Patent Publication Number: US-10764197-B2

Title: Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals

Description:
This application is a Continuation Application of U.S. patent application Ser. No. 15/439,671, filed Feb. 22, 2017, which is a continuation of U.S. patent application Ser. No. 14/495,386, filed on Sep. 24, 2014, and claims the benefit of U.S. Provisional Application Nos. 61/883,962 and 61/883,957 filed on Sep. 27, 2013 in the US, the entire contents of which is hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an apparatus for transmitting broadcast signals, an apparatus for receiving broadcast signals and methods for transmitting and receiving broadcast signals. 
     DISCUSSION OF THE RELATED ART 
     As analog broadcast signal transmission comes to an end, various technologies for transmitting/receiving digital broadcast signals are being developed. A digital broadcast signal may include a larger amount of video/audio data than an analog broadcast signal and further include various types of additional data in addition to the video/audio data. 
     That is, a digital broadcast system can provide HD (high definition) images, multi-channel audio and various additional services. However, data transmission efficiency for transmission of large amounts of data, robustness of transmission/reception networks and network flexibility in consideration of mobile reception equipment need to be improved for digital broadcast. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to an apparatus for transmitting broadcast signals and an apparatus for receiving broadcast signals for future broadcast services and methods for transmitting and receiving broadcast signals for future broadcast services. 
     An object of the present invention is to provide an apparatus and method for transmitting broadcast signals to multiplex data of a broadcast transmission/reception system providing two or more different broadcast services in a time domain and transmit the multiplexed data through the same RF signal bandwidth and an apparatus and method for receiving broadcast signals corresponding thereto. 
     Another object of the present invention is to provide an apparatus for transmitting broadcast signals, an apparatus for receiving broadcast signals and methods for transmitting and receiving broadcast signals to classify data corresponding to services by components, transmit data corresponding to each component as a data pipe, receive and process the data 
     Still another object of the present invention is to provide an apparatus for transmitting broadcast signals, an apparatus for receiving broadcast signals and methods for transmitting and receiving broadcast signals to signal signaling information necessary to provide broadcast signals. 
     To achieve the object and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the present invention provides a method of transmitting broadcast signals. The method of transmitting broadcast signals includes processing input streams into BB (Base Band) frames of PLPs (Physical Layer Pipes), wherein the input streams include a plurality of input packets, wherein each of the input packets include a packet header including information about synchronization of the input streams, wherein the processing input streams into BB frames further includes compressing the packet headers of the input packets in the input streams, generating the BB frames by using the compressed input packets; encoding data of the PLPs; building at least one signal frame by mapping the encoded data of the PLPs; and modulating data in the built signal frame by OFDM (Orthogonal Frequency Division Multiplexing) method and transmitting the broadcast signals having the modulated data. 
     Preferably, the information about synchronization in each of the input packets are removed in step of the compressing the packet headers. 
     Preferably, when at least two successive input packets in the input streams have same packet headers except a continuity counter field, the compressing the packet headers further includes: processing a packet header of first input packet of the at least two successive input packets, deleting packet headers of the other input packets of the at least two successive input packets. 
     Preferably, the continuity counter fields in each of the at least two successive input packets increases in order from the continuity counter field of the first input packet of the at least two successive input packets. 
     Preferably, the processing a packet header of first input packet further includes replacing the information about synchronization in the first input packet to a packet number field, wherein the packet number field indicates a number of the other input packets that the packet headers are deleted. 
     Preferably, the encoding data of the PLPs further includes, encoding the BB frames of the PLPs with LDPC (Low Density Parity Check) codes, bit interleaving the LDPC encoded data in the PLPs, mapping the bit interleaved data onto constellations, MIMO (Multi Input Multi Output) encoding the mapped data, and time interleaving the MIMO encoded data. 
     In other aspect, the present invention provides a method of receiving broadcast signals. The method of receiving broadcast signals includes receiving the broadcast signals having at least one signal frame and demodulating data in the at least one signal frame by OFDM (Orthogonal Frequency Division Multiplexing) method; parsing the at least one signal frame by demapping data of PLPs (Physical Layer Pipes); decoding the data of the PLPs; and processing BB (Base Band) frames of the PLPs to output output streams, wherein the processing BB frames of the PLPs further includes decompressing a compressed packet header of data packets in the BB frames, generating the output streams by using the decompressed data packets. 
     Preferably, information about synchronization of the output streams are regenerated in step of the decompressing a compressed packet header, for each of the data packets. 
     Preferably, the decompressing a compressed packet header of data packets further includes: regenerating packet headers for each of the data packets by using a packet number field in the compressed packet header, wherein the packet number field indicates a number of the data packets that the packet headers are deleted. 
     Preferably, the regenerated packet headers for each of the data packets include continuity counter fields, wherein the continuity counter fields in the regenerated packet headers increases in order from a continuity counter field in the compressed packet header. 
     Preferably, the decompressing a compressed packet header of data packets further includes: replacing the packet number field in the compressed packet header to the information about synchronization, for the compressed packet header. 
     Preferably, the decoding the data of the PLPs further includes, time deinterleaving the data of the PLPs, MIMO (Multi Input Multi Output) decoding the time deinterleaved data of the PLPs, demapping the MIMO decoded data from constellations, bit deinterleaving the demapped data, and processing the bit deinterleaved data with LDPC (Low Density Parity Check) codes to output BB frames. 
     In another aspect, the present invention provides an apparatus for transmitting broadcast signals. The apparatus for transmitting broadcast signals includes an input formatting module configured to process input streams into BB (Base Band) frames of PLPs (Physical Layer Pipes), wherein the input streams include a plurality of input packets, wherein each of the input packets include a packet header including information about synchronization of the input streams, wherein the input formatting module further configured to compress the packet headers of the input packets in the input streams, and generate the BB frames by using the compressed input packets; an encoding module configured to encode data of the PLPs; a frame building module configured to build at least one signal frame by mapping the encoded data of the PLPs; and a modulating module configured to modulate data in the built signal frame by OFDM (Orthogonal Frequency Division Multiplexing) method and transmit the broadcast signals having the modulated data. 
     Preferably, the information about synchronization in each of the input packets are removed by compressing the packet headers. 
     Preferably, when at least two successive input packets in the input streams have same packet headers except a continuity counter field, the compressing the packet headers further includes: processing a packet header of first input packet of the at least two successive input packets, deleting packet headers of the other input packets of the at least two successive input packets. 
     Preferably, the continuity counter fields in each of the at least two successive input packets increases in order from the continuity counter field of the first input packet of the at least two successive input packets. 
     Preferably, the processing a packet header of first input packet further includes replacing the information about synchronization in the first input packet to a packet number field, wherein the packet number field indicates a number of the other input packets that the packet headers are deleted. 
     Preferably, the encoding module further includes, a LDPC block for encoding the BB frames of the PLPs with LDPC (Low Density Parity Check) codes, a bit interleaving block for bit interleaving the LDPC encoded data in the PLPs, a constellation mapping block for mapping the bit interleaved data onto constellations, a MIMO (Multi Input Multi Output) block for MIMO encoding the mapped data, and a time interleaving block for time interleaving the MIMO encoded data. 
     In another aspect, the present invention provides an apparatus for receiving broadcast signals. The apparatus for receiving broadcast signals includes a receiving module configured to receive the broadcast signals having at least one signal frame and demodulate data in the at least one signal frame by OFDM (Orthogonal Frequency Division Multiplexing) method; a parsing module configured to parse the at least one signal frame by demapping data of PLPs (Physical Layer Pipes); a decoding module configured to decode the data of the PLPs; and an output processing module configured to process BB (Base Band) frames of the PLPs to output output streams, wherein the output processing module further configured to decompress a compressed packet header of data packets in the BB frames, generate the output streams by using the decompressed data packets. 
     Preferably, information about synchronization of the output streams are regenerated by decompressing the compressed packet header, for each of the data packets. 
     Preferably, the decompressing a compressed packet header of data packets further includes: regenerating packet headers for each of the data packets by using a packet number field in the compressed packet header, wherein the packet number field indicates a number of the data packets that the packet headers are deleted. 
     Preferably, the regenerated packet headers for each of the data packets include continuity counter fields, wherein the continuity counter fields in the regenerated packet headers increases in order from a continuity counter field in the compressed packet header. 
     Preferably, the decompressing the compressed packet header of data packets further includes: replacing the packet number field in the compressed packet header to the information about synchronization, for the compressed packet header. 
     Preferably, the decoding module further includes, a time deinterleaving block for time deinterleaving the data of the PLPs, a MIMO (Multi Input Multi Output) decoding block for MIMO decoding the time deinterleaved data of the PLPs, a constellation demapping block for demapping the MIMO decoded data from constellations, a bit deinterleaving block for bit deinterleaving the demapped data, and a LDPC decoding block for processing the bit deinterleaved data with LDPC (Low Density Parity Check) codes to output BB frames. 
     The present invention can process data according to service characteristics to control QoS (Quality of Services) for each service or service component, thereby providing various broadcast services. 
     The present invention can achieve transmission flexibility by transmitting various broadcast services through the same RF signal bandwidth. 
     The present invention can improve data transmission efficiency and increase robustness of transmission/reception of broadcast signals using a MIMO system. 
     According to the present invention, it is possible to provide broadcast signal transmission and reception methods and apparatus capable of receiving digital broadcast signals without error even with mobile reception equipment or in an indoor environment. 
    
    
     
       BRIEF DESCRIPTION OF THE 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 an input formatting block according to another embodiment of the present invention. 
         FIG. 5  illustrates a BICM block according to an embodiment of the present invention. 
         FIG. 6  illustrates a BICM block according to another embodiment of the present invention. 
         FIG. 7  illustrates a frame building block according to one embodiment of the present invention. 
         FIG. 8  illustrates an OFMD generation block according to an embodiment of the present invention. 
         FIG. 9  illustrates a structure of an apparatus for receiving broadcast signals for future broadcast services according to an embodiment of the present invention. 
         FIG. 10  illustrates a frame structure according to an embodiment of the present invention. 
         FIG. 11  illustrates a signaling hierarchy structure of the frame according to an embodiment of the present invention. 
         FIG. 12  illustrates preamble signaling data according to an embodiment of the present invention. 
         FIG. 13  illustrates PLS data according to an embodiment of the present invention. 
         FIG. 14  illustrates PLS2 data according to an embodiment of the present invention. 
         FIG. 15  illustrates PLS2 data according to another embodiment of the present invention. 
         FIG. 16  illustrates a logical structure of a frame according to an embodiment of the present invention. 
         FIG. 17  illustrates PLS mapping according to an embodiment of the present invention. 
         FIG. 18  illustrates EAC mapping according to an embodiment of the present invention. 
         FIG. 19  illustrates FIC mapping according to an embodiment of the present invention. 
         FIG. 20  illustrates a type of DP according to an embodiment of the present invention. 
         FIG. 21  illustrates DP mapping according to an embodiment of the present invention. 
         FIG. 22  illustrates an FEC structure according to an embodiment of the present invention. 
         FIG. 23  illustrates a bit interleaving according to an embodiment of the present invention. 
         FIG. 24  illustrates a cell-word demultiplexing according to an embodiment of the present invention. 
         FIG. 25  illustrates a time interleaving according to an embodiment of the present invention. 
         FIG. 26  illustrates the basic operation of a twisted row-column block interleaver according to an embodiment of the present invention. 
         FIG. 27  illustrates an operation of a twisted row-column block interleaver according to another embodiment of the present invention. 
         FIG. 28  illustrates a diagonal-wise reading pattern of a twisted row-column block interleaver according to an embodiment of the present invention. 
         FIG. 29  illustrates interleaved XFECBLOCKs from each interleaving array according to an embodiment of the present invention. 
         FIG. 30  shows a mode adaptation module according to another embodiment of the present invention. 
         FIG. 31  shows a header compression block according to another embodiment of the present invention. 
         FIG. 32  shows an output processor according to another embodiment of the present invention. 
         FIG. 33  shows a header decompression block according to another embodiment of the present invention. 
         FIG. 34  illustrates an initial packet header which is not deleted in a header compression scheme #1 according to an embodiment of the present invention. 
         FIG. 35  illustrates compression and restoration processes according to the header compression scheme #1 in the embodiment of the present invention. 
         FIG. 36  illustrates an initial packet header which is not deleted in a header compression scheme #2 according to an embodiment of the present invention. 
         FIG. 37  illustrates compression and restoration processes according to the header compression scheme #2 in the embodiment of the present invention. 
         FIG. 38  illustrates a method of transmitting broadcast signal according to an embodiment of the present invention. 
         FIG. 39  illustrates a method of receiving broadcast signal according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without such specific details. 
     Although most terms used in the present invention have been selected from general ones widely used in the art, some terms have been arbitrarily selected by the applicant and their meanings are explained in detail in the following description as needed. Thus, the present invention should be understood based upon the intended 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 apparatuses and methods for transmitting according to an embodiment of the present invention may be categorized into a base profile for the terrestrial broadcast service, a handheld profile for the mobile broadcast service and an advanced profile for the UHDTV service. 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. This can be changed according to intention of the designer. 
     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 19  data cells 
               
               
                 Pitot 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 
               
               
                   
               
             
            
               
                 LOPC 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 K bch  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 T S  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 N cells  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 structure 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 STUFF1 (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, STUFF1 is set to ‘0’ and the BBF has no stuffing field. Otherwise STUFF1 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 an input formatting block according to another embodiment of the present invention. 
     The input formatting block illustrated in  FIG. 4  corresponds to an embodiment of the input formatting block  1000  described with reference to  FIG. 1 . 
       FIG. 4  illustrates a stream adaptation block of the input formatting module when the input signal corresponds to multiple input streams. 
     Referring to  FIG. 4 , the mode adaptation block for respectively processing the multiple input streams can include a scheduler  4000 , an I-Frame delay block  4010 , a stuffing insertion block  4020 , an in-band signaling  4030 , a BB Frame scrambler  4040 , a PLS generation block  4050  and a PLS scrambler  4060 . Description will be given of each block of the stream adaptation block. 
     Operations of the stuffing insertion block  4020 , the BB Frame scrambler  4040 , the PLS generation block  4050  and the PLS scrambler  4060  correspond to those of the stuffing insertion block, BB scrambler, PLS generation block and the PLS scrambler described with reference to  FIG. 2  and thus description thereof is omitted. 
     The scheduler  4000  can determine the overall cell allocation across the entire frame from the amount of FECBLOCKs of each DP. Including the allocation for PLS, EAC and FIC, the scheduler generate the values of PLS2-DYN data, which is transmitted as in-band signaling or PLS cell in FSS of the frame. Details of FECBLOCK, EAC and FIC will be described later. 
     The I-Frame delay block  4010  can delay the input data by one transmission frame such that scheduling information about the next frame can be transmitted through the current frame for in-band signaling information to be inserted into the DPs. 
     The in-band signaling  4030  can insert un-delayed part of the PLS2 data into a DP of a frame. 
     The above-described blocks may be omitted or replaced by blocks having similar or identical functions. 
       FIG. 5  illustrates a BICM block according to an embodiment of the present invention. 
     The BICM block illustrated in  FIG. 5  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, et. 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 SSD encoding block  5040  can precode cells in two (2D), three (3D), and four (4D) dimensions to increase the reception robustness under difficult fading conditions. 
     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 (e 1,i  and e 2,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 I of their respective TX antennas. 
     The above-described blocks may be omitted or replaced by blocks having similar or identical functions. 
       FIG. 6  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. 6  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 , a constellation mapper  6020  and time interleaver  6030 . 
     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, C ldpc , parity bits, P ldpc  are encoded systematically from each zero-inserted PLS information block, I ldpc  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 ]  [Expression 1]
 
     The LDPC code parameters for PLS1 and PLS2 are as following table 4. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                 Signaling Type 
                 K sig   
                 K bch   
                 N bch _parity 
                 K ldpc  (=N bch ) 
                 N ldpc   
                 N ldpc _parity 
                 code 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 interleaved PLS1 data and PLS2 data onto constellations. 
     The time interleaver  6030  can interleave the mapped PLS1 data and PLS2 data. 
     The above-described blocks may be omitted or replaced by blocks having similar or identical functions. 
       FIG. 7  illustrates a frame building block according to one embodiment of the present invention. 
     The frame building block illustrated in  FIG. 7  corresponds to an embodiment of the frame building block  1020  described with reference to  FIG. 1 . 
     Referring to  FIG. 7 , 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. 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. Details of operations of the frequency interleaver  7020  will be described later. 
     The above-described blocks may be omitted or replaced by blocks having similar or identical functions. 
       FIG. 8  illustrates an OFMD generation block according to an embodiment of the present invention. 
     The OFMD generation block illustrated in  FIG. 8  corresponds to an embodiment of the OFMD 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. 8 , the frame building 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 . Description will be given of each block of the frame building block. 
     The pilot and reserved tone insertion block  8000  can insert pilots and the reserved tone. 
     Various cells within the OFDM symbol are modulated with reference information, known as pilots, which have transmitted values known a priori in the receiver. The information of pilot cells is made up of scattered pilots, continual pilots, edge pilots, FSS (frame signaling symbol) pilots and FES (frame edge symbol) pilots. Each pilot is transmitted at a particular boosted power level according to pilot type and pilot pattern. The value of the pilot information is derived from a reference sequence, which is a series of values, one for each transmitted carrier on any given symbol. The pilots can be used for frame synchronization, frequency synchronization, time synchronization, channel estimation, and transmission mode identification, and also can be used to follow the phase noise. 
     Reference information, taken from the reference sequence, is transmitted in scattered pilot cells in every symbol except the preamble, FSS and FES of the frame. Continual pilots are inserted in every symbol of the frame. The number and location of continual pilots depends on both the FFT size and the scattered pilot pattern. The edge carriers are edge pilots in every symbol except for the preamble symbol. They are inserted in order to allow frequency interpolation up to the edge of the spectrum. FSS pilots are inserted in FSS(s) and FES pilots are inserted in FES. They are inserted in order to allow time interpolation up to the edge of the frame. 
     The system according to an embodiment of the present invention supports the SFN network, where distributed MISO scheme is optionally used to support very robust transmission mode. The 2D-eSFN is a distributed MISO scheme that uses multiple TX antennas, each of which is located in the different transmitter site in the SFN network. 
     The 2D-eSFN encoding block  8010  can process a 2D-eSFN processing to distorts the phase of the signals transmitted from multiple transmitters, in order to create both time and frequency diversity in the SFN configuration. Hence, burst errors due to low flat fading or deep-fading for a long time can be mitigated. 
     The IFFT block  8020  can modulate the output from the 2D-eSFN encoding block  8010  using OFDM modulation scheme. Any cell in the data symbols which has not been designated as a pilot (or as a reserved tone) carries one of the data cells from the frequency interleaver. The cells are mapped to OFDM carriers. 
     The PAPR reduction block  8030  can perform a PAPR reduction on input signal using various PAPR reduction algorithm in the time domain. 
     The guard interval insertion block  8040  can insert guard intervals and the preamble insertion block  8050  can insert preamble in front of the signal. Details of a structure of the preamble will be described later. 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. Data related to respective broadcast services can be transmitted through different frames. 
     The DAC block  8070  can convert an input digital signal into an analog signal and output the analog signal. The signal output from the DAC block  7800  can be transmitted through multiple output antennas according to the physical layer profiles. A Tx antenna according to an embodiment of the present invention can have vertical or horizontal polarity. 
     The above-described blocks may be omitted or replaced by blocks having similar or identical functions according to design. 
       FIG. 9  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  9100  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  9100  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  9400  to restore scheduling information generated by the apparatus for transmitting broadcast signals. 
     The demapping &amp; decoding module  9200  can convert the input signals into bit domain data and then deinterleave the same as necessary. The demapping &amp; decoding module  9200  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  9200  can obtain transmission parameters necessary for demapping and decoding by decoding the data output from the signaling decoding module  9400 . 
     The output processor  9300  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  9300  can acquire necessary control information from data output from the signaling decoding module  9400 . 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  9400  can obtain PLS information from the signal demodulated by the synchronization &amp; demodulation module  9000 . As described above, the frame parsing module  9100 , demapping &amp; decoding module  9200  and output processor  9300  can execute functions thereof using the data output from the signaling decoding module  9400 . 
       FIG. 10  illustrates a frame structure according to an embodiment of the present invention. 
       FIG. 10  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. 11  illustrates a signaling hierarchy structure of the frame according to an embodiment of the present invention. 
       FIG. 11  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. 12  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 ‘I’, 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_PROFILE = 
                 PHY_PROFILE = 
                 PHY_PROFILE = 
                 PHY_PROFILE = 
               
               
                   
                 ‘000’ 
                 ‘001’ 
                 ‘010’ 
                 ‘111’ 
               
               
                   
                 (base) 
                 (handheld) 
                 (advanced) 
                 (FEF) 
               
               
                   
               
             
            
               
                 FRU_CONFIGURE = 
                 Only base 
                 Only handheld 
                 Only advanced 
                 Only FEF 
               
               
                 000 
                 profile present 
                 profile present 
                 profile present 
                 present 
               
               
                 FRU_CONFIGURE = 
                 Handheld profile 
                 Base profile 
                 Base profile 
                 Base profile 
               
               
                 1XX 
                 present 
                 present 
                 present 
                 present 
               
               
                 FRU_CONFIGURE = 
                 Advanced 
                 Advanced 
                 Handheld profile 
                 Handheld profile 
               
               
                 X1X 
                 profile 
                 profile 
                 present 
                 present 
               
               
                   
                 present 
                 present 
                   
                   
               
               
                 FRU_CONFIGURE = 
                 FEF 
                 FEF 
                 FEF 
                 Advanced 
               
               
                 XX1 
                 present 
                 present 
                 present 
                 profile 
               
               
                   
                   
                   
                   
                 present 
               
               
                   
               
            
           
         
       
     
     RESERVED: This 7-bit field is reserved for future use. 
       FIG. 13  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) t  (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) 01  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) t  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 C total_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 C total_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 C total_partial_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. 14  illustrates PLS2 data according to an embodiment of the present invention. 
       FIG. 14  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 
               
               
                   
               
             
            
               
                 00 
                 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 ‘I’ 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 P 1 , the number of the frames to which each TI group is mapped, and there is one TI-block per TI group (N TI =1). The allowed P I  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 N TI  per TI group, and there is one TI group per frame (P I =1). The allowed PI values with 2-bit field are defined in the below table 18. 
     
       
         
           
               
               
               
             
               
                 TABLE 18 
               
               
                   
               
               
                 2-bit field 
                 P l   
                 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 (I JUMP ) 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. 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 DP_PAY- 
                 If DP_PAY- 
                 If 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 ‘I’: 
     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. 15  illustrates PLS2 data according to another embodiment of the present invention. 
       FIG. 15  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 ‘I’, 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 ‘I’: 
     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. 16  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. 17  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) N FSS  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 N FSS  FSS(s) in a top-down manner as shown in an example in  FIG. 17 . 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. 18  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. 18 . Depending on the EAS message size, EAC cells may occupy a few symbols, as shown in  FIG. 18 . 
     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. 19  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. 20  illustrates a type of DP according to an embodiment of the present invention. 
     (a) shows type 1 DP and (b) shows type 2 DP. 
     After the preceding channels, i.e., PLS, EAC and FIC, are mapped, cells of the DPs are mapped. A DP is categorized into one of two types according to mapping method: 
     Type 1 DP: DP is mapped by TDM 
     Type 2 DP: DP is mapped by FDM 
     The type of DP is indicated by DP_TYPE field in the static part of PLS2.  FIG. 20  illustrates the mapping orders of Type 1 DPs and Type 2 DPs. Type 1 DPs are first mapped in the increasing order of cell index, and then after reaching the last cell index, the symbol index is increased by one. Within the next symbol, the DP continues to be mapped in the increasing order of cell index starting from p=0. With a number of DPs mapped together in one frame, each of the Type 1 DPs are grouped in time, similar to TDM multiplexing of DPs. 
     Type 2 DPs are first mapped in the increasing order of symbol index, and then after reaching the last OFDM symbol of the frame, the cell index increases by one and the symbol index rolls back to the first available symbol and then increases from that symbol index. After mapping a number of DPs together in one frame, each of the Type 2 DPs are grouped in frequency together, similar to FDM multiplexing of DPs. 
     Type 1 DPs and Type 2 DPs can coexist in a frame if needed with one restriction; Type 1 DPs always precede Type 2 DPs. The total number of OFDM cells carrying Type 1 and Type 2 DPs cannot exceed the total number of OFDM cells available for transmission of DPs:
 
 D   DP1   +D   OP2   ≤D   DP   [Expression 2]
 
     where D DP1  is the number of OFDM cells occupied by Type 1 DPs, D DP2  is the number of cells occupied by Type 2 DPs. Since PLS, EAC, FIC are all mapped in the same way as Type 1 DP, they all follow “Type 1 mapping rule”. Hence, overall, Type 1 mapping always precedes Type 2 mapping. 
       FIG. 21  illustrates DP mapping according to an embodiment of the present invention. 
     (a) shows an addressing of OFDM cells for mapping type 1 DPs and (b) shows an an addressing of OFDM cells for mapping for type 2 DPs. 
     Addressing of OFDM cells for mapping Type 1 DPs (0, . . . , D DP1 −1) is defined for the active data cells of Type 1 DPs. The addressing scheme defines the order in which the cells from the TIs for each of the Type 1 DPs are allocated to the active data cells. It is also used to signal the locations of the DPs in the dynamic part of the PLS2. 
     Without EAC and FIC, address 0 refers to the cell immediately following the last cell carrying PLS in the last FSS. If EAC is transmitted and FIC is not in the corresponding frame, address 0 refers to the cell immediately following the last cell carrying EAC. If FIC is transmitted in the corresponding frame, address 0 refers to the cell immediately following the last cell carrying FIC. Address 0 for Type 1 DPs can be calculated considering two different cases as shown in (a). In the example in (a), PLS, EAC and FIC are assumed to be all transmitted. Extension to the cases where either or both of EAC and FIC are omitted is straightforward. If there are remaining cells in the FSS after mapping all the cells up to FIC as shown on the left side of (a). 
     Addressing of OFDM cells for mapping Type 2 DPs (0, . . . , D DP2 −1) is defined for the active data cells of Type 2 DPs. The addressing scheme defines the order in which the cells from the TIs for each of the Type 2 DPs are allocated to the active data cells. It is also used to signal the locations of the DPs in the dynamic part of the PLS2. 
     Three slightly different cases are possible as shown in (b). For the first case shown on the left side of (b), cells in the last FSS are available for Type 2 DP mapping. For the second case shown in the middle, FIC occupies cells of a normal symbol, but the number of FIC cells on that symbol is not larger than C FSS . The third case, shown on the right side in (b), is the same as the second case except that the number of FIC cells mapped on that symbol exceeds C FSS . 
     The extension to the case where Type 1 DP(s) precede Type 2 DP(s) is straightforward since PLS, EAC and FIC follow the same “Type 1 mapping rule” as the Type 1 DP(s). 
     A data pipe unit (DPU) is a basic unit for allocating data cells to a DP in a frame. 
     A DPU is defined as a signaling unit for locating DPs in a frame. A Cell Mapper  7010  may map the cells produced by the TIs for each of the DPs. A Time interleaver  5050  outputs a series of TI-blocks and each TI-block comprises a variable number of XFECBLOCKs which is in turn composed of a set of cells. The number of cells in an XFECBLOCK, N cells , is dependent on the FECBLOCK size, N ldpc , and the number of transmitted bits per constellation symbol. A DPU is defined as the greatest common divisor of all possible values of the number of cells in a XFECBLOCK, N cells , supported in a given PHY profile. The length of a DPU in cells is defined as L DPU . Since each PHY profile supports different combinations of FECBLOCK size and a different number of bits per constellation symbol, L DPU  is defined on a PHY profile basis. 
       FIG. 22  illustrates an FEC structure according to an embodiment of the present invention. 
       FIG. 22  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  h 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 
                 N bch  − 
               
               
                 Rate 
                 N ldpc   
                 K ldpc   
                 K bch   
                 capability 
                 K bch   
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 5/15 
                 64800 
                 21600 
                 21408 
                 12 
                 192 
               
               
                 6/15 
                   
                 25920 
                 25728 
               
               
                 7/15 
                   
                 30240 
                 30048 
               
               
                 8/15 
                   
                 34560 
                 34368 
               
               
                 9/15 
                   
                 33880 
                 38688 
               
               
                 10/15  
                   
                 43200 
                 43008 
               
               
                 11/15  
                   
                 47520 
                 47328 
               
               
                 12/15  
                   
                 51840 
                 51648 
               
               
                 13/15  
                   
                 56160 
                 55968 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 29 
               
               
                   
               
               
                   
                   
                   
                   
                 BCH error 
                   
               
               
                 LDPC 
                   
                   
                   
                 correction 
                 N bch  − 
               
               
                 Rate 
                 N ldpc   
                 K ldpc   
                 K bch   
                 capability 
                 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 B ldpc  (FECBLOCK), P ldpc  (parity bits) is encoded systematically from each I ldpc  (BCH-encoded BBF), and appended to I ldpc . The completed B ldpc  (FECBLOCK) are expressed as follow Expression.
 
 B   ldpc =[ I   ldpc   P   ldpc ]=[ i   0   ,i   1   , . . . ,i   K     ldpc     −1   ,p   0   ,p   1   , . . . ,p   N     ldpc     −K     ldpc     −1 ]  [Expression 3]
 
     The parameters for long FECBLOCK and short FECBLOCK are given in the above table 28 and 29, respectively. 
     The detailed procedure to calculate N ldpc −K ldpc  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  [Expression 4]
 
     2) Accumulate the first information bit—i 0 , 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   [Expression 5]
 
     3) For the next 359 information bits, i s , s=1, 2, . . . , 359 accumulate is at parity bit addresses using following Expression.
 
{ x +( s  mod 360)×   ldpc } mod( N   ldpc   −K   ldpc )  [Expression 6]
 
     where x denotes the address of the parity bit accumulator corresponding to the first bit i 0 , and Q ldpc  is a code rate dependent constant specified in the addresses of parity check matrix. Continuing with the example, Q ldpc =24 for rate 13/15, so for information bit i 1 , the following operations are performed:
 
 p   1007   =p   1007   ⊕i   0    p   2839   =p   2839   ⊕i   0  
 
 p   4863   =p   4863   ⊕i   0    p   5013   =p   5013   ⊕i   0  
 
 p   6162   =p   6162   ⊕i   0    p   6482   =p   6482   ⊕i   0  
 
 p   6945   =p   6945   ⊕i   0    p   6998   =p   6998   ⊕i   0  
 
 p   7596   =p   7596   ⊕i   0    p   8284   =p   8284   ⊕i   0  
 
 p   8520   =p   8520   ⊕i   0   [Expression 5]
 
     4) For the 361 st  information bit i 0 , 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 Expression 6, where x denotes the address of the parity bit accumulator corresponding to the information bit i 360 , 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  [Expression 8]
 
     where final content of p i , i=0, 1, . . . N ldpc −K ldpc −1 is equal to the parity bit p i . 
     
       
         
           
               
               
               
             
               
                   
                 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 t 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. 23  illustrates a bit interleaving according to an embodiment of the present invention. 
     The outputs of the LDPC encoder are bit-interleaved, which consists of parity interleaving followed by Quasi-Cyclic Block (QCB) interleaving and inner-group interleaving. 
     (a) shows Quasi-Cyclic Block (QCB) interleaving and (b) shows inner-group interleaving. 
     The FECBLOCK may be parity interleaved. At the output of the parity interleaving, the LDPC codeword consists of 180 adjacent QC blocks in a long FECBLOCK and 45 adjacent QC blocks in a short FECBLOCK. Each QC block in either a long or short FECBLOCK consists of 360 bits. The parity interleaved LDPC codeword is interleaved by QCB interleaving. The unit of QCB interleaving is a QC block. The QC blocks at the output of parity interleaving are permutated by QCB interleaving as illustrated in  FIG. 23 , where N cells =64800/η mod  or 16200/η mod  according to the FECBLOCK length. The QCB interleaving pattern is unique to each combination of modulation type and LDPC code rate. 
     After QCB interleaving, inner-group interleaving is performed according to modulation type and order (η mod ) which is defined in the below table 32. The number of QC blocks for one inner-group, N   CB_IG , is also defined. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 32 
               
               
                   
                   
               
               
                   
                 Modulation type 
                 η mod   
                 N QCB     —     IG   
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 QAM-16 
                 4 
                 2 
               
               
                   
                 NUC-16 
                 4 
                 4 
               
               
                   
                 NUQ-64 
                 6 
                 3 
               
               
                   
                 NUC-64 
                 6 
                 6 
               
               
                   
                 NUQ-256 
                 8 
                 4 
               
               
                   
                 NUC-256 
                 8 
                 8 
               
               
                   
                 NUQ-1024 
                 10 
                 5 
               
               
                   
                 NUC-1024 
                 10 
                 10 
               
               
                   
                   
               
            
           
         
       
     
     The inner-group interleaving process is performed with N   CB_IG  QC blocks of the QCB interleaving output. Inner-group interleaving has a process of writing and reading the bits of the inner-group using 360 columns and N   CB_IG  rows. In the write operation, the bits from the QCB interleaving output are written row-wise. The read operation is performed column-wise to read out m bits from each row, where m is equal to 1 for NUC and 2 for NUQ. 
       FIG. 24  illustrates a cell-word demultiplexing according to an embodiment of the present invention. 
     (a) shows a cell-word demultiplexing for 8 and 12 bpcu MIMO and (b) shows a cell-word demultiplexing for 10 bpcu MIMO. 
     Each cell word (c 0,1 , c 1,1 , . . . , c n mod-1,1 ) of the bit interleaving output is demultiplexed into (d 1,0,m , d 1,1,m , . . . , d 1,n mod-1,m ) and (d 2,0,m , d 2,1,m , . . . , d 2,n mod-1,m ) as shown in (a), which describes the cell-word demultiplexing process for one XFECBLOCK. 
     For the 10 bpcu MIMO case using different types of NUQ for MIMO encoding, the Bit Interleaver for NUQ-1024 is re-used. Each cell word (c 0,1 , c 1,1 , . . . , c n mod-1,1 ) of the Bit Interleaver output is demultiplexed into (d 1,0,m , d 1,1,m , . . . , d 1,n mod-1,m ) and (d 2,0,m , d 2,1,m , . . . , d 2,n mod-1,m ), as shown in (b). 
       FIG. 25  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 N TI  per TI group. For DP_TI_TYPE=‘1’, this parameter is the number of frames P 1  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 I JUMP  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 N xBLOCK_Group (n) and is signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note that N xBLOCK_Group (n) may vary from the minimum value of 0 to the maximum value N xBLOCK_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 P i  frames. Each TI group is also divided into more than one TI blocks(N TI ), 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 33. 
     
       
         
           
               
               
             
               
                 TABLE 33 
               
               
                   
               
               
                 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’. 
               
               
                 Optlon-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. 
               
               
                   
               
            
           
         
       
     
     In each DP, the TI memory stores the input XFECBLOCKs (output XFECBLOCKs from the SSD/MIMO encoding block). Assume that input XFECBLOCKs are defined as 
     
       
         
           
             
               ( 
               
                 
                   d 
                   
                     n 
                     , 
                     s 
                     , 
                     0 
                     , 
                     0 
                   
                 
                 , 
                 
                   d 
                   
                     n 
                     , 
                     s 
                     , 
                     0 
                     , 
                     1 
                   
                 
                 , 
                 … 
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     where d n,s,r,q  is the qth cell of the rth XFECBLOCK in the sth TI block of the nth TI group and represents the outputs of SSD and MIMO encodings as follows. 
     
       
         
           
             
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     In addition, assume that output XFECBLOCKs from the time interleaver are defined as 
     
       
         
           
             
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     where h n,s,i  is the ith output cell (for i=0, . . . ,N xBLOCK_TI (n,s)×N cells −1) in the sth TI block of the nth TI group. 
     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 DR 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 cells  while the number of columns N, is equal to the number N xBLOCK_TI (n,s) 
       FIG. 26  illustrates the basic operation of a twisted row-column block interleaver according to an embodiment of the present invention. 
     shows a writing operation in the time interleaver and (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 expression. 
     
       
         
           
             
               
                 
                   
                     GENERATE 
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     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 xBLOCK_TI_MAX  given in the PLS2-STAT as follows expression. 
     
       
         
           
             
               
                 
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     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. 27  illustrates an operation of a twisted row-column block interleaver according to another embodiment of the present invention. 
     More specifically,  FIG. 27  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 xBLOCK_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 expression. 
     
       
         
           
               
             
               
                   
               
             
            
               
                 [Expression 11] 
               
            
           
           
               
               
            
               
                   
                 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; 
               
               
                   
                 } 
               
            
           
           
               
               
            
               
                   
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     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., N TI =1, I JUMP =1, and P I =1. The number of XFECBLOCKs, each of which has N cells =30 cells, per TI group is signaled in the PLS2-DYN data by N xBLOCK_TI (0,0)=3, N xBLOCK_TI (1,0)=6, and N xBLOCK_TI (2,0)=5, respectively. The maximum number of XFECBLOCK is signaled in the PLS2-STAT data by N xBLOCK_Group_MAX , which leads to └N xBLOCK_Group_MAX /N TI ┘=N xBLOCK_TI_MAX =6. 
       FIG. 28  illustrates a diagonal-wise reading pattern of a twisted row-column block interleaver according to an embodiment of the present invention. 
     More specifically  FIG. 28  shows a diagonal-wise reading pattern from each interleaving array with parameters of N′ xBLOCK_TI_MAX =7 and S shift =(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 V i  is skipped and the next calculated value of V i  is used. 
       FIG. 29  illustrates interleaved XFECBLOCKs from each interleaving array according to an embodiment of the present invention. 
       FIG. 29  illustrates the interleaved XFECBLOCKs from each interleaving array with parameters of N′ xBLOCK_TI_MAX =7 and S shift =3. 
       FIG. 30  shows a mode adaptation module according to another embodiment of the present invention. 
     The input formatting module described above may include the mode adaptation module as described in the foregoing. The mode adaptation module shown in  FIG. 30  may correspond to another embodiment of the mode adaptation module described above. 
     The mode adaptation module according to another embodiment may include a pre-processing block, an input stream synchronizer block, a compensation delay block, a null packet deletion block, a header compression block, a cyclical redundancy check (CRC) encoder block, a BB frame slicer block, and/or a BB frame header insertion block. 
     Here, the pre-processing block may correspond to the above-described input stream splitter. The input stream synchronizer block may correspond to the above-described input stream synchronizer. The compensation delay block may correspond to the above-described compensation delay block. The null packet deletion block may correspond to the above-described null packet deletion block. 
     The header compression block may correspond to the above-described head compression block. The header compression block may correspond to another example of the above-described head compression block. The present invention may relate to the header compression block in the mode adaptation module shown in  FIG. 30 . The present invention related to the header compression block is described below. 
     The CRC encoder block may correspond to the above-described CRC-8 encoder. The CRC encoder block shown in  FIG. 30  may perform CRC-16 encoding and CRC-32 encoding depending on an embodiment. CRC encoding to be performed may be signaled in a PLS2 field. 
     The BB frame slicer block maps a plurality of input bits of an input stream to an internal logical-bit format. The BB frame slicer block allocates input bits of an input stream suitable for an available data field capacity. The BB frame slicer block may allocate a plurality of user packets to a payload area of a BB frame. As a result, a user packet may be cut. In a payload area of a subsequent BB frame, a location of a first user packet which is intact (not cut) may be signaled by a field referred to as SYNCD. 
     The BB frame header insertion block may correspond to the above-described BB header insertion block. 
     The above-described blocks may be omitted depending on an embodiment. In addition, locations of the above-described blocks may be changed depending on an embodiment. 
     The present invention proposes a header compression scheme using deletion of a transport stream (TS) packet header. The header compression scheme proposed in the present invention may be performed by the above-described header compression block. A TS corresponding to a type of input stream may include a plurality of contiguous TS packets. Each of the TS packets may include a TS packet header. 
     When a TS is input as an input stream to a next generation broadcast system, a TS packet header may be deleted to enhance transmission efficiency. When all TS packet header values of a plurality of TS packets except for continuity counter values are the same, the present invention proposes a scheme of deleting the same TS headers except for a first TS header. 
     According to an embodiment of the present invention, a sync bite (8 bits) of a TS packet header may be replaced by a NUM_TS field. NUM_TS may signal the number of deleted TS packet headers. According to another embodiment of the present invention, a sync bit of a TS packet header may be deleted, and a 4-bit continuity counter may be replaced by a NUM-TS field. In this case, NUM_TS may signal the number of deleted TS packet headers. 
     According to the scheme of deleting TS packet headers proposed in the present invention, it is possible to enhance compression efficiency of an input packet, and enhance transmission efficiency of data. The present invention is specifically described below. 
       FIG. 31  shows a header compression block according to another embodiment of the present invention. 
     The header compression block according to another embodiment of the present invention may correspond to a header compression block within the above-described mode adaptation module according to another embodiment of the present invention. As described in the foregoing, the header compression scheme proposed in the present invention may be performed by the header compression block shown in  FIG. 31 . 
     The header compression block according to another embodiment of the present invention may include a PID check block, a TS packet deletion block, and/or a TS header replacement block. 
     The PID check block may detect input TS packets continuously having the same TS packet headers among input TS packets. Here, a PID refers to a packet identifier. The PID check block determines that input TS packets have the same TS packet headers when the TS packet headers have the same value except for continuity counters. The reason is that values of continuity counters successively increase. 
     The TS packet deletion block may delete packet headers of input TS packets except for a packet header of a first input TS packet among input TS packets detected by the PID check block. Here, the first input TS packet may refer to a first input TS packet among contiguous input TS packets. The deleted packet headers have the same values except for continuity counters. 
     The TS header replacement block may transform a packet header of a first input TS packet among input TS packets detected by the PID check block. A sync byte may be deleted in the packet header of the first input TS packet. Here, the sync byte corresponds to a field indicating a start of an input packet, and may be used for synchronization of an input stream. In general, the sync byte may have a value of 0x47. 
     According to an embodiment of the present invention, the TS header replacement block may insert a NUM_TS field into a position of deleted sync byte. The NUM_TS field is a field that signals the number of deleted TS packet headers. NUM_TS corresponds to 8 bits, and may indicate that 0 to 255 TS packet headers are deleted. A NUM_TS value 00000000 indicates that no TS packet header is deleted. 
     According to another embodiment of the present invention, the TS header replacement block may replace a continuity counter field with a NUM_TS field. Similarly, the NUM_TS field may signal the number of deleted TS packet headers. However, unlike the embodiment in which NUM_TS replaces a sync bite corresponding to 8 bits, a continuity counter has a size of 4 bits. Therefore, in this embodiment, NUM_TS may use 4 bits to indicate that 0 to 16 TS packet headers are deleted. Similarly, a NUM_TS value 0000 indicates that no TS packet header is deleted. 
       FIG. 32  shows an output processor according to another embodiment of the present invention. 
     The output processor may be a module or a block positioned on a receiving side. The output processor may be a module or a block corresponding to the above-described input formatting block. 
     The output processor may perform a reverse process of a compression/signal processing process applied to enhance transmission efficiency in a transmission device. A final output of the output processor may correspond to a signal input to the transmission device. The final output may be an MPEG-TS, an IP stream (v4 or v6), and/or a generic stream. 
     A BB frame header parser block may parse a BB frame header from a BB frame. In this way, the BB frame header parser block may acquire an STUFF1 and/or SYNCD value. Separated and received signals may be combined using the STUFF1 and/or SYNCD value. 
     A CRC detector block may detect whether CRC encoding is performed. The CRC encoding may be performed by determining CRC encoding performed at a transmitting end. As described in the foregoing, examples of the CRC encoding may include CRC-8 encoding, CRC-16 encoding, CRC-32 encoding, and the like. 
     A header decompression block may be a component corresponding to the header compression block of the transmitting end. The header decompression block may restore compression of a compressed packet header. As described in the foregoing, a packet header may be compressed to enhance transmission efficiency of a TS or IP input stream. 
     TS packets processed by the scheme of deleting TS packet headers proposed in the present invention may be restored by the header decompression block. A detailed restoration process is described below. 
     A null packet insertion block may restore a deleted null packet within a stream with reference to information about a restored deleted null packet (DNP), and may output common data. The null packet within the stream may be deleted at the transmitting end. The DNP information may be received from a signaling block or the BB frame header parser block. 
     A TS clock regeneration block may restore detailed time synchronization of an output packet based on input stream clock reference (ISCR) information. Depending on an embodiment, the ISCR information may be received from the signaling block or the BB frame header. 
     A de-jitter buffer block may compensate for a delay arbitrarily inserted at the transmitting end to synchronize multiple data pipes with each other according to a restored time to output (TTO) parameter. 
     A TS recombining block may recombine common data output from the above-described null packet insertion block and related data pipes to restore and output an MPEG-TS, an IP stream (v4 or v6), or a generic stream. The above-described TTO, DNP, and ISCR information may be acquired using a BB frame header. 
     The above-described blocks may be omitted depending on an embodiment. In addition, positions of the above-described blocks may be changed depending on an embodiment. 
       FIG. 33  shows a header decompression block according to another embodiment of the present invention. 
     The header decompression block according to another embodiment of the present invention may be the header decompression block within the output processor according to another embodiment of the present invention described above. As described in the foregoing, information compressed by the header compression scheme proposed in the present invention may be restored by the header decompression block shown in  FIG. 33 . 
     The header decompression block according to another embodiment of the present invention may include a TS header parsing block and/or a deleted TS header regeneration block. 
     The TS header parsing block may parse an initially received TS packet header. Here, the initially received TS packet header refers to a packet header of a first TS packet among contiguous TS packets having the same TS packet headers at a transmitting end. The TS header parsing block may acquire a NUM_TS field value by parsing the initially received TS packet header. The TS header parsing block may count deleted TS packet headers using the NUM_TS field value. 
     In an embodiment of the present invention in which a sync byte is replaced by NUM_TS, the TS header parsing block may acquire a continuity counter value of the initially received TS packet header to restore continuity counters of the deleted packet headers. In another embodiment of the present invention in which a continuity counter is replaced by NUM_TS, an initially received TS packet header may not include a continuity counter value. 
     The deleted TS header regeneration block may restore deleted TS packet headers at the transmitting end. In this instance, a NUM_TS field value is used so that TS packet headers corresponding to the NUM_TS field value may be restored. 
     A plurality of TS packet headers may not be deleted at the transmitting end. A distance between a current non-deleted TS packet header and a subsequent non-deleted TS packet header may be 184*(NUM_TS+1) bytes. According to an embodiment, the length of a TS packet may be 188 bytes, and the length of a TS packet having a packet header deleted at the transmitting end may be 184 bytes. Therefore, a subsequent TS packet header may be present after 184*(NUM_TS+1) bytes. 
     The deleted TS header regeneration block may restore continuity counter values. Deleted continuity counter values successively increase. Thus, continuity counter values of received TS packet headers may be restored so that restored continuity counter values successively increase by 1. 
     An initial value of successively increasing continuity counters may change depending on an embodiment of the present invention. In an embodiment of the present invention in which a sync byte is replaced by NUM_TS, a continuity counter value of a TS packet header which is not deleted at the transmitting end may be the initial value. The continuity counter value of the TS packet header which is not deleted at the transmitting end may be acquired by the TS header parsing block as described above. In another embodiment of the present invention in which a continuity counter is replaced by NUM_TS, a continuity counter of a TS packet received without an error is designated as 1, and continuity counter values of TS packet headers restored thereafter are successively increased by 1. 
       FIG. 34  illustrates an initial packet header which is not deleted in a header compression scheme #1 according to an embodiment of the present invention. 
     The header compression scheme #1 according to the embodiment of the present invention is the above-described header compression scheme according to the embodiment in which a sync byte is replaced by NUM_TS. 
     As described in the foregoing, the header compression scheme #1 is a scheme of deleting TS packet headers to enhance transmission efficiency. When all values of TS packet headers of a plurality of TS packets are the same except for continuity counter values, the same TS headers except for an initial TS header may be deleted. 
     An initial packet header which is not deleted in the header compression scheme #1 is illustrated. A packet header on the left side is a packet header before transformation, and a packet header on the right side is a packet header transformed according to the header compression scheme #1. According to the embodiment, a packet header may have a total size of 4 bytes (32 bits). 
     The packet header before transformation may include information about a sync byte, a PID, and the like. A sync byte is a byte for synchronization of reception, and has a constant value of 0x47 and the like. A transport error indicator is referred to as a TEI, and indicates the presence of an error failed to be corrected by a demodulator. The TEI may be used to determine whether to ignore a packet. A payload unit start indicator may indicate whether the packet is a packetized elementary stream (PES) packet, or includes a PSI section. A transport priority indicates a priority of the packet. A PID is an identifier of the packet. A scrambling control may indicate the presence and a type of scrambling of the packet. An adaptation field control may indicate the presence of an adaptation field within the packet. Continuity counters correspond to values increasing by 1 in TS packets having the same PID, and may count from 0000 to 1111 (4 bits). A structure and specific figures of a TS packet header may be changed according to an embodiment. 
     The initial packet header which is not deleted in the header compression scheme #1 may have a deleted sync byte. A sync byte is known data, and may be deleted. NUM_TS may be inserted into a position of the deleted sync byte. NUM_TS may signal the number of deleted TS packet headers. 
     In the header compression scheme #1, the transport error indicator may not be transmitted, and a DNP may be transmitted. A DNP within a stream may be restored with reference to a value of the DNP. 
       FIG. 35  illustrates compression and restoration processes according to the header compression scheme #1 in the embodiment of the present invention. 
       FIG. 35( a )  illustrates contiguous input packets before header compression. In this embodiment, three contiguous input packets have PIDs of 0x011, and two contiguous input packets have PIDs of 0x012 thereafter. In general, a TS packet has a length of 188 bytes, a packet header has a length of 4 bytes, and a packet payload has a length of 184 bytes. Continuity counter values of the input packets having PIDs of 0x011 are 4, 5, and 6, respectively, and continuity counter values of the input packets having PIDs of 0x012 are 8 and 9, respectively. 
     Header compression is performed according to the above-described header compression scheme #1. Packet headers of the first, second, and third input packets have the same value except for continuity counters. Therefore, the packet headers of the second and third input packets are deleted and not transmitted. The packet header of the first input packet is not deleted, and has a sync byte replaced by NUM_TS. Here, since the packet headers of the second and third input packets are deleted, two packet headers are deleted in total. Therefore, NUM_TS has a value of 2. The same value 4 may be transmitted as a continuity counter. 
       FIG. 35( b )  illustrates input packets after header compression is performed according to the header compression scheme #1 in the embodiment of the present invention. As described in the foregoing, the packet headers of the second and third input packets are deleted. The packet header of the first input packet may be transformed and transmitted. 
       FIG. 35( c )  illustrates that compressed headers are restored at a receiving end. A receiver may acquire NUM_TS and a continuity counter value from the initial packet header which is not deleted at a transmitting side. The deleted TS packet headers may be restored using the acquired NUM_TS. In this instance, continuity counter values of the restored TS packet headers may successively increase by 1 from the continuity counter value of the initial packet header as an initial value. Therefore, the continuity counter values may be 5 and 6, respectively. 
       FIG. 36  illustrates an initial packet header which is not deleted in a header compression scheme #2 according to an embodiment of the present invention. 
     The header compression scheme #2 according to the embodiment of the present invention is the above-described header compression scheme according to the embodiment in which a continuity counter is replaced by NUM_TS. 
     As described in the foregoing, the header compression scheme #2 is a scheme of deleting TS packet headers to enhance transmission efficiency. When all values of TS packet headers of a plurality of TS packets are the same except for continuity counter values, the same TS headers except for an initial TS header may be deleted. 
     An initial packet header which is not deleted in the header compression scheme #2 is illustrated. A packet header on the left side is a packet header before transformation, and a packet header on the right side is a packet header transformed according to the header compression scheme #2. 
     Information included in the packet header before transformation is as described above. 
     In the header compression scheme #2, a sync byte of an initial packet header which is not deleted may be deleted and not be transmitted. Similarly to the header compression scheme #1, a transport error indicator is not transmitted, and is replaced by a DNP value. 
     In addition, a continuity counter (4 bits) may not be transmitted, and be replaced by NUM_TS. NUM_TS may signal the number of deleted TS packet headers. 
       FIG. 37  illustrates compression and restoration processes according to the header compression scheme #2 in the embodiment of the present invention. 
       FIG. 37( a )  illustrates contiguous input packets before header compression. Similarly to the above-described embodiment, three contiguous input packets have PIDs of 0x011, and two contiguous input packets have PIDs of 0x012 thereafter. Continuity counter values of the input packets having PIDs of 0x011 are 4, 5, and 6, respectively, and continuity counter values of the input packets having PIDs of 0x012 are 8 and 9, respectively. 
     Header compression is performed according to the above-described header compression scheme #2. Packet headers of the first, second, and third input packets have the same values except for continuity counters. Therefore, the packet headers of the second and third input packets are deleted and not transmitted. 
     A sync byte of the first input packet header is deleted, and a continuity counter field is replaced by NUM_TS. Since a total of two packet headers are deleted, NUM_TS has a value of 2. 
       FIG. 37( b )  illustrates input packets after header compression is performed according to the header compression scheme #2 in the embodiment of the present invention. The second and third packet headers are deleted, and the first packet header is transformed and transmitted. 
       FIG. 37( c )  illustrates that compressed headers are restored at a receiving end. A receiver may acquire NUM_TS from the initial packet header which is not deleted at a transmitting side. The deleted TS packet headers may be restored using the acquired NUM_TS. 
     In this instance, continuity counter values are deleted at the transmitting side and thus may not be acquired at a receiving end. Therefore, an initial value of continuity counters may be set to 1. Continuity counter values of TS packet headers may be restored thereafter by being increased from 1 by 1. Therefore, continuity counter values may be 1, 2, and 3 in order. 
     According to compression schemes, it is possible to significantly enhance compression efficiency of TS packets. In particular, since existing systems limit the length of a TS packet to a fixed value, the above-described compression schemes may not be used. However, the header compression schemes proposed in the present invention may be used when the length of a TS packet is variable, and packet compression efficiency is enhanced and thus transmission efficiency is greatly enhanced. 
     According to embodiments, various header compression schemes including the above-described header compression schemes may be used in a system. A plurality of header compression schemes may be used for each packet or packet group in an input stream. A used header compression scheme may be signaled in a signaling field. For example, a header compression scheme may be signaled in the above-described PLS2 field. 
       FIG. 38  illustrates a method of transmitting broadcast signal according to an embodiment of the present invention. 
     The method includes processing input streams, encoding data of the PLPs (Physical Layer Pipes)s, building at least one signal frame, and/or modulating data by OFDM method &amp; transmitting broadcast signals. 
     In step of processing input streams, the above described input formatting module may process input streams. The input formatting module can process input streams into BB (Base Band) frames of PLPs. The PLP can be divided into BB frames. The input formatting module can demultiplex input streams into PLPs. 
     In this embodiment, the input streams include a plurality of input packets. Each of the input packets can include a packet header including information about synchronization of the input streams. The information about synchronization may correspond to a sync byte, described above. The input packet may correspond to TS packet. 
     The step of processing input streams further includes compressing the packet headers and generating the BB frames. The compressing the packet headers may correspond to packet header compression step in input formatting module. Here, the packet headers of the input packets in the input streams can be compressed. The generating the BB frames is conducted by using the compressed input packets. This step may correspond to BB frame slicer and/or BB frame header insertion block, described above. 
     In step of encoding data of the PLPs, the above described coding &amp; modulation module may encode data of the PLPs. The PLP can be also referred to as DP. This step may include LDPC (Low Density Parity Check) encoding, bit interleaving, mapping onto constellations, MIMO (Multi Input Multi Output) encoding, and/or time interleaving. The data in in each data path can be encoded based on a code rate. 
     In step of building at least one signal frame, the above-described frame structure module can build signal frames by mapping the encoded data of the PLPs. 
     In step of modulating data by OFDM method &amp; transmitting broadcast signals, the above-described waveform generation module can modulate data in OFDM method, and transmit the broadcast signals. 
     In a method of transmitting broadcast signals according to other embodiment of the present invention, the information about synchronization in each of the input packets are removed in step of the compressing the packet headers. The information about synchronization may correspond to a sync byte, described above. 
     In a method of transmitting broadcast signals according to another embodiment of the present invention, the step of compressing the packet headers further includes processing a packet header of first input packet, and deleting packet headers of the other input packets, when at least two successive input packets in the input streams have same packet headers. Here, having same packet headers means that values of the packet headers are the same except a continuity counter field. The continuity counter field may correspond to continuity counter field, described above. These additional steps may correspond to header compression method #1, which is described above. By processing a packet header of first input packet of the at least two successive input packets, and by deleting packet headers of the other input packets of the at least two successive input packets, the packet headers are compressed and transmitted efficiently. 
     In a method of transmitting broadcast signals according to another embodiment of the present invention, the continuity counter fields in each of the at least two successive input packets increases. The continuity counter fields may correspond to continuity counter fields in each of the input packets. The continuity counter fields increases in order from the one in the first input packet of the at least two successive input packets. For example, if the first input packet has continuity counter field of value ‘4’, the next input packet has continuity counter field of value ‘5’, and the next one has ‘6’, and so on. 
     In a method of transmitting broadcast signals according to another embodiment of the present invention, the processing a packet header of first input packet further includes replacing the sync byte. This step may describe packet header compression method #1, and how the sync byte is replaced with the NUM_TS field. NUM_TS field can be also referred to as a packet number field. As described above, the NUM_TS field indicates a number of the other input packets whose packet headers are deleted. The NUM_TS field can be used at the receiver side, when the packet headers are regenerated. 
     In a method of transmitting broadcast signals according to another embodiment of the present invention, the step of the encoding data of the PLPs further includes, encoding the BB frames of the PLPs with LDPC (Low Density Parity Check) codes, bit interleaving the LDPC encoded data in the PLPs, mapping the bit interleaved data onto constellations, MIMO (Multi Input Multi Output) encoding the mapped data, and/or time interleaving the MIMO encoded data. 
     The encoding with LDPC codes may correspond to LDPC encoding by LDPC encoder. The LDPC encoder may encode BB frames in the PLPs with LDPC codes. Bit interleaving may correspond to bit interleaving by bit interleaver. Constellation mapping may correspond to the constellation mapping conducted by constellation mapper. MIMO encoding can refer to MIMO encoding performed by above described MIMO encoder. Time interleaving can correspond to time interleaving by time interleaver. 
     The above-described steps can be omitted or replaced by steps executing similar or identical functions according to design. 
       FIG. 39  illustrates a method of receiving broadcast signal according to an embodiment of the present invention. 
     The method includes receiving broadcast signals &amp; demodulating data by OFDM method, parsing the at least one signal frame, decoding the data of the PLPs, and/or processing BB frames. 
     In step of receiving broadcast signals &amp; demodulating data by OFDM method, the above-described synchronization &amp; demodulation module receives broadcast signals, and demodulates data by OFDM method. 
     In step of parsing the at least one signal frame, the above-described frame parsing module parses the signal frame by demapping data of the PLPs. 
     In step of decoding the data of the PLPs, the above-described demapping &amp; decoding module decodes the PLP data. Step of decoding the PLP data can include time deinterleaving, MIMO (Multi Input Multi Output) decoding, and so on. 
     In step of processing BB frames, the above described output processor may conduct output processing on the BB frames of the PLPs. The output processor may output output streams. 
     In this embodiment, the step of processing BB frames further includes, decompressing a compressed packet header of data packets in the BB frames, and generating the output streams by using the decompressed data packets. The decompressing may be conducted by header decompression block, described above. The generating the output streams may corresponds to series of steps in output processor, after the decompressing the packet header. The compressed packet header is a packet header of the first input packet, which is compressed at the transmitter side by the packet header compression method #1. 
     In a method of receiving broadcast signals according to other embodiment of the present invention, information about synchronization of the output streams are regenerated in step of the decompressing a compressed packet header, for each of the data packets. The information about synchronization may correspond to a sync byte, described above. 
     In a method of receiving broadcast signals according to another embodiment of the present invention, the decompressing a compressed packet header of data packets further includes regenerating packet headers for each of the data packets. As a reverse step of deleting packet headers, at the transmitter side, this regeneration step is needed at the receiver side. By using a packet number field in the compressed packet header, the packet header can be regenerated/restored. Here, the packet number field may correspond to NUM_TS field, which indicates a number of the data packets whose packet headers are deleted. 
     In a method of receiving broadcast signals according to another embodiment of the present invention, the regenerated packet headers for each of the data packets include continuity counter fields. The continuity counter field may correspond to continuity counter field, described above. The continuity counter fields increases in order from a continuity counter field in the compressed packet header. 
     In a method of receiving broadcast signals according to another embodiment of the present invention, the decompressing a compressed packet header of data packets further includes replacing the packet number field in the compressed packet header. The packet number field in the compressed packet header is replaced to the information about synchronization. Here, the information about synchronization is a sync byte for the compressed packet header. This is one of the reverse process of the packet header compression method #1. 
     In a method of receiving broadcast signals according to another embodiment of the present invention, the decoding the data of the PLPs further includes, time deinterleaving the data of the PLPs, MIMO (Multi Input Multi Output) decoding the time deinterleaved data of the PLPs, demapping the MIMO decoded data from constellations, bit deinterleaving the demapped data, and/or processing the bit deinterleaved data with LDPC (Low Density Parity Check) codes to output BB frames. 
     In step of time deinterleaving, the above-described time deinterleaver can conduct time deinterleaving PLP data. In step of MIMO decoding, the above-described MIMO decoder can conduct MIMO decoding PLP data. MIMO decoding can be conducted by using MIMO matrix including MIMO coefficient. MIMO coefficient can be used for adjusting power imbalance. In step of demapping from constellations, the above-described constellation demapper can conduct demapping. The demapping can be conducted on PLP data. In step of bit deinterleaving, the above-described bit deinterleaver can conduct bit deinterleaving. In step of LDPC decoding, the above-described LDPC decoder (or FEC decoder) can decode PLP data according to LDPC code, to output BB frames. 
     The above-described steps can be omitted or replaced by steps executing similar or identical functions according to design. 
     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. And, if a recording medium readable by a computer, in which programs for executing the embodiments mentioned in the foregoing description are recorded, is designed in necessity of those skilled in the art, it may belong to 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. And, 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 codes 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 discs, optical data storage devices, and the like for example and also include such a carrier-wave type implementation as a transmission via Internet. Furthermore, as the processor-readable recording medium is distributed to a computer system connected via network, processor-readable codes can be saved and executed according to a distributive system. 
     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 apparatus and method inventions are mentioned in this specification and descriptions of both of the apparatus and method inventions may be complementarily applicable to each other. 
     Various embodiments have been described in the best mode for carrying out the invention. 
     The present invention is available in 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 covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.