Patent Document

PRIORITY  
       [0001]     This application claims priority under 35 U.S.C. § 119(a) of a Korean Patent Application filed in the Korean Intellectual Property Office on Feb. 3, 2006 and assigned Serial No. 2006-10576, the entire disclosure of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates generally to an apparatus and method for receiving data in a wireless communication system, and in particular, to an apparatus and method for receiving data in a mobile broadcasting terminal.  
         [0004]     2. Description of the Related Art  
         [0005]     Today&#39;s wireless communication systems have typically been developed to transmit and receive data over the air. With the progress of these wireless communication systems, there is now a discussion regarding wireless broadcast services that support both portability and mobility. Such wireless broadcast systems would basically provide unidirectional services, although bidirectional services are also now under discussion.  
         [0006]     A Digital Video Broadcasting-Handheld (DVB-H) system is one of the typical wireless broadcast systems. The DVB-H system, which is currently being developed to take the portability and mobility into consideration, is an European digital TV mobile broadcast standard improved from a Digital Video Broadcasting-Terrestrial (DVB-T) system. However, in order to increase the portability of the terminal receiving the broadcast service, it is necessary to reduce battery consumption at a receiver. As a result, the DVB-H system utilizes a time slicing technique, as illustrated in  FIG. 1 .  
         [0007]      FIG. 1  is a conceptual diagram illustrating a time slicing technique used in a conventional communication system.  
         [0008]     The time slicing technique, as shown in  FIG. 1 , instantaneously transmits data at a high data rate for a short time and transmits no data for the other time, instead of continuously transmitting data for a give time. Here, a particular time for which data is transmitted is called a burst duration  100 , and the time for which no burst is transmitted is called an off-time  101 . The off-time  101  is defined as such for a particular service only. Actually, however, bursts for several other services can be transmitted in the off-time  101 . Therefore, in the time slicing technique, data of several different services is transmitted for an inter-burst interval after undergoing Time Division Multiplexing (TDM), by way of sharing the same frequency band in units of bursts. Hence, with use of the time slicing technique, the DVB-H system can transmit a plurality of services in one band, and can provide a data rate of 8˜31 Mbps per frequency band.  
         [0009]     To increase the mobility, the DVB-H system additionally introduces an error correction technique to a Multi-Protocol Encapsulation (MPE) layer, which is a link layer of the DVB-T system, thereby improving the capability of controlling errors even in the channel environment where fading is considerable. The added error correction technique uses a Reed-Solomon (RS) code, and with use of it, performs Forward Error Correction (FEC). This is called MPE-FEC and is a conventional method for transmitting data using the MPE-FEC technique. In operation the MPE-FEC technique generates parity bits by performing RS coding on an Internet Protocol (IP) datagram received from an upper layer, and configures an MPE-FEC frame with them, as illustrated in  FIGS. 2A  to  2 C.  
         [0010]      FIGS. 2A  to  2 C are conceptual diagrams for a description of an MPE-FEC frame structure and a method for configuring an MPE-FEC frame.  
         [0011]     In  FIG. 2A , an MPE-FEC frame is comprised of an application data table  201  for storing IP datagrams and an RS data table  202  for storing parity bits. Here, a RS coding method used for this performs a byte coding process with RS ( 255 ,  191 ,  64 ).  FIG. 2B  illustrates an order of arranging IP datagrams. In a process of arranging the IP datagrams in the application data table, data is first arranged in a direction denoted by reference numeral  211 . Thereafter, the next column is selected, and data is then arranged therein as shown by reference numeral  212 . This is continuously repeated up to the last position of the application data table. For example, data is continuously stored as shown by reference numerals  213  and  214 . In sum, the IP datagrams are stored in the application data table in the up-to-down direction and the left-to-right direction.  
         [0012]     Next,  FIG. 2C  shows a process of acquiring parities. After the data is stored, as described in  FIG. 2B , parities are filled in the RS data table using the data written in each row. For example, parities are acquired using the data corresponding to a first row  221 , and the acquired parities are then stored as shown by reference numeral  231 . Similarly, parities are acquired using the data in the next row  222 , and the acquired parities are stored as shown by reference numeral  232 . This is repeated until parities are acquired using the data in the last row  223  stored in the application data table  201 , and the acquired parities are stored in the RS data table  202  as shown by reference numeral  233 .  
         [0013]     Consequently, an MPE-FEC frame is configured as shown in  FIG. 2A .  FIG. 2B , however, shows a method for transmitting the configured MPE-FEC frame.  
         [0014]     In a process of transmitting a MPE-FEC frame, the application data table  201  is first transmitted and then, the RS data table  202  is transmitted. In a process of transmitting data stored in each table, data is transmitted in units of columns in the up-to-down direction and the left-to-right direction. Here, the data is transmitted in the same direction as that in which IP datagrams are stored in  FIG. 2B . Thus, by transmitting data in this manner, it is possible to obtain a virtual interleaving effect.  
         [0015]     In addition, an IP datagram includes a header with its address, and a Cyclic Redundancy Check (CRC) for error correction, thereby forming a section. In order to transmit the data according to a Moving Picture Expert Group (MPEG) Transport Stream (TS) format, a physical layer divides the sections into packets, and performs FEC coding and Orthogonal Frequency Division Multiplexing (OFDM) modulation thereon before transmission.  
         [0016]     A receiver performs a reverse process of the transmission process. In the receiver, after a physical layer performs Viterbi decoding and RS ( 204 ,  188 ,  8 ) decoding, a link layer detects an IP datagram by moving a header and CRC of an MPE-FEC section. Thereafter, the receiver stores the received data in the application data table and the RS data table of an MPE-FEC memory, and then performs MPE-FEC decoding thereon.  
         [0017]      FIG. 3  is a functional schematic diagram for MPE-FEC processing in a mobile broadcasting receiver based on the DVB-H standard.  
         [0018]     A signal received at the receiver is thereafter converted into a baseband signal, and then sequentially undergoes OFDM demodulation, Viterbi decoding, convolutional deinterleaving, and RS decoding. The process of OFDM demodulation, Viterbi decoding, and convolutional deinterleaving is generally called a “preprocessing process.” An RS decoder  311  performs RS ( 204 ,  188 ,  8 ) decoding and outputs decoded data. An output of the RS decoder  311  has a format of an MPEG TS packet, and several TS packets constitute one MPE-FEC section. The MPE-FEC section is detected by a checker  312  and information on an error CRC-checked by the checker  312  is provided to a datagram extractor  313 . Then the datagram extractor  313  extracts an IP datagram in the section determined by the checker  312  that there is no error, and stores the extracted IP datagram in a buffer  314 . However, the section determined to have a CRC error undergoes error or erasure processing in the buffer  314 , and then is error-corrected by an MPE-FEC RS decoder  315 . Thereafter, the error-corrected IP datagram is delivered to an application controller (or application processor)  316  as a baseband channel chip output. Then the application controller  316  performs audio/video decoding thereon.  
         [0019]      FIG. 4  is a timing diagram for data processing at a mobile broadcasting receiver supporting N parallel services in a DVB-H system. With reference to  FIG. 4 , a description will now be made of the data processing timing.  
         [0020]     To receive one burst, the receiver converts a Radio Frequency (RF) signal into a baseband signal, and performs an OFDM synchronization process thereon before the burst. In a DVB-H system supporting Conditional Access (CA), the receiver should receive an Entitlement Control Message (ECM) before the burst. Therefore, at a time  401 , the receiver receives an RF signal, performs an OFDM synchronization process thereon, and receives and decodes an ECM for Conditional Access.  
         [0021]     The receiver receives data transmitted in the burst and performs OFDM modulation thereon in duration  402 , performs Viterbi decoding in duration  403 , and performs RS decoding in duration  404 . The time required for this is approximately 10 ms. Thereafter, about a 1-burst time is required for detecting a section and storing the MPE-FEC data for MPE-FEC demodulation, and is shown as duration  405 .  FIG. 4  shows a processing time at a DVB-H receiver, and parameters used therein are set such that a burst bandwidth  103  is 10 Mbps, a constant bandwidth  102  is 500 kbps, and a burst size is 2 M bits, so 1-burst duration  100  is assumed to be 200 ms. If the number of parallel services is N, the burst duration increases N times. Here, a demodulation time of the MPE-FEC is assumed to be 25 ms like duration  406 , an approximately (200×N+35)-ms time is required until before transmission of an error-corrected IP datagram to an Application Processor (AP) chip, i.e. before start of duration  407 .  
         [0022]      FIG. 5  is a flow diagram illustrating a general process of receiving a burst signal and performing MPE-FEC processing thereon in a mobile broadcasting receiver.  
         [0023]     An RF unit (not shown) of the receiver receives a burst signal in step  500 , wherein m is set to 1 (m=1). Thereafter, an RS decoder  311  of the receiver performs RS decoding in units of TS packets in step  502 . A checker  312  of the receiver detects a m th  section in step  504 . After detecting the m th  section, a datagram extractor  313  of the receiver stores a datagram with a section header and CRC excluded therefrom in a buffer  314  in step  506 . The datagram extractor  313  of the receiver determines in step  508  whether the stored datagram is at the end of the burst. For example, the datagram extractor  313  determines if burst transmission duration ends according to the time slicing technique as described in  FIG. 1 . If it is determined that the stored datagram is not at the end of the burst, the datagram extractor  313  increases the value m by 1 in step  510  and then proceeds to step  506  to repeat the above process. However, if the stored datagram is at the end of the burst, the receiver performs RS decoding using its RS decoder  315  in step  512 . After completion of RS decoding, the RS decoder  315  of the receiver sequentially transmits datagrams to the Application Processor (AP) in step  514 .  
         [0024]     Taking into account that the total processing time required in the baseband application controller  316  is approximately “200×N+35” ms, as described above, it can be understood that the time required for storing in the buffer  314 , which is an MPE-FEC memory, is much greater than the other processing time in the DVB-H receiver. In particular, as the burst size increases or the number of parallel services increases, the processing time required for storing in the MPE-FEC memory increases proportionally. The increase in the processing time in the receiver causes an increase in the time required for channel switching of a mobile broadcast, inconveniencing the user.  
       SUMMARY OF THE INVENTION  
       [0025]     An aspect of the present invention is to address at least the problems and/or disadvantages and to provide at least the advantages described below. Accordingly, one aspect of the present invention is to provide a data reception apparatus and method capable of reducing a reception time in a mobile broadcasting terminal.  
         [0026]     Another aspect of the present invention is to provide a data reception apparatus and method capable of reducing power consumption in a mobile broadcasting terminal.  
         [0027]     Another aspect of the present invention is to provide a data reception apparatus and method capable of reducing a channel switching time in a mobile broadcasting terminal.  
         [0028]     According to one aspect of the present invention, there is provided an apparatus for receiving and processing a broadcast signal in a mobile broadcasting terminal. The apparatus includes a preprocessor for receiving a broadcast signal, converting the broadcast signal into a baseband signal, and then performing OFDM demodulation, Viterbi decoding, and convolutional deinterleaving thereon; a first Reed-Solomon (RS) decoder for RS-decoding the signal output from the preprocessor, and outputting a Transport Stream (TS) packet; a checker for checking Cyclic Redundancy Check (CRC) of the TS packet; a datagram extractor for extracting a datagram having a good CRC result; a datagram controller for receiving the datagram having a good CRC result and outputting the received datagram to an application controller; and the application controller for decoding broadcast data using the datagram received from the datagram controller and providing the decoded broadcast data to a user.  
         [0029]     According to another aspect of the present invention, there is provided a method for receiving and processing a broadcast signal in a mobile broadcasting terminal. The method includes receiving a broadcast signal, converting the broadcast signal into a baseband signal, and then performing OFDM demodulation, Viterbi decoding, and convolutional deinterleaving thereon; Reed-Solomon (RS)-decoding the preprocessed signal, and outputting a Transport Stream (TS) packet; checking Cyclic Redundancy Check (CRC) of the TS packet; outputting a datagram having a good CRC result; and decoding broadcast data using the received datagram and providing the decoded broadcast data to a user.  
         [0030]     According to further another aspect of the present invention, there is provided a method for receiving and processing a broadcast signal in a mobile broadcasting terminal. The method includes receiving a broadcast signal, converting the broadcast signal into a baseband signal, and then performing OFDM demodulation, Viterbi decoding, and convolutional deinterleaving thereon; Reed-Solomon (RS)-decoding the preprocessed signal and outputting a Transport Stream (TS) packet; checking Cyclic Redundancy Check (CRC) of the TS packet; outputting a datagram having a good CRC result separately; storing erasure information and datagrams based on the CRC result; correcting an error of the datagrams using the CRC result and outputting the datagrams; and decoding broadcast data using the received datagrams and providing the decoded broadcast data to a user.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0031]     The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:  
         [0032]      FIG. 1  is a conceptual diagram for a description of a time slicing technique used in a conventional communication system;  
         [0033]      FIGS. 2A  to  2 D are conceptual diagrams for a description of an MPE-FEC frame structure and a method for configuring an MPE-FEC frame;  
         [0034]      FIG. 3  is a functional block diagram for MPE-FEC processing in a mobile broadcasting receiver based on the DVB-H standard;  
         [0035]      FIG. 4  is a timing diagram for data processing at a mobile broadcasting receiver supporting N parallel services in a DVB-H system;  
         [0036]      FIG. 5  is a flow diagram illustrating a general process of receiving a burst signal and performing MPE-FEC processing thereon in a conventional mobile broadcasting receiver;  
         [0037]      FIG. 6  is an internal schematic diagram of a data receiver for MPE-FEC in a mobile broadcasting receiver according to an exemplary embodiment of the present invention;  
         [0038]      FIGS. 7 and 8  are processing timing diagrams for a MPE-FEC processing scheme applied to a mobile broadcasting terminal according to an exemplary embodiment of the present invention;  
         [0039]      FIG. 9  is a flow diagram illustrating MPE-FEC signal processing in a mobile broadcasting terminal according to an exemplary embodiment of the present invention; and  
         [0040]      FIG. 10  is a flow diagram illustrating an operation performed in an application controller during MPE-FEC processing in a mobile broadcasting terminal according to an exemplary embodiment of the present invention. 
     
    
       [0041]     Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features and structures.  
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0042]     Exemplary embodiments of the present invention will now be described in detail with reference to the annexed drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for clarity and conciseness.  
         [0043]      FIG. 6  is an internal schematic diagram of a data receiver for MPE-FEC in a mobile broadcasting receiver according to an exemplary embodiment of the present invention. In  FIG. 6  the receiver is equal in structure to the conventional receiver of  FIG. 3 , and a detailed description of the equal parts will not be given herein.  
         [0044]     A datagram extractor  613 , unlike a conventional extractor, uses an interface scheme which immediately transmits an IP datagram to an application controller upon detecting that the IP datagram determined that there is no error by detecting a CRC included in a MPE-FEC section as a result of the MPE-FEC processing. However, if it is determined that there is an error in the burst, the datagram extractor  613  acquires error-corrected IP datagrams by performing a MPE-FEC RS decoding process, so as to selectively transmit the parts untransmitted to the AP chip.  
         [0045]     A Viterbi decoded signal is input to a RS decoder  311  after undergoing a convolutional deinterleaver (not shown), and converted into a TS packet therein. As described in  FIG. 3 , the process of OFDM demodulation, Viterbi decoding, and convolutional deinterleaving is called a “preprocessing process.” The TS packet is input to a checker  312  and the datagram extractor  613 . Then the checker  312  receives TS packets, detects sections of them, and performs CRC check thereon, thereby verifying reliability of IP datagrams which are payloads in the sections. The datagram extractor  613 , before it stores the IP datagram reliability-verified by the CRC check in a buffer  314  which stores the MPE-FEC data, transmits the IP datagram to an application controller  612  via a datagram controller  611 , thereby removing an unnecessary waiting time and reducing a processing time. In addition, in order to correct an error of an error-included section by the CRC, the datagram extractor  613  stores the MPE-FEC data in the buffer  314  for storing the MPE-FEC data, so that the IP datagram part of the error-included section undergoes error or erasure processing by the CRC. Thereafter, a datagram including an error, as a result of CRC check in one burst, is error-corrected by a MPE-FEC RS decoder  315 , and then delivered to the application controller  612  via the datagram controller  611 .  
         [0046]     The datagram controller  611  selects datagrams to be transmitted to the application controller  612 . The datagram controller  611  first transmits IP datagrams with the CRC=‘good’ among the datagrams to be transmitted from the datagram extractor  613  to the application controller  612 , and for an IP datagram part with CRC=‘bad’, the datagram controller  611  receives the output of the MPE-FEC RS decoder  315  and transmits it to the application controller  612 . If one datagram is divided into several sections during its transmission, the datagram controller  611  transmits the sections to the application controller  612  in units of datagrams using a section number “section_number” and a last section number “last_section_number” included in a MPE section header. Herein, because the last section number means the number of sections constituting one datagram and the section number means a position of a received section in the datagram, it is possible to find out the datagram from the section using the section number and the last section number. Therefore, if there is an error-included (“CRC=bad”) section among the sections constituting one datagram as a result of the CRC check, the datagram controller  611  transmits the datagram to the application controller  612  after performing the MPE-FEC decoding thereon using the RS decoder  315 , instead of directly transmitting the datagram to the application controller  612 .  
         [0047]     For example, assume that a burst composed of 10 MPE-FEC sections is received. Also, assume that the MPE-FEC sections are individually allocated numbers 1 to 10 in their received order, and errors have occurred in the 3 rd  and 7 th  sections. In this case, the conventional receiver transmits the sections to the application controller of the mobile broadcasting receiver in the following manner. Here, the receiver stores the sections in the buffer  314 , which is a MPE-FEC memory, error-corrects the sections using the RS decoder, which is a second decoder, and sequentially transmits the sections with section numbers 1 to 10.  
         [0048]     However, the new receiver according to the present invention immediately transmits the CRC=‘good’ sections with section numbers 1, 2, 4, 5, 6, 8, 9 and 10 to the application controller, upon detecting them. The receiver transmits the 3 rd  and 7 th  error correction-required sections to the application controller  612  after error correction using the RS decoder  315 . Therefore, as the signal quality is higher, the amount of data immediately transmitted to the application controller  612  after being decoded in the first RS decoder  311  in the baseband channel chip increases, thereby contributing to a reduction in the time required for transmitting all datagrams to the application controller  612 .  
         [0049]      FIGS. 7 and 8  show two processing timing diagrams for a MPE-FEC processing scheme applied to a mobile broadcasting terminal according to an exemplary embodiment of the present invention.  FIG. 7  illustrates a timing diagram for a CRC=‘good’ channel environment and, conversely,  FIG. 8  illustrates a timing diagram for a CRC=‘bad’ channel environment.  
         [0050]     In duration  701 , as described above and illustrated in  FIG. 7 , the receiver converts an RF signal into a baseband signal and performs an OFDM synchronization process thereon before the burst, in order to receive one burst. In a DVB-H system supporting CA, the receiver should receive an Entitlement Control Message (ECM) before the burst. Therefore, at time  701 , the receiver receives an RF signal, performs an OFDM synchronization process thereon, and receives and decodes an ECM for Conditional Access.  
         [0051]     The receiver receives data transmitted in the burst and performs OFDM modulation thereon in duration  702 , performs Viterbi decoding in duration  703 , and performs an RS decoding process in duration  704 . The time required for this is approximately 10 ms. However, because the new receiver outputs the datagram to the application controller  612  for the CRC=‘good’ data, data is output in duration  707 . In addition, because there is no CRC error in  FIG. 7 , datagrams are directly input to the application controller without being stored in the buffer. Therefore, the duration  707  and the duration  705  are the same time duration. If, however, there is a CRC error, the datagrams should undergo MPE-FEC decoding in duration  706 . Here, because it is assumed in  FIG. 7  that there is no error, the receiver, upon expiration of the duration  707 , can immediately perform audio/video decoding in the application controller  612  without MPE-FEC decoding in the duration  706 , thereby providing the service.  
         [0052]     Therefore, the new receiver in the present invention, compared with the conventional receiver, rapidly delivers the datagrams to the application processor  612 , thereby reducing the total processing time. Particularly, in the good-channel environment where a signal-to-noise ratio (SNR) is high, if the CRC check result is ‘good’ in all sections as shown in  FIG. 7 , the datagrams detected in all sections output from the first RS decoder  311  are delivered to the application controller  612  in their received order, so there is no need to activate the second RS decoder  315 . Therefore, in the conventionally required delay time of “200×N+25” ms except for the 10-ms processing time required until section detection, the 25-ms time for MPE-FEC decoding is not required, and if the CRC check result is ‘good’ after completion of the CRC check in 1-burst duration, the receiver immediately transmits datagrams increasing the data processing time, thereby contributing to a noticeable reduction in the channel switching time. In particular, as the number N of parallel services increases, the reduction effect of the processing time increases, thereby further increasing the reduction effect of the channel switching time.  
         [0053]     For example, assuming that the receiver supports five (5) parallel services per burst, the use of the existing MPE-FEC processing method causes a delay time of about 1 second, but the proposed MPE-FEC processing method in the present invention decreases by about 1 second the channel switching time because it does not need the delay time in the good-channel environment.  
         [0054]      FIG. 8  illustrates the case where the SNR is low (i.e. the number of CRC=‘bad’ sections increases.).  
         [0055]     Duration  801  of  FIG. 8  is equal to the duration  701  of  FIG. 7 , duration  802  is equal to the duration  702 , duration  803  is equal to the duration  703 , and duration  804  is equal to the duration  704 . However, because there are the CRC=‘bad’ sections according to the CRC check result, the receiver should store the CRC=‘bad’ sections and the CRC=‘good’ sections in the buffer  314 , perform an error correction on the stored sections, and then output the resulting sections to the application controller  612 . Therefore, the time  807  required for the outputting datagrams to the application controller  612  is longer than that of  FIG. 7 . For example, if the channel condition is poor, the amount of error-corrected datagrams increases. The present invention provides two processing methods for the case where there are the CRC=‘bad’ sections. One method delivers only the CRC=‘good’ sections to the application controller  612  and performs the A/V MPEG decoding thereon. Another method delivers the CRC=‘good’ sections and the error-corrected datagrams to the application controller  612  and performs the A/V MPEG decoding thereon. In the former method, because it delivers only the CRC=‘good’ sections to the application controller  612 , as the SNR is lower, the number of sections delivered to the application controller  612  decreases, causing a reduction in performance after MPEG decoding. Therefore, this method may suffer from image degradation, but can contribute to a reduction in the channel switching time. However, the latter method can improve the A/V MPEG decoding performance even in the low-SNR environment, because error-corrected datagrams are delivered to the application controller  612  in the baseband channel chip after the CRC=‘good’ sections are first delivered to the application controller  612 .  
         [0056]     For example,  FIG. 8  shows the second exemplary method which can facilitate improvement in the image quality, but increases in the channel switching time compared with the former method. However, compared with the conventional method, this method has the same image quality but can advantageously reduce the channel switching time. In addition, the new method has a sufficient processing time for data transmission to the chip constituting the application controller  612 , thereby reducing the operation speed and thus reducing power consumption. In particular, the new method increases the reduction effect of the channel switching time, as the SNR is higher and the number of parallel services is greater.  
         [0057]      FIG. 9  is a flow diagram illustrating MPE-FEC signal processing in a mobile broadcasting terminal according to an exemplary embodiment of the present invention.  
         [0058]     An RF unit (not shown) of a receiver receives a burst signal in step  900 , wherein m is set to 1 (m=1). Thereafter, an RS decoder  311  of the receiver performs the RS decoding in units of TS packets in step  902 . In step  904 , a checker  312  of the receiver detects an m th  section, checks the CRC thereof, and outputs the CRC result. Based on the CRC check result on the detected m th  section, received from the checker  312 , a datagram extractor  613  of the receiver determines in step  906  whether the CRC check result of the section is ‘good’. If it is determined that the CRC check result is not ‘good’, the datagram extractor  613  proceeds to step  910 . Otherwise, the datagram extractor  613  proceeds to step  908 . In step  908 , the datagram extractor  613  of the receiver transmits a datagram with a section header and CRC excluded therefrom to an application controller  612  via a datagram controller  611 . However, when the datagram extractor  613  proceeds to step  910  because the CRC check result is not ‘good’, the datagram extractor  613  buffers the datagrams in a buffer  314 . Thereafter, the datagram extractor  613  of the receiver determines in step  912  whether the current section is at the end of the burst. If it is determined that the current section is at the end of the burst, i.e. if the current section is an end of the data transmitted by the time slicing technique as described in  FIG. 1 , the datagram extractor  613  proceeds to step  916 . Otherwise, the datagram extractor  613  proceeds to step  914  where it increases the value m by 1 and then repeats the above process from step  904 .  
         [0059]     After proceeding to step  916 , the datagram controller  611  determines whether there is any datagram untransmitted to the application controller  612 , by checking section numbers. If it is determined that there is an untransmitted datagram(s), i.e. if there is data to be decoded by a RS decoder  315  as there is a CRC=‘bad’ section, the datagram controller  611  error-corrects the CRC=‘bad’ datagram using the RS decoder  315  in step  918 , and transmits the untransmitted datagram to the application controller  612  in step  920 . However, there is no datagram untransmitted to the application controller  612 , the application controller  612  ends the routine and waits for the next burst.  
         [0060]     The MPE-FEC processing scheme of the present invention, unlike the conventional scheme of delivering sections in their received order, preferentially delivers a datagram of a CRC=‘good’ section to the application controller  612 . Therefore, for the datagrams delivered to the application controller  612 , there is a need for an additional process of reordering the datagrams. A description thereof will be made below with reference to  FIG. 10 .  
         [0061]     In an upper layer signal processing process, the application controller  612  performs reordering in one datagram taking the order of data included in a Realtime Transport Protocol (RTP) header. Therefore, the application controller  612  has no additional load, even though the proposed MPE-FEC scheme is applied thereto. In particular, because the application controller  612  has a processing delay time that should be secured for synchronization datagrams through which audio and video are transmitted, it is possible to prevent an additional processing delay time by performing the reordering for the time.  
         [0062]      FIG. 10  is a flow diagram illustrating an operation performed in an application controller during MPE-FEC processing in a mobile broadcasting terminal according to an exemplary embodiment of the present invention.  
         [0063]     In step  1000 , an application controller  612  detects an RTP header from a received datagram and detects order of the datagram. Thereafter, in step  1002 , the application controller  612  reorders the datagrams accorder to their orders and stores the reordered datagrams. Because this process is performed depending on the RTP headers, the application controller  612  has no additional processing delay time and/or no additional load as described above. In step  1004 , the application controller  612  sets synchronization. The synchronization setting process matches synchronizations of audio and video data. In step  1006 , the application controller  612  performs MPEG decoding and outputs the decoded data to a corresponding output unit. That is, as for an audio signal, the application controller  612  outputs the audio signal through a speaker (not shown), and as for a video signal, the application controller  612  outputs the video signal through a display device (not shown) such as a monitor or a Liquid Crystal Display (LCD).  
         [0064]     Because the reordering process performed in the application controller  612  is for reordering orders of the error-corrected datagrams, the amount of the error-corrected datagrams noticeably decreases in the higher-SNR environment, thus reducing the amount of datagrams to be reordered.  
         [0065]     As can be understood from the foregoing description, the use of the new MPE-FEC processing scheme in the present invention can reduce the channel switching time at the DVB-H receiver. In particular, the reduction effect of the channel switching time increases, as the SNR is higher and as the number of parallel services is greater. In addition, the number of required calculations decreases in a higher-SNR environment, contributing to a decrease in power consumption of the channel chip. Furthermore, as the proposed adaptive processing technique uses a distributed processing scheme for preferentially transmitting the CRC=‘good’ sections to the application controller, it has a sufficient data processing time, thereby reducing the operation speed and thus reducing power consumption. In addition, the proposed method is equal to the existing method in terms of the demodulation performance, while reducing the channel switching time and the power consumption.  
         [0066]     While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Technology Category: y