLP to acquire the signaling information, the context signaling can be also received. After the signaling acquisition is done, the PLP to receive packet stream can be selected. In other words, the receiver may acquire the signaling information including the context information by selecting the initial PLP. Here, the initial PLP may be the above-described signaling PLP. Thereafter, the receiver may select a PLP for acquiring a packet stream. In this way, the context information may be acquired prior to reception of the packet stream. 
     After the PLP for acquiring the packet stream is selected, the adaptation module can detect IR-DYN packet form received packet flow. Then, the adaptation module parses the static chain from the context information in the signaling data. This is similar to receiving the IR packet. For the same context identifier, IR-DYN packet can be recovered to IR packet. Recovered ROHC packet flow can be sent to ROHC decompressor. Thereafter, decompression may be started. 
       FIG. 62  illustrates a link mapping table (LMT) and an RoHC-U description table according to an embodiment of the present invention. 
     Hereinafter, link layer signaling will be described. 
     Generally, link layer signaling is operates under IP level. At the receiver side, link layer signaling can be obtained earlier than IP level signaling such as Service List Table (SLT) and Service Layer Signaling (SLS). Therefore, link layer signaling can be obtained before session establishment. 
     For link layer signaling, there can be two kinds of signaling according input path: internal link layer signaling and external link layer signaling. The internal link layer signaling is generated in link layer at transmitter side. And the link layer takes the signaling from external module or protocol. This kind of signaling information is considered as external link layer signaling. If some signaling need to be obtained prior to IP level signaling, external signaling is transmitted in format of link layer packet. 
     The link layer signaling can be encapsulated into link layer packet as described above. The link layer packets can carry any format of link layer signaling, including binary and XML. The same signaling information may not be transmitted in different formats for the link layer signaling. 
     Internal link layer signaling may include signaling information for link mapping. The Link Mapping Table (LMT) provides a list of upper layer sessions carried in a PLP. The LMT also provides addition information for processing the link layer packets carrying the upper layer sessions in the link layer. 
     An example of the LMT (tsib 14010 ) according to the present invention is illustrated. 
     signaling_type can be an 8-bit unsigned integer field that indicates the type of signaling carried by this table. The value of signaling_type field for Link Mapping Table (LMT) can be set to 0x01. 
     PLP_ID can be an 8-bit field that indicates the PLP corresponding to this table. 
     num_session can be an 8-bit unsigned integer field that provides the number of upper layer sessions carried in the PLP identified by the above PLP_ID field. When the value of signaling_type field is 0x01, this field can indicate the number of UDP/IP sessions in the PLP. 
     src_IP_add can be a 32-bit unsigned integer field that contains the source IP address of an upper layer session carried in the PLP identified by the PLP_ID field. 
     dst_IP_add can be a 32-bit unsigned integer field that contains the destination IP address of an upper layer session carried in the PLP identified by the PLP_ID field. 
     src_UDP_port can be a 16-bit unsigned integer field that represents the source UDP port number of an upper layer session carried in the PLP identified by the PLP_ID 
     FIELD 
     dst_UDP_port can be a 16-bit unsigned integer field that represents the destination UDP port number of an upper layer session carried in the PLP identified by the PLP_ID field. 
     SID_flag can be a 1-bit Boolean field that indicates whether the link layer packet carrying the upper layer session identified by above 4 fields, Src_IP_add, Dst_IP_add, Src_UDP_Port and Dst_UDP_Port, has an SID field in its optional header. When the value of this field is set to 0, the link layer packet carrying the upper layer session may not have an SID field in its optional header. When the value of this field is set to 1, the link layer packet carrying the upper layer session can have an SID field in its optional header and the value the SID field can be same as the following SID field in this table. 
     compressed_flag can be a 1-bit Boolean field that indicates whether the header compression is applied the link layer packets carrying the upper layer session identified by above 4 fields, Src_IP_add, Dst_IP_add, Src_UDP_Port and Dst_UDP_Port. When the value of this field is set to 0, the link layer packet carrying the upper layer session may have a value of 0x00 of Packet_Type field in its base header. When the value of this field is set to 1, the link layer packet carrying the upper layer session may have a value of 0x01 of Packet_Type field in its base header and the Context_ID field can be present. 
     SID can be an 8-bit unsigned integer field that indicates sub stream identifier for the link layer packets carrying the upper layer session identified by above 4 fields, Src_IP_add, Dst_IP_add, Src_UDP_Port and Dst_UDP_Port. This field can be present when the value of SID_flag is equal to 1. 
     context_id can be an 8-bit field that provides a reference for the context id (CID) provided in the ROHC-U description table. This field can be present when the value of compressed_flag is equal to 1. 
     An example of the RoHC-U description table (tsib 14020 ) according to the present invention is illustrated. As described in the foregoing, the RoHC-U adaptation module may generate information related to header compression. 
     signaling_type can be an 8-bit field that indicates the type of signaling carried by this table. The value of signaling_type field for ROHC-U description table (RDT) can be set to “0x02”. 
     PLP_ID can be an 8-bit field that indicates the PLP corresponding to this table. 
     context_id can be an 8-bit field that indicates the context id (CID) of the compressed IP stream. In this system, 8-bit CID can be used for large CID. 
     context_profile can be an 8-bit field that indicates the range of protocols used to compress the stream. This field can be omitted. 
     adaptation_mode can be a 2-bit field that indicates the mode of adaptation module in this PLP. Adaptation modes have been described above. 
     context_config can be a 2-bit field that indicates the combination of the context information. If there is no context information in this table, this field may be set to “0x0”. If the static_chain( ) or dynamic_chain( ) byte is included in this table, this field may be set to “0x01” or “0x02” respectively. If both of the static_chain( ) and dynamic_chain( ) byte are included in this table, this field may be set to “0x03”. 
     context_length can be an 8-bit field that indicates the length of the static chain byte sequence. This field can be omitted. 
     static_chain_byte ( ) can be a field that conveys the static information used to initialize the ROHC-U decompressor. The size and structure of this field depend on the context profile. 
     dynamic_chain_byte ( ) can be a field that conveys the dynamic information used to initialize the ROHC-U decompressor. The size and structure of this field depend on the context profile. 
     The static_chain_byte can be defined as sub-header information of IR packet. The dynamic_chain_byte can be defined as sub-header information of IR packet and IR-DYN packet. 
       FIG. 63  illustrates a structure of a link layer on a transmitter side according to an embodiment of the present invention. 
     The present embodiment presumes that an IP packet is processed. From a functional point of view, the link layer on the transmitter side may broadly include a link layer signaling part in which signaling information is processed, an overhead reduction part, and/or an encapsulation part. In addition, the link layer on the transmitter side may include a scheduler for controlling and scheduling an overall operation of the link layer and/or input and output parts of the link layer. 
     First, signaling information of an upper layer and/or a system parameter tsib 15010  may be delivered to the link layer. In addition, an IP stream including IP packets may be delivered to the link layer from an IP layer tsib 15110 . 
     As described above, the scheduler tsib 15020  may determine and control operations of several modules included in the link layer. The delivered signaling information and/or system parameter tsib 15010  may be filterer or used by the scheduler tsib 15020 . Information, which corresponds to a part of the delivered signaling information and/or system parameter tsib 15010 , necessary for a receiver may be delivered to the link layer signaling part. In addition, information, which corresponds to a part of the signaling information, necessary for an operation of the link layer may be delivered to an overhead reduction controller tsib 15120  or an encapsulation controller tsib 15180 . 
     The link layer signaling part may collect information to be transmitted as a signal in a physical layer, and convert/configure the information in a form suitable for transmission. The link layer signaling part may include a signaling manager tsib 15030 , a signaling formatter tsib 15040 , and/or a buffer for channels tsib 15050 . 
     The signaling manager tsib 15030  may receive signaling information delivered from the scheduler tsib 15020  and/or signaling (and/or context) information delivered from the overhead reduction part. The signaling manager tsib 15030  may determine a path for transmission of the signaling information for delivered data. The signaling information may be delivered through the path determined by the signaling manager tsib 15030 . As described in the foregoing, signaling information to be transmitted through a divided channel such as the FIC, the EAS, etc. may be delivered to the signaling formatter tsib 15040 , and other signaling information may be delivered to an encapsulation buffer tsib 15070 . 
     The signaling formatter tsib 15040  may format related signaling information in a form suitable for each divided channel such that signaling information may be transmitted through a separately divided channel. As described in the foregoing, the physical layer may include separate physically/logically divided channels. The divided channels may be used to transmit FIC signaling information or EAS-related information. The FIC or EAS-related information may be sorted by the signaling manager tsib 15030 , and input to the signaling formatter tsib 15040 . The signaling formatter tsib 15040  may format the information based on each separate channel. When the physical layer is designed to transmit particular signaling information through a separately divided channel other than the FIC and the EAS, a signaling formatter for the particular signaling information may be additionally provided. Through this scheme, the link layer may be compatible with various physical layers. 
     The buffer for channels tsib 15050  may deliver the signaling information received from the signaling formatter tsib 15040  to separate dedicated channels tsib 15060 . The number and content of the separate channels may vary depending on embodiments. 
     As described in the foregoing, the signaling manager tsib 15030  may deliver signaling information, which is not delivered to a particular channel, to the encapsulation buffer tsib 15070 . The encapsulation buffer tsib 15070  may function as a buffer that receives the signaling information which is not delivered to the particular channel 
     An encapsulation block for signaling information tsib 15080  may encapsulate the signaling information which is not delivered to the particular channel. A transmission buffer tsib 15090  may function as a buffer that delivers the encapsulated signaling information to a DP for signaling information tsib 15100 . Here, the DP for signaling information tsib 15100  may refer to the above-described PLS region. 
     The overhead reduction part may allow efficient transmission by removing overhead of packets delivered to the link layer. It is possible to configure overhead reduction parts corresponding to the number of IP streams input to the link layer. 
     An overhead reduction buffer tsib 15130  may receive an IP packet delivered from an upper layer. The received IP packet may be input to the overhead reduction part through the overhead reduction buffer tsib 15130 . 
     An overhead reduction controller tsib 15120  may determine whether to perform overhead reduction on a packet stream input to the overhead reduction buffer tsib 15130 . The overhead reduction controller tsib 15120  may determine whether to perform overhead reduction for each packet stream. When overhead reduction is performed on a packet stream, packets may be delivered to a robust header compression (RoHC) compressor tsib 15140  to perform overhead reduction. When overhead reduction is not performed on a packet stream, packets may be delivered to the encapsulation part to perform encapsulation without overhead reduction. Whether to perform overhead reduction of packets may be determined based on the signaling information tsib 15010  delivered to the link layer. The signaling information may be delivered to the encapsulation controller tsib 15180  by the scheduler tsib 15020 . 
     The RoHC compressor tsib 15140  may perform overhead reduction on a packet stream. The RoHC compressor tsib 15140  may perform an operation of compressing a header of a packet. Various schemes may be used for overhead reduction. Overhead reduction may be performed using a scheme proposed by the present invention. The present invention presumes an IP stream, and thus an expression “RoHC compressor” is used. However, the name may be changed depending on embodiments. The operation is not restricted to compression of the IP stream, and overhead reduction of all types of packets may be performed by the RoHC compressor tsib 15140 . 
     A packet stream configuration block tsib 15150  may separate information to be transmitted to a signaling region and information to be transmitted to a packet stream from IP packets having compressed headers. The information to be transmitted to the packet stream may refer to information to be transmitted to a DP region. The information to be transmitted to the signaling region may be delivered to a signaling and/or context controller tsib 15160 . The information to be transmitted to the packet stream may be transmitted to the encapsulation part. 
     The signaling and/or context controller tsib 15160  may collect signaling and/or context information and deliver the signaling and/or context information to the signaling manager in order to transmit the signaling and/or context information to the signaling region. 
     The encapsulation part may perform an operation of encapsulating packets in a form suitable for a delivery to the physical layer. It is possible to configure encapsulation parts corresponding to the number of IP streams. 
     An encapsulation buffer tsib 15170  may receive a packet stream for encapsulation. Packets subjected to overhead reduction may be received when overhead reduction is performed, and an input IP packet may be received without change when overhead reduction is not performed. 
     An encapsulation controller tsib 15180  may determine whether to encapsulate an input packet stream. When encapsulation is performed, the packet stream may be delivered to a segmentation/concatenation block tsib 15190 . When encapsulation is not performed, the packet stream may be delivered to a transmission buffer tsib 15230 . Whether to encapsulate packets may be determined based on the signaling information tsib 15010  delivered to the link layer. The signaling information may be delivered to the encapsulation controller tsib 15180  by the scheduler tsib 15020 . 
     In the segmentation/concatenation block tsib 15190 , the above-described segmentation or concatenation operation may be performed on packets. In other words, when an input IP packet is longer than a link layer packet corresponding to an output of the link layer, one IP packet may be segmented into several segments to configure a plurality of link layer packet payloads. On the other hand, when an input IP packet is shorter than a link layer packet corresponding to an output of the link layer, several IP packets may be concatenated to configure one link layer packet payload. 
     A packet configuration table tsib 15200  may have configuration information of a segmented and/or concatenated link layer packet. A transmitter and a receiver may have the same information in the packet configuration table tsib 15200 . The transmitter and the receiver may refer to the information of the packet configuration table tsib 15200 . An index value of the information of the packet configuration table tsib 15200  may be included in a header of the link layer packet. 
     A link layer header information block tsib 15210  may collect header information generated in an encapsulation process. In addition, the link layer header information block tsib 15210  may collect header information included in the packet configuration table tsib 15200 . The link layer header information block tsib 15210  may configure header information according to a header structure of the link layer packet. 
     A header attachment block tsib 15220  may add a header to a payload of a segmented and/or concatenated link layer packet. The transmission buffer tsib 15230  may function as a buffer to deliver the link layer packet to a DP tsib 15240  of the physical layer. 
     The respective blocks, modules, or parts may be configured as one module/protocol or a plurality of modules/protocols in the link layer. 
       FIG. 64  illustrates a structure of a link layer on a receiver side according to an embodiment of the present invention. 
     The present embodiment presumes that an IP packet is processed. From a functional point of view, the link layer on the receiver side may broadly include a link layer signaling part in which signaling information is processed, an overhead processing part, and/or a decapsulation part. In addition, the link layer on the receiver side may include a scheduler for controlling and scheduling overall operation of the link layer and/or input and output parts of the link layer. 
     First, information received through a physical layer may be delivered to the link layer. The link layer may process the information, restore an original state before being processed at a transmitter side, and then deliver the information to an upper layer. In the present embodiment, the upper layer may be an IP layer. 
     Information, which is separated in the physical layer and delivered through a particular channel tsib 16030 , may be delivered to a link layer signaling part. The link layer signaling part may determine signaling information received from the physical layer, and deliver the determined signaling information to each part of the link layer. 
     A buffer for channels tsib 16040  may function as a buffer that receives signaling information transmitted through particular channels. As described in the foregoing, when physically/logically divided separate channels are present in the physical layer, it is possible to receive signaling information transmitted through the channels. When the information received from the separate channels is segmented, the segmented information may be stored until complete information is configured. 
     A signaling decoder/parser tsib 16050  may verify a format of the signaling information received through the particular channel, and extract information to be used in the link layer. When the signaling information received through the particular channel is encoded, decoding may be performed. In addition, according to a given embodiment, it is possible to verify integrity, etc. of the signaling information. 
     A signaling manager tsib 16060  may integrate signaling information received through several paths. Signaling information received through a DP for signaling tsib 16070  to be described below may be integrated in the signaling manager tsib 16060 . The signaling manager tsib 16060  may deliver signaling information necessary for each part in the link layer. For example, the signaling manager tsib 16060  may deliver context information, etc. for recovery of a packet to the overhead processing part. In addition, the signaling manager tsib 16060  may deliver signaling information for control to a scheduler tsib 16020 . 
     General signaling information, which is not received through a separate particular channel, may be received through the DP for signaling tsib 16070 . Here, the DP for signaling may refer to PLS, L1, etc. Here, the DP may be referred to as a PLP. A reception buffer tsib 16080  may function as a buffer that receives signaling information delivered from the DP for signaling. In a decapsulation block for signaling information tsib 16090 , the received signaling information may be decapsulated. The decapsulated signaling information may be delivered to the signaling manager tsib 16060  through a decapsulation buffer tsib 16100 . As described in the foregoing, the signaling manager tsib 16060  may collate signaling information, and deliver the collated signaling information to a necessary part in the link layer. 
     The scheduler tsib 16020  may determine and control operations of several modules included in the link layer. The scheduler tsib 16020  may control each part of the link layer using receiver information tsib 16010  and/or information delivered from the signaling manager tsib 16060 . In addition, the scheduler tsib 16020  may determine an operation mode, etc. of each part. Here, the receiver information tsib 16010  may refer to information previously stored in the receiver. The scheduler tsib 16020  may use information changed by a user such as channel switching, etc. to perform a control operation. 
     The decapsulation part may filter a packet received from a DP tsib 16110  of the physical layer, and separate a packet according to a type of the packet. It is possible to configure decapsulation parts corresponding to the number of DPs that can be simultaneously decoded in the physical layer. 
     The decapsulation buffer tsib 16100  may function as a buffer that receives a packet stream from the physical layer to perform decapsulation. A decapsulation controller tsib 16130  may determine whether to decapsulate an input packet stream. When decapsulation is performed, the packet stream may be delivered to a link layer header parser tsib 16140 . When decapsulation is not performed, the packet stream may be delivered to an output buffer tsib 16220 . The signaling information received from the scheduler tsib 16020  may be used to determine whether to perform decapsulation. 
     The link layer header parser tsib 16140  may identify a header of the delivered link layer packet. It is possible to identify a configuration of an IP packet included in a payload of the link layer packet by identifying the header. For example, the IP packet may be segmented or concatenated. 
     A packet configuration table tsib 16150  may include payload information of segmented and/or concatenated link layer packets. The transmitter and the receiver may have the same information in the packet configuration table tsib 16150 . The transmitter and the receiver may refer to the information of the packet configuration table tsib 16150 . It is possible to find a value necessary for reassembly based on index information included in the link layer packet. 
     A reassembly block tsib 16160  may configure payloads of the segmented and/or concatenated link layer packets as packets of an original IP stream. Segments may be collected and reconfigured as one IP packet, or concatenated packets may be separated and reconfigured as a plurality of IP packet streams. Recombined IP packets may be delivered to the overhead processing part. 
     The overhead processing part may perform an operation of restoring a packet subjected to overhead reduction to an original packet as a reverse operation of overhead reduction performed in the transmitter. This operation may be referred to as overhead processing. It is possible to configure overhead processing parts corresponding to the number of DPs that can be simultaneously decoded in the physical layer. 
     A packet recovery buffer tsib 16170  may function as a buffer that receives a decapsulated RoHC packet or IP packet to perform overhead processing. 
     An overhead controller tsib 16180  may determine whether to recover and/or decompress the decapsulated packet. When recovery and/or decompression are performed, the packet may be delivered to a packet stream recovery block tsib 16190 . When recovery and/or decompression are not performed, the packet may be delivered to the output buffer tsib 16220 . Whether to perform recovery and/or decompression may be determined based on the signaling information delivered by the scheduler tsib 16020 . 
     The packet stream recovery block tsib 16190  may perform an operation of integrating a packet stream separated from the transmitter with context information of the packet stream. This operation may be a process of restoring a packet stream such that an RoHC decompressor tsib 16210  can perform processing. In this process, it is possible to receive signaling information and/or context information from a signaling and/or context controller tsib 16200 . The signaling and/or context controller tsib 16200  may determine signaling information delivered from the transmitter, and deliver the signaling information to the packet stream recovery block tsib 16190  such that the signaling information may be mapped to a stream corresponding to a context ID. 
     The RoHC decompressor tsib 16210  may restore headers of packets of the packet stream. The packets of the packet stream may be restored to forms of original IP packets through restoration of the headers. In other words, the RoHC decompressor tsib 16210  may perform overhead processing. 
     The output buffer tsib 16220  may function as a buffer before an output stream is delivered to an IP layer tsib 16230 . 
     The link layers of the transmitter and the receiver proposed in the present invention may include the blocks or modules described above. In this way, the link layer may independently operate irrespective of an upper layer and a lower layer, overhead reduction may be efficiently performed, and a supportable function according to an upper/lower layer may be easily defined/added/deleted. 
       FIG. 65  illustrates a configuration of signaling transmission through a link layer according to an embodiment of the present invention (transmitting/receiving sides). 
     In the present invention, a plurality of service providers (broadcasters) may provide services within one frequency band. In addition, a service provider may provide a plurality of services, and one service may include one or more components. It can be considered that the user receives content using a service as a unit. 
     The present invention presumes that a transmission protocol based on a plurality of sessions is used to support an IP hybrid broadcast. Signaling information delivered through a signaling path may be determined based on a transmission configuration of each protocol. Various names may be applied to respective protocols according to a given embodiment. 
     In the illustrated data configuration tsib 17010  on the transmitting side, service providers (broadcasters) may provide a plurality of services (Service #1, #2, . . . ). In general, a signal for a service may be transmitted through a general transmission session (signaling C). However, the signal may be transmitted through a particular session (dedicated session) according to a given embodiment (signaling B). 
     Service data and service signaling information may be encapsulated according to a transmission protocol. According to a given embodiment, an IP/UDP layer may be used. According to a given embodiment, a signal in the IP/UDP layer (signaling A) may be additionally provided. This signaling may be omitted. 
     Data processed using the IP/UDP may be input to the link layer. As described in the foregoing, overhead reduction and/or encapsulation may be performed in the link layer. Here, link layer signaling may be additionally provided. Link layer signaling may include a system parameter, etc. Link layer signaling has been described above. 
     The service data and the signaling information subjected to the above process may be processed through PLPs in a physical layer. Here, a PLP may be referred to as a DP. The example illustrated in the figure presumes a case in which a base DP/PLP is used. However, depending on embodiments, transmission may be performed using only a general DP/PLP without the base DP/PLP. 
     In the example illustrated in the figure, a particular channel (dedicated channel) such as an FIC, an EAC, etc. is used. A signal delivered through the FIC may be referred to as a fast information table (FIT), and a signal delivered through the EAC may be referred to as an emergency alert table (EAT). The FIT may be identical to the above-described SLT. The particular channels may not be used depending on embodiments. When the particular channel (dedicated channel) is not configured, the FIT and the EAT may be transmitted using a general link layer signaling transmission scheme, or transmitted using a PLP via the IP/UDP as other service data. 
     According to a given embodiment, system parameters may include a transmitter-related parameter, a service provider-related parameter, etc. Link layer signaling may include IP header compression-related context information and/or identification information of data to which the context is applied. Signaling of an upper layer may include an IP address, a UDP number, service/component information, emergency alert-related information, an IP/UDP address for service signaling, a session ID, etc. Detailed examples thereof have been described above. 
     In the illustrated data configuration tsib 17020  on the receiving side, the receiver may decode only a PLP for a corresponding service using signaling information without having to decode all PLPs. 
     First, when the user selects or changes a service desired to be received, the receiver may be tuned to a corresponding frequency and may read receiver information related to a corresponding channel stored in a DB, etc. The information stored in the DB, etc. of the receiver may be configured by reading an SLT at the time of initial channel scan. 
     After receiving the SLT and the information about the corresponding channel, information previously stored in the DB is updated, and information about a transmission path of the service selected by the user and information about a path, through which component information is acquired or a signal necessary to acquire the information is transmitted, are acquired. When the information is not determined to be changed using version information of the SLT, decoding or parsing may be omitted. 
     The receiver may verify whether SLT information is included in a PLP by parsing physical signaling of the PLP in a corresponding broadcast stream (not illustrated), which may be indicated through a particular field of physical signaling. It is possible to access a position at which a service layer signal of a particular service is transmitted by accessing the SLT information. The service layer signal may be encapsulated into the IP/UDP and delivered through a transmission session. It is possible to acquire information about a component included in the service using this service layer signaling. A specific SLT-SLS configuration is as described above. 
     In other words, it is possible to acquire transmission path information, for receiving upper layer signaling information (service signaling information) necessary to receive the service, corresponding to one of several packet streams and PLPs currently transmitted on a channel using the SLT. The transmission path information may include an IP address, a UDP port number, a session ID, a PLP ID, etc. Here, depending on embodiments, a value previously designated by the IANA or a system may be used as an IP/UDP address. The information may be acquired using a scheme of accessing a DB or a shared memory, etc. 
     When the link layer signal and service data are transmitted through the same PLP, or only one PLP is operated, service data delivered through the PLP may be temporarily stored in a device such as a buffer, etc. while the link layer signal is decoded. 
     It is possible to acquire information about a path through which the service is actually transmitted using service signaling information of a service to be received. In addition, a received packet stream may be subjected to decapsulation and header recovery using information such as overhead reduction for a PLP to be received, etc. 
     In the illustrated example (tsib 17020 ), the FIC and the EAC are used, and a concept of the base DP/PLP is presumed. As described in the foregoing, concepts of the FIC, the EAC, and the base DP/PLP may not be used. 
       FIG. 66  is a view showing a protocol stack for a next generation broadcasting system according to an embodiment of the present invention. 
     The broadcasting system according to the present invention may correspond to a hybrid broadcasting system in which an Internet Protocol (IP) centric broadcast network and a broadband are coupled. 
     The broadcasting system according to the present invention may be designed to maintain compatibility with a conventional MPEG-2 based broadcasting system. 
     The broadcasting system according to the present invention may correspond to a hybrid broadcasting system based on coupling of an IP centric broadcast network, a broadband network, and/or a mobile communication network (or a cellular network). 
     Referring to the figure, a physical layer may use a physical protocol adopted in a broadcasting system, such as an ATSC system and/or a DVB system. For example, in the physical layer according to the present invention, a transmitter/receiver may transmit/receive a terrestrial broadcast signal and convert a transport frame including broadcast data into an appropriate form. 
     In an encapsulation layer, an IP datagram is acquired from information acquired from the physical layer or the acquired IP datagram is converted into a specific frame (for example, an RS Frame, GSE-lite, GSE, or a signal frame). The frame main include a set of IP datagrams. For example, in the encapsulation layer, the transmitter include data processed from the physical layer in a transport frame or the receiver extracts an MPEG-2 TS and an IP datagram from the transport frame acquired from the physical layer. 
     A fast information channel (FIC) includes information (for example, mapping information between a service ID and a frame) necessary to access a service and/or content. The FIC may be named a fast access channel (FAC). 
     The broadcasting system according to the present invention may use protocols, such as an Internet Protocol (IP), a User Datagram Protocol (UDP), a Transmission Control Protocol (TCP), an Asynchronous Layered Coding/Layered Coding Transport (ALC/LCT), a Rate Control Protocol/RTP Control Protocol (RCP/RTCP), a Hypertext Transfer Protocol (HTTP), and a File Delivery over Unidirectional Transport (FLUTE). A stack between these protocols may refer to the structure shown in the figure. 
     In the broadcasting system according to the present invention, data may be transported in the form of an ISO based media file format (ISOBMFF). An Electrical Service Guide (ESG), Non Real Time (NRT), Audio/Video (A/V), and/or general data may be transported in the form of the ISOBMFF. 
     Transport of data through a broadcast network may include transport of a linear content and/or transport of a non-linear content. 
     Transport of RTP/RTCP based A/V and data (closed caption, emergency alert message, etc.) may correspond to transport of a linear content. 
     An RTP payload may be transported in the form of an RTP/AV stream including a Network Abstraction Layer (NAL) and/or in a form encapsulated in an ISO based media file format. Transport of the RTP payload may correspond to transport of a linear content. Transport in the form encapsulated in the ISO based media file format may include an MPEG DASH media segment for A/V, etc. 
     Transport of a FLUTE based ESG, transport of non-timed data, transport of an NRT content may correspond to transport of a non-linear content. These may be transported in an MIME type file form and/or a form encapsulated in an ISO based media file format. Transport in the form encapsulated in the ISO based media file format may include an MPEG DASH media segment for A/V, etc. 
     Transport through a broadband network may be divided into transport of a content and transport of signaling data. 
     Transport of the content includes transport of a linear content (A/V and data (closed caption, emergency alert message, etc.)), transport of a non-linear content (ESG, nontimed data, etc.), and transport of a MPEG DASH based Media segment (A/V and data). 
     Transport of the signaling data may be transport including a signaling table (including an MPD of MPEG DASH) transported through a broadcasting network. 
     In the broadcasting system according to the present invention, synchronization between linear/non-linear contents transported through the broadcasting network or synchronization between a content transported through the broadcasting network and a content transported through the broadband may be supported. For example, in a case in which one UD content is separately and simultaneously transported through the broadcasting network and the broadband, the receiver may adjust the timeline dependent upon a transport protocol and synchronize the content through the broadcasting network and the content through the broadband to reconfigure the contents as one UD content. 
     An applications layer of the broadcasting system according to the present invention may realize technical characteristics, such as Interactivity, Personalization, Second Screen, and automatic content recognition (ACR). These characteristics are important in extension from ATSC 2.0 to ATSC 3.0. For example, HTML5 may be used for a characteristic of interactivity. 
     In a presentation layer of the broadcasting system according to the present invention, HTML and/or HTML5 may be used to identify spatial and temporal relationships between components or interactive applications. 
     In the present invention, signaling includes signaling information necessary to support effective acquisition of a content and/or a service. Signaling data may be expressed in a binary or XMK form. The signaling data may be transmitted through the terrestrial broadcasting network or the broadband. 
     A real-time broadcast A/V content and/or data may be expressed in an ISO Base Media File Format, etc. In this case, the A/V content and/or data may be transmitted through the terrestrial broadcasting network in real time and may be transmitted based on IP/UDP/FLUTE in non-real time. Alternatively, the broadcast A/V content and/or data may be received by receiving or requesting a content in a streaming mode using Dynamic Adaptive Streaming over HTTP (DASH) through the Internet in real time. In the broadcasting system according to the embodiment of the present invention, the received broadcast A/V content and/or data may be combined to provide various enhanced services, such as an Interactive service and a second screen service, to a viewer. 
     An example of the physical layer (a Broadcast PHY and a Broadband PHY) of the transmitter may be the structure shown in  FIG. 1 . An example of the physical layer of the receiver may be the structure shown in  FIG. 9 . 
     The signaling data and the IP/UDP datagram may be transmitted through a specific data pipe (hereinafter, DP) of a transport frame (or a frame) delivered to the physical layer. For example, the input formatting block  1000  may receive signaling data and IP/UDP datagram and demultiplex each of the signaling data and the IP/UDP datagram into at least one DP. The output processor  9300  may perform an operation contrary to that of the input formatting block  1000 . 
       FIG. 67  illustrates a receiver of a next generation broadcasting system according to an embodiment of the present invention. 
     The receiver according to the present embodiment may include a receiving unit (not illustrated), a channel synchronizer J 32010 , a channel equalizer J 32020 , a channel decoder J 32030 , a signaling decoder J 32040 , a baseband operation controller J 32050 , a service map database (DB) J 32060 , a transport packet interface J 32070 , a broadband packet interface J 32080 , a common protocol stack J 32090 , a service signaling channel processing buffer &amp; parser J 32100 , an A/V processor J 32110 , a service guide processor J 32120 , an application processor J 32130  and/or a service guide DB J 32140 . 
     The receiving unit (not illustrated) receives a broadcast signal. 
     The channel synchronizer J 32010  synchronizes a symbol frequency and timing so as to decode a signal received in a baseband. Here, the baseband refers to a region in which the broadcast signal is transmitted/received. 
     The channel equalizer J 32020  performs channel equalization upon a received signal. The channel equalizer J 32020  compensates for the received signal when the signal is distorted due to multipath, Doppler effect, or the like. 
     The channel decoder J 32030  restores the received signal to a meaningful transport frame. The channel decoder J 32030  performs forward error correction (FEC) on data or a transport frame included in the received signal. 
     The signaling decoder J 32040  extracts and decodes signaling data included in the received signal. Here, the signaling data includes signaling data and/or service information to be described below. 
     The baseband operation controller J 32050  controls processing of a signal in the baseband. 
     The service map DB J 32060  stores the signaling data and/or the service information. The service map DB J 32060  may store signaling data which is transmitted by being included in a broadcast signal and/or the signaling data which is transmitted by being included in a broadband packet. 
     The transport packet interface J 32070  extracts a transport packet from a transport frame or a broadcast signal. The transport packet interface J 32070  extracts signaling data or an IP datagram from the transport packet. 
     The broadband packet interface J 32080  receives a broadcasting-related packet through the Internet. The broadband packet interface J 32080  extracts the packet acquired through the Internet, and combines or extracts signaling data or A/V data from the packet. 
     The common protocol stack J 32090  processes a received packet according to a protocol which is included in a protocol stack. For example, the common protocol stack J 32090  may process the received packet according to the above-described protocol stack. 
     The service signaling channel processing buffer &amp; parser J 32100  extracts signaling data included in the received packet. The service signaling channel processing buffer&amp; parser J 32100  extracts signaling information related to scanning and/or acquisition of a service and/or content from an IP datagram and the like, and parses the extracted signaling information. The signaling data may be present at a certain position or channel in the received packet. The position or channel may be referred to as a service signaling channel. For example, the service signaling channel may have a particular IP address, a UDP port number, a transmission session identifier, and the like. The receiver may recognize data transmitted to the particular IP address, the UDP port number, the transmission session, and the like as signaling data. 
     The A/V processor J 32110  decodes and presents received A/V data. 
     The service guide processor J 32120  extracts announcement information from the received signal, manages the service guide DB J 32140  and provides a service guide. 
     The application processor J 32130  extracts application data and/or application-related information included in the received packet, and processes the extracted data and/or information. 
     The service guide DB J 32140  stores service guide data. 
       FIG. 68  is a view showing a broadcast receiver according to an embodiment of the present invention. 
     The broadcast receiver according to an embodiment of the present invention includes a service/content acquisition controller J 2010 , an Internet interface J 2020 , a broadcast interface J 2030 , a signaling decoder J 2040 , a service map database J 2050 , a decoder J 2060 , a targeting processor J 2070 , a processor J 2080 , a managing unit J 2090 , and/or a redistribution module J 2100 . In the figure is shown an external management device J 2110  which may be located outside and/or in the broadcast receiver. 
     The service/content acquisition controller J 2010  receives a service and/or content and signaling data related thereto through a broadcast/broadband channel. Alternatively, the service/content acquisition controller J 2010  may perform control for receiving a service and/or content and signaling data related thereto. 
     The Internet interface J 2020  may include an Internet access control module. The Internet access control module receives a service, content, and/or signaling data through a broadband channel. Alternatively, the Internet access control module may control the operation of the receiver for acquiring a service, content, and/or signaling data. 
     The broadcast interface J 2030  may include a physical layer module and/or a physical layer I/F module. The physical layer module receives a broadcast-related signal through a broadcast channel. The physical layer module processes (demodulates, decodes, etc.) the broadcast-related signal received through the broadcast channel. The physical layer I/F module acquires an Internet protocol (IP) datagram from information acquired from the physical layer module or performs conversion to a specific frame (for example, a broadcast frame, RS frame, or GSE) using the acquired IP datagram. 
     The signaling decoder J 2040  decodes signaling data or signaling information (hereinafter, referred to as ‘signaling data’) acquired through the broadcast channel, etc. 
     The service map database J 2050  stores the decoded signaling data or signaling data processed by another device (for example, a signaling parser) of the receiver. 
     The decoder J 2060  decodes a broadcast signal or data received by the receiver. The decoder J 2060  may include a scheduled streaming decoder, a file decoder, a file database (DB), an on-demand streaming decoder, a component synchronizer, an alert signaling parser, a targeting signaling parser, a service signaling parser, and/or an application signaling parser. 
     The scheduled streaming decoder extracts audio/video data for real-time audio/video (A/V) from the IP datagram, etc. and decodes the extracted audio/video data. 
     The file decoder extracts file type data, such as NRT data and an application, from the IP datagram and decodes the extracted file type data. 
     The file DB stores the data extracted by the file decoder. 
     The on-demand streaming decoder extracts audio/video data for on-demand streaming from the IP datagram, etc. and decodes the extracted audio/video data. 
     The component synchronizer performs synchronization between elements constituting a content or between elements constituting a service based on the data decoded by the scheduled streaming decoder, the file decoder, and/or the on-demand streaming decoder to configure the content or the service. 
     The alert signaling parser extracts signaling information related to alerting from the IP datagram, etc. and parses the extracted signaling information. 
     The targeting signaling parser extracts signaling information related to service/content personalization or targeting from the IP datagram, etc. and parses the extracted signaling information. Targeting is an action for providing a content or service satisfying conditions of a specific viewer. In other words, targeting is an action for identifying a content or service satisfying conditions of a specific viewer and providing the identified content or service to the viewer. 
     The service signaling parser extracts signaling information related to service scan and/or a service/content from the IP datagram, etc. and parses the extracted signaling information. The signaling information related to the service/content includes broadcasting system information and/or broadcast signaling information. 
     The application signaling parser extracts signaling information related to acquisition of an application from the IP datagram, etc. and parses the extracted signaling information. The signaling information related to acquisition of the application may include a trigger, a TDO parameter table (TPT), and/or a TDO parameter element. 
     The targeting processor J 2070  processes the information related to service/content targeting parsed by the targeting signaling parser. 
     The processor J 2080  performs a series of processes for displaying the received data. 
     The processor J 2080  may include an alert processor, an application processor, and/or an A/V processor. 
     The alert processor controls the receiver to acquire alert data through signaling information related to alerting and performs a process for displaying the alert data. 
     The application processor processes information related to an application and processes a state of an downloaded application and a display parameter related to the application. 
     The A/V processor performs an operation related to audio/video rendering based on decoded audio data, video data, and/or application data. 
     The managing unit J 2090  includes a device manager and/or a data sharing &amp; communication unit. 
     The device manager performs management for an external device, such as addition/deletion/renewal of an external device that can be interlocked, including connection and data exchange. 
     The data sharing &amp; communication unit processes information related to data transport and exchange between the receiver and an external device (for example, a companion device) and performs an operation related thereto. The transportable and exchangeable data may be signaling data, a PDI table, PDI user data, PDI Q&amp;A, and/or A/V data. 
     The redistribution module J 2100  performs acquisition of information related to a service/content and/or service/content data in a case in which the receiver cannot directly receive a broadcast signal. 
     The external management device J 2110  refers to modules, such as a broadcast service/content server, located outside the broadcast receiver for providing a broadcast service/content. A module functioning as the external management device may be provided in the broadcast receiver. 
     A detailed transmission frame and transport packet transmitting broadcast service will be described with reference to  FIGS. 69 to 72 . 
       FIG. 69  is a view illustrating a broadcast transmission frame according to an embodiment of the present invention. 
     According to the embodiment of  FIG. 69 , the broadcast transmission frame includes a P1 part, an L1 part, a common PLP part, an interleaved PLP part (e.g., a scheduled &amp; interleaved PLP&#39;s part), and an auxiliary data part. 
     According to the embodiment of  FIG. 69 , the broadcast transmission device transmits information on transport signal detection through the P1 part of the transmission frame. Additionally, the broadcast transmission device may transmit turning information on broadcast signal tuning through the P1 part. 
     According to the embodiment of  FIG. 69 , the broadcast transmission device transmits a configuration of the broadcast transmission frame and characteristics of each PLP through the L1 part. At this pint, the broadcast reception device  100  decodes the L1 part on the basis of the P1 part to obtain the configuration of the broadcast transmission frame and the characteristics of each PLP. 
     According to the embodiment of  FIG. 69 , the broadcast transmission device may transmit information commonly applied to PLPs through the common PLP part. According to a specific embodiment of the present invention, the broadcast transmission frame may not include the common PLP part. 
     According to the embodiment of  FIG. 69 , the broadcast transmission device transmits a plurality of components included in broadcast service through an interleaved PLP part. At this point, the interleaved PLP part includes a plurality of PLPs. 
     Moreover, according to the embodiment of  FIG. 69 , the broadcast transmission device may signal to which PLP components configuring each broadcast service are transmitted through an L1 part or a common PLP part. However, the broadcast reception device  100  decodes all of a plurality of PLPs of an interleaved PLP part in order to obtain specific broadcast service information on broadcast service scan. 
     Unlike the embodiment of  FIG. 69 , the broadcast transmission device may transmit a broadcast transmission frame including a broadcast service transmitted through a broadcast transmission frame and an additional part that includes information on a component included in the broadcast service. At this point, the broadcast reception device  100  may instantly obtain information on the broadcast service and the components therein through the additional part. This will be described with reference to  FIG. 79 . 
       FIG. 70  is a view of a broadcast transmission frame according to another embodiment of the present invention. 
     According to the embodiment of  FIG. 70 , the broadcast transmission frame includes a P1 part, an L1 part, a fast information channel (FIC) part, an interleaved PLP part (e.g., a scheduled &amp; interleaved PLP&#39;s part), and an auxiliary data part. 
     Except the FIC part, other parts are identical to those of  FIG. 69 . 
     The broadcast transmission device transmits fast information through the FIC part. The fast information may include configuration information of a broadcast stream transmitted through a transmission frame, simple broadcast service information, and service signaling relating to a corresponding service/component. The broadcast reception device  100  may scan broadcast service on the basis of the FIC part. In more detail, the broadcast reception device  100  may extract information on broadcast service from the FIC part. 
       FIG. 71  is a view illustrating a structure of a transport packet transmitting a broadcast service according to an embodiment of the present invention. 
     In the embodiment of  FIG. 71 , a transport packet transmitting a broadcast service includes a Network Protocol field, an Error Indicator field, a Stuffing Indicator field, a Pointer field, a Stuffing bytes field, and payload data. 
     The Network Protocol field represents the type of a network protocol. According to a specific embodiment of the present invention, a value of the Network Protocol field may represent the IPv4 protocol or a frame packet type. In more detail, as shown in the embodiment of  FIG. 70 , when a value of the Network Protocol field is 000, it may represent the IPv4 protocol. In more detail, as shown in the embodiment of  FIG. 70 , when a value of the Network Protocol field is 111, it may represent a frame_packet_type protocol. At this point, framed_packet_type may be a protocol defined by ATSC A/153. In more detail, framed_packet_type may represent a network packet protocol not including a field representing information on the length. According to a specific embodiment of the present invention, the Network Protocol may be a 3-bit field. 
     The Error Indicator field represents that an error is detected from a corresponding transport packet. In more detail, if a value of the Error Indicator field is 0, it represents that no error is detected from a corresponding packet and if a value of the Error Indicator field is 1, it represents that an error is detected from a corresponding packet According to a specific embodiment of the present invention, the Error Indicator field may be a 1-bit field. 
     The Stuffing Indicator field represents whether stuffing bytes are included in a corresponding transport packet. At this point, the stuffing bytes represent data included in a payload to maintain the length of a fixed packet. According to a specific embodiment of the present invention, when a value of the Stuffing Indicator field is 1, a transport packet includes a stuffing byte and when a value of the Stuffing Indicator field is 0, a transport packet includes no stuffing byte According to a specific embodiment of the present invention, the Stuffing Indicator field may be a 1-bit field. 
     The Pointer field represents a start point of a new network packet in a payload part of a corresponding transport packet. According to a specific embodiment of the present invention, when a value of the Pointer field is 0x7FF, it may represent that there is no start point of a new network packet. Additionally, According to a specific embodiment of the present invention, when a value of the Pointer field is not 0x7FF, it may represent an offset value from the last part of a transport packet header to the start point of a new network packet. According to a specific embodiment of the present invention, the Pointer field may be an 11-bit field. 
     The Stuffing Bytes field represents a stuffing byte filling between the header and the payload data to maintain a fixed packet length. 
     A configuration of a broadcast reception device for receiving broadcast service will be described below. 
       FIG. 73  is a view that a broadcast service signaling table and broadcast service transmission path signaling information signal broadcast service and a broadcast service transmission path. 
     The broadcast service signaling table may signal broadcast service information. In more detail, the broadcast service signaling table may signal a media component that broadcast service includes. Additionally, the broadcast service signaling table may signal broadcast service and a transmission path of a media component that the broadcast service includes. For this, the broadcast service signaling table may include broadcast service transmission path signaling information. In the above-described embodiment, the broadcast service signaling table includes information on a plurality of broadcast services. At this point, the broadcast service signaling table includes media component signaling information signaling a plurality of media components respectively included in a plurality of broadcast services. Especially, the broadcast service signaling table includes broadcast service transmission path signaling information signaling transmission paths of a plurality of media components. For example, it is shown that the broadcast reception device  100  may transmit Video 1 in Service 0 through PLP 0 according to the signaling table. Additionally, it is shown that the broadcast reception device  100  may transmit Audio 1 in Service N through internet network according to the signaling table. At this point, the PLP is a series of logical data delivery paths identifiable on a physical layer. The PLP may be also referred to as a data pipe. 
       FIG. 74  is a view illustrating a broadcast service signaling table according to an embodiment of the present invention. 
     The broadcast service signaling table may include at least one of broadcast service identification information, information representing the current state of a broadcast service, the name of a broadcast service, information representing whether a protection algorithm for broadcast service is applied, category information of a broadcast service, and media component signaling information signaling a media component that a broadcast service includes. The media component signaling information signaling a media component that the broadcast service includes may include information representing whether each media component is essential to a corresponding broadcast service. Additionally, the media component signaling information signaling a media component that the broadcast service includes may include information relating to each component. 
     In more detail, as shown in the embodiment of  FIG. 74 , the broadcast service signaling table may include at least one of a table_id field, section_syntax_indicator field, a private_indicator field, a section_length field, a table_id_extension field, a version_number field, a current_next_indicator field, a section_number field, a last_section_numberr field, a num_services field, a service_id field, a service_status field, an SP_indicator field, a short_service_name_length field, a short_service_name field, a channel_number field, a service_category field, a num_components field, an essential_component_indicator field, a num_component_level_descriptor field, a component_level_descriptor field, a num_service_level_descriptors field, and a service_level_descriptor field. 
     The table_id field represents an identifier of a broadcast service signaling information table. At this point, a value of the table_id field may be one of reserved id values defined in ATSC A/65. According to a specific embodiment of the present invention, the table_id field may be an 8-bit field. 
     The section_syntax_indicator field represents whether the broadcast service signaling information table is a private section table in a long format of MEPG-2 TS standard. According to a specific embodiment of the present invention, the section_syntax_indicator field may be a 1-bit field. 
     The private_indicator field represents whether a current table corresponds to a private section. According to a specific embodiment of the present invention, the private_indicator field may be a 1-bit field. 
     The section_length field represents the length of a section after the section_length field. According to a specific embodiment of the present invention, the section_length field may be a 12-bit field. 
     The table_id_extension field represents a value for identifying a broadcast service signaling information table in combination with the table_id field. Especially, the table_id field may include a SMT_protocol_version field representing a protocol version of a service signaling information table. According to a specific embodiment of the present invention, the SMT_protocol_version field may be an 8-bit field. 
     The version_number field represents a version of a service signaling table. The broadcast reception device  100  may determine the availability of a service signaling information table on the basis of a value of the vserion_number field. In more detail, when a value of the version_number field is identical to a version of a previously received service signaling table, the information of the service signaling table may not be used. According to a specific embodiment of the present invention, the version_number field may be a 5-bit field. 
     The current_next_indicator field represents whether information of a broadcast service signaling table is currently available. In more detail, when a value of the current_next_indicator field is 1, it may represent that the information of the broadcast service signaling table is available. Moreover, when a value of the current_next_indicator field is 1, it may represent that the information of the broadcast service signaling table is available next time. According to a specific embodiment of the present invention, the current_next_indicator field may be a 1-bit field. 
     The section_number field represents a current section number. According to a specific embodiment of the present invention, the section_number field may be an 8-bit field. 
     The last_section_number field represents the last section number. When the size of a broadcast service signaling table is large, it may be divided into a plurality of sections and then transmitted. At this point, the broadcast reception device  100  determines whether all sections necessary for a broadcast service signaling table are received on the basis of the section_number field and the last_section_number field. According to a specific embodiment of the present invention, the last_section_number field may be an 8-bit field. 
     The service_id field represents a service identifier for identifying a broadcast service. According to a specific embodiment of the present invention, the service_id field may be a 16-bit field. 
     The service_status field represents the current state of a broadcast service. In more detail, it may represent whether the broadcast service is available currently. According to a specific embodiment of the present invention, when a value of the service_status field is 1, it may represent that the broadcast service is available currently. According to a specific embodiment of the present invention, the broadcast reception device  100  may determine whether to display a corresponding broadcast service in a broadcast service list and a broadcast service guide on the basis of a value of the service_status field. For example, when a corresponding broadcast service is unavailable, the broadcast reception device  100  may not display the corresponding broadcast service in a broadcast service list and a broadcast service guide. According to another specific embodiment of the present invention, the broadcast reception device  100  may limit an access to a corresponding broadcast service on the basis of a value of the service_status field. For example, when a corresponding broadcast service is unavailable, the broadcast reception device  100  may limit an access to a corresponding broadcast service through a channel up/down key. According to a specific embodiment of the present invention, the service_status field may be a 2-bit field. 
     The SP_indicator field may represent whether service protection is applied to at least one component in a corresponding broadcast service. For example, when a value of SP_indicator is 1, it may represent that service protection is applied to at least one component in a corresponding broadcast service. According to a specific embodiment of the present invention, the SP_indicator field may be a 1-bit field. 
     The short_service_name_length field represents the size of the short_service_name field. 
     The short_service_name field represents the name of a broadcast service. In more detail, the short_service_name field may be displayed by summarizing the name of a broadcast service. 
     The channel_number field displays a virtual channel number of a corresponding broadcast service. 
     The service_category field represents a category of a broadcast service. In more detail, the service_category field may represent at least one of TV service, radio service, broadcast service guide, RI service, and emergency alerting. For example, as shown in the embodiment of  FIG. 75 , in the case that a value of the service_category field is 0x01, it represents TV service. In the case that a value of the service_category field is 0x02, it represents radio service. In the case that a value of the service_category field is 0x03, it represents RI service. In the case that a value of the service_category field is 0x08, it represents service guide. In the case that a value of the service_category field is 0x09, it represents emergency alerting. According to a specific embodiment of the present invention, the service_category field may be a 6-bit field. 
     The num_component field represents the number of media components that a corresponding broadcast service includes. According to a specific embodiment of the present invention, the num_component field may be a 5-bit field. 
     The essential_component_indicator field represents whether a corresponding media component is an essential media component essential to a corresponding broadcast service presentation. According to a specific embodiment of the present invention, the essential_component_indicator field may be a 1-bit field. 
     The num_component_level_descriptor field represents the number of component_level_descrptor fields. According to a specific embodiment of the present invention, the num_component_level_descriptor field may be a 4-bit field. 
     The component_level_descriptor field includes an additional property for a corresponding component. 
     The num_service_level_descriptors field represents the number of service_level_descriptor fields. According to a specific embodiment of the present invention, the num_service_level_descriptors field may be a 4-bit field. 
     The service_level_descriptor field includes an additional property for a corresponding service. 
     The service signaling table may further include information on ensemble. When the same Forward Error Correction (FEC) is applied to at least one service and transmitted, the ensemble represents a collection of the at least one service.  FIG. 78  is a view of a broadcast service signaling table according to another embodiment of the present invention. 
     In more detail, as shown in the embodiment of  FIG. 78 , the broadcast service signaling table may further include a num_ensemble_level_descriptors field and an ensemble_level_descriptor field. 
     The num_ensemble_level_descriptors field represents the number of ensemble_level_descriptor fields. According to a specific embodiment of the present invention, the num_ensemble_level_descriptors field may be a 4-bit field. 
     The ensemble_level_descriptor field includes an additional property for a corresponding ensemble. 
     Additionally, the service signaling table may further include stream identifier information for identifying a media component. This will be described in more detail with reference to  FIG. 77 . 
       FIG. 77  is a view of a stream identifier descriptor according to another embodiment of the present invention. 
     The stream identifier information includes at least one of a descriptor_tag field, a descriptor_length field, and a component_tag field. 
     The descriptor_tag field represents a descriptor including stream identifier information. According to a specific embodiment of the present invention, the descriptor_tag field may be an 8-bit field. 
     The descriptor_length field represents the length of stream identifier information after a corresponding field. According to a specific embodiment of the present invention, the descriptor_length field may be an 8-bit field. 
     The component_tag field represents a media component identifier for identifying a media component. At this point, the media component identifier may have a different unique value than a media component identifier of another media component on a corresponding signaling information table. According to a specific embodiment of the present invention, the component_tag field may be an 8-bit field. 
     An operation for transmitting/receiving a broadcast service signaling table will be described with reference to  FIGS. 93 and 99 . 
     The above broadcast service table is described as in a bitstream format but according to a specific embodiment of the present invention, a broadcast service table may be in an XML format. 
       FIG. 78  is a view illustrating an operation when a broadcast transmission device transmits a broadcast service signaling table according to an embodiment of the present invention. 
     The broadcast transmission device may include a transmission unit for transmitting a broadcast signals and a control unit for controlling operations of the broadcast transmission unit. A transmission unit may include one or more processors, one or more circuits, and one or more hardware modules, which perform each of a plurality of functions that the transmission unit performs. In more detail, the transmission unit may be a System On Chip (SOC) in which several semiconductor parts are integrated into one. At this point, the SOC may be semiconductor in which various multimedia components such as graphics, audio, video, and modem and a semiconductor such as a processor and D-RAM are integrated into one. The control unit may include one or more processors, one or more circuits, and one or more hardware modules, which perform each of a plurality of functions that the control unit performs. In more detail, the control unit may be a System On Chip (SOC) in which several semiconductor parts are integrated into one. At this point, the SOC may be semiconductor in which various multimedia components such as graphics, audio, video, and modem and a semiconductor such as a processor and D-RAM are integrated into one. 
     The broadcast transmission device obtains data to be contained in a transport packet and transmitted through the control unit in operation S 101 . The data that the broadcast transmission device transmits may be real-time content or metadata relating to real-time content. In more detail, real-time content may be a broadcast A/V content transmitted through a terrestrial broadcast network or enhancement data relating to broadcast AV content. 
     The broadcast transmission device determines whether data obtained through the control unit exceeds the size that a transport packet for data transmission contains in operation S 103 . In more detail, a transport packet that the broadcast transmission device is to use may be based on a protocol using a fixed packet length. At this point, when data to be transmitted exceeds the size that a packet covers, it is difficult to transmit data smoothly. Additionally, when data to be transmitted is very smaller than a packet, it is inefficient to transmit only a small size of one data in one packet. Accordingly, in order to overcome the inefficiency, the broadcast transmission device compares the sizes of a transport packet and data through the control unit. 
     If it is determined that a transport packet cannot contain the size of data that the broadcast transmission device is to transmit, the broadcast transmission device segments data to be transmitted through the control unit in operation S 107 . The segmented data may be divided in a plurality of transport packets and then transmitted. Then, the plurality of transport packets may additionally include information for identifying the segmented data. According to another embodiment, the information for identifying segmented data may be transmitted through additional datagram instead of a transport packet. 
     The broadcast transmission device packetizes data having a smaller size than segmented data or a transport packet through the control unit in operation S 109 . In more detail, the broadcast transmission device processes data to be in a delivery from. The processed broadcast packet may include a packet header and packet payload. Additionally, the packet payload may include data and the header of a payload. Herein, besides the packet header, the payload header is a field for signaling payload data in the packet payload. Additionally, the packet payload including segmented data may include a segmented data header in addition to the header of a payload. Herein, besides the payload header, the segmented data header is a field for signaling payload data in the packet payload. 
     According to an embodiment, the broadcast transmission device may packetize one data in one packet. According to another embodiment, the broadcast transmission device may packetize a plurality of data in one packet. According to another embodiment, the broadcast transmission device may segment and packetize one data in a plurality of packets. 
     As mentioned above, according to the size of data or the length of a packet, a packetized transport packet may vary. Therefore, it is necessary for the broadcast transmission device to transmit different transport packets in distinguishable forms. According to an embodiment, the broadcast transmission device may packetize data by including information representing the form of a packet in the payload header of a transport packet through the control unit. According to another embodiment, when it is difficult to distinguish data to be transmitted only with information in the payload header, the control unit of the broadcast transmission device may packetize data by additionally including information for identifying the type of a transport packet. 
     The broadcast transmission device transmits the packetized broadcast packet through the transmission unit in operation S 1111 . According to an embodiment, a broadcast packet may be transmitted through a terrestrial broadcast network. According to another embodiment, a broadcast packet may be transmitted through an internet network. 
       FIG. 79  is a view illustrating an operation when a broadcast reception device receives a packetized broadcast packet according to an embodiment of the present invention. 
     The broadcast reception device  100  receives a packetized transport packet through the broadcast reception unit  110  in operation S 201 . 
     The broadcast reception device  100  extracts a payload header from the received transport packet through the control unit  150  in operation S 203 . The control unit  150  may obtain payload data including data and a payload header signaling the payload data from the payload of the transport packet. In more detail, the control unit  150  of the broadcast reception device  100  may extract additional information for providing at least one of a broadcast content in the packet payload and an enhancement content relating to the broadcast content, from the received transport packet. 
     According to an embodiment, the control unit  150  of the broadcast reception device  100  may extract at least one of payload error determination information, payload priority information, and payload type information from the payload header. In more detail, the payload error determination information represents whether there is an error in the payload in a broadcast packet or whether a corresponding payload includes a content violating a predetermined syntax. 
     Additionally, the priority information represents a priority of data in the payload. Additionally, the priority information represents property information of data in the payload. For example, in the case of a payload including signaling information of file format media data, the priority information of a corresponding packet is set to the highest priority. 
     Additionally, the payload type information represents the type of a packet payload including payload data. For example, the payload type information may represent whether the broadcast transmission device packetizes one data in one packet payload or divides and packetizes one data in a plurality of packet payloads. 
     The broadcast reception device  100  determines whether data in the payload is media data from information in the extracted payload header through the control unit  150  in operation S 205 . In more detail, the control unit  150  of the broadcast reception device  100  may determine the type of a payload in a corresponding packet on the basis of the packet header information. According to an embodiment, the type of a payload may be media data including broadcast content and an enhancement content relating to the broadcast content. According to another embodiment, the type of a payload may be metadata including additional information necessary for providing media data. 
     When it is determined that data in the payload is media data, the control unit  150  of the broadcast reception device  100  determines whether entire media data is included in one transport packet in operation S 207 . According to a specific embodiment, according to the length of a transport packet and the size of entire media data, the broadcast transmission device may packetize the entire media data in one transport packet. According to another embodiment, the broadcast transmission device may divide entire media data and packetize them in different transport packets. Accordingly, the control unit  150  of the broadcast reception device  100  may determine the type of a broadcast packet through the payload header so as to extract complete media data for content output. 
     On the other hand, according to an embodiment of the present invention, when the control unit  150  of the broadcast reception device  100  determines that data in the payload is not media data, this will be described in more detail with reference to  FIG. 104 . 
     When it is determined that entire media data is included in one transport packet, the control unit  150  extracts media data from one packet payload in operation S 209 . According to an embodiment, the control unit  150  of the broadcast reception device  100  may extract only one media data from one transport packet. According to another embodiment, the control unit  150  of the broadcast reception device  100  may extract a plurality of media data from one transport packet. On the other hand, when it is determined that entire media data is not included in a transport packet, the control unit  150  extracts media data from a plurality of packet payloads on the basis of a payload header and a segment data header in operation  5211 . In more detail, the control unit  150  may obtain information of divided and packetized media data from the payload header and the segment data header. Accordingly, the control unit  150  may identify divided media data according to the obtained information. That is, the control unit  150  may obtain the order of divided media data according to the obtained information. The control unit  150  may concatenate media data obtained from different transport packets on the basis of a corresponding order. 
     The broadcast reception device  100  provides content through the control unit  150  in operation S 213 . According to an embodiment, the control unit  150  may provide content on the basis of extracted media data. According to another embodiment, the control unit  150  may provide content on the basis of concatenated media data. 
     The control unit  150  may output A/V content. According to another embodiment, the broadcast reception device  100  may output enhancement data relating to A/V content. 
       FIG. 80  is a view illustrating a segment configuration according to an embodiment of the present invention. 
     On a packet based data transfer protocol, each packet is configured with a packet header and a packet payload in general. The packet header may include information of a packet payload in a packet. The packet payload may include media data to be transmitted via a broadcast network or an internet network. Media data that the packet payload includes may be at least one of audio, video, enhancement service, and additional information. 
       FIG. 81  is a view illustrating a structure of a real-time transport protocol (RTP) packet for real-time content transmission according to an embodiment of the present invention. 
     An RTP packet may include an RTP Header and an RTP Payload. The RTP header include at least one of a Timestamp, a Synchronization source identifier, and a Contributing source identifier. 
     The RTP Header may include at least one of a V(version) field, a P(padding) field, an X(extension) field, a CC field, an M(Marker bit) field, a Payload Type field, a Sequence Number field, and a Timestamp field. 
     The V(version) field represents version information of a corresponding RTP. According to a specific embodiment of the present invention, the V(version) field may be a 2-bit field. 
     The P(padding) field represents whether there are padding bits in a payload. According to a specific embodiment of the present invention, the P(padding) field may be a 1-bit field. 
     The X(extension) field represents whether there is an extension field in the RTP Header. According to a specific embodiment of the present invention, the X(extension) field may be a 1-bit field. 
     The CC field represents the number of Contributing sources. According to a specific embodiment of the present invention, the CC field may be a 4-bit field. 
     The M(Marker bit) field may represent a different meaning according to the Payload type. For example, when a transport object is a file, the M(Marker bit) field may represent the end of the file. According to another embodiment, when a transport object is video or audio data, the M(Marker bit) field may represent the first or last object of related access units. According to a specific embodiment of the present invention, the M(Marker bit) field may be a 1-bit field. 
     The Payload Type field represents the type of an RTP Payload. According to a specific embodiment of the present invention, the Payload Type field may be a 7-bit field. 
     The Sequence Number field represents the sequence number of an RTP packet. According to a specific embodiment of the present invention, the Sequence Number field may be a 16-bit field. 
     The Timestamp field may represent time information relating to an RTP packet. The Timestamp field may be interpreted differently according to a value of the Payload Type field. According to a specific embodiment of the present invention, the Timestamp field may be a 32-bit field. 
     RTP payload may be included in an audio/video access unit according to the payload type of RTP Header. For example, in the case of H.264, a network abstract layer (NAL) unit may be included. 
       FIG. 82  is a view illustrating a media file format based on an ISO base media file format (ISO BMFF) according to an embodiment of the present invention. 
     As shown in  FIG. 82 , the media file format may include one ftyp and at least one moov, moof, and mdat in general. 
     ftyp represents the type and suitability of a media file. Ftyp is located at the front in a media file if possible. 
     moov is a container for all media data. In more detail, moov is a container box for single track of presentation. Presentation may be configured with one or more tracks. Each track is separated from another track in presentation. According to an embodiment, a track may contain media data and according to another embodiment, a track may contain information for packetized streaming protocol. 
     mdat is a container of media data and moof contains information on mdat. 
       FIG. 83  is a view illustrating a configuration of a payload header in a packet payload according to an embodiment of the present invention. 
     Currently, a real-time transport protocol is mostly transmitted based on an access unit of a media file. In more detail, an access unit refers to a minimum unit for transmitting a media file or data. Accordingly, there is insufficient consideration on a method of transmitting media file format based data in real-time. 
     According to an embodiment of the present invention, a broadcast transmission device may transmit one file format based media data through a payload included in one transport packet. In this case, the transport packet may be referred to as a single unit packet. According to an embodiment of the present invention, a broadcast transmission device may transmit a plurality of file format based media data through a payload included in one transport packet. In this case, the transport packet may be referred to as an aggregation packet. According to another embodiment of the present invention, a broadcast transmission device may divide one file format based media data into several transport packets and may then transmit them. In this case, the transport packet may be referred to as a fragmented packet. According to another embodiment of the present invention, a broadcast transmission device may transmit one or a plurality of metadata for media stream through the payload of one transport packet. According to another embodiment, the broadcast transmission device may transmit one metadata through the payloads of a plurality of transport packets. 
     Additionally, a broadcast transmission device according to an embodiment of the present invention may transmit media data through various protocols. The protocol may include at least one of a real-time transport protocol (RTP), an asynchronous layered coding(ALC), and a layered coding transport (LCT). 
     In more detail, a broadcast transmission device may insert a field representing information on a payload type in the header of a transport packet to represent that there is file format based media data in a payload through a corresponding field. For example, in the case of the RTP, the payload type field of a header may represent the data type of a payload and a specific value may be assigned to a corresponding field as a payload type value for file format based media data. Then, in this case, when data including the end of one media file is included in the payload of a packet, the M field of an RTP packet header may be set to 1. 
     In order to overcome the above issues, a payload header according to an embodiment of the present invention may include at least one of information representing whether there is an error or syntax error on data in a payload, information representing the priority of data, and information representing the type of data. In this case, information representing whether there is an error or syntax error on data in the payload of a payload header may be referred to as an F field. According to an embodiment, the information representing whether there is an error or syntax error on data in the payload of a payload header may be set to 1 as forbidden_zero_bit when there is an error or syntax violation on data in a payload. In more detail, the information representing whether there is an error or syntax error on data in the payload of a payload header may be one bit. 
     Additionally, information representing the priority of data in a payload header may be referred to as an information Priority field. According to an embodiment, the information representing the priority of data is a field representing the priority of payload data. Then, the information representing the priority of data may represent whether payload data includes important metadata on a media file format. 
     For example, in ISO BMFF, in the case of payload data including ftyp and moov, information representing the priority of data may be set to the highest priority. According to an embodiment, information representing the priority of data may represent the highest priority highest (highest), a relatively lower priority than the highest priority (medium), and the lowest priority (low) through a control unit of a broadcast transmission device. In this case, information representing the priority of data may be set to 0x00 in the case of the highest priority, 0x01 in the case of a relatively lower priority than the highest priority, and 0x02 in the case of the lowest priority. The above setting value is just one exemplary and may be wet to another arbitrary value. 
     Additionally, in this case, information representing the type of data may be referred to as a type field. In more detail, through information representing the type of data, the control unit  150  of the broadcast reception device  100  may identify whether a transport packet is a packet transmitting one data by one packet, a packet transmitting a plurality of different data by one packet, or a packet transmitting data obtained by dividing one into a plurality of data. 
     Additionally, through information representing the type of data, the control unit  150  of the broadcast reception device  100  may identify whether a transport packet is a packet transmitting metadata including time information of content or a packet transmitting metadata including description information of content. 
     According to an embodiment, in the case of a packet transmitting one data by one packet, the broadcast reception device may set information representing the type of data to 0x00. Additionally, in the case of a packet transmitting a plurality of different data by one packet, the broadcast reception device may set information representing the type of data to 0x01. Additionally, in the case of a packet dividing one data and transmitting divided data, the broadcast reception device may set information representing the type of data to 0x02. 
     Additionally, the broadcast transmission device may packetize metadata including presentation or decoding time information of content instead of media data and may then transmit the packetized metadata. In the case the broadcast reception device may set information representing the type of data to 0x03. Moreover, the time information may be referred to as timeline data. 
     Additionally, the broadcast transmission device may packetize and transmit metadata including description information of content. In the case the broadcast reception device may set information representing the type of data to 0x04. Moreover, the time information may be referred to as labeling data. 
     However, the above setting values are just exemplary so that the present invention is not limited to the above values. According to a specific embodiment of the present invention, the type field may be a 5-bit field. 
       FIGS. 99 and 100  are views illustrating a payload configuration of a transport packet in which one media data is packetized in one packet. 
     As shown in  FIG. 84 , a packet in which one media data is included in one packet may be referred to as a single unit packet. The payload of a single unit packet may include a payload header and payload data. The payload data may include fragmented data including one file format based media data. According to an embodiment, when a transport protocol uses a transport packet of a fixed length, payload data may include padding bits in addition to fragmented data. Herein the padding bit refers to a bit for filling the remaining space after filling data in a transport packet. 
       FIG. 85  is a detailed view of a transport packet shown in  FIG. 84 . As shown in  FIG. 85 , a payload header may include at least one of information representing whether there is an error or syntax error in data in a payload, information representing the priority of data, and information representing the type of data. 
     As shown in  FIG. 85 , information representing whether there is an error or syntax error on data in a payload may include a value representing a content that there is no error and syntax violation. According to a specific embodiment of the present invention, a corresponding value may be 0. 
     Since a media file in payload data includes important data such as ftyp, Information representing the priority of data may have the highest priority. As mentioned above, in the case of ftyp, since ftyp includes information for signaling a media file, it may have the highest priority. According to a specific embodiment of the present invention, a value representing the highest priority may be 0x00. 
     Since one media file is all included in one packet payload, Information representing the type of data may represent a single unit packet. According to a specific embodiment, information representing the type of data may have a value of 0x00. Additionally, a padding bit may be selectively inserted into payload data according to the length and transport protocol of media file. 
       FIGS. 86 and 87  are views illustrating a configuration of a transport packet in which a plurality of media data are packetized in one packet. The above packet may be referred to as an aggregation packet. As shown in  FIG. 86 , when the payload of one transport packet includes a plurality of different file format based media data, payload data may include a plurality of aggregation units. Each aggregation unit may include another file format based media data. According to an embodiment, when a transport protocol uses a packet of a fixed length, payload data may include padding bits in addition to fragmented data. 
     According to an embodiment, one aggregation unit may include at least one of information representing the length of an aggregation unit and aggregation data. In this case, information representing the length of an aggregation unit may be referred to as an aggregation unit length field. According to a specific embodiment of the present invention, the aggregation unit may be 16 bits. Additionally, aggregation unit data represent data in one file. 
       FIG. 87  is a view illustrating a configuration of an aggregation unit according to another embodiment of the present invention. One aggregation unit may further include information representing the type of a file in an aggregation unit in addition to the embodiment of  FIG. 86 . 
     Information representing the type of aggregation may be referred to as an aggregation unit type field. According to a specific embodiment, the broadcast transmission device may set the aggregation type to 0x00. 
     According to another embodiment, the aggregation type may represent that a corresponding aggregation unit includes a file in Self-initializing Segment format on MPEG-Dynamic Adaptive Streaming over HTTP (DASH). Herein, a self-initializing segment is obtained by integrating an initializing segment and a media segment without an additional initializing segment. In more detail, the self-initializing segment may include a media segment and its media form. According to a specific embodiment, in this case, the broadcast transmission device may set the aggregation type to 0x01. 
     According to another embodiment, the aggregation type may represent that a corresponding aggregation unit includes a file in Initialization Segment format on MPEG-DASH. Herein, the initializing segment is a format following ISO BMFF. In more detail, the initializing segment needs to include ftyp and moov. But, it does not include moof. According to a specific embodiment, in this case, the broadcast transmission device may set the aggregation type to 0x02. 
       FIGS. 88 and 94  are views illustrating a payload configuration of a transport packet (hereinafter referred to as a fragmented packet) in which one media data is divided and packetized into a plurality of transport packets.  FIG. 88  is a view illustrating the payload of a fragmented packet according to an embodiment of the present invention. As shown in  FIG. 88 , the payload of a fragmented packet may include a fragmentation unit. Additionally, when a transport protocol uses a packet of a fixed length, the payload of a fragmented packet may include padding bits. 
     According to an embodiment, a fragmentation unit FU may include at least one a Fragmentation unit header and Fragmentation unit data. The Fragmentation unit data may include part of one file format based media data. The Fragmentation unit header may include information of fragmentation unit data. 
     In more detail, the fragmentation unit header may include at least one of information representing whether fragmentation unit data includes the start part data among entire file media data, information representing whether fragmentation unit data includes the end part data among entire file media data, and information representing the type of a fragmentation unit. 
     According to an embodiment, the information representing whether fragmentation unit data includes the start part data among entire file media data may be referred to as a start bit field. In more detail, the start part data may be part of entire data including the first bit of entire media data. 
     For example, the fragmentation unit data of a corresponding payload includes start part data, the broadcast transmission device may set information representing whether fragmentation unit data includes the start part data among entire file media data to 1. In more detail, the information representing whether fragmentation unit data includes the start part data among entire file media data may be one bit. 
     According to an embodiment, the information representing whether fragmentation unit data includes the end part data among entire file media data may be referred to as an end bit field. In more detail, the end part data may be part of entire data including the end bit of entire media data. 
     For example, the fragmentation unit data of a corresponding payload includes end part data, the broadcast transmission device may set information representing whether fragmentation unit data includes the end part data among entire file media data to 1. In more detail, the information representing whether fragmentation unit data includes the end part data among entire file media data may be one bit. 
     According to an embodiment, information representing the type of a fragmentation unit may be referred to as a fragmentation unit type field. 
     According to an embodiment, a fragmentation unit type may represent that a corresponding packet indicates that a fragmentation unit includes a file format based basic file. In more detail, the file format based basic file may be a media file having a file format based on ISO BMFF. According to a specific embodiment, the broadcast transmission device may set the fragmentation unit type to 0x00. 
     According to another embodiment, the fragmentation unit type may represent that a corresponding fragmentation unit includes a file in Self-initializing Segment format on MPEG-DASH. According to a specific embodiment, in this case, the broadcast transmission device may set the fragmentation unit type to 0x01. 
     According to another embodiment, the fragmentation unit type may represent that a corresponding fragmentation unit includes a file in Initialization Segment format on MPEG-DASH. According to a specific embodiment, in this case, the broadcast transmission device may set the fragmentation unit to 0x02. 
     According to another embodiment, the fragmentation unit type may represent that a corresponding fragmentation unit includes a file in media Segment format on MPEG-DASH. According to a specific embodiment, in this case, the broadcast transmission device may set the fragmentation unit to 0x03. 
     In more detail, information representing a fragmentation unit type may be six bits. 
       FIG. 89  is a view illustrating a configuration of a payload in a fragmented packet according to another embodiment of the present invention. The embodiment of  FIG. 89  may be applied to the case there is no information relating to the order of a transport packet in the header therein. 
     As shown in  FIG. 89 , the fragmentation unit header in a fragmentation unit FU may include at least one of information representing whether fragmentation unit data includes the start part data among entire file media data, information representing whether fragmentation unit data includes the end part data among entire file media data, information representing the type of a fragmentation unit, and information representing the order in entire data of a fragmentation unit. Among the information, the remaining information other than the information representing the order of a fragmentation unit is identical to that described with reference to  FIG. 88 . 
     The information representing the order of a fragmentation unit may be referred to as a fragmentation number field. In more detail, when file format based media data is divided into a plurality of fragmented packets, the broadcast transmission device may set a value to the information representing the order of a fragmentation unit to assign the order of a corresponding packet. According to a specific embodiment of the present invention, the Fragmentation number field may be an 8-bit field. 
       FIG. 90  is a view when a broadcast transmission device fragments an ISO BMFF based media file into a plurality of packets. As shown in the above figure, in ISO BMFF based media file may include ftyp and moov, and a plurality of moof and mdat. 
     The broadcast transmission device may divide an ISO BMFF based media file into a plurality of files and may then include them in different fragmentation unit data. Additionally, the broadcast transmission device may include related information in a payload header by dividing an ISO BMFF based media file. 
       FIG. 91  is a view illustrating first fragmentation unit data packetized by the broadcast transmission device of  FIG. 90 . 
     As shown in  FIG. 91 , according to an embodiment of the present invention, the broadcast transmission device determines that there is no error or syntax error in a corresponding packet and sets the F field to 0. 
     Additionally, the broadcast transmission device may set the Priority field to a value representing the highest priority. According to a specific embodiment of the present invention, a corresponding value may be 0x00. 
     Additionally, the broadcast transmission device may set the Type field to a value representing a packet for dividing one file format based media file into several payloads and transmitting them. According to a specific embodiment of the present invention, a corresponding value may be 0x02. 
     The payload data may include a fragmentation unit. Again, the fragmentation unit may include a Start bit field, an End bit field, a fragmentation unit type field, and a fragmentation unit data field. 
     The broadcast transmission device may set the Start bit field to a value representing a content that a corresponding packet includes the start data of a media file. In more detail, since a first fragmentation unit includes the start data of media data, the broadcast transmission device may set a value representing a corresponding content to the start bit field. 
     Moreover, the broadcast transmission device may set the End bit field of a first fragmentation unit shown in  FIG. 91  to a value representing a content that the end data of a media file is not included. According to a specific embodiment, the broadcast transmission device may set the End bit field to 0 to represent a content that a corresponding packet does not include the end data of a media file. 
     Moreover, as shown in  FIG. 91 , the broadcast transmission device may set the fragmentation unit type field to a value representing a content that the first fragmentation unit includes a file format based basic form of file. In more detail, the file format based basic form may be file format data following ISO BMFF. According to a specific embodiment, the broadcast transmission device may set the fragmentation unit type field to 0x00 to represent corresponding content. 
       FIGS. 92 to 94  are views illustrating a fragmentation unit including remaining data except for the start data in the fragmentation unit data of  FIG. 90  according to an embodiment of the present invention. 
     As shown in  FIG. 92 , according to an embodiment of the present invention, the broadcast transmission device may set the F field of a payload header to a value representing that there is no error or syntax error in a corresponding packet. According to a specific embodiment, the broadcast transmission device may set the F field to 0. Additionally, the broadcast transmission device sets the Priority field to a value representing the payload data shown in  FIG. 92  has a relatively low priority. 
     According to a specific embodiment, data signaling entire media data may not be included from a second fragment unit. Accordingly, since the second fragmentation unit has a relatively lower priority than the first fragmentation unit, the priority field may be set to a value having a relatively lower priority. For example, a corresponding value may be 0x01. 
     Additionally, the broadcast transmission device may set the Type field to 0x02 as a Fragmented packet that a corresponding packet represents a packet dividing one file format based media file into several payloads and transmitting them.  FIG. 93  is a view illustrating a payload configuration when payload data does not include fragmentation unit data including start data and fragmentation unit data including end data. 
     According to an embodiment of the present invention, since the fragmentation unit data of  FIG. 93  does not include start data and end data, the broadcast transmission device may set the start bit field and the end bit field to a value representing corresponding information. According to a specific embodiment, the broadcast transmission device may set the start bit and end bit fields to 0. 
     Additionally, the broadcast transmission device may set the content that a fragmentation unit type field includes a file format based basic form of file to a specific value of a fragmentation unit type field. In more detail, the file format based basic form may be file format data following ISO BMFF. According to a specific embodiment, the broadcast transmission device may set the fragmentation unit type field to 0x00 to represent corresponding content. File format based media data divided into packets may have a unique order from an entire file. The broadcast reception device  100  may identify that the fragmentation unit data divided through the control unit  150  includes the start part among entire data on the basis of the start bit field. Additionally, the fact that the fragmentation unit data includes the end part in entire data may be identified on the basis of the End bit field. However, there may be a case that cannot be identified only by the Start bit field and the End bit field. 
     When the fragmentation unit data does not include start data or end data in entire data, the broadcast reception device  100  may identify a corresponding packet through information representing the order of the fragmentation unit data included in a payload according to an embodiment. In more detail, information representing the order of fragmentation unit data may be a fragmentation number field. Additionally, a broadcast transmission device may set the order of corresponding fragmentation unit data to the above-mentioned presentation field. 
     However, according to another embodiment, a transport packet may not include order information of fragmentation unit data. In this case, according to an embodiment, a broadcast transmission device may insert information for identifying the order of fragmentation unit data into a packet header. The information for identifying the order of fragmentation unit data into a packet header may be referred to as a sequence number field. According to another embodiment, a broadcast transmission device may insert information for identifying the order of fragmentation unit data into offset information of an IP datagram. 
       FIG. 94  is a view illustrating a configuration of a payload including a fragmentation unit including the end data among divided entire media data. In more detail,  FIG. 94  is a view illustrating a payload configuration when payload data does not include fragmentation unit data including start data but includes fragmentation unit data including end data. 
     According to an embodiment of the present invention, since the fragmentation unit data includes end data, the broadcast transmission device may set the start bit field and the end bit field to a value representing corresponding information. According to a specific embodiment, the broadcast transmission device may set the start field to 0. Then, the broadcast transmission device may set the end bit field to 1. 
     Additionally, a broadcast transmission device may set the fragmentation unit type field to represent the content that media data including a corresponding packet includes a basic form of file starting from ISO BMFF based ftyp. According to a specific embodiment, a broadcast transmission device may set the fragmentation unit type field to 0x00. 
     Data that a broadcast transmission device transmits through a transport packet may include metadata in addition to the above-mentioned media data. The metadata represents additional information necessary for providing media data. Hereinafter, referring to  FIGS. 95 to 102 , suggested are a broadcast transmission device and an operating method thereof, and a broadcast reception device and an operating method thereof, in order for packetizing metadata in a transport packet and transmitting and receiving it. 
     Additionally, hereinafter, timeline information is mainly described as one example of metadata. The timeline information is a series of time information for media content. In more detail, the timeline information may be a series of time information for presentation or decoding. 
     Additionally, the timeline information may include base timeline information. The basic timeline means a reference timeline necessary for synchronizing media data transmitted through a plurality of different transmission networks. In more detail, when the timeline of media data transmitted through a second transmission network is mapped into the timeline of media data transmitted through a first transmission network, the timeline of the media data transmitted through the first transmission network becomes a basic timeline. 
     Moreover, the broadcast transmission device may express the metadata in XML format. Additionally, the broadcast transmission device may express the metadata in a descriptor format includable in a signaling table. 
       FIG. 95  is a view illustrating a timeline signaling table of metadata according to an embodiment of the present invention. 
     According to an embodiment of the present invention, the timeline signaling table may include information representing metadata relating to a timeline or information that corresponding metadata includes a timeline component access unit. The above information may be referred to as an identifier field. According to a specific embodiment of the present invention, the identifier field may be an 8-bit field. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include information representing the length of timeline information of a timeline component access unit. The above information may be referred to as an AU_length field. According to a specific embodiment of the present invention, the AU_length field may be a 32-bit field. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include information on whether including location information on services and content components relating to a timeline component access unit. The above information may be referred to as a location_flag field. According to a specific embodiment of the present invention, the location_flag field may be a 1-bit field. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include version information of a timestamp in a timeline component access unit. The timestamp represents time information through which a corresponding access unit needs to be outputted in a continuous timeline. The above information may be referred to as a timestamp_version field. According to a specific embodiment of the present invention, the timestamp_version field may be a 1-bit field. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include timestamp type information of a timeline component access unit. The above information may be referred to as a timestamp_type field. 
     According to an embodiment, the timestamp type information may be set to a value representing a decoding time of a service or content component relating to a timeline component access unit. In more detail, the decoding time of a content component may be referred to as a decoding timestamp. According to a specific embodiment, the broadcast transmission device may set timestamp type information to 0x00 when corresponding information represents a decoding time. 
     According to another embodiment, the timestamp type information may be set to a value representing the presentation time of a service or content component relating to a timeline component access unit. In more detail, the presentation time of a content component may be referred to as a presentation timestamp. According to a specific embodiment, the broadcast transmission device may set timestamp type information to 0x01 when corresponding information represents a presentation time. 
     Moreover, according to a specific embodiment of the present invention, the timestamp_type field may be a 1-bit field. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include timestamp format information of a timeline component access unit. The above information may be referred to as a timestamp_format field. 
     According to an embodiment, the timestamp format information may represent that a timestamp in a timeline component access unit is a format of a media time. According to a specific embodiment, the broadcast transmission device may set the timestamp_format field to 0x00 to represent that the timestamp format of a corresponding access unit is a media time format. 
     According to another embodiment, the timestamp format information may represent that a timestamp in a timeline component access unit is a format of a Network time protocol (NTP). According to a specific embodiment, the broadcast transmission device may set the timestamp_format field to 0x01 to represent that the timestamp format of a corresponding access unit is an NTP format. 
     According to another embodiment, the timestamp format information may represent that a timestamp in a timeline component access unit is a format of a precision time protocol (PTP). According to a specific embodiment, the broadcast transmission device may set the timestamp_format field to 0x02 to represent that the timestamp format of a corresponding access unit is a PTP format. 
     According to another embodiment, the timestamp format information may represent that a timestamp in a timeline component access unit is a format of a timecode. According to a specific embodiment, the broadcast transmission device may set the timestamp_format field to 0x03 to represent that the timestamp format of a corresponding access unit is a timecode format. Moreover, according to a specific embodiment of the present invention, the timestamp_format field may be a 4-bit field. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include location information on a component of service or content relating to information in a timestamp in a timeline component access unit. The above information may be referred to as a location field. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include information representing the length of the location information. The information representing a location information length may be referred to as a location_length field. According to a specific embodiment of the present invention, the location_length field may be an 8-bit field. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include timestamp format version information of a basic timestamp that is a matching reference. The above information may be referred to as an origin_timestamp_version field. 
     According to an embodiment, when the origin_timestamp_version field is set to 0, this represents that a timestamp format has a 32-bit format. According to another embodiment, when the origin_timestamp_version field is set to 1, this represents that a timestamp format has a 64-bit format. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include timestamp type information of a basic timeline. The above information may be referred to as an origine_timestamp_type field. 
     According to an embodiment, the origine_timestamp_type field may be set to a value representing a decoding time of a service or content component relating to a basic timeline. In more detail, the decoding time of a content component may be referred to as a decoding timestamp. According to a specific embodiment, the broadcast transmission device may set the origine_timestamp_type field to 0x00 when corresponding information represents a decoding time. 
     According to another embodiment, the origine_timestamp_type field may be set to a value representing a presentation time of a service or content component relating to a basic timeline. In more detail, the presentation time of a content component may be referred to as a presentation timestamp. According to a specific embodiment, the broadcast transmission device may set the origine_timestamp_type field to 0x01 when corresponding information represents a presentation time. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include information representing a timestamp format for a base timeline. The above information may be referred to as an origine_timestamp_format field. 
     According to an embodiment, the origin_timestamp_format field may represent that a timestamp of a basic timeline is a format of a media time. According to a specific embodiment, the broadcast transmission device may set the origin_timestamp_format field to 0x00 to represent that the timestamp format of a corresponding basic timeline is a media time format. 
     According to another embodiment, the origin_timestamp_format field may represent that a timestamp of a basic timeline is a format of an NTP. According to a specific embodiment, the broadcast transmission device may set the origin_timestamp_format field to 0x01 to represent that the timestamp format of a corresponding basic timeline is an NTP format. 
     According to another embodiment, the origin_timestamp_format field may represent that a timestamp of a basic timeline is a format of a precision time protocol (PTP). According to a specific embodiment, the broadcast transmission device may set the timestamp_format field to 0x02 to represent that the timestamp format of a corresponding basic timeline is a PTP format. 
     According to another embodiment, the origin_timestamp_format field may represent that a timestamp of a basic timeline is a format of a timecode. According to a specific embodiment, the broadcast transmission device may set the origin_timestamp_format field to 0x03 to represent that the timestamp format of a corresponding basic timeline is a timecode format. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include information on whether including location information on services and content components relating to a basic timeline that is a timeline mapping reference. The above information may be referred to as an origin_location_flag field. According to an embodiment, when the origin_location_flag field is set to a value other than 0, a timeline AU may include at least one of an origin_location_length field and an origin_location field. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include location information on a service or content relating to a basic timeline. The above information may be referred to as an origin_location field. According to a specific embodiment, information in the origin_location field may be an IP address, a port number, or a URI form. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include length information of position information on a service or content relating to a basic timeline. The above information may be referred to as an origin_location_length field. According to a specific embodiment of the present invention, the origin_location_length field may be an 8-bit field. 
     Additionally, according to an embodiment of the present invention, when a basic timeline that the reference of timeline mapping is a format of a media time, the timeline signaling table may include information of an available time scale. The above information may be referred to as an origin_timescale field. For example, in the case of MPEG-2 TS, the time scale may represent 9000 Hz. According to a specific embodiment of the present invention, the origin_timescale field may be a 32-bit field. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include media time information on a basic timeline. The above information may be referred to as an origin_media_time field. Moreover, the origin_media_time field may mean differently according to origin_timestamp_type. For example, when origin_timestamp_type means PTS, the origin_media_time field may represent a presentation time. For example, when origin_timestamp_type means DTS, the origin_media_time field may represent a decoding time. According to a specific embodiment, the origin_media_time field may be 32 bits when the origin_timestamp_version field is set to 0 and may be 64 bits when the origin_timestamp_version field is set to 1. 
     Additionally, according to an embodiment of the present invention, the timeline signaling table may include timestamp type information of a basic timeline. The above information may be referred to as an origin_timestamp field. The basic timeline timestamp information may represent different formats of timestamps according to a value of the origin_timestamp_format field. Additionally, the basic timeline timestamp information may represent different meanings according to a value of the origin_timestamp_type field. For example, when origin_timestamp_type signals PTS, the basic timeline timestamp information may represent a presentation time. 
     For example, when the origin_timestamp_type field represents DTS and the origin_timestamp_format field is 0x01, the corresponding origin_timestamp field may represent a decoding time expressed in NTP. According to a specific embodiment, the origin_timestamp field may be 32 bits when the origin_timestamp_version field is set to 0 and may be 64 bits when the origin_timestamp_version field is set to 1. 
     According to an embodiment, when the origin_timestamp_format field represents reserved, a timeline AU may include at least one of a private_data_length field and a private_data_bytes( ) field. 
     The private_data_length field may represent the byte unit length of the private_data_bytes( ) field. According to a specific embodiment of the present invention, the private_data_length field may be a 16-bit field. 
     The private_data_bytes( ) field may define by the length that the private_data_length field represents or may include future expansion content. 
       FIG. 96  is a view illustrating a configuration of payload data in which one metadata is packetized in payload data of a transport packet. According to an embodiment, the payload data may include metadata and the metadata may include media stream related timeline data. Additionally, according to an embodiment, when a broadcasts transmission device uses a packet of a fixed length in a transport protocol, payload data may include a padding bit additionally. 
       FIG. 97  is a view when payload data of a transport packet includes metadata for a timeline according to an embodiment of the present invention. 
     As shown in  FIG. 97 , according to an embodiment, the payload header may include at least one of an F field, a Priority field, and a Type field. 
     According to an embodiment, a broadcast transmission device may set the F field to a value representing there is no error or syntax violation in a payload. In more detail, the broadcast transmission device may set the F field to 0. Additionally, the broadcast transmission device may set the Priority field to a value representing the highest priority as payload data includes all important data of a media file configuration. In more detail, the broadcast transmission device may set the Priority field to 0x00. Additionally, the broadcast transmission device may set the Type field to a value representing information including metadata of timeline information in a payload. In more detail, the broadcast transmission device may set the Type field to 0x03. Additionally, the metadata may include the aforementioned syntax. 
       FIG. 98  is a view when a plurality of metadata are packetized in one transport packet. 
     As shown in  FIG. 98 , the case that one transport packet includes a plurality of metadata may be referred to as an aggregation packet. According to an embodiment, the payload data may include a plurality of aggregation units. 
     According to an embodiment, the aggregation unit may include information representing the length of metadata. According to another embodiment, when there is a metadata header field additionally, the aggregation unit may include information on the sum of a metadata header field and a metadata field length. The above information may be referred to as a metadata length field. 
       FIG. 99  is a view when one transport packet includes several timeline information. In more detail,  FIG. 99  illustrates the case that one transport packet includes a plurality of timeline information having different references in relation to one media stream. According to an embodiment, a transport packet may include a payload header and a content of the payload header is identical to that of  FIG. 98 . 
     Additionally, according to an embodiment, the payload data may include two aggregation units. However, the number of aggregation units in payload data may be two or more. 
     According to an embodiment, as shown in  FIG. 98 , each aggregation unit may include at least one of a metadata length field, a metadata header field, and a metadata field including timeline information. 
     However, the first aggregation unit shown in  FIG. 99  may include a metadata field including a first timeline and the second aggregation unit may include a metadata field including a second timeline. According to a specific embodiment, each timeline may have data based on different references. For example, the first timeline may have data based on a media time and the second timeline may have data based on NTP. 
       FIG. 100  is a view illustrating a packet payload in which one metadata is divided and packetized in a plurality of transport packets. 
     According to an embodiment, when the length of one metadata is greater than the length of a transport packet, in this case, a broadcast transmission device may divide corresponding metadata in several transport packets and may then transmit them. As shown in  FIG. 102 , a transport packet may include at least one of a payload header, a metadata fragment header, and a metadata fragment. Additionally, when a transport protocol uses a packet of a fixed length, a transport packet may include padding bits. 
     As shown in  FIG. 100 , according to an embodiment, a metadata fragment header may include information representing whether a metadata fragment in payload data of a corresponding transport packet includes the start part of entire metadata. In more detail, the start part data may be part of entire data including the first bit of entire media data. The above information may be referred to as a start bit field. According to a specific embodiment of the present invention, the start bit field may be a 1-bit field. According to an embodiment, the broadcast transmission device may set start bit to 1 when a metadata fragment in a corresponding transport packet includes the start part of entire metadata. 
     According to another embodiment, a metadata fragment header may include information representing whether a metadata fragment in payload data of a corresponding transport packet includes the end part of entire metadata. In more detail, the end part data may be part of entire data including the end bit of entire media data. The above information may be referred to as an end bit field. According to a specific embodiment of the present invention, the end bit field may be a 1-bit field. According to an embodiment, the broadcast transmission device may set end bit to 1 when a metadata fragment in a corresponding transport packet includes the end part of entire metadata. 
     According to another embodiment, the metadata header may include information representing a metadata type. The above information may be referred to as a metadata type field. According to a specific embodiment, the metadata type may represent that a corresponding metadata fragment includes timeline information. In this case, the broadcast transmission device may set the metadata type field to 0x00. According to another embodiment, the metadata type may represent that a corresponding metadata fragment includes metadata relating to labeling. In this case, the broadcast transmission device may set the metadata type field to 0x01. According to a specific embodiment of the present invention, the metadata type field may be a 5-bit field. 
       FIG. 101  is a view illustrating a metadata fragment header according to another embodiment of the present invention. Hereinafter, description for the same content as that of  FIG. 100  is omitted. 
     According to an embodiment of the present invention, a metadata fragment header may include information representing the order of a metadata fragment in a corresponding packet payload. The above information may be referred to as a Fragmentation number field. The broadcast reception device  100  may determine which number metadata is included in a corresponding packet on the basis of metadata fragment order information in a packet payload. 
       FIG. 102  is a view illustrating an operation when a broadcast reception device receives a broadcast packet according to an embodiment of the present invention. 
     When it is determined that the data in the payload is not the media data in operation S 205 , the control unit  150  of the broadcast reception device  100  determines whether entire metadata is included one transport packet in operation S 301 . In more detail, the control unit  150  may determine that data in a payload is not metadata instead of media data from payload header information. Then, the control unit  150  may determine whether corresponding entire metadata is included in one transport packet and transmitted. As mentioned above, one or more different metadata may be included in one transport packet. Or, one metadata is divided and included in a plurality of different transport packets. 
     According to an embodiment of the present invention, when the control unit  150  of the broadcast reception device  100  determines that entire metadata is included in one transport packet, the control unit  150  extracts metadata from one packet payload in operation S 303 . In more detail, the control unit  150  extracts a payload header and extracts metadata on the basis of the extracted payload header. According to an embodiment, the control unit  150  may extract one metadata from one packet payload. Moreover, according to another embodiment, the control unit  150  may extract a plurality of metadata from one packet payload. According to another embodiment of the present invention, the control unit  150  of the broadcast reception device  100  may determine that one metadata is divided and included in a plurality of transport packets. In this case, the control unit  150  extracts metadata from a plurality of packets payloads in operation S 305 . According to a specific embodiment, one metadata may be divided and packetized in a plurality of transport packets. The control unit  150  of the broadcast reception device  100  obtains metadata signaling data from a packet payload. Then, the control unit  150  may extract metadata from a plurality of packet payloads on the basis of the obtained signaling data. 
     The control unit  150  of the broadcast reception device  100  provides content on the basis of the extracted metadata in operation S 307 . According to a specific embodiment, the control unit  150  may obtain the presentation or decoding time information of a content from metadata. According to another embodiment, the control unit  150  may obtain content describing information from metadata. 
       FIG. 103  is a view when video stream is transmitted using RTP through broadcast network and video stream is transmitted using file format based media data through an internet network. In this case, after receiving an RTP packet or IP/UDP packet including timeline related metadata, the broadcast reception device  100  may allow decoding and presentation between related streams by matching an RTP protocol based video stream and a DASH based video stream. 
     As mentioned above, a conventional broadcast transmission device loads time information relating to the presentation of data (or object) included in a transport packet into a payload and transmits the payload. Or, the broadcast transmission device transmits additional signaling for transmitting time information. In the case of a conventional method, since time information is loaded into an additional transport packet or packet payload, the capacity of a packet header or the capacity of a transport become small relatively. However, in the case of a conventional method, since time information is transmitted through a packet separated from data to be transmitted, effectiveness may be reduced in terms of accurate and fast synchronization. 
     On the other hand, an embodiment of the present invention includes time information relating to the decoding or presentation of a corresponding packet in the packet header of a transport packet for supporting real time content. Accordingly, since time information of a corresponding packet is included in the header of a corresponding packet, compared to a conventional method, relatively accurate and fast synchronization is possible. Especially, according to an embodiment of the present invention, suggested is a content of packetizing a transport packet by setting the time information relating to decoding or presentation in the header extension in the packet header. Herein, the header extension may be part of the packet header including a selective header field that is not essential or has a changeable size. Or, a transport packet may be generated based on an object and accordingly, the object may be a target to be transmitted through a transport packet. The object may be included in a session and transmitted. 
       FIG. 104  is a view illustrating a configuration of a transport packet according to an embodiment of the present invention. The transport packet may use a transport protocol for supporting reliable data transmission. According to a specific embodiment, a reliable data transmission protocol may be Asynchronous Layered Coding (ALC). According to another embodiment, a reliable data transmission protocol may be Layered Coding Transport (LCT). 
     A packet header according to an embodiment of the present invention may include version information of a packet. In more detail, the packet header may include version information of a transport packet using a corresponding transport protocol. According to a specific embodiment, the information may be a V field. Additionally, the V field may be a 4-bit field. 
     Additionally, a packet header according to an embodiment of the present invention may include information relating to the length of information for congestion control. In more detail, the packet header may include multiple information relating to the multiplication of the length of information for congestion control and a base unit thereof. 
     According to a specific embodiment, the information may be a C field. According to an embodiment, the C field may be set to 0x00 and in this case, represents that the length of information for congestion control is 32 bits. According to another embodiment, the C field may be set to 0x01 and in this case, represents that the length of information for congestion control is 64 bits. According to another embodiment, the C field may be set to 0x02 and in this case, represents that the length of information for congestion control is 96 bits. According to another embodiment, the C field may be set to 0x03 and in this case, represents that the length of information for congestion control is 128 bits. The C field may be a 2 bit field. 
     Additionally, a packet header according to an embodiment of the present invention may include information specified for protocol. According to a specific embodiment, the information may be a PSI field. Additionally, the PSI field may be a 2-bit field. 
     Additionally, a packet header according to an embodiment of the present invention may include information relating to the length of a field representing identification information of a transport session. In more detail, the packet header may include multiple information of a field representing identification information of a transport session. The above information may be referred to as an S field. The S field may be a 1 bit field. 
     Additionally, a packet header according to an embodiment of the present invention may include information relating to the length of a field representing identification information of a transport object. In more detail, the packet header may include multiple information multiplied to the base length of a field representing identification information of a transport object. The above information may be referred to as an O field. The O field may be a 2 bit field. 
     Additionally, a packet header according to an embodiment of the present invention may include additional information relating to the length of a field representing identification information of a transport session. Then, the packet header may include additional information relating to the length of a field representing identification information of a transport object. The additional information may be information on whether to add half-word. Since a field representing identification information of a transport packet and a field representing identification information of a transport object should exist, the S field and the H field, or the O field and the H field cannot represent zero at the same time. 
     Additionally, a packet header according to an embodiment of the present invention may include information representing that a session is terminated or the end is imminent. The above information may be referred to as an A field. According to a specific embodiment, when the A field represents session termination or imminent end, it may be set to 1. Accordingly, in typical cases, the A field may be set to 0. When a broadcast transmission device set the A field to 1, it represents that the last packet is transmitted through a session. When the A field is set to 1, the broadcast transmission device may need to maintain the A field as 1 until all packets following a corresponding packet are transmitted completely. Additionally, when the A field is set to 1, a broadcast reception device may recognize that the broadcast transmission device stops packet transmission through a session immediately. That is, when the A field is set to 1, the broadcast reception device may recognize that there is no more packet transmission through a session. According to an embodiment, the A field may be a 1-bit field. 
     Additionally, a packet header according to an embodiment of the present invention may include information representing that object transmission is terminated or the end is imminent. The above information may be referred to as a B field. According to a specific embodiment, when object transmission termination is imminent, a broadcast transmission device may set the B field to 1. Accordingly, in typical cases, the B field may be set to 0. When information for identifying a transport object is not in a transport packet, the B field may be set to 1. Then, it may represent that object transmission termination in a session identified by out-of-band information is imminent. Or, when the last packet for an object is transmitted, the B field may be set to 1. Or, when the last packet for an object is transmitted, the B field may be set to 1. When the B field of a packet for a specific object is set to 1, the broadcast transmission device may need to set the B field to 1 until the transmission of packets following a corresponding packet is terminated. Additionally, when the B field is set to 1, a broadcast reception device  100  may recognize that the broadcast transmission device is to stop the transmission of a packet for object. That is, the broadcast reception device  100  may recognize that there is no more object transmission through a session from the B field set to 1. According to an embodiment, the B field may be a 1-bit field. 
     Additionally, a packet header according to an embodiment of the present invention may include information representing the total length of a header. The above information may be referred to as an HDR_LEN field. The HDR_LEN field may be a 32 multiple bit field. According to a specific embodiment, when HDR_LEN field is set to 5, the total length of a packet header may be 160 bits that are five multiples of 32. Additionally, the HDR_LEN field may be an 8-bit field. 
     Additionally, a packet header according to an embodiment of the present invention may include information relating to encoding or decoding of a payload included in a corresponding packet. The above information may be referred to as a Codepoint field. According to an embodiment, the Codepoint field may be an 8-bit field. 
     Additionally, a packet header according to an embodiment of the present invention may include information for congestion control. The above information may be referred to as a Congestion Control Information (CCI) field. According to a specific embodiment, the CCI field may include at least one of a Current time slot index (CTSI) field, a channel number field, and a packet sequence number field. 
     Additionally, a packet header according to an embodiment of the present invention may include information for identifying a transport session. The above information may be a Transport Session Identifier (TSI). Additionally, a field in a packet header including TSI information may be referred to as a TSI field. 
     Additionally, a packet header according to an embodiment of the present invention may include information for identifying an object transmitted through a transport session. The above information may be a Transport Object Identifier (TOI). Additionally, a field in a packet header including TOI information may be referred to as a TOI field. 
     Additionally, a packet header according to an embodiment of the present invention may include information for transmitting additional information. The above information may be referred to as a Header Extension field. According to an embodiment, the additional information may be time information relating to the presentation of a transport object. According to another embodiment, the additional information may be time information relating to the decoding of a transport object. 
     Additionally, a packet header according to an embodiment of the present invention may include payload identification information. According to an embodiment, the identification information may be payload identification information relating to a Forward Error Correction (FEC) scheme. Herein, the FEC may be one type of payload format defined in RFC 5109. The FEC may be used in RTP or SRTP. The above information may be referred to as an FEC Payload ID field. 
     According to an embodiment, the FEC Payload ID field may include information for identifying a source block of an object. The above information may be referred to as a Source block number field. For example, when the Source block number field is set to N, source blocks in an object may be numbered with 0 to N−1. 
     According to another embodiment, the FEC Payload ID field may include information for identifying a specific encoding symbol. The above information may be referred to as an Encoding symbol ID field. 
     Additionally, a transport packet according to an embodiment of the present invention may include data in a payload. The field including data may be referred to as an Encoding symbol(s) field. According to an embodiment, the broadcast reception device  100  may reconfigure an object by extracting the Encoding symbol(s) field. In more detail, data in the Encoding symbol(s) field may be generated from a source block transmitted through a packet payload. 
       FIG. 105  is a view illustrating a configuration of a packet header according to an embodiment of the present invention. 
     In order to support the transmission of real time content, it is effective that a transport packet received by the broadcast reception device  100  includes property information of a packet and timing information relating to decoding or presentation. Accordingly, in order to solve the above issue, as shown in  FIG. 105 , a packet header may be configured. 
     The packet header of  FIG. 105  has a configuration mostly similar to that of the packet header of  FIG. 104 . Therefore, description of the same parts will be omitted. 
     A packet header according to an embodiment of the present invention may include information representing the type of an object for transmission. The above information may be referred to as a type field. The type field may be a 2 bit field. 
     According to a specific embodiment, the type field may represent that the type of an object for transmission is a regular file. Herein, the regular file may be an ISO BMFF based media file. In more detail, the regular file may be obtained by encapsulating a media file in ISO BMFF format. In this case, the type field may be set to 01 (2) . According to another embodiment, the type field may represent that the type of an object for transmission is an HTTP entity type. In this case, the type field may be set to 10 (2) . According to another embodiment, the type field may represent that the type of an object for transmission is an audio access unit or a video access unit. Additionally, the type field may represent that an object type is a network abstract layer (NAL) unit. In this case, the type field may be set to 11 (2) . 
     Additionally, a packet header according to an embodiment of the present invention may represent that a corresponding transport packet includes the first part or end part of a transport object. Information representing that a transport packet includes the first part or end part of a transport object may be a marker bit. According to a specific embodiment, the marker bit may be an M field. In more detail, the M field may be interpreted differently according to a value of the type field. For example, when the type of an object for transmission is a file, it may represent that a corresponding transport packet includes the end part of a file. Herein, the end part is part including the last bit of a file. For another example, when the type of an object for transmission is Audio or Video (AV) data, it may represent that a corresponding transport packet includes the first or last bit of an access unit. 
       FIGS. 106 and 107  are views illustrating a configuration of a header extension including time information. The header extension shown in  FIG. 106  an  107  may included in the header extension field shown in  FIG. 105 . 
     As shown in  FIG. 106 , a header extension according to an embodiment of the present invention may include type information of a header extension. The above information may be referred to as a Header Extension Type (HET) field. 
     Additionally, a header extension according to an embodiment of the present invention may include the length information of the header extension. The above information may be referred to as a Header Extension length (HEL) field. 
     Additionally, a header extension according to an embodiment of the present invention may represent the current time of a broadcast transmission device. That is, the header extension may include corresponding packet transmission time information of a broadcast transmission device. For example, the broadcast transmission device may be a server. According to a specific embodiment, information representing the current time of a broadcast transmission device may be a Sender Current Time (SCT) field. 
     Additionally, a header extension according to an embodiment of the present invention may represent whether the SCT field is a 64 bit field. In more detail, the header extension may represent whether the SCT field is included in a header extension configured with 64 bits. According to a specific embodiment, information representing whether the SCT field is 64 bits may be an SCT Hi field. 
     Additionally, a header extension according to an embodiment of the present invention may represent whether the SCT field is a 32 bit field. In more detail, the header extension may represent whether the SCT field is included in a header extension configured with 32 bits. According to a specific embodiment, information representing whether the SCT field is 32 bits may be an SCT Low field. 
     Additionally, a header extension according to an embodiment of the present invention may include expected residual time information of an object for transmission. The above information may be an Expected Residual Time (ERT) field. 
     Additionally, a header extension according to an embodiment of the present invention may represent whether the ERT field exits in a corresponding packet. Corresponding information may be an ERT flag field. 
     Additionally, a header extension according to an embodiment of the present invention may include information on a time at which a session is changed lastly. The above information may be an SLC field. 
     Additionally, a header extension according to an embodiment of the present invention may represent whether the SLC field exits in a corresponding packet. Corresponding information may be an SLC flag field. 
     Additionally, a header extension according to an embodiment of the present invention may include a field extended and used according to a transport protocol that a broadcast transmission device uses. Corresponding information may be a PI-specific Use field. 
       FIG. 107  is a view illustrating a header extension having an added configuration according to another embodiment of the present invention. 
     A header extension according to another embodiment of the present invention may include timing information of data included in a packet payload. The above information may be a Timestamp field. For example, the Timestamp field may include information on a time point at which the first byte of data included in a packet payload is decoded. For another example, the Timestamp field may include information on a presentation time point of data. Furthermore, the Timestamp field may include timescale information or timescale based timing information. Herein, the timescale information may be a unit representing a time for a decoding or presentation time point of a transport object. In the case of timescale based timing information, the broadcast reception device may obtain information a decoding or presentation time point by multiplying a value of the Timestamp field and a timescale. 
     A header extension according to another embodiment of the present invention may include format information of a Timestamp field. The above information may be a TS format field. According to a specific embodiment, the TS format field may represent that timing information included in a transport packet is in the format of media time. The media time is a media presentation time according to an arbitrary media timeline. In this case, the TS format field may be set to 0x01. Additionally, the TS format field may represent that timing information included in a transport packet is in the format of Network Time Protocol (NTP). In this case, the TS format field may be set to 0x02. Additionally, the TS format field may represent that timing information included in a transport packet is in the format of normal playing time. The format of normal playing time may be a playing time expressed relative from a presentation start time point and may be expressed in hour, minute, second, or second decimal point unit. In this case, the TS format field may be set to 0x03. Additionally, the TS format field may represent that timing information included in a transport packet is in the format of SMPTE time code. Society of Motion Picture and Television Engineers (SMPTE) time code is time code defined in SMPTE. In more detail, the SMPTE time code may be a time information format defined for individual frame labeling of video in SMPTE. In this case, the TS format field may be set to 0x04. Additionally, the TS format field may represent that timing information included in a transport packet is 90 KHz timing information. In this case, the TS format field may be set to 0x05. 
     A header extension according to another embodiment of the present invention may represent a configuration of a timestamp field. Information representing a configuration of timing information may be referred to as a TS version field. For example, the TS version field may represent that the timestamp field is a 32 bit field. In this case, the TS version field may be set to 0. For another example, the TS version field may represent that the timestamp field is a 64 bit field. In this case, the TS version field may be set to 1. 
       FIGS. 108 to 111  are views illustrating a configuration of a header extension according to another embodiment of the present invention. In more detail, the header extension structure shown in  FIGS. 108 to 111  may include at least one of object type information and timing information for transmission. Additionally, a corresponding header extension structure may be included in a header extension field (header extension). Additionally, it may be used as part of a packet header transmitting content. 
     As shown in  FIG. 108 , a structure (EXT_OBJ_INFO) of a header extension according to another embodiment of the present invention may include type information of header extension part. The above type information may be referred to as an HET field. Additionally, the header extension structure may include length information of header extension part. The above length information may be referred to as an HEL field. Additionally, the header extension structure may include type information of a transport object. The above object type information may be referred to as an Object type field. 
     In a specific embodiment, the Object type field may represent that a transport object is the type of a regular file. Herein, the regular file may be an ISO BMFF based media file. In more detail, the regular file may be obtained by encapsulating a media file in ISO BMFF format. In this case, the Object type field may be set to 0x01. According to another embodiment, the Object type field may represent that a transport object is the type of an HTTP entity type. In this case, the Object type field may be set to 0x02. According to another embodiment, the Object type field may represent that a transport object is an audio data type. The Object type field may represent that a transport object is an AAC based audio data type. At this point, the AAC based audio data type may be audio data encoded through AAC. In this case, the Object type field may be set to 0x03. According to another embodiment, the Object type field may represent that a transport object is an audio data type. In more detail, the Object type field may represent that a transport object is an H.264 type. In this case, the Object type field may be set to 0x04. According to another embodiment, the Object type field may represent that a transport object is an HEVC based video data type. At this point, the HEVC based video data type may be encoded video data encoded through HEVC. In this case, the Object type field may be set to 0x05. According to another embodiment, the Object type field may represent that a transport object is an ISO BMFF based file type. In this case, the Object type field may be set to 0x06. According to another embodiment, the Object type field may represent that a transport object is metadata. In this case, the Object type field may be set to 0x07. 
     Additionally, a structure (EXT_OBJ_INFO) of a header extension according to another embodiment of the present invention may represent that a corresponding transport packet includes the first part or end part of a transport object. Information representing that a transport packet includes the first part or end part of a transport object may be a marker bit. According to a specific embodiment, the marker bit may be an M field. The M field may be interpreted differently according to a value of the Object type field. For example, when the type of an object for transmission is a file, it may represent that a corresponding transport packet includes the end part of a file. Herein, the end part is part including the last bit of a file. For another example, when the type of an object for transmission is Audio or Video (AV) data, it may represent that a corresponding transport packet includes the first or last bit of an access unit. 
     Additionally, a structure (EXT_OBJ_INFO) of a header extension according to another embodiment of the present invention may include timing information of data included in a packet payload. The above information may be a Timestamp field. For example, the Timestamp field may include information on a time at which the first byte of data included in a packet payload is decoded. For another example, the Timestamp field may include information on a presentation time of data. Furthermore, the Timestamp field may include timescale information or timescale based timing information. Herein, the timescale information may be a unit representing a time for a decoding or presentation time point of a transport object. In the case of the timescale based timing information, a broadcast reception device may obtain information on a decoding or presentation time point by multiplying the value of the Timestamp field by a timescale. 
       FIG. 109  is a view illustrating some configurations added to the header extension structure of  FIG. 108  according to another embodiment of the present invention. 
     As shown in  FIG. 109 , the header extension structure may represent whether a timestamp field exists in a corresponding header structure. Information representing whether the Timestamp field exists may be referred to as a TS flag field. In a specific embodiment, when the TS flag field is set to 1, it may represent that the timestamp field exists in a corresponding header structure. 
     Additionally, a structure of a header extension according to another embodiment of the present invention may include format information of a Timestamp field. The above information may be a TS format field. According to a specific embodiment, the TS format field may represent that timing information included in a transport packet is in the format of media time. The media time may be a media presentation time according to an arbitrary media timeline. In this case, the TS format field may be set to 0x01. Additionally, the TS format field may represent that timing information included in a transport packet is in the format of Network Time Protocol (NTP). In this case, the TS format field may be set to 0x02. Additionally, the TS format field may represent that timing information included in a transport packet is in the format of a normal playing time. The format of a normal playing time may be a presentation time expressed relative from a presentation start time point and may be expressed in hour, minute, second, or second decimal point unit. In this case, the TS format field may be set to 0x03. Additionally, the TS format field may represent that timing information included in a transport packet is in the format of SMPTE time code. The SMPTE time code is time code defined in Society of motion picture and television engineers (SMPTE). In this case, the TS format field may be set to 0x04. Additionally, the TS format field may represent that timing information included in a transport packet is 90 KHz timing information. In this case, the TS format field may be set to 0x05. 
     Additionally, a structure of a header extension according to another embodiment of the present invention may represent a configuration of a timestamp field. In more detail, a structure of a header extension may represent a configuration of timing information relating to object presentation or decoding included in the timestamp field. The above information may be referred to as a TS version field. For example, the TS version field may represent that the timestamp field is a 32 bit field. In this case, the TS version field may be set to 0. For another example, the TS version field may represent that the timestamp field is a 64 bit field. In this case, the TS version field may be set to 1. 
       FIG. 110  is a view illustrating some configurations added to the header extension structure of  FIG. 108  according to another embodiment of the present invention. 
     As shown in  FIG. 110 , a structure of a header extension according to another embodiment of the present invention may include additional information relating to a transport object. According to a specific embodiment, a structure of a header extension may include location information of an object. For example, the location information of an object may represent URL information of an ISO BMFF based segment. In more detail, the location information of an object may represent URL information through which ISO BMFF based segments are downloaded. In this case, additional information relating to a transport object may be referred to as an Extension field. 
     Additionally, a structure of a header extension according to another embodiment of the present invention may represent whether an Extension field exists in a corresponding header extension structure. In this case, Information representing whether the Extension field exists may be referred to as an Ext Flag field. 
       FIG. 111  is a view when a new header extension structure is used as part of a packet header according to an embodiment of the present invention. As shown in  FIG. 111 , the part of the packet header may include timing information of a transport object. The part of the packet header including timing information of a transport object may be an EXT_MEDIA_TIME field. 
     The EXT_MEDIA_TIME field may include timing information of data included in a packet payload. The above information may be a Timestamp field. For example, the Timestamp field may include information on a time at which the first byte of data included in a packet payload is decoded. For another example, the Timestamp field may include information on a presentation time of data. Furthermore, the Timestamp field may include timescale information or timescale based timing information. Herein, the timescale information may be a unit representing a time for a decoding or presentation time point of a transport object. In the case of the timescale based timing information, a broadcast reception device may obtain information on a decoding or presentation time point by multiplying the value of the Timestamp field by a timescale. 
     Additionally, the EXT_MEDIA_TIME field may include format information of a Timestamp field. The above information may be a TS format field. According to a specific embodiment, the TS format field may represent that timing information included in a transport packet is in the format of media time. In this case, the TS format field may be set to 0x01. Additionally, the TS format field may represent that timing information included in a transport packet is in the format of Network Time Protocol (NTP). In this case, the TS format field may be set to 0x02. Additionally, the TS format field may represent that timing information included in a transport packet is in the format of normal playing time. In this case, the TS format field may be set to 0x03. Additionally, the TS format field may represent that timing information included in a transport packet is in the format of SMPTE time code. The SMPTE time code is time code defined in Society of motion picture and television engineers (SMPTE). In this case, the TS format field may be set to 0x04. Additionally, the TS format field may represent that timing information included in a transport packet is 90 KHz timing information. In this case, the TS format field may be set to 0x05. Additionally, the TS format field may represent that timing information included in a transport packet is in a GPS time format. In this case, the TS format field may be set to 0x06. 
     Additionally, the EXT_MEDIA_TIME field may represent a configuration of a Timestamp field. A structure of a header extension may represent a configuration of timing information relating to object presentation or decoding included in the timestamp field. The above information may be referred to as a TS version field. For example, the TS version field may represent that the timestamp field is a 32 bit field. In this case, the TS version field may be set to 0. For another example, the TS version field may represent that the timestamp field is a 64 bit field. In this case, the TS version field may be set to 1. 
     Additionally, the EXT_MEDIA_TIME field may include additional information relating to timing information. For example, data information relating to timing information to be mapped may be included. The additional information relating to timing information may be referred to as an Extension field. 
     Additionally, the EXT_MEDIA_TIME field may include information on a configuration of the Extension field. In more detail, various information may be included in the Extension field and flags may form a set in various information. In this case, a set of flags may be referred to as an Ext Flags field. 
     A transport object that the broadcast reception device  100  receives through a broadcast reception unit may need to synchronize with timing information having a different format or reference time. In more detail, the broadcast reception device  100  may need to synchronize timing information of a transport object with a base timeline that is the reference for synchronization having a different format or reference time than timing information of a transport object. According to an embodiment, timing information for synchronization may be a presentation timing of a transport object. Timing information for synchronization according to another embodiment may be a decoding timing of a transport object. In this case, a broadcast transmission device may need to transmit information on a mapping relationship between different timing information and timing information of a transport object to the broadcast reception device  100 . According to an embodiment of the present invention to solve the above issue, metadata including the above-mentioned timeline_component_AU may be transmitted as one transport object. 
     According to an embodiment of the present invention to solve the above issue, the above-mentioned header extension may include additional mapping information different from timing information of a transport object. In more detail, a header extension (EXT_TIME_MAP) may include information for mapping a timestamp of a transport object into another timeline. For example, the broadcast reception device  100  may map a presentation time of a packet payload into a GPS time by using the above information through the control unit  150 . In this case, the GPS time may be a base timeline. 
       FIG. 112  is a view illustrating a structure of a header extension for supporting mapping with another timing information according to an embodiment of the present invention. 
     As shown in  FIG. 112 , the header extension may include format information of a Timestamp field. The above information may be a TS format field. According to a specific embodiment, the TS format field may represent that a timestamp included in a transport packet is in the format of media time. In this case, the TS format field may be set to 0x01. Additionally, the TS format field may represent that a timestamp included in a transport packet is in the format of Network Time Protocol (NTP). In this case, the TS format field may be set to 0x02. Additionally, the TS format field may represent that a timestamp included in a transport packet is in the format of normal playing time. In this case, the TS format field may be set to 0x03. Additionally, the TS format field may represent that a timestamp included in a transport packet is in the format of SMPTE time code. The SMPTE time code is time code defined in Society of motion picture and television engineers (SMPTE). In this case, the TS format field may be set to 0x04. Additionally, the TS format field may represent that a timestamp included in a transport packet is a 90 KHz based timestamp. In this case, the TS format field may be set to 0x05. Additionally, the TS format field may represent that a timestamp included in a transport packet is in a GPS time format. In this case, the TS format field may be set to 0x06. 
     Additionally, the header extension may represent the version or configuration of a timestamp field. A structure of a header extension may represent a configuration of timing information relating to object presentation or decoding included in the timestamp field. The above information may be referred to as a TS version field. For example, the TS version field may represent that the timestamp field is a 32 bit field. In this case, the TS version field may be set to 0. For another example, the TS version field may represent that the timestamp field is a 64 bit field. In this case, the TS version field may be set to 1. 
     Additionally, the header extension may represent whether timing information of a time line into which a timestamp of a transport object is mapped exists. In this case, information representing the presence may be referred to as an OTS flag field. In a specific embodiment, when the OTS flag field is set to 1, it may represent that timing information of a timeline into which a timestamp of a transport object is mapped exists. 
     Additionally, a header extension may represent a timestamp format of a time line into which a timestamp of a transport object is mapped. In more detail, a timestamp of a transport object may be at least one of a presentation time and a decoding time of an object. Additionally, a timeline in which a transport object is mapped into a timestamp may be a base timeline. Herein, the base timeline is a reference timeline for synchronization between a plurality of different timelines. 
     The above information may be an OTS format field. According to a specific embodiment, the OTS format field may represent that a timestamp mapped into a timestamp of a transport object included in a transport packet is in the format of a media time. In this case, the OTS format field may be set to 0x01. Additionally, the OTS format field may represent that timing information included in a transport packet is in the format of Network Time Protocol (NTP). In this case, the OTS format field may be set to 0x02. Additionally, the OTS format field may represent that a timestamp mapped into a timestamp of a transport object included in a transport packet is in the format of normal playing time. In this case, the OTS format field may be set to 0x03. Additionally, the OTS format field may represent that a timestamp mapped into a timestamp of a transport object included in a transport packet is in the format of SMPTE time code. The SMPTE time code is time code defined in Society of motion picture and television engineers (SMPTE). In this case, the OTS format field may be set to 0x04. Additionally, the OTS format field may represent that a timestamp mapped into a timestamp of a transport object included in a transport packet is 90 KHz based timing information. In this case, the OTS format field may be set to 0x05. Additionally, the OTS format field may represent that a timestamp mapped into a timestamp of a transport object included in a transport packet is in a GPS time format. In this case, the OTS format field may be set to 0x06. 
     Additionally, a header extension may represent a version or configuration of a timestamp of a timeline mapped into a timestamp of an object and a timestamp of a transport object. In more detail, a timestamp of a transport object may be at least one of a presentation time and a decoding time of an object. Additionally, a timeline in which a transport object is mapped into a timestamp may be a base timeline. Herein, the base timeline is a reference timeline for synchronization between a plurality of different timelines. 
     In this case, information representing a configuration or version of a timestamp mapped into a timestamp of a transport object may be referred to as an OTS version field. For example, the OTS version field may represent that a timestamp mapped into a timestamp of a transport object is 32 bits. In this case, the OTS version field may be set to 0. For another example, the OTS version field may represent that a timestamp mapped into a timestamp of a transport object is 64 bits. In this case, the OTS version field may be set to 1. 
     Additionally, the header extension may represent whether location information is included. In this case, information representing whether location information is included may be a Location flag field. For example, when the Location flag field is set to 1, it may represent that location information is included in a corresponding header extension. 
     Additionally, the header extension may include a timestamp of a transport object and timing information of a timeline mapped into the timestamp of the transport object. The above information may be referred to as a timestamp field. 
     Additionally, the header extension may include a timestamp of a corresponding header extension and timing information relating to a transport object mapped into a timestamp of a transport object. The above information may be an Origin timestamp field. 
     Additionally, the header extension may include location information of data relating to a timeline mapped into a timestamp of an object. The above information may be referred to as a location field. In an embodiment, when mapping with a timeline of a specific ISO BMFF based data segment is required, the Location field may include the URL of a corresponding data segment. 
       FIG. 113  is a view illustrating a method of operating a broadcast transmission device according to an embodiment of the present invention. 
     The broadcast transmission device obtains an object for transmission through a control unit in operation S 401 . According to an embodiment, the object may be AV content. According to another embodiment, an object may be AV content related enhancement data. 
     The broadcast transmission device may obtain time information and format information of an object through a control unit in operation S 403 . According to an embodiment, the time information may be a timestamp of a transport object. According to another embodiment, the time information may be timing information of a timeline to be mapped into a timestamp of a transport object. According to another embodiment, the time information may be a timestamp of a header extension structure. According to another embodiment, the time information may be timing information of a transport object to be mapped into a timestamp of a header extension structure. Additionally, the format information may be at least one of a regular file, an HTTP entity, and an audio/video access unit. 
     In more detail, a timestamp of a transport object may be at least one of a presentation time and a decoding time of an object. Additionally, a timeline in which a transport object is mapped into a timestamp may be a base timeline. Herein, the base timeline is a reference timeline for synchronization between a plurality of different timelines. For example, the base timeline may be GPS time and information for synchronizing a transport object with the GPS time may be included in the above header extension. 
     The broadcast transmission device sets the time information and format information obtained through the control unit in a packet header and packetizes a transport packet in operation S 405 . In more detail, a control unit of a broadcast transmission device packetizes a packet header including the obtained time information and a packet payload including data according to a transport protocol. According to another embodiment, the broadcast transmission device may set time information and format information in a header extension that is selectively included in a packet header through the control unit. 
     In more detail, the time information may be information relating to a presentation time of an object. The information relating to a presentation time may be at least one of a presentation time point (timing information) and a decoding time point (timing information) of a transport object. According to another embodiment, the additional information may be type information of a transport object. The broadcast transmission device may set at least one of whether a header extension exists in a packet header, the length of a header extension, and type information of a header extension, in a normal packet header. 
     The broadcast transmission device transmits the packetized transport packet through a transmission unit in operation S 407 . The transmission unit may transmit a transport packet through at least one of a terrestrial broadcast network and an internet network. 
       FIG. 114  is a view illustrating a method of operating a broadcast reception device according to an embodiment of the present invention. 
     The broadcast reception device  100  receives a transport packet through the broadcast reception unit  110  in operation S 411 . As described with reference to  FIG. 113 , a transport packet may include a packet header and a packet payload and the packet header may include a header extension selectively. 
     The control unit  150  of the broadcast reception device  100  extracts a packet header and a header extension from the received transmission packet in operation S 412 . According to a specific embodiment, the control unit  150  may extract a packet header included in a transport packet. Additionally, a header extension that is selectively included in a packet header may be extracted from a packet header. 
     The control unit  150  of the broadcast reception device  100  obtains at least one of time information relating to a transport object and format information of a transport object on the basis of a packet header in operation S 413 . According to another embodiment, the control unit  150  may obtain at least one of the time information and the format information from a header extension that is selectively included in a packet header. According to a specific embodiment, the control unit  150  may obtain a timestamp of a transport object on the basis of a header extension. Additionally, the control unit  150  may obtain format information of a transport object. The format information of the transport object may represent at least one of a regular file, an HTTP entity, and an audio/video access unit. Herein, the regular file may be an ISO BMFF based media file. 
     The control unit  150  of the broadcast reception device  100  determines whether information for mapping into another time information is obtained from a packet header in operation S 414 . In more detail, the control unit  150  determines whether another time information mapping into time information for a corresponding transport object exists in a packet header. According to another embodiment, the control unit  150  may determine the other time information on the basis of specific information extracted from a header extension that is selectively included in a packet header. 
     According to an embodiment, when the control unit  150  determines that information for mapping into another time information from a packet header, it obtains information for mapping from the packet header in operation S 415 . Herein, the other time information may be the above mentioned timing information of the base timeline. Additionally, the timing information may include at least one of presentation timing information and decoding timing information of a transport object. According to a specific embodiment, the control unit  150  may obtain timing information of a timeline mapped into a transport object on the basis of a packet header. According to another embodiment, the control unit  150  may obtain timing information of a transport object mapped into a timestamp of a corresponding packet header on the basis of a packet header. Additionally, the control unit  150  may obtain location information of data mapped into a transport object on the basis of a packet header. According to another embodiment, the control unit  150  may obtain information for mapping from a header extension that is selectively included in a packet header. 
     The control unit  150  of the broadcast reception device  100  obtains a transport object on the basis of the obtained time information in operation S 416 . According to an embodiment, when the control unit  150  does not obtain another time information and mapping information, it outputs an object on the basis of a timestamp of a corresponding transport object. According to another embodiment, when the control unit  150  obtains the other time information and the mapping information, it outputs an object on the basis of corresponding mapping information and a timestamp of an object. 
       FIG. 115  is a view illustrating a structure of a packet header including information on a configuration of a transport packet. 
     A packet header according to an embodiment of the present invention may represent that the first or end part data in an entire transport object is included in a packet payload. In this case, Information representing that the first or end part data is included may be a marker bit. According to a specific embodiment, the marker bit may be an M field. The M field may be a 1 bit field. 
     Additionally, a packet header according to an embodiment of the present invention may include information on a configuration of a corresponding transport packet. In this case, the information on the configuration of the transport packet may be a type field. The type field may be a 2 bit field. 
     In another case, the information on the configuration of the transport packet may be included in a codepoint field. The Codepoint field may be an 8 bit field. 
     According to a specific embodiment, the Type field may represent that a corresponding transport object has a regular packet structure. In more detail, it represents that a corresponding packet uses an existing transport packet structure shown in  FIG. 104  as it is. In this case, the transport packet may include at least one of a packet header, a header extension, a packet payload, an identifier, and data. Additionally, the broadcast transmission device may set the Type field to 0x00. 
     Additionally, according to a specific embodiment, the Type field may represent that a corresponding transport packet does not include a payload. In more detail, it represents that a corresponding transport packet includes only a packet header and a header extension. In this case, the broadcast transmission device may set the type field to 0x01. 
     Additionally, according to a specific embodiment, the Type field may represent that a corresponding transport packet includes offset information for an entire transport object. Herein, the offset information is offset information of data including an encoding symbol field of a corresponding transport packet. That is, the offset information represents offset information of data of a corresponding transport packet in an entire transport object. At this point, according to an embodiment, a corresponding transport packet may have a structure and configuration identical to those of a regular transport packet but the payload identifier field may be replaced with a data offset field. In this case, the broadcast transmission device may set the type field to 0x02. 
     Additionally, according to a specific embodiment, the Type field may represent that a corresponding transport packet includes a different configuration than a structure of an existing regular transport packet. In this case, the broadcast transmission device may set the type field to 0x03. According to a specific embodiment, the Type field may represent that a corresponding transport object does not include a payload identifier field. In this case, the broadcast transmission device may set the type field to 0x04.  FIG. 116  is a view illustrating a configuration of the transport packet described with reference to  FIG. 115 . As shown in  FIG. 116 , the Type field may represent a structure of a transport packet. However, the present invention is not limited to the transport packet shown in  FIG. 116  and also is not limited to the set value in  FIG. 116 . 
       FIG. 117  is a view illustrating a method of operating a broadcast transmission device according to an embodiment of the present invention. 
     The broadcast transmission device obtains structure information of a transport packet through a control unit in operation S 421 . According to an embodiment, a structure of a transport packet may be an existing regular packet structure. According to another embodiment, a structure of a transport packet may have a structure configured with only a packet header and a header extension. According to another embodiment, a structure of a transport packet may be a structure including a configuration that replaces an existing payload identifier. According to another embodiment, a structure of a transport packet may be a structure not including a payload identifier. 
     The broadcast transmission device packetizes a transport packet by setting a value that represents information of a corresponding structure in a packet header on the basis of a structure of the transport packet obtained through the control unit in operation S 423 . In more detail, the control unit may set information of a corresponding structure in the Type field. 
     The broadcast transmission device transmits the packetized transport packet through a transmission unit in operation S 425 . According to an embodiment, the transmission unit may transmit the packetized transport packet through a terrestrial broadcast network. According to another embodiment, the transmission unit may transmit the packetized transport packet through an internet network. 
       FIG. 118  is a view illustrating a method of operating a broadcast reception device according to an embodiment of the present invention. 
     The broadcast reception device  100  receives a transport packet through the broadcast reception unit  110  in operation S 431 . According to an embodiment, the broadcast reception unit  110  may receive a transport packet through a terrestrial broadcast network. According to another embodiment, an IP communication unit  130  may receive a transport packet through an internet network. 
     The broadcast reception device  100  extracts a packet header from the received transport packet through the control unit  150  in operation S 433 . In more detail, the transport packet may include at least one of a packet header and a packet payload. Accordingly, the control unit  150  may extract a packet header signaling a packet payload from a transport packet. 
     The broadcast reception device  100  obtains configuration information of a transport packet from the extracted packet header in operation S 435 . In more detail, the packet header may include information representing a structure of a transport packet. Accordingly, the broadcast reception device  100  obtains information representing a structure of a transport packet from a packet header through the control unit  150 . According to an embodiment, a structure of a transport packet may be an existing regular transport packet structure. According to another embodiment, a structure of a transport packet may be a structure including only a packet header and a header extension. According to another embodiment, a structure of a transport packet may be a structure including offset information that replaces a packet payload identifier. According to another embodiment, a structure of a transport packet may be a structure not including a packet payload identifier. 
       FIG. 119  illustrates a hybrid broadcast reception device according to an embodiment of the present invention. The hybrid broadcast system may transmit a broadcast signal in conjunction with a terrestrial broadcast network and an Internet network. The hybrid broadcast reception device may receive a broadcast signal through a terrestrial broadcast network (broadcast) and an Internet network (broadband). The hybrid broadcast reception device may include a physical layer module, a physical layer I/F module, a service/content acquisition controller, an Internet access control module, a signaling decoder, a service signaling manager, a service guide manager, an App signaling manager, an alert signal manager, an alert signal parser, a targeting signal parser, a streaming media engine, a non-real-time file processor, a component synchronizer, a targeting processor, an application processor, an A/V processor, a device manager, a data sharing and communication unit, a redistribution module, a companion device and/or an external module. 
     The physical layer module(s) may receive and process broadcast-related signals through a terrestrial broadcast channel, convert the same into appropriate forms, and transmit the converted signals to the physical layer I/F module. 
     The physical layer I/F module(s) may acquire IP datagrams from the information obtained from the physical layer module. In addition, the physical layer I/F module may convert the acquired IP datagram or the like into a specific frame (for example, RS frame, GSE). 
     The service/content acquisition controller may perform control operations for acquiring services, content and signaling data associated therewith over a broadcast and/or broadband channel. 
     The Internet access control module(s) may control receiver operations to acquire services, content, and the like over a broadband channel 
     The signaling decoder may decode the signaling information acquired over a broadcast channel or the like. 
     The service signaling manager may extract, parse, and manage signaling information related to service scan and services/content from the IP datagram and the like. 
     The service guide manager may extract announcement information from IP datagrams, manage an SG (Service Guide) database, and provide a service guide. 
     The App signaling manager may extract, parse, and manage signaling information related to application acquisition and the like from IP datagrams and the like. 
     The alert signal parser may extract, parse, and manage alerting related signaling information from IP datagrams and the like. 
     The targeting signal parser may extract, parse, and manage signaling information related to service/content personalization or targeting from IP datagrams and the like. The targeting signal parser may also deliver the parsed signaling information to the targeting processor. 
     The streaming media engine may extract and decode audio/video data for A/V streaming from IP datagrams and the like. 
     The non-real time file processor may extract, decode, and manage NRT data and file type data such as applications from IP datagrams and the like. 
     The component synchronizer may synchronize services and content such as streaming audio/video data and NRT data. 
     The targeting processor may process operations related to personalization of the service/content based on the targeting signaling data received from the targeting signal parser. 
     The application processor (App processor) may process application-related information, the status of a downloaded application and display parameters. 
     The A/V processor may perform audio/video rendering related operations based on decoded audio and video data, application data, and the like. 
     The device manager may perform connection and data exchange with an external device. The device manager may also perform management of external devices such as addition/deletion/update of operatively connectable external devices. 
     The data sharing and communication unit (Data Sharing &amp; Comm) may process information related to data transmission and exchange between the hybrid broadcast receiver and an external device. Here, the data that may be transmitted and exchanged may be signaling, A/V data, and the like. 
     The redistribution module(s) may acquire related information about the next generation broadcast service and content when the broadcast receiver cannot directly receive the terrestrial broadcast signal. The redistribution module may also support acquisition of broadcast services and content by the next generation broadcast system when the broadcast receiver cannot directly receive the terrestrial broadcast signal. 
     The companion device(s) may be coupled to the broadcast receiver of the present invention to share audio, video, or signaling-containing data. The companion device may refer to an external device connected to the broadcast receiver. 
     An external management module (External Management) may refer to a module for providing broadcast service/content, for example, a next generation broadcast service/content server. The external module may refer to an external device connected to the broadcast receiver. 
       FIG. 120  is a block diagram illustrating a hybrid broadcast receiver according to an embodiment of the present invention. 
     The hybrid broadcast receiver may receive the hybrid broadcast service through operative connection of terrestrial broadcast and broadband in the DTV service of the next generation broadcast system. The hybrid broadcast receiver may receive broadcast audio/video (A/V) content transmitted through a terrestrial broadcast and receive part of enhancement data or broadcast A/V content associated therewith in real time through broadband. In this specification, the broadcast audio/video (A/V) content may be referred to as media content. 
     The hybrid broadcast receiver may include a physical layer controller D 55010 , a tuner D 55020 , a physical frame parser D 55030 , a link layer frame parser D 55040 , an IP/UDP datagram filter D 55050 , an ATSC 3.0 DTV (Digital Television) Control Engine D 55060 , an ALC/LCT+ Client D 55070 , a timing control D 55080 , a signaling parser D 55090 , a DASH (Dynamic Adaptive Streaming over HTTP) client D 55100 , an HTTP access client D 55110 , an ISO BMFF parser D 55120 , and/or a media decoder D 55130 . 
     The physical layer controller D 55010  may control operations of the tuner D 55020 , the physical frame parser D 55030 , and the like using radio frequency (RF) information about a terrestrial broadcast channel to be received by the hybrid broadcast receiver. 
     The tuner D 55020  may receive and process broadcast related signals through a terrestrial broadcast channel and convert the same into an appropriate form. For example, the tuner D 55020  may convert a received terrestrial broadcast signal into a physical frame. 
     The physical frame parser D 55030  may parse the received physical frame and acquire a link layer frame through related processing. 
     The link layer parser D 55040  may acquire link layer signaling from the link layer frame or perform related operations to acquire an IP/UDP datagram or an MPEG-2 TS. The link layer parser D 55040  may output at least one IP/UDP datagram or the like. 
     The IP/UDP datagram filter D 55050  may filter a specific IP/UDP datagram from at least one received IP/UDP datagram or the like. That is, the IP/UDP datagram filter D 55050  may selectively filter an IP/UDP datagram selected by the ATSC 3.0 DTV control engine D 55060  among the at least one IP/UDP datagram output from the link layer parser D 55040 . The IP/UDP datagram filter D 55050  may output an application layer transport protocol packet such as ALC/LCT+. 
     The ATSC 3.0 DTV control engine D 55060  may serve as an interface between modules included in each hybrid broadcast receiver. The ATSC 3.0 DTV control engine D 55060  may also provide necessary parameters for each module, thereby controlling the operation of each module. In the present invention, the ATSC 3.0 DTV control engine D 55060  may deliver a media presentation description (MPD) and/or an MPD URL to the DASH client D 55100 . In the present invention, the ATSC 3.0 digital television control engine D 55060  may also deliver a delivery mode and/or a transport session identifier (TSI) to the ALC/LCT+ client D 55070 . Here, TSI may represent the identifier of a session for transmitting a transport packet including a signaling message such as MPD or MPD URL related signaling, for example, the identifier of a FLUTE session or an ALC/LCT+ session, which is an application layer transmission protocol. The TSI may correspond to the Asset id of MMT. 
     The ALC/LCT+ client D 55070  may process application layer transport protocol packets such as ALC/LCT+, and collect and process a plurality of packets to create one or more ISO Base Media File Format (ISOBMFF) objects. The application layer transport protocol packets may include ALC/LCT packets, ALC/LCT+ packets, ROUTE packets, and/or MMTP packets. 
     The timing control D 55080  may process a packet including system time information to control the system clock. 
     The signaling parser D 55090  may acquire and parse DTV broadcast service related signaling, and generate and manage a channel map and the like based on the parsed signaling. In the present invention, the signaling parser may parse the extended MPD or MPD related information from the signaling information. 
     The DASH client D 55100  may perform operations related to real-time streaming or adaptive streaming. The DASH client D 55100  may receive DASH content from the HTTP server through the HTTP access client D 55110 . The DASH client D 55100  may process the received DASH segment and output an ISO Base Media File Format object. In the present invention, the DASH client D 55100  may deliver a Fully Qualified Representation ID or a segment URL to the ATSC 3.0 DTV control engine D 55060 . Here, the Fully Qualified Representation ID may refer to an ID that combines, for example, the MPD URL, period@id, and representation@id. The DASH client D 55100  may also receive the MPD or MPD URL from the ATSC 3.0 DTV control engine D 55060 . The DASH client D 55100  may receive a desired media stream or DASH segment from the HTTP server using the received MPD or MPD URL. In this specification, the DASH client D 55100  may be referred to as a processor. 
     The HTTP access client D 55110  may make a request for specific information to the HTTP server, and may receive and process a response from the HTTP server. Here, the HTTP server may process the request received from the HTTP access client and provide a response thereto. 
     The ISO BMFF parser D 55120  may extract audio/video data from the ISO Base Media File Format object. 
     The media decoder D 55130  may decode the received audio and/or video data and perform processing to present the decoded audio/video data. 
     The hybrid broadcast receiver of the present invention is required to extend or modify the MPD in order to provide the hybrid broadcast service through operative connection between the terrestrial broadcast network and the broadband. The terrestrial broadcast system may transmit the extended or modified MPD, and the hybrid broadcast receiver may receive the broadcast or broadband content using the extended or modified MPD. That is, the hybrid broadcast receiver may receive the extended or modified MPD through terrestrial broadcasting and receive content via terrestrial broadcasting or broadband based on MPD. The following describes elements and attributes that should be additionally included in the extended or modified MPD compared to the existing MPD. In the following description, the extended or modified MPD may be referred to as an MPD. 
     The MPD may be extended or modified to represent ATSC 3.0 services. An extended or modified MPD may additionally include MPD@anchorPresentationTime, Common@presentable, Common.Targeting, Common.TargetDevice and/or Common@ associatedTo. 
     MPD@ anchorPresentationTime may represent the presentation time anchor of segments included in the MPD, that is, a base time. Hereinafter, MPD@ anchorPresentationTime may be used as an effective time of the MPD. MPD @ anchorPresentationTime may represent the earliest playback point in time among the segments included in the MPD. 
     The MPD may further include common attributes and elements. The common attributes and elements may be applied to the AdaptionSet, Representation, SubRepresentation, and the like in the MPD. Common@presentable may indicate that the media described by MPD is a presentable component. 
     Common.Targeting may indicate the targeting properties and/or personalization properties of the media described by the MPD. 
     Common.TargetDevice may represent a target device or target devices of the media described by the MPD. 
     Common@ associatedTo may represent an adaptationSet and/or representation associated with the media described by the MPD. 
     In addition, the MPD@id, Period@id, and AdaptationSet@id included in the MPD may be required to specify the media content described by the MPD. In other words, the DASH client may specify the content to be received as MPD@id, Period@id, and AdaptationSet@id based on the MPD and deliver the same to the ATSC 3.0 DTV control engine. The ATSC 3.0 DTV control engine may receive the content and deliver the same to the DASH client. 
       FIG. 121  shows a protocol stack of a next generation hybrid broadcast system according to an embodiment of the present invention. As shown in the figure, a next generation broadcast system supporting IP-based hybrid broadcasting may encapsulate audio or video data of a broadcast service in an ISO Base Media File Format (hereinafter referred to as ISO BMFF). Here, the encapsulation may be in the form of a DASH segment or an MPU (Media Processing Unit) of MMT. In addition, the next generation broadcast system may transmit encapsulated data over the broadcast network and the Internet network equally or differently according to the properties of each transmission network. The next generation broadcast system may also transmit the encapsulated data using at least one of broadcast or broadband. In case of broadcast network, the broadcast system may transmit data encapsulated in ISO Base Media File (ISO BMFF) through an application layer transport protocol packet supporting real time object transmission. For example, the broadcast system may encapsulate the data with Real-Time Object Delivery over Unidirectional Transport (ROUTE) or MMTP transport packet. Then, the broadcast system may generate an IP/UDP datagram from the encapsulated data, and transmit the same through a broadcast signal. When broadband is used, the broadcast system may transmit the encapsulated data to the receiving side based on a streaming technique such as DASH. 
     In addition, the broadcast system may transmit the signaling information of the broadcast service in the following manner. In the case of a broadcast network using broadcasting, the broadcast system may transmit signaling information through the physical layer of the next generation broadcast transmission system and the broadcast network according to the attribute of the signaling. Here, the broadcast system may transmit signaling information through a specific data pipe (DP) of a transport frame included in the broadcast signal. The broadcast signaling may be encapsulated in a bit stream or an IP/UDP datagram. When using broadband, the broadcast system may return signaling data in response to the request of the receiver. 
     In addition, the broadcast system may transmit the ESG or NRT content of the broadcast service in the following manner. In the case of a broadcast network, the broadcast system may encapsulate ESG or NRT content in an application layer transport protocol packet, for example, Real-Time Object Delivery over Unidirectional Transport (ROUTE), MMTP transport packet, or the like. Then, the broadcast system may generate an IP/UDP datagram from the encapsulated ESG or NRT content and transmit the same through a broadcast signal. When using broadband, the broadcast system may return the ESG or NRT content in response to the request of the receiver. 
       FIG. 122  shows a structure of a transport frame transmitted to a physical layer of a next generation broadcast transmission system according to an embodiment of the present invention. The next generation broadcast system may broadcast a transport frame. In the figure, P1, located at the front part of a transport frame, may refer to a symbol including information for transport signal detection. P1 may contain tuning information and the receiver may decode the L1 part located after P1 based on the parameters contained in the P1 symbol. The broadcast system may include information on the configuration of the transport frame and the characteristics of each data pipe (DP) in the L1 part. That is, the receiver may obtain information on the configuration of the transport frame and the characteristics of each DP by decoding the L1 part. In addition, the receiver may acquire information to be shared between the DPs via a common DP. Depending on the embodiment, the transport frame may not include the common DP. 
     In the transport frame, components such as Audio, Video, and Data are transmitted in the interleaved DP area composed of DP1 to DP n. Here, a DP through which a component constituting each service (channel) is transmitted may be signaled through L1, common PLP, or the like. 
     In addition, the next generation broadcast system may transmit information for quickly acquiring information on a service included in a transport frame. That is, the next generation broadcast system may enable the next generation broadcast receiver to quickly acquire the broadcast service and the content related information included in the transport frame. In addition, when a service/content generated by one or more broadcast stations exists in the frame, the next generation broadcast system may enable the receiver to efficiently recognize the service/content according to the broadcast stations. That is, the next-generation broadcast system may transmit service list information for a service in a transport frame. 
     The broadcast system may transmit broadcast service related information through a separate channel, for example, a Quick Information Channel (FIC), in order to enable the receiver to quickly scan the broadcast service and content within the frequency. As shown in the middle part of  FIG. 122 , the broadcast system may transmit information for scan and acquiring broadcast services in a transport frame. Herein, the area including the information for scan and acquisition of broadcast services may be referred to as FIC. The receiver may acquire information on the broadcast service generated and transmitted by one or more broadcast stations through the FIC, thereby making it possible to easily and quickly perform scan of the broadcast services available on the receiver. 
     In addition, a specific DP included in the transport frame may operate as a base DP for quickly and robustly transmitting signaling of a broadcast service and content transmitted in the corresponding transport frame. The data transmitted through each DP of the transport frame of the physical layer are exemplarily shown at the bottom of  FIG. 122 . That is, link layer signaling or IP datagrams may be encapsulated in a specific type of generic packet and then transmitted through the DP. Here, the generic packet may include signaling data. Link (low) layer signaling may include signaling related to quick service scan/acquisition, context information of IP header compression, emergency alert, and the like. 
       FIG. 123  illustrates a first packet structure according to an embodiment of the present invention. 
     The present invention proposes a method for transmitting data formatted in two or more data unit types using a single transmission protocol in a process of transmitting the data. That is, the present invention proposes a method for modifying/extending a transport packet structure proposed by one transport protocol such that the transport packet structure effectively contains data formatted in various formats. 
     For example, in a system configured to transmit both data formatted in the MPEG DASH segment format and data formatted in the MMTP MPU format, a method of delivering the data through a transport packet according to the ROUTE protocol or the MMT protocol may be conceived. Furthermore, it is possible to modify/extend a ROUTE packet structure according to the ROUTE protocol to effectively transmit any data formatted in various formats according to an embodiment. 
     The illustrated first packet structure may be a packet structure based on ALC/LCT according to ROUTE. The first packet can be divided into a header and a payload. As shown, the header may include V, C, PSI, S, O, . . . , payload ID fields. Some fields may be omitted according to an embodiment. The first packet does not mean one packet or a first packet and may refer to a packet of a first type. 
     The V field indicates version information of the corresponding transport protocol packet, that is, the first packet. The C field indicates a flag related to the length of a congestion control information field. The congestion control information field will be described below. The PSI field indicates protocol-specific information. What this field means may vary depending on embodiments. 
     The S field indicates a flag related to the length of a TSI (transport session identifier) field. The O field indicates a flag related to the length of a TOI (transport object identifier) field. The H field indicates whether a half-word (16 bits) is added to the length of the TSI or TOI field. Res is reserved for future use. 
     The A field indicates that the corresponding session is ended or end of the session is imminent. The A field may serve as a close session flag. The B field indicates that object transmission is ended or end of object transmission is imminent. The B field may serve as a close object flag. 
     The HDR_LEN field may have information related to a header length. The code point field represents information related to encoding or decoding of the payload of the corresponding packet. For example, the code point field can be used to indicate the type of the corresponding payload. 
     The congestion control information may have information related to congestion control. Here, congestion control refers to control for dispersing requests which have been congested or overloaded for specific information or session. 
     The TSI (Transport Session Identifier) field indicates an identifier of a transport session. That is, the TSI can be used as an identifier of each LCT session. The TSI may be called a TSI value. The TOI (Transport Object Identifier) field indicates an identifier of an object transmitted through a transport session. A TOI value can be used to identify objects delivered through the corresponding LCT session. 
     The header extension field indicates an extended header part when the header of the transport packet is extended. An extended header part can be defined according to various embodiments, and an extended header can be positioned in the header extension field. An extended header can be used to transmit additional information of a header. The payload ID field can be used to indicate an identifier of the payload of the transport packet or to indicate an offset of payload data in a transport object. 
     The numerals shown in parentheses refer to the numbers of bits allocated to the fields, but the numbers of bits may be varied according to embodiments. 
     Embodiments of extending/modifying the shown first packet structure will be described. 
     In an embodiment, the PSI field can be used in the header structure of the first packet. In this embodiment, the aforementioned PSI field can be used as a TYPE field. Here, the TYPE field can indicate the type of data included in the payload of the corresponding transport packet. For example, the payload includes signaling or metadata when the TYPE field is 0x00, includes real-time service data when the TYPE field is 0x01 and includes non-real-time service data when the TYPE field is 0x02. The value of 0x03 indicates that the payload is reserved for future use. 
     In another embodiment, the TYPE field may be positioned at the Res part instead of the PSI field. That is, a part reserved for future use may be used as the TYPE 
     FIELD 
     In another embodiment, the aforementioned PSI field may be replaced by the TYPE field and the Res part may be replaced by a TYPE-ext field. That is, a payload type can be indicated using the PSI field and the Res part in this embodiment. In this case, the values of the TYPE field may indicate the aforementioned payload types. Here, the TYPE_ext field can indicate the format of the payload type indicated by the TYPE field. 
     For example, payload data has a signaling metadata format when the TYPE_ext field is 0x00, a format in an entity mode when the TYPE_ext field is 0x01, a file format when the TYPE_ext field is 0x02, and an MPU format defined in MMT when the TYPE_ext field is 0x03. 
     That is, in a process of transmitting data formatted in two or more data unit types as described above, the TYPE_ext field can be used to transmit the data using a single transport packet structure. The TYPE_ext field can be used to indicate a type of data included in the payload. For example, when the TYPE_ext field is 0x02, the payload has a “file” format. Here, a file may include a DASH segment. When the TYPE_ext field is 0x03, the payload has an MPU format. In this manner, the TYPE_ext field can indicate a type of data included in the payload. 
       FIG. 124  illustrates a structure of the first packet according to another embodiment of the present invention. 
     In a header structure of the first packet according to another embodiment, the PSI field can be used as a CO field and an RAP field. 
     Here, the CO field may be a flag indicating whether the corresponding transport packet structure supports compatibility with the ALC/LCT packet structure. When the CO field is 1, the transport packet structure has compatibility with the ALC/LCT packet structure and the corresponding transport packet may have the aforementioned congestion control information field. That is, the corresponding transport packet may include the congestion control information filed having congestion control related information. However, when the CO field is 0, the congestion control information field of the transport packet may have information other than congestion control related information. That is, compatibility with the ALC/LCT packet structure, indicated by the CO field, may represent whether information of the congestion control information field is related to congestion control related information. 
     The RAP field may be a flag indicating whether information contained in the payload of the transport packet includes information related to a random access point. The information may be included in the information contained in the payload of the transport packet when the RAP field is 1 and the information may not be included when the RAP field is 0. 
     When the CO field is 0, various embodiments depending on information included in the congestion control information field may be present. 
     In an embodiment, the congestion control information field may have a payload ID or offset information when the CO field is 0. The payload ID may refer to the identifier of the payload of the corresponding transport packet and the offset information may refer to an offset value of data of the payload of the transport packet in transport objects. If the congestion control information field is insufficient, the conventional payload ID field (or offset field) may be used as an extension field of the payload ID/offset. 
     In another embodiment, the congestion control information field may have timestamp information when the CO field is 0. The timestamp information may be related to data of the payload. The corresponding timestamp may be used to indicate presentation time of the data of the payload. 
     In another embodiment, the congestion control information field may have MPU sequence number information when the CO field is 0. In this case, the payload of the transport packet may include an MMTP payload defined in the MMT. In the case of a transport packet according to the MMT protocol, the MPU sequence number information is included in the payload header of the payload. In this case, a receiver can recognize MPU sequence number information by parsing not only the header of the transport packet but also the payload header in the payload. This may act as an operation load in the receiver. To reduce the operation load, the transport packet structure may be modified such that the transport packet header includes the MPU sequence number information. That is, the transport packet structure according to the present embodiment can be regarded as a structure for improving efficiency in transmission of MPU type information. 
     The congestion control information field may have various types of information in addition to the aforementioned information when the CO field is 0. To represent this, a MODE field may be inserted into the Res part. The MODE field indicates a type of information included in the congestion control information field. For example, a payload ID or offset information may be included in the congestion control information field when the MODE field is 0x00, a timestamp may be included in the congestion control information field when the MODE field is 0x01, and MPU sequence number information may be included in the congestion control information field when the MODE field is 0x02. When the MODE field is 0x03, the congestion control field is reserved for future use. 
     In the shown transport packet structure, the payload part is omitted. Furthermore, the remaining fields shown in the figure are as described above. 
       FIG. 125  illustrates a structure of the first packet according to another embodiment of the present invention. 
     In a header structure of the first packet according to another embodiment, the PSI field can be used as a P field and a RAP field. The RAP field has been described. 
     The P field indicates information about protocols supported by the corresponding transport packet. The P field may indicate different types of information according to embodiments. For example, the corresponding transport packet supports the ALC/LCT protocol and the transport packet structure supports compatibility with the ROUTE (ALC/LCT) transport packet structure when the P field is 0. When the P field is 1, a transport protocol (e.g., MMT) other than ROUTE (ALC/LCT) is supported. 
     In this embodiment, the Res part may be used as the TYPE field. The TYPE field indicates the type of data included in the payload of the corresponding transport protocol packet. That is, the payload may include signaling or metadata when the TYPE field is 0x00, real-time service data when the TYPE field is 0x01 and non-real-time service data when the TYPE field is 0x02. When the TYPE field is 0x03, the payload may be reserved for future use. 
       FIG. 126  illustrates payload structures of the first packet according to another embodiment of the present invention. 
     When the P field is 1, the transport packet can support a transport protocol other than ROUTE (ALC/LCT), as described above. For example, when the MMT is supported, the transport packet can include an MMTP payload defined in the MMT. According to an embodiment, the payload of the transport packet may include data such as an MPU, a GFD file, MPD metadata or an MFU. 
     For example, when the P field is 1 and the transport packet supports the MMT protocol, the following various payload types may be present according to the TYPE field. 
     In an embodiment, the value of the TYPE field may represent that the payload includes signaling/metadata. In this case, the corresponding packet can include a payload such as t 123010  or signaling/metadata. That is, an MMT payload t 123010  defined for signaling data can be positioned at the payload of the packet. 
     In another embodiment, the value of the TYPE field may represent that the payload includes non-real-time data or a generic file. In this case, the corresponding packet can include a payload such as t 123020  or the non-real-time data/general file. That is, an MMT payload t 123020  defined for the non-real-time data/generic file can be positioned at the payload of the packet. 
     In another embodiment, the value of the TYPE field may represent that the payload includes real-time data. In this case, the corresponding packet can include a payload such as t 123030  or the real-time data (an MPU, a movie fragment, an MFU (DU) or the like). That is, an MMT payload t 123030  (MPU mode payload) defined for the real-time data can be positioned at the payload of the packet. 
       FIG. 127  illustrates a header structure and a payload header structure of a second packet according to an embodiment of the present invention. 
     As described above, the present invention proposes the method for transmitting data formatted in two or more data unit types using a single transport protocol. For a packet different from the aforementioned first packet, that is, a second packet, a method of modifying/extending the structure of the second packet such that the packet structure can effectively contain data formatted in various formats can be proposed. 
     Here, the second packet may have a transport packet structure for containing data based on a different protocol from data contained in the first packet. To contain data based on a different protocol, the second packet can be extended/modified. For example, TOI information and the like may be further included for extension. 
     The shown second packet structure may be an MMTP packet structure according to the MMTP. The second packet can be divided into a header and a payload. The payload may be divided into a payload header and payload data according to an embodiment. As shown (t 124010 ), the header may include V, C, FEC, r, . . . , header extension fields. Some fields may be omitted according to an embodiment. The second packet does not mean a second packet and may refer to a packet of a second type. 
     The V field may indicate version information of the corresponding transport protocol packet, that is, the second packet. The C field may be a flag indicating presence or absence of a Packet_Counter field. The FEC field may indicate an FEC scheme related to the corresponding transport packet. For example, the FEC field can indicate a source packet or a repair packet when AL-FEC is applied/not applied. 
     The X field may be a flag indicating presence or absence of header extension. R may be a flag indicating whether the payload of the transport packet includes a random access point (RAP). The TYPE field may indicate the type of payload data of the transport packet. For example, the TYPE field can indicate types such as signaling, a generic object, an MPU, a DASH segment and a repair symbol. 
     The packet_id field may indicate the identifier of the transport packet. This field can indicate an identifier for a flow of transport packets, that is, a packet flow, like the aforementioned TSI field of the first packet. The timestamp field may indicate a timestamp related to the corresponding transport packet or a server time corresponding to a transmission time of the corresponding packet. The timestamp field may indicate information on a time when the first byte of data included in the transport packet starts to be transmitted or a payload data presentation time. 
     The Packet_Sequence_Number field may indicate sequence numbers of transport packets having the same packet_id field. The header extension field may include an extension header for transmission of additional information of the header. 
     The numerals shown in parentheses refer to the numbers of bits allocated to the corresponding fields, but the numbers of bits may be varied according to embodiments. 
     The payload of the second packet may include only payload data or include a payload header and payload data. When the payload includes the payload header and payload data, payload header information as shown may be included in the payload (t 124020 ). Such a payload header may be included in the aforementioned header extension field. 
     A header length field may indicate the length of the payload header. A start object flag (SO) field may represent that transmission of a transport object included in the payload is started. A close object flag (CO) field may represent that transmission of a transport object included in the payload is ended or the end of transmission is imminent. 
     An offset scheme field may indicate a scheme representing a payload ID or offset of the payload. A payload format field may indicate the format of the payload. For example, the format may be a generic file, entity form, DASH segment, MPU or the like. 
     A code point field may indicate information related to encoding or decoding of the payload of the packet. The TOI field may indicate the identifier of a transport object included in the payload. A payload ID (or offset) field may indicate the identifier of the payload or offset information of data included in the payload in a transport object. 
     The payload data of the transport packet may include effective data such as a DASH segment, an MPU, a generic file and signaling/metadata. 
     Embodiments of extending/modifying the shown second packet structure will be described. 
     In an embodiment, the packet_id field of the second packet structure may be replaced by a packet_flow_id field. The packet_flow_id field may indicate an identifier for a corresponding packet flow. For example, the packet_flow_id field can indicate an identifier of packets related to a plurality of packets (audio, video and the like) associated with one component. That is, packets related to the same component can have the same packet_flow_id field value. 
     In another embodiment, the second packet structure may include a P field at an r part reserved for future use. The P field may be a flag indicating whether the corresponding transport packet includes a packet_sequence_number field. The transport packet includes the packet_sequence_number field when the P field is 1 and does not include the same when the P field is 0. 
       FIG. 128  illustrates packet structures of the second packet according to another embodiment of the present invention. 
     In another embodiment (t 125010 ), the second packet structure may include a T field and an O field in the Res part reserved for future use. 
     The T field may be a flag indicating whether the TOI field is included in the corresponding transport packet. The TOI field is included in the transport packet when the T field is 1 and is not included therein when the T field is 0. The O field may be a flag indicating whether an offset field is included in the transport packet. The offset field is included in the transport packet when the O field is 1 and is not included therein when the O field is 0. 
     The TOI field may indicate the identifier of a transport object (a DASH segment, signaling, an MPU, a generic file or the like) included in the payload of the transport packet. Since a TOI value is generally positioned in the payload header in the MMTP packet structure, a receiver needs to parse the payload to check the TOI value. However, overhead with respect to such a receiver operation can be reduced by locating the TOI value in the header. 
     The offset field may include an offset value of payload data in a transport object. 
     In another embodiment (t 125020 ), the second packet structure may include the T field and the CO field in the Res part reserved for future use. The T field and the TOI field may be as described above. 
     Here, the CO (close object flag) field may represent that transmission of a transport object included in the payload is ended or the end of transmission is imminent. This information can be located in the transport packet header instead of the payload header, differently from the normal MMTP packet structure, to reduce overhead in the receiver. 
     In another embodiment (t 125030 ), the second packet structure may include the T field and the SO field in the Res part reserved for future use. The T field and the TOI field may be as described above. 
     Here, the SO (start object flag) field may represent that transmission of a transport object included in the payload is started. This information can be located in the transport packet header instead of the payload header, differently from the normal MMTP packet structure, to reduce receiver overhead. 
       FIG. 129  illustrates header extension structures of the second packet according to another embodiment of the present invention. 
     In another embodiment (t 126010 ), the second packet structure may have information as shown in the header extension field. That is, the TYPE field, length field and offset scheme field may be included in Header Extension. Here, the TYPE field may indicate the type of information included in Header Extension. The length field may indicate the length of Header Extension. The offset scheme field and the offset field may be as described above. 
     In another embodiment (t 126020 ), the second packet structure may have information as shown in the header extension field. That is, a presentation timestamp field may be included along with the TYPE field and length field in the second packet structure. Here, the presentation timestamp field (PTS field) may include time information indicating a presentation time of data included in the payload. 
       FIG. 130  illustrates a process in which the first packet or the second packet is transmitted according to an embodiment of the present invention. 
     Media data (media essence), signaling information and the like can be transmitted through transport packets having the aforementioned extended/modified structures. 
     Signaling information can be encapsulated into transport packets with the aforementioned headers attached thereto according to a transport protocol. Transport headers TPH may conform to the above-described various embodiments. In addition, media data can be divided into an initialization segment having an ftyp box, a moov box and the like, and media segments when the media data is formatted into DASH segments. The media segments can include an styp box, an sidx box, a moof box, an mdat box, etc. The mdat box may include effective media data. 
     Such segments can be encapsulated into transport packets with the aforementioned headers attached thereto. Transport headers TPH may conform to the above-described various embodiments. The transport packets generated in this manner can be transmitted through a transport session (ROUTE, MMTP or the like). 
       FIG. 131  illustrates a method of transmitting a broadcast signal according to an embodiment of the present invention. 
     The method of transmitting a broadcast signal according to an embodiment of the present invention may include a step of generating a service list table, a step of generating first service data and service signaling information, a step of processing the first service data, the service list table and the service signaling information into a broadcast stream and/or a step of transmitting the broadcast stream. 
     A first module of a transmission side may generate the service list table including information for identifying a transport session delivering service signaling information. Here, the service signaling information may correspond to the aforementioned SLS. The transport session may refer to the aforementioned LCT or ROUTE session. The information for identifying the transport session may refer to IP and UDP information of the aforementioned ROUTE session. The service signaling information may include access information of the first service data. Here, access information may be the aforementioned bootstrap information. The first module may be a hardware module in charge of generation of the service list table. 
     The aforementioned first module may generate the first service data and the service signaling information. The first module may generate effective service data and/or an SLS with respect thereto. 
     A second module of the transmission side may process the first service data, the service list table and/or the service signaling information into the broadcast stream. The second module may take charge of processing of the aforementioned physical layer. As described above, the second module may perform operations such as encoding, interleaving, framing and modulation. 
     A third module of the transmission side may transmit the broadcast stream. The third module may be included in the second module according to an embodiment. The third module may correspond to an antenna. 
     In a method of transmitting a broadcast signal according to another embodiment of the present invention, the first service data and the service signaling information may be encapsulated into transport packets of a transport session and delivered, and each transport packet may have a header and a payload. Here, the transport packet may be the aforementioned ROUTE packet or LCT packet. The transport packet may be an MMTP packet according to an embodiment. 
     In a method of transmitting a broadcast signal according to another embodiment of the present invention, a method of processing service data may further include a step of generating second service data based on a different protocol from the first service data. Here, the different protocol may refer to the MMTP. The first service data may be delivered according to the ROUTE protocol and the second service data may be delivered according to the MMTP. The protocols may be switched. A transmission method according to each protocol has been described above. The first service data may be data regarding a first service and the second service data may be data regarding a second service. Alternatively, the first service data and the second service data may correspond to service components included in the same service. At least one transport packet may include the second service data and an extension header for delivering the second service data. As described above, a transport packet may be extended to include information for data delivered according to two or more protocols. 
     In a method of transmitting a broadcast signal according to another embodiment of the present invention, an extension header may further include header mode information and may include sequence number information or timestamp information of the second service data according to the header mode information. Here, the header mode information may correspond to the aforementioned MODE information. The sequence number information and the timestamp information may correspond to the aforementioned MPU sequence number field and timestamp field. Although an MMT transport packet may not include timestamp related information, in general, the ROUTE packet can be extended and thus can provide such timestamp information. 
     In a method of transmitting a broadcast signal according to another embodiment of the present invention, a payload of at least one transport packet may include a payload header and payload data including the second service data, and the payload header may have a different structure according to whether the second service data is real-time service data. 
     In a method of transmitting a broadcast signal according to another embodiment of the present invention, the extension header may further include payload type information indicating a payload header type. The payload type information may correspond to the aforementioned TYPE field. 
     In a method of transmitting a broadcast signal according to another embodiment of the present invention, a header of a transport packet may further include a transport object identifier for identifying data included in a payload. Here, the transport object identifier may correspond to the aforementioned TOI field for filtering. 
     In a method of transmitting a broadcast signal according to another embodiment of the present invention, the transport object identifier may further include fragment type information, fragment type extension information and fragment version information. The fragment type information may indicate the type of service signaling information delivered by a transport packet, the fragment type extension information may indicate the subtype of the service signaling information, and the fragment version information may indicate the version of the service signaling information. Here, the fragment type information, the fragment type extension information and the fragment version information may correspond to the aforementioned information for TOI filtering. 
     In a method of transmitting a broadcast signal according to another embodiment of the present invention, the transport session may be a ROUTE session. The transport sessions may be MMTP sessions and the transport session containing the second service data may be a ROUTE session according to an embodiment. 
     In a method of transmitting a broadcast signal according to another embodiment of the present invention, the service signaling information may be delivered through a dedicated channel of a transport session. As described above, the SLS may be delivered through a specific LCT session (tsi=0) of a ROUTE session. 
     A method of receiving a broadcast signal according to an embodiment of the present invention will be described. This method is not shown in the drawings. 
     The method of receiving a broadcast signal according to an embodiment of the present invention may include a step in which a first module receives a broadcast signal, a step in which a second module physically processes the broadcast signal, a step in which a third module acquires a service list table, a step in which a fourth module acquires service data using the service list table and/or a step in which a fifth module provides a service using the acquired service data. Here, physical processing may be a reverse process of a corresponding operation of a transmission side. 
     Methods of receiving a broadcast signal according to embodiments of the present invention may correspond to the above-described methods of transmitting a broadcast signal according to the embodiments of the present invention. The methods of receiving a broadcast signal may be performed by hardware modules corresponding to the modules (e.g., the first, second and third modules of the transmission side) used in the methods of transmitting a broadcast signal. The methods of receiving a broadcast signal may correspond to the above-described embodiments of the methods of transmitting a broadcast signal. 
     The above-described steps may be omitted or replaced by other steps of performing similar/identical operations according to embodiments. 
       FIG. 132  illustrates an apparatus for transmitting a broadcast signal according to an embodiment of the present invention. 
     The apparatus for transmitting a broadcast signal according to an embodiment of the present invention may include the aforementioned first, second and/or third modules of the transmission side. The blocks and modules have been described above. 
     The apparatus for transmitting a broadcast signal and internal modules/blocks thereof according to an embodiment of the present invention may perform the aforementioned methods of transmitting a broadcast signal according to embodiments of the present invention. 
     An apparatus for receiving a broadcast signal according to an embodiment of the present invention will be described. The apparatus is not shown in the drawings. 
     The apparatus for receiving a broadcast signal according to an embodiment of the present invention may include the aforementioned first, second, third, fourth and/or fifth modules of the reception side. The blocks and modules have been described above. 
     The apparatus for receiving a broadcast signal and internal modules/blocks thereof according to an embodiment of the present invention may perform the aforementioned methods of receiving a broadcast signal according to embodiments of the present invention. 
     The internal blocks/modules of the aforementioned apparatuses may be processors that execute continuous procedures stored in a memory or may be hardware elements located inside/outside of the apparatuses according to embodiments. 
     The above-described steps may be omitted or replaced by other steps of performing similar/identical operations according to embodiments. 
     A time interleaver structure and a time interleaving method which selectively use a convolutional interleaver (CI) and a block interleaver (BI) according to a physical layer pipe (PLP) mode or use both the CI and BI will be described. A PLP according to an embodiment of the present invention is a physical path having the same concept as the aforementioned DP, and the name thereof may be changed according to designer. 
     The PLP mode according to an embodiment of the present invention may include a single PLP mode or a multiple-PLP mode depending on the number of PLPs processed in a broadcast signal transmitter or a broadcast signal transmission apparatus. The single PLP mode corresponds to a case in which the number of PLPs processed in a broadcast signal transmission apparatus is one. The single PLP mode may be called a single PLP. 
     The multiple-PLP mode corresponds to a case in which the number of PLPs processed in a broadcast signal transmission apparatus is one or more. The multiple-PLP mode may be called multiple PLPs. 
     In the present invention, time interleaving of applying different time interleaving methods depending on PLP modes may be referred to as hybrid time interleaving. Hybrid time interleaving according to an embodiment of the present invention is applied per PLP (or PLP level) in the case of the multiple-PLP mode. 
       FIG. 133  is a table showing interleaving types applied depending on the number of PLPs. A time interleaver according to an embodiment of the present invention may determine an interleaving type on the basis of the value of PLP_NUM. PLP_NUM is a signaling field indicating a PLP mode. When the value of PLP_NUM is 1, this indicates a single PLP. The single PLP according to an embodiment of the present invention can be applied to the convolutional interleaver (CI) only. 
     When the value of PLP_NUM is greater than 1, this indicates multiple PLPs. The multiple PLPs according to an embodiment of the present invention can be applied to the convolutional interleaver (CI) and the block interleaver (BI). In this case, the convolutional interleaver can perform inter-frame interleaving and the block interleaver can perform intra-frame interleaving. Details of inter-frame interleaving and intra-frame interleaving have been described above. 
       FIG. 134  is a block diagram illustrating a first embodiment of the aforementioned hybrid time interleaver structure. The hybrid time interleaver according to the first embodiment may include a BI and a CI. The time interleaver according to the present invention may be located between a BICM chain block and a frame builder. The BICM chain block shown in  FIGS. 134 and 135  may include blocks other than the time interleaver  5050  in the processing block  5000  of the BICM block shown in  FIG. 5 . The frame builder shown in  FIGS. 134 and 135  may execute the same function as the frame building block  1020  of  FIG. 1 . 
     As described above, whether the block interleaver according to the first embodiment of the hybrid time interleaver structure is applied may be determined depending on the value of PLP_NUM. That is, when PLP_NUM=1, the block interleaver is not applied (block interleaver off) and only the convolutional interleaver is applied. When PLP_NUM&gt;1, both the block interleaver and the convolutional interleaver can be applied (block interleaver on). The structure and operation of the convolutional interleaver applied when PLP_NUM&gt;1 may be identical or similar to the structure and operation of the convolutional interleaver applied when PLP_NUM=1. 
       FIG. 135  is a block diagram illustrating a second embodiment of the aforementioned hybrid time interleaver structure. 
     Operations of the blocks included in the second embodiment of the hybrid time interleaver structure are identical to those described in  FIG. 134 . Whether a block interleaver according to the second embodiment of the hybrid time interleaver structure is applied may be determined according to the value of PLP_NUM. The blocks of the hybrid time interleaver according to the second embodiment may perform operations according to embodiments of the present invention. Here, the structure and operation of the convolutional interleaver applied when PLP_NUM=1 may differ from the structure and operation of the convolutional interleaver applied when PLP_NUM&gt;1. 
       FIG. 136  is a block diagram illustrating a first embodiment of a hybrid time deinterleaver structure. 
     The hybrid time deinterleaver according to the first embodiment may perform an operation corresponding to a reverse of the operation of the aforementioned hybrid time interleaver according to the first embodiment. Accordingly, the hybrid time deinterleaver according to the first embodiment, shown in  FIG. 136 , may include a convolutional deinterleaver (CDI) and a block deinterleaver (BDI). 
     The structure and operation of the convolutional deinterleaver applied when PLP_NUM&gt;1 may be identical or similar to the structure and operation of the convolutional deinterleaver applied when PLP_NUM=1. 
     Whether the block deinterleaver according to the first embodiment of the hybrid time deinterleaver structure is applied may be determined depending on the value of PLP_NUM. That is, when PLP_NUM=1, the block deinterleaver is not applied (block deinterleaver off) and only the convolutional deinterleaver is applied. 
     The convolutional deinterleaver of the hybrid time deinterleaver can perform inter-frame deinterleaving and the block deinterleaver can perform intra-frame deinterleaving. Details of inter-frame deinterleaving and intra-frame deinterleaving have been described above. 
     The BICM decoding block shown in  FIGS. 136 and 137  may perform an operation corresponding to a reverse of the operation of the BICM chain block shown in  FIGS. 134 and 135 . 
       FIG. 137  is a block diagram illustrating a second embodiment of the hybrid time deinterleaver structure. 
     The hybrid time deinterleaver according to the second embodiment may perform an operation corresponding to a reverse of the operation of the aforementioned hybrid time interleaver according to the second embodiment. Operations of the blocks included in the second embodiment of the hybrid time deinterleaver structure may be identical to those described in  FIG. 136 . 
     Whether the block deinterleaver according to the second embodiment of the hybrid time deinterleaver structure is applied may be determined depending on the value of PLP_NUM. The blocks of the hybrid time deinterleaver according to the second embodiment may perform operations according to embodiments of the present invention. Here, the structure and operation of the convolutional deinterleaver applied when PLP_NUM=1 may differ from the structure and operation of the convolutional deinterleaver applied when PLP_NUM&gt;1. 
     The module or unit may be one or more processors designed to execute a series of execution steps stored in the memory (or the storage unit). Each step described in the above-mentioned embodiments may be implemented by hardware and/or processors. Each module, each block, and/or each unit described in the above-mentioned embodiments may be realized by hardware or a processor. In addition, the above-mentioned methods of the present invention may be realized by code written on recoding media configured to be read by a processor so that the code can be read by the processor of the apparatus. 
     Although the description of the present invention is explained with reference to each of the accompanying drawings for clarity, it is possible to design new embodiment(s) by merging the embodiments shown in the accompanying drawings with each other. If a recording medium readable by a computer, in which programs for executing the embodiments mentioned in the foregoing description are recorded, is designed by those skilled in the art, it may be within the scope of the appended claims and their equivalents. 
     An apparatus and method according to the present invention may be non-limited by the configurations and methods of the embodiments mentioned in the foregoing description. The embodiments mentioned in the foregoing description can be configured in a manner of being selectively combined with one another entirely or in part to enable various modifications. 
     In addition, a method according to the present invention can be implemented with processor-readable code in a processor-readable recording medium provided to a network device. The processor-readable medium may include all kinds of recording devices capable of storing data readable by a processor. The processor-readable medium may include one of ROM, RAM, CD-ROM, magnetic tapes, floppy disks, optical data storage devices, and the like for example and also include a carrier-wave type implementation such as a transmission over the Internet. Furthermore, as the processor-readable recording medium is distributed to a computer system connected via network, processor-readable code can be saved and executed in a distributed manner. 
     It will be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 
     Both a product invention and a process invention are described in the specification and the description of both inventions may be supplementarily applied as needed. 
     It will be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 
     Both apparatus and method inventions are mentioned in this specification and descriptions of both of apparatus and method inventions may be complementarily applicable to each other. 
     MODE FOR INVENTION 
     Various embodiments have been described in the best mode for carrying out the invention. 
     INDUSTRIAL APPLICABILITY 
     The embodiments of the present invention are applicable to a series of broadcast signal provision fields. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.