KR20070025851A - Frame boundary detection method and apparatus for reed-solomon decoding in a dvb-h receiver and method for decoding multi protocol encapsulation -forward error correction frame using the same - Google Patents

Abstract

A frame boundary detection method and apparatus for Reed-Solomon decoding in a DVB-H(Digital Video Broadcasting-Handheld) receiver and a method for decoding an MPE-FEC frame using the same are provided to recover an IP datagram and detect a frame boundary value to provide a user with broadcast data even when a boundary value of an MPE-FEC frame is not received so that an abnormal operation can be prevented. An MPE-FEC(Multiprotocol Encapsulation-Forward Error Correction) frame decoding method comprises the following steps. A packet identifier included in a received transport stream packet is filtered and broadcast service information is detected. A transport stream packet including section data is detected(1200). A section data type is checked by detecting a table identifier from header information of the received section data. A frame buffering process is performed. A counting process is performed during a time preset in maximum burst duration information(1201). It is detected whether the last MPE-FEC section has been received on the basis of frame boundary information(1202). An error-corrected IP(Internet Protocol) datagram is output using buffered Reed-Solomon data(1210).

Description

FRAME BOUNDARY DETECTION METHOD AND APPARATUS FOR REED-SOLOMON DECODING IN A DVB-H RECEIVER AND METHOD FOR DECODING MULTI PROTOCOL ENCAPSULATION -FORWARD ERROR CORRECTION FRAME USING THE SAME}

1 is a diagram illustrating a data structure of a TS packet in a general DVB-H system.

2 is a diagram for explaining an R-S encoding operation performed at a transmitting end of a general DVB-H system;

3 is a view illustrating in detail the R-S encoding process of FIG. 2 and the transmission process of the MPE section and the MPE-FEC section resulting from the encoding;

4 is a view for explaining a time slicing method for transmitting a TS packet in a transmitter of a general DVB-H system;

5 is a block diagram showing the internal configuration of a transmitter in a typical DVB-H system,

FIG. 6 is a diagram illustrating the structure and field format of an MPE section generated by a typical DVB-H transmitter; FIG.

7 is a diagram illustrating a structure and a field format of an MPE-FEC section generated by a general DVB-H transmitter;

8 is a diagram illustrating a message format of a real time parameter mentioned in FIGS. 6 and 7;

9 is a block diagram showing an internal configuration of a receiver in a DVB-H system according to an embodiment of the present invention;

10 is a block diagram showing an internal configuration of an MPE-FEC frame decoding apparatus according to an embodiment of the present invention;

11A to 11C are flowcharts illustrating a decoding method of an MPE-FEC frame according to an embodiment of the present invention;

12 is a flowchart illustrating an operation of performing R-S decoding when the controller does not receive frame boundary information in step 1136 of FIG. 11C according to an embodiment of the present invention;

13 is a flowchart illustrating an operation for transmitting to a higher layer when a controller does not receive frame boundary information when only a MPE section is transmitted by a transmitter according to an embodiment of the present invention.

The present invention relates to an apparatus and method for receiving a digital broadcast service, and more particularly, to an apparatus and method for performing R-S decoding for receiving a broadcast service in a DVB (Digital Video Broadcastion) -H (Handheld) system.

 In general, a broadcast service is a service provided for the purpose of providing all users with a terminal. Such broadcast services are classified into audio broadcasting services such as radio broadcasting providing only voice, and multimedia broadcasting services including video-oriented broadcasting services such as television providing voice and video services and voice, video and data services. These broadcast services are based on the analog method, and digital broadcasting is being performed according to the rapid development of technology. In addition, the broadcasting service is a method of providing a multimedia service using a multimedia service and a satellite of a wired network that provides high quality and high speed data by wire, away from the method provided based on a conventional transmission tower, and simultaneously uses a wired and satellite. It is evolving in a variety of ways.

One of these methods is spurring commercial services to DMB (Digital Multimedia Broadcasting). This DMB method is based on Digital Audio Broadcasting (DAB) and is based on Eureka-147 (European REserch Coordination Agency progect-147), a technical standard of DAB implemented in Europe.

On the other hand, in Europe, the origin of DAB technology, a group called Digital Video Broadcasting (DVB) is organized for multimedia broadcasting service, and a separate technical standardization work for mobile broadcasting is underway under the name 'DVB-H'. DVB-H (Handheld) is a digital audio broadcasting (DAB) standardization organization for digital TV broadcasting in Europe. It is used for satellite digital TV (DVB-S), digital cable TV (DVB-C), and terrestrial digital TV (DVB-T). It is a broadcasting standard under development.

The DVB Group decided that third-generation mobile communication (UMTS or IMT-2000), terrestrial digital TV, and digital audio broadcasting (DAB) could not realize mass multimedia contents such as movies and broadcasting dramas through mobile terminals. (eXtention), and then more clearly, the name DVB-H, which stands for the concept of 'mobile broadcasting'.

DVB-H is a standard for enhancing mobility in DVB-T, a European digital TV transmission standard, and is an extension of DVB-T in consideration of low power, mobility, and portability of mobile terminals and portable video devices. Thus, most of the physical layer specifications of DVB-H follow the DVB-T specifications and add some additional functions for portable / mobile reception.

The DVB-H system supports additional error correction encoding for Layer 3 Internet Protocol (IP) packets. This additional error correction encoding process is called Multi Protocol Encapsulation-Forward Error Correction (MPE-FEC).

In the DVB-H system, broadcast data is generated as an IP datagram, and an MPE-FEC frame is formed by reed-solomon encoding the IP datagram. Accordingly, the MPE-FEC frame is composed of an MPE section carrying an IP datagram and an MPE-FEC section carrying parity data according to R-S encoding. The MPE section and the MPE-FEC section are carried in a payload of a transport stream (TS) packet, which is a transport unit of a DVB-H system, and transmitted through a physical layer.

1 is a diagram illustrating a data structure of a TS packet in a general DVB-H system. In FIG. 1, reference numeral 100 denotes an IP datagram, and means a packet including a header 102 in which address information of an end to which data is transmitted and a payload 104 carrying broadcast data. Reference numeral 106 shows an MPE section carrying the IP datagram 100 or an MPE-FEC section carrying parity data of the IP datagrams 100. The MPE or MPE-FEC section consists of a header 108 and a payload 110. The header 108 contains information indicating whether the data contained in the payload is an MPE section or an MPE-FEC section. The payload 110 stores parity data of the IP datagram 100 or the IP datagram 100. Reference numeral 112 shows a TS packet in which an MPE section or an MPE-FEC section 106 is stored. Here, one TS packet 112 may include multiple MPE sections or MPE-FEC sections 106, or one MPE section or MPE-FEC sections 106 may be transmitted through multiple TS packets 112. . If a packet identifier (PID) indicates a packet for transmitting an MPE section or an MPE-FEC section to the header 114 of the TS packet 112, the receiving side transmits an MPE section or an MPE-through a payload 116. If the FEC section 106 is deemed received and the PID of the header 114 does not indicate a packet carrying an MPE section or an MPE-FEC section, the payload 116 contains program specific information and service information (Program Specific). Information / Service Information (PSI / SI) (hereinafter referred to as "broadcast service information") may be found.

In the DVB-H system, the MPE-FEC frame is formed by R-S encoding the IP datagrams 100 as a result of the MPE-FEC process. The data constituting the MPE-FEC frame are reconstructed in a transmission unit called a section, and the IP datagram 100 is reconstructed into an MPE section by adding a section header 108 and cyclic redundancy checking (CRC) 32 bits. Parity data generated through RS encoding is also reconstructed into an MPE-FEC section by adding a section header and CRC 32 bits. The section header 108 includes information necessary for MPE-FEC decoding and time slicing, which will be described later, and is located at the beginning of the section. CRC 32 bits are located later in the section. These sections are ultimately carried in the payload 116 portion of the Transport Stream (TS) packet 112 and transmitted over the physical layer.

Hereinafter, a process of generating an MPE section or an MPE-FEC section at the transmitter will be described with reference to FIG. 2.

2 is a diagram for explaining an R-S encoding operation performed at a transmitting end of a general DVB-H system. In general, the DVH-B transmitter performs R-S encoding once in the physical layer and the link layer. The R-S encoding described in FIG. 2 is performed in the link layer.

In FIG. 2, reference numeral 200 denotes the horizontal direction of the MPE-FEC frame in the DVB-H system, and reference numeral 202 denotes the length of the vertical direction of the MPE-FEC frame. In the horizontal direction, that is, the column 200 is composed of 255 bytes, and the left area of the broadcast data table area in which the MPE section including the IP datagram 100, which is broadcast data, is stored. Table region 204 and a horizontal length of 191 bytes, and the right region is an RS data table region 206 in which RS data or parity data generated as a result of RS encoding broadcast data stored in the broadcast data table region 204 is stored. ) Is 64 bytes wide. On the other hand, the vertical direction, ie, the row 202 is variable and may be up to 1024 rows long.

As shown in FIG. 2, N IP datagrams 100 are stored in the vertical direction in the broadcast data table region 204. If the broadcast data table region 204 is configured to store IP datagrams from 1 to N as shown in FIG. If not, the remaining space is filled with zero padding ("zero") as shown by reference numeral 208 to fill all of the broadcast data table area 204. When the result of IP datagram or zero padding fills the broadcast data table area 204 with “0”, RS encoding is performed in a horizontal direction, and the parity resulting from the RS encoding is performed. Data is filled in the RS data table area 206 in the horizontal direction as shown in FIG.

3A is a conceptual diagram illustrating a process of generating an MPE-FEC frame in a DVB-H transmitter.

The MPE-FEC frame illustrated in FIG. 3A has a horizontal direction of 255 bytes (200) in the horizontal direction and a maximum of 1024 rows (202) in the vertical direction as described in FIG. As mentioned above, several conditions exist. First, the IP datagrams 300, 302, 304, and 306 are filled in the vertical direction. The broadcast data table area should be filled for R-S encoding. Accordingly, if the IP datagrams 300, 302, 304, and 306 are not all filled, padding padding with "0" should be performed as shown by reference numeral 308.

In FIG. 3A, R-S codewords are calculated in a horizontal direction in the broadcast data table area, and R-S columns 310 and 312 are formed in a vertical direction.

Row (k) is optional and may have a length up to 1024 rows.

In FIG. 3A, the R-S encoding is performed in the horizontal direction by the portion separated by a dotted line, and the result is stored in the R-S data table area. The MPE-FEC frame generated as described above is stored in a memory of a transmitter, not shown.

The broadcast data table area and the R-S data table area of the MPE-FEC frame stored in the memory are generated and transmitted to the MPE section and the MPE-FEC section in the vertical direction, respectively.

That is, IP datagram 1 300 is MPE section 1 314, IP datagram 2 302, and part of IP datagram 3 304 in the second column is MPE section 2 316, IP stored in the third column. Part of datagram 3 (304) and part of IP datagram 4 (306) in the third column are created by MPE section 3 (318), and finally, IP datagram 4 (306) in the fourth column by MPE section 4 (320). do. Here, the zero padding portion 308 is not included in the generation of the MPE section, but is just a portion filled with "0" to perform R-S encoding for generating R-S data. At the receiving end, the zero padded portion is filled with "0" and the IP datagram is output through R-S decoding.

In addition, the R-S data stored in the R-S data table is also extracted in the vertical direction, respectively, and generated in the MPE-FEC section 1 322 and the MPE-FEC section 2 324.

3B is a conceptual diagram illustrating a process of transmitting the MPE-FEC frame generated in FIG. 3A. The MPE sections 314, 316, 318, 320 and MPE-FEC sections 322, 324 generated as in FIG. 3A are to be transmitted through a modulator not shown, and the order of MPE sections 1 314 to MPE is as follows. Are transmitted in FEC section 2 324 order.

The receiver performs R-S decoding based on the parity information of the received IP datagram to restore the failed IP datagram. That is, if an error occurs in reference numeral 326, the receiver recovers the error based on the R-S data included in the received MPE-FEC sections 1 322 and 2 324 as shown by reference numeral 328.

FIG. 4 is a diagram for describing a time slicing method for transmitting a TS packet in a transmitter of a general DVB-H system.

A general transmitter transmits data with a constant bandwidth as shown by reference numeral 406, but the transmitter of the DVB-H system transmits a burst, which is a bundle of predetermined data, as indicated by reference numeral 410. FIG.

In addition, DVB-H systems support time slicing to reduce receiver power consumption. Time slicing refers to a method of transmitting data in burst form. That is, the data to be transmitted during the entire time interval 400 is transmitted only during the burst period by increasing the data rate. Accordingly, the entire time period 400 is divided into a burst period 402 in which data is transmitted and an off time interval 404 in which no data is transmitted.

In FIG. 4, reference numeral 406 denotes an average bandwidth when a general stream is transmitted without time slicing, and reference numeral 408 denotes a burst bandwidth transmitted by a transmitting end of a DVB-H system. it means. In addition, as described above, the entire time interval 400 means a period from the time when the transmission of the current burst starts to the time when the transmission of the next burst starts, and no data is transmitted with the period 402 in which the burst is transmitted. Off-Time 404 section. The burst duration 402 denotes a start period and an end period in which a burst is transmitted, and there is an off time in which a transport packet is not transmitted between burst periods. In addition, one MPE-FEC frame may be transmitted in one burst size 410.

FIG. 5 is a block diagram illustrating an internal configuration of a transmitter in a general DVB-H system. The characteristics of the DVB-H system illustrated in FIGS. 1 to 4 transmit IP data as broadcast data to a plurality of users. RS data (or RS parity data: in the present invention, two terms are used in the same sense) is transmitted together for error correction of broadcast data.

In FIG. 5, the MPE-FEC encoder 502 generates an MPE section including an IP datagram to transmit an IP datagram transmitted as broadcast data in section units, and forward error correction (FEC) of the MPE section. Create an MPE-FEC section containing parity data for correction. The parity data is generated through RS encoding, which is a well-known external encoding technique. The output of the MPE-FEC encoder 501 is delivered to a time slicing processor 503 to perform time division processing for transmitting broadcast data in bursts. As described above, one MPE-FEC frame is transmitted through one burst period. On the other hand, IP datagrams that have undergone time slicing are processed through HP (High Priority) streams, and then serialized / parallel according to the modulation order and the hierarchical or non-hierarchical transmission mode. The signal may be converted into a signal.

In FIG. 5, the bit interleaver 505 and the symbol interleaver 507 perform interleaving in units of bits and interleaving in units of symbols, respectively, to distribute transmission errors. The interleaved signal is symbol-mapped according to a predetermined modulation scheme such as QPSK, 16 QAM, or 64 QAM through a symbol mapper 509, and transferred to an inverse fast fourier transform (IFFT) unit 511. The IFFT unit 511 converts a signal in a frequency domain into a signal in a time domain, and outputs a IFFT processed signal by inserting a guard interval through a guard interval inserter (not shown) to provide a baseband OFDM symbol signal. Is generated. The OFDM symbol is pulse-formed by a digital baseband filter and then modulated by the RF modulator 513 and finally transmitted through the antenna 515 as a TS packet, which is a DVB-H signal.

FIG. 6 shows the structure and field format of an MPE section generated by a typical DVB-H transmitter. As described above with reference to FIGS. 1 and 3, the MPE section extracts an IP datagram 600 from the broadcast data table region 204 of the MPE-FEC frame in a vertical direction and a section header 602. ) And Cyclic Redundancy Checking (CRC) 32 bit 604 are added to reconstruct the MPE section. Reference numeral 606 shows the message format of the MPE section including the above-mentioned section header 602, broadcast data IP datagram 602, CRC bit 604. The receiving end detects the reference numeral 608 "0x3eb" and knows that the received data is an MPE section.

Reference numeral 610 is a real time parameter. When the transmitting end sends an MPE section without RS encoding and the receiving end confirms that the MPE-FEC frame is normally received, the IP datagram is received. It includes frame boundary (Frame_boundary) information indicating a time point for transmission to a higher layer. The real time parameter will be described with reference to FIG. 8 below.

7 illustrates the structure and field format of an MPE-FEC section generated by a general DVB-H transmitter.

Parity data (R-S data) 700 generated through R-S encoding of the MPE section is also reconstructed into an MPE-FEC section by adding a section header 702 and a CRC 32 bit 704. As described above, the section header 708 includes information necessary for MPE-FEC decoding and time slicing described later, and is located at the beginning of the section. CRC 32 bit 704 is located later in the section. These sections are ultimately carried in the payload 116 portion of the Transport Stream (TS) packet 112 and transmitted over the physical layer.

Reference numeral 706 illustrates the message format of the MPE-FEC section including the above-mentioned section header 702, R-S data 702, and CRC bit 704. The receiving end detects the reference numeral 708 "0x78b" and knows that the received data is the MPE-FEC section.

Reference numeral 710 denotes a real time parameter. When the transmitting end sends an MPE section and an MPE-FEC section after performing RS encoding, the receiving end requires MPE- to perform RS decoding on the received MPE section. The frame boundary information (Frame_boundary) of the FEC frame and the table boundary information (Table_boundary) of the broadcast data table region are included, which will be described with reference to FIG. 8 below.

FIG. 8 illustrates the message format of the real time parameter mentioned in FIGS. 6 and 7.

Delta-t (delta-t) 800 indicates the time when the next MPE-FEC frame is transmitted, that is, the burst period starts.

Table boundary information (802) informs whether the MPE section generated at the transmitting end of the DVH-B system is the last MPE section in the broadcast data table area. If the table boundary information 802 is set to "1", it means that the currently transmitted MPE section is the last section of the broadcast data table area in the MPE-FEC frame.

Frame boundary information (804) informs whether the section created at the transmitting end of the DVB-H system is the last MPE-FEC section of the MPE-FEC frame. If the frame boundary information 804 is set to "1", it means that the currently transmitted MPE-FEC section is the last MPE-FEC section of the MPE-FEC frame.

If the transmitter does not perform R-S encoding, the table boundary information 802 and the frame boundary information 804 have an equivalent meaning. Therefore, when only the MPE section which does not perform R-S encoding is sent by the transmitter, the receiver calculates a time point for transmitting the received MPE section to the higher layer based on the table boundary information 802.

When the receiving end determines that the MPE-FEC frame is normally received based on the CRC check based on the frame boundary information 804, the receiving end may know a time point for transmitting the IP datagram to the higher layer.

That is, a receiver of a typical DVB-H system needs to extract a section from a TS packet in order to recover a pure IP datagram from a TS packet received through a physical layer. The payloads of each section must be reconstructed into MPE-FEC frames and can be restored to an IP datagram when the R-S decoding process is performed.

As described above, the transmitter of the DVB-H system transmits the MPE-FEC frame only to the burst section 402 by using a time slicing method. If the transmitting end performs R-S encoding on the broadcast data table region 204 and transmits the data, the receiving end performs decoding on the received MPE-FEC frame during the off time 404. On the other hand, if the transmitting end transmits the MPE section that is the broadcast data table region 204 without performing RS encoding, the receiving end transmits the MPE section of the received broadcast data table region 204 to a higher layer during the off time 404. In this case, the broadcast service can be provided to the user.

Therefore, in order to start the R-S decoding process, it must be determined that the receiver has completed reconstruction of the MPE-FEC frame. Since the last section constituting the MPE-FEC frame has information that the current section is the last section in the section header as described above with reference to FIG. 8, it can be determined that the MPE-FEC frame has been reconstructed at the receiver with this information.

However, if the last section constituting the frame is not properly received, that is, if the table boundary information 800 or the frame boundary information 802 is not received, it is impossible to determine whether the MPE-FEC frame has been reconstructed. As a result, the receiving end cannot perform R-S decoding (decoding), and thus performs an abnormal operation in which the receiver stays in a standby state without starting R-S decoding. That is, when the receiving end does not receive the frame boundary information 802 of the real time parameter 702 described with reference to FIG. 7, there is a problem in that R-S decoding cannot be performed.

In addition, when the receiving end receives the MPE section that is not R-S coded, if the table boundary information 800 is not received, a problem arises in that it is not possible to know when to deliver the received MPE section to the upper layer.

An object of the present invention is to provide a decoding method of an MPE-FEC frame that receives a TS packet in a DVB-H system and restores an IP datagram as broadcast data.

Another object of the present invention is to provide a method for providing broadcast data to a user even if a receiver of a DVB-H system does not receive a boundary value of an MPE-FEC frame.

Another object of the present invention is to provide a method and apparatus for detecting a frame boundary even if a receiver of a DVB-H system does not detect a frame boundary of an MPE-FEC frame.

In the present invention for achieving the above object, a method for decoding an MPE-FEC frame, the broadcast service by filtering the packet identifier information (Packet Identifier: PID) included in the transport stream packet received during the burst period over the wireless network Detecting information (PSI / SI), filtering packet identifier information included in a transport stream packet received during a burst period through a wireless network, and detecting a transport stream packet including section data; Detecting a table ID from the header information of the received section data to confirm the type of the section data, and if the section data is identified as the MPE-FEC section, Reed-Solomon data and MPE extracted from the MPE-FEC section Frame buffering the IP datagram of the section; and a burst duration timer is assigned to the broadcast service information. Counting a predetermined time in the maximum burst duration information included; detecting whether the last MPE-FEC section is received based on frame boundary information in the header information of the section data; and not receiving the last MPE-FEC section. Otherwise, checking whether the burst duration timer has counted the preset time, and when the burst duration timer has counted the preset time, correcting an error using the buffered Reed-Solomon data. Outputting the generated IP datagram.

The apparatus of the present invention for detecting the boundary of the MPE-FEC frame, which is an object of the present invention described above, comprises: a buffer for dividing and storing an MPE section and an MPE-FEC section extracted from a transport stream packet received through a wireless network; A Reed-Solomon decoder which performs error correction of the IP datagram of the MPE section by using the Reed-Solomon data included in the MPE-FEC section, and is included in the broadcast service information included in the header of the packet of the transport stream. Operating the burst duration timer based on a burst duration timer that counts time by a time set in the maximum burst duration information, and information on a start time of a current burst duration included in a previously received MPE-FEC frame; If the MPE-FEC section is not the last section, the burst interval timer is set by the preset time in the maximum burst interval information. Check that coefficient between, and, if the count by the time the burst interval timer is the preset, the lead-in and a controller for decoding control of the IP datagram received to control the Solomon decoder.

The method of the present invention for detecting a boundary of an MPE-FEC frame, which is an object of the present invention described above, is a process of frame buffering an MPE section and an MPE-FEC section extracted from a transport stream packet received during a burst period through a wireless network. And driving a burst interval timer for counting time between burst sections based on information included in a section header extracted from a previously received transport stream packet, and wherein the extracted MPE-FEC section is the last section. If the MPE-FEC section is not the last section, if the burst section timer counts the time by the burst section beforehand, and if the counted time is the burst section, Performing Reed-Solomon decoding and transmitting the decoded IP datagram to a higher layer.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same components in the figures represent the same numerals wherever possible. Specific details are set forth below, which are provided to aid a more general understanding of the present invention. In describing the present invention, when it is determined that description of related known functions or configurations may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

9 is a block diagram showing the internal configuration of a receiver in a DVB-H system according to an embodiment of the present invention.

In FIG. 9, the TS packets received from the wireless network are received by the RF demodulator 903 through the antenna 901, and the OFDM symbols of the TS packets which are frequency down-converted and converted into digital signals by the RF demodulator 903 are FFT ( Fast Fourier Transform (905) is used to transform the signal in the frequency domain. The symbol demapper 907 symbol demaps the received signal corresponding to a predetermined modulation scheme such as QPSK, 16 QAM, or 64 QAM, and a symbol deinterleaver 909 and a bit deinterleaver. Deinterleaver) 911 restores the original signal by performing symbol interleaving and bit interleaving. The time slicing processor 913 repeats the switching operation to receive a TS packet including an MPE-FEC frame or a TS packet including only an MPE frame for each predetermined burst period. Here, the burst section may be included in the header of each MPE section and the MPE-FEC section to receive delta t information 800 indicating the start time of the next burst section.

In FIG. 9, the MPE-FEC decoder 915 performs packet identifier (PID) filtering so that a packet identifier (PID) of an MPE or MPE-FEC section is obtained from header information of a TS packet. If the packet is transmitted, it is assumed that the MPE section or the MPE-FEC section has been received. Otherwise, the program specific information and service information (PSI / SI) (hereinafter, "Broadcast service information") to receive service information related to broadcast reception such as time slicing and whether MPE-FEC is applied. Meanwhile, the MPE-FEC decoder 915 receiving the broadcast service information (PSI / SI) distinguishes the IP datagram of the MPE section constituting the MPE-FEC frame from the received TS packet and the parity data of the MPE-FEC section. Each is stored in the internal data buffer application data table region and the RS data table region, and RS decoding is performed to restore the original broadcast data.

FIG. 10 is a block diagram showing an internal configuration of an MPE-FEC frame decoding apparatus according to an embodiment of the present invention, which shows the configuration of the MPE-FEC decoder 915 of FIG.

The apparatus of FIG. 10 includes a buffer 1010 for temporarily storing the IP datagram of the MPE section extracted from the received TS packet and the parity data of the MPE-FEC section, and correcting an error of the IP datagram using the parity data. The RS decoder 1030 and the broadcast service information (PSI / SI) information transmitted from the transmitter through the physical layer are analyzed to confirm whether the MPE-FEC is applied, as well as the MPE section and the MPE-FEC section. Extract the IP datagram and the parity data from each other and store them in the buffer 1010, and include them in the real time parameter shown in FIG. 8 based on the delta t (800) information indicating when the next burst section starts. The low burst period timer 1070 controls the timing at which the maximum burst period to be described later is counted, and performs overall operation of RS decoding the IP datagram through the RS decoder 1030. Which it is configured by a controller (1050).

In FIG. 10, the buffer 1010 distinguishes between a circular buffer 1011 for performing CRC on an MPE section and an MPE-FEC section, and an IP datagram of an MPE section and parity data of an MPE-FEC section. And a frame buffer 1013 for storing and performing RS decoding, and an erasure buffer 1015 for marking reliability information according to the CRC result.

When the TS packet is received, the controller 1050 first analyzes broadcast service information (PSI / SI) information to determine whether the MPE-FEC is applied and then removes the header information from the received TS packet. A FEC section is stored in the circular buffer 1011 to perform CRC.

If the CRC result is 'GOOD', the controller 1050 checks the header information of the corresponding section data, and the payload (IP datagram) of the MPE section is stored in the broadcast data table area of the frame buffer 1013. The payload (parity data) of the FEC section is stored in the RS data table area of the frame buffer 1013. In addition, the controller 1050 marks whether the IP datagram and the parity data are normally received according to the CRC result as reliability information in the erasure buffer 1015, and the reception error is generated through the RS decoder 1030. The RS is decoded using the parity data, and the error is corrected and output to the upper layer.

The controller 1050 skips the RS decoding operation when reliability information is marked in all regions of the erasure buffer 1015 (that is, when all IP datagrams of an MPE-FEC frame are normally received). In addition, the controller 1050 controls the burst interval timer to prevent the user from receiving frame boundary information or table boundary information so as not to know when to perform R-S decoding or when to transfer the received MPE section to a higher layer. At this time, the controller 1050 transmits the start time of the next burst section to the burst section timer 1070 based on the delta t800 information of the real time parameter described above, and the burst section timer 1070 is the delta t. Based on the information, it is possible to know when to count a predetermined time.

In addition, the controller 1050 indicates a time for the burst duration timer 1070 to count based on the maximum burst duration information (max_burst_duration) described in <Table 1> included in the broadcast service information, and the burst duration timer ( If 1070 counts the time to count and counts a predetermined time, the result is output to the controller 1050, or the controller 1050 periodically measures the value counted by the burst duration timer 1070, It can be seen whether the burst section has ended.

Accordingly, the controller 1050 transmits the received IP datagram to the upper layer at the time of controlling the R-S decoder for R-S decoding based on the value.

Here, the maximum burst duration information refers to the maximum size of the burst duration transmitted when the MPE-FEC frame is transmitted by the time slicing scheme in the DVB-H system, and the burst duration timer 1070 is received from the controller in the previous burst duration. The maximum burst duration max_burst_duration is counted from the start of the burst duration indicated by the delta t (800) information.

The burst duration timer 1070 is a timer that operates only during the burst duration 402 for transmitting the MPE-FEC frame at the transmitting end of the DVB-H system. That is, as described above, the burst period timer 1070 starts to receive the MPE-FEC frame transmitted by the transmitter under the control of the controller 1050 and simultaneously counts the burst period 402. The controller 1050 may inform the controller 1050 of the end time of the burst period 402, and the controller 1050 determines the end time of the burst period 402 by checking the time when the count of the burst period timer 1070 ends. Able to know. Here, the time point at which the burst period timer 1070 starts counting the burst period may be known as delta t800 information included in a real time parameter of a previous MPE-FEC frame, and the controller 1050 may determine the delta time. The t (800) information informs the start time of counting the burst period.

When the burst interval timer 1070 counts a predetermined time, the controller 1050 may know when to decode the R-S or transmit the received IP datagram to the higher layer based on the burst time timer 1070.

Here, a brief description will be given of how the burst period timer 1070 counts the burst period. If the maximum burst section max_burst_duration described in Table 1 is 30 seconds, the burst section timer 1070 counts 30 seconds and outputs a predetermined signal at a predetermined time point. At this time, if the burst interval timer 1070 down counts the 30 seconds, "0" will be a predetermined time. On the other hand, if the burst interval timer 1070 up counts, "60" will be a predetermined time.

The burst interval timer 1070 may transmit a time point for counting the predetermined time to the controller 1050, and the controller 1050 outputs the predetermined time "0" or "60" by the burst interval timer 1070. By periodically checking the time point, it is possible to know whether or not the burst period has ended. In the exemplary embodiment of the present invention, only the down count and the up count are given, but there may be a method of outputting the end point of the burst period in another manner.

 In this case, the controller 1050 sets a time for the burst duration timer 1070 to count, referring to the maximum burst duration (max_burst_duration) information which is one of the received PSI / SI information included in the TS packet of the transmitter.

If the last section is properly received and the frame threshold field is set to '1', the controller 1050 causes the RS decoder 1030 to perform RS decoding at the same time that frame buffering is terminated in the frame buffer 1013. If not, the RS decoder 1030 assumes that the reception of the MPE-FEC frame is completed at the moment when the burst period timer 1070 counts the time of the burst period and outputs "0". Control or transmit the received MPE section to a higher layer.

Accordingly, the controller 1050 controls RS decoding or RS encoding at the time when the burst duration timer 1070 becomes “0” even when the table boundary 800 information frame boundary 802 information is not received. MPE sections that are not present can be sent to higher layers. At this time, it is described in descriptor information for time slicing and FEC execution included in the PSI / SI information, which is shown in Table 1 below.

Syntax Number of bits Identifier time_slice_fec_identifier_descriptor () { descriptor_tag 6  uimsbf descriptor_length 8  uimsbf time_slicing One  bslbf mpe_fec 2  uimsbf reserved_for_future_use 2  bslbf frame_size 3  uimsbf max_burst_duration 8  uimsbf max_average_rate 4  uimsbf time_slice_fec_id 4  uimsbf for (i = 0; i <N; i ++) { id_selector_byte 8  bslbf } }

Hereinafter, the MPE-FEC frame decoding operation of the present invention performed by the MPE-FEC frame decoding apparatus will be described in more detail with reference to FIGS. 11 to 12.

11A to 11C are flowcharts showing in detail a method of decoding an MPE-FEC frame according to an embodiment of the present invention.

In operation 1100 of FIG. 11A, the controller 1050 of FIG. 10 receives a TS packet from a physical layer, and performs PID filtering on the TS packet received in operation 1102. If it is determined that the MPE PID of the TS packet carrying the MPE section or the MPE-FEC section has not been detected as a result of the PID filtering, in step 1104, the controller 1050 transmits the corresponding TS packet to broadcast service information (PSI / SI). The packet is regarded as a packet, and the broadcast service information (PSI / SI) is analyzed to determine whether time slicing and MPE-FEC are applied. In operation 1100, the controller 1050 receives the next TS packet, and when the MPE PID is detected from the received TS packet, considers the TS packet as a TS packet including an MPE section or an MPE-FEC section. Proceed to step 1106.

In step 1106, when the MPE-FEC is not applied using the analysis result of the broadcast service information (PSI / SI) in step 1104, the controller 1050 proceeds to step 1108 to receive only the MPE section from the corresponding TS packet. Perform. If it is determined in step 1106 that the MPE-FEC is applied, the controller 1050 proceeds to step 1110 to remove the 4-byte header portion from the TS packet and insert the 184-byte payload portion into the circular buffer 1011 of FIG. 10. Store sequentially in units. The purpose of the circular buffering is to perform CRC on the currently received MPE section or MPE-FEC section and receive until the payload of the section consisting of IP datagram or parity data is delivered to the frame buffer 1013. Is to store the data. When the last address of the circular buffer 1011 is filled with data, the next storage location is address zero.

In addition, in step 1110, the controller 1050 checks the start and end of the MPE section or the MPE-FEC section transmitted in the payload of the TS packet, and performs RS decoding on the MPE-FEC frames configured by the sections. In order to obtain reliability information, a CRC check is performed each time a table ID (table_id) to be described later is detected. This process will be referred to as section detection. The MPE section or the entire MPE-FEC section is transmitted, for example, with 32 bits of CRC data appended to the end of each section. In the present invention, when the CRC 'GOOD' occurs, the controller 1050 considers that at least one MPE section or MPE-FEC section exists in the test section that generated the CRC 'GOOD' and the MPE-FEC frame from the header information of the section. Extract information needed for decoding.

Table 2 below shows information required in a decoding process of an MPE-FEC frame among header information extracted from an MPE section or an MPE-FEC section.

Header information Contents table_id  Indicates the type of MPE section or MPE-FEC section section_length  Indicates the section length in bytes from the fourth byte of the section to the end of the section containing CRC 32 bits. padding_columns  Indicates the number of zero-padded columns in the broadcast data table area of the MPE-FEC frame (has a value between 0 and 190) table_boundary  Indicates that the current section is the last section in the broadcast data table area or R-S data table area of the MPE-FEC frame (when set to '1'). address  Indicates the byte position occupied by the first byte of the payload of the currently received section in each region of the MPE-FEC frame.

In this embodiment, the controller 1050 includes at least one CRC checker (not shown) to perform the CRC check as described above. The controller 1050 may perform multiple CRC checks by allocating a new CRC checker every time a table ID (table_id) is detected until the CRC check is 'GOOD'. The controller 1050 of FIG. 10 extracts the header information of the section data detected in step 1110, and then the CRC test section of the CRC checker that generates the CRC 'GOOD', and the section length of the header information of <Table 2>. section_length) is compared to finally confirm that the section is normally received when the section length and the CRC check interval coincide, and this operation is performed to perform section detection more accurately and may be selectively performed.

When the section detection is completed according to the step 1110, the controller 1050 reads the table ID table_id of Table 2 from the header information of the section detected in the step 1112, so that the detected section is the MPE section or the MPE-FEC. Check which section it is. If the MPE section is identified in step 1112, the controller 1050 proceeds to step 1114 of FIG. 11B and removes the header information and the CRC bits from the MPE section. Then, the controller 1050 removes the header information and the CRC bits from the MPE section. Frame buffer IP datagrams. Since the IP datagram frame-buffered in step 1114 is reliable data that has undergone CRC checking, the controller 1050 marks reliability information about bytes of the corresponding IP datagram in the erasure buffer 1015 (step 1116). Marking).

On the other hand, after marking reliability information in the erasure buffer 1015 according to step 1116, the controller 1050 inquires table boundary information from the header information of the corresponding MPE section in step 1118 to display the currently received MPE section. Verify that it is the last MPE section that fills the application data table region. The controller 1050 determines that the currently received MPE section is not the last MPE section when the table boundary information is set to '0', for example, and proceeds to step 1122, where the end of the MPE section is the end of the TS packet. Check if it matches with. If the end of the MPE section coincides with the end of the TS packet as a result of checking in step 1122, the controller 1050 proceeds to step 1100 to receive the next TS packet. The next MPE section or MPE-FEC section from the detected TS packet.

In step 1118, when the table boundary information (table_boundary) is set to '1', the controller 1050 determines the current MPE section as the last MPE section. In step 1120, the controller 1050 inquires the reliability information of the erasure buffer 1015. It is checked whether reliability information is marked for all IP datagrams in the received application data table.

If the reliability information is marked for all IP datagrams as a result of checking in step 1120, all IP datagrams in the broadcast data table area are normally received. In this case, the controller 1050 proceeds to step 1124 to correct errors. RS decoding is omitted, and IP datagrams of the frame buffer 1013 are output to the upper layer as they are. On the other hand, if the reliability information is not marked even in at least one IP datagram in the broadcast data table region as a result of step 1120, proceed to step 1100 through step 1122 to receive the next TS packet or step 1112. Performs an operation of receiving an MPE-FEC section for RS decoding.

According to the operation as described above, the MPE-FEC frame decoding apparatus of the present invention receives the MPE section, and the process of performing R-S decoding by receiving the MPE-FEC section with reference to FIG. 11C will be described in detail.

First, in step 1112 of FIG. 11A, the controller 1050 inquires the table ID (table_id) of the <Table 2> from the header information of the section, and when the section detected in step 1110 corresponds to the MPE-FEC section, 1126 of FIG. 11C. In step S, the padding column number information padding_columns is queried from the header information of the MPE-FEC section, and the portion of the broadcasting data table area to be filled with '0' is checked. That is, the broadcast data table area of the two areas of the MPE-FEC frame may be transmitted without being filled with all IP datagrams at the transmitting side. In this case, the unfilled broadcast data table area is RS coded instead of filled with '0' bytes (hereinafter referred to as "zero padding"), and no actual transmission is performed.

Therefore, in order to correctly perform decoding of the MPE-FEC frame at the receiver, zero padding of a non-transmitted padding column portion must be performed before RS decoding. The number of zero padded portions is indicated in units of columns, and the controller 1050 inquires the padding column number information padding_columns and performs zero padding. The padding column processing in the controller 1050 is divided into two cases according to the normal reception of the last MPE section as in step 1128. The first is a case where the IP datagram of the last MPE section transmitted by the sender is properly received, and the second is a case where the IP datagram of the last MPE section is not properly received.

In the first case, the controller 1050 zero-pads the remaining area of the broadcast data table area after the last MPE section in step 1130 and marks reliability information at the position of the corresponding erasure buffer 1015 in step 1134. . On the other hand, in the second case, since the last MPE section is not properly received and it is not known exactly which byte should be started with zero padding, the controller 1050 proceeds to step 1132 except for the unreceived portion. Only zero bytes are padded corresponding to the number of padding columns indicated by the information padding_columns, and the zero padded portion is marked as reliability information.

In the present embodiment, the eraser buffer 1015 of FIG. 10 is initially set to unreliable bytes (unreliable bytes) where reliability information is not marked and the entire area is a non-shaded area. Therefore, a separate reliability information marking operation is not required for untrusted bytes whose CRC result is not 'GOOD'.

Meanwhile, when padding column processing and reliability information marking according to steps 1126 to 1132 are performed on the currently received MPE-FEC section or when padding column number information (padding_columns) is not checked in step 1126, the controller 1050 is 1134. In step 1, parity data is extracted from the MPE-FEC section, frame buffering of the RS data table is performed, and reliability information of the RS data table region is marked in step 1138 using the CRC result of step 1110.

Thereafter, the controller 1050 controls the R-S decoder 1030 to perform R-S decoding on the broadcast data table region by using parity data of the R-S data table region in step 1140. After the R-S decoding is performed in step 1140, the IP datagrams in which the error is corrected are output to the upper layer in step 1142.

12 is a flowchart illustrating an operation of performing R-S decoding when the controller 1050 does not receive the frame boundary information 802 in step 1136 of FIG. 11C according to an embodiment of the present invention. That is, a flowchart illustrating the operation of the receiver when the last MPE FEC section has not been received.

Since operations of the receiver of the DVB-H system have been described in detail with reference to FIG. 11, FIG. 12 briefly illustrates the operation of the receiver.

In FIG. 12, a case where the transmitting end receives an MPE-FEC frame including an MPE section and an MPR-FEC section will be described as an example.

First, in step 1200, the controller 1050 receives the MPE-FEC section from the transport stream packet transmitted by the transmitter, and in step 1201, the burst period from the moment when the MPE-FEC frame is received, that is, the burst period starts. The timer 1070 is operated. At this time, if the MPE-FEC section is received, it is assumed that all MPE sections have already been received. This is because the transmitting end does not transmit only the MPE-FEC section, and as described in FIG. 3B, the MPE section is transmitted before the MPE-FEC section.

In step 1202, it is determined whether the received MPE-FEC section is the last section. At this time, the controller 1050 checks table boundary information (table_boundary) as described above with reference to FIG. 11 to determine whether the corresponding MPE-FEC section is the last MPE-FEC section that fills the R-S data table. If the MPE-FEC section is the last section, the flow proceeds to step 1204 to perform a CRC check on the frame region to mark reliability information. On the other hand, if the last MPE-FEC section has not been received in step 1202, the controller 1050 proceeds to step 1206 and checks whether the burst duration timer 1070 counts a predetermined time "0". On the other hand, in the embodiment of the present invention in step 1206 has been described as the controller 1050 checks whether the burst interval timer 1070 has counted a predetermined time, the controller 1050 does not check, burst duration timer 1070 ) May count a predetermined time and output the result to the controller 105.

When the controller 105 checks that the burst duration timer 1070 has counted a predetermined time in step 1206, the controller 105 determines that all MPE-FEC frames have been received, and proceeds to step 1204. On the other hand, if the controller 105 checks that the burst duration timer 1070 has not counted the predetermined time in step 1206, the controller 105 proceeds to step 1200 to continue receiving the MPE-FEC section.

In operation 1208, the controller 1050 performs R-S decoding on the MPE section received through the R-S decoder 1030. However, if all reliability information is marked for the broadcast data region of the MPE section in step 1206 (that is, if all IP datagrams of the MPE-FEC frame are normally received), step 1210 is not performed. Proceed and send the IP datagram to the upper layer.

FIG. 13 is a flowchart illustrating an operation for transmitting to a higher layer when the controller 105 does not receive the frame boundary information 802 when the transmitting end transmits only the MPE section according to an embodiment of the present invention. That is, when the last MPE section is not received, an operation for transmitting the received MPE section to the upper layer will be described.

In step 1300, the controller 1050 receives the MPE section from the transport stream packet transmitted by the transmitter, and operates the burst period timer 1070 from the moment of receiving the MPE section in step 1302, that is, at the start of the burst period. Let's do it.

In step 1304 it is determined whether the received MPE section is the last section. At this time, the controller 1050 queries the table boundary information (table_boundary) as described above with reference to FIG. 11 to determine whether the corresponding MPE section is the last MPE section that fills the broadcast data table area.

In step 1304, if the MPE section is the last section, the flow proceeds to step 1306 to transmit the IP datagram included in the received MPE section to the upper layer.

On the other hand, if the last MPE section has not been received in step 1304, the controller 1050 proceeds to step 1308 and checks whether the burst interval timer 1070 counts a predetermined time "0". In the embodiment of the present invention in step 1308 has been described as the controller 1050 checks whether the burst interval timer 1070 has counted a predetermined time, the controller 1050 does not check, the burst interval timer 1070 is The predetermined time may be counted and the result may be output to the controller 105.

If the burst interval timer 1050 does not count the predetermined time in step 1308, the controller 1050 proceeds to step 1300 and continues to receive the MPE section, and counts the predetermined time in step 1306. Proceed and send the IP datagram included in the MPE section to the upper layer.

Therefore, according to the present invention, when the receiver of the DVB-H system reconstructs the MPE-FEC frame for RS decoding, when the last section that is the basis for reconstruction completion is not properly received, the boundary of the MPE-FEC frame is not received. It can prevent abnormal operation that does not proceed with RS decoding because it cannot judge.

Claims (12)

A method for decoding a multi-protocol encapsulated forward error correction (MPE-FEC) frame in a receiver of a DVB-H type digital broadcasting system, Detecting packet service information (PSI / SI) by filtering packet identifier information (Packet Identifier: PID) included in a transport stream packet received during a burst period through a wireless network; Detecting a transport stream packet including section data by filtering packet identifier information included in a transport stream packet received during a burst period through a wireless network; Determining a type of the section data by detecting a table ID from the header information of the received section data; Frame buffering the Reed-Solomon data extracted from the MPE-FEC section and the IP datagram of the MPE section when the section data is identified as the MPE-FEC section; Counting, by a burst duration timer, a preset time in maximum burst duration information included in the broadcast service information; Detecting whether the last MPE-FEC section is received based on frame boundary information in the header information of the section data; If the last MPE-FEC section has not been received, Checking whether the burst duration timer has counted the preset time; And outputting an error corrected IP datagram using the buffered Reed-Solomon data when the burst duration timer counts the preset time. -Solomon decryption method. According to claim 1, If the last MPE-FEC section is received, a process of outputting an error-corrected IP datagram using the frame-buffered Reed-Solomon data outputs a Reed-Solomon decoding method in a DV-H receiver. . The method of claim 1, wherein when the section data is identified as an MPE section, Detecting whether the last MPE section has been received based on table boundary information in the header information of the section data; If the last MPE section has not been received, Checking whether the burst duration timer has counted the preset time; And outputting an IP datagram of the buffered MPE section to a higher layer when the burst duration timer counts the preset time. 4. The method of claim 3, wherein if the last MPE section has been received, And outputting the frame-buffered IP datagram to an upper layer. A frame boundary detection method for decoding an application data table region in a receiver of a DVB-H digital broadcasting system, Frame buffering an MPE section and an MPE-FEC section extracted from a transport stream packet received during a burst period through a wireless network; Driving a burst duration timer for counting time of the burst duration based on information included in a section header extracted from a previously received transport stream packet; Checking whether the extracted MPE-FEC section is the last section; If the MPE-FEC section is not the last section, Checking whether the burst interval timer counts the time by the burst interval in advance; And performing the Reed-Solomon decoding when the counted time is the burst period, and transmitting the decoded IP datagram to a higher layer. The method of claim 5, wherein when the extracted MPE-FEC section is the last, And performing a Reed-Solomon decoding on the buffered MPE section, and transmitting the decoded IP datagram to a higher layer. The method of claim 5, wherein if the extracted MPE section is not last, Checking whether the burst interval timer counts the time by the burst interval in advance; And transmitting the received IP datagram to a higher layer when the counted time is the burst period. 8. The method of claim 7, wherein when the extracted MPE section is last, And transmitting the received IP datagram to a higher layer. In the frame boundary detection apparatus for decoding an application data table region in a receiver of a DVB-H digital broadcasting system, A buffer that distinguishes and stores the MPE section and MPE-FEC section extracted from the transport stream packet received through the wireless network; A Reed-Solomon decoder for performing error correction on the IP datagram of the MPE section by using the Reed-Solomon data included in the MPE-FEC section; A burst duration timer for counting time by a time set in maximum burst duration information included in broadcast service information included in a header of a packet of a transport stream; The burst duration timer is operated based on information on a current burst duration start time included in a previously received MPE-FEC frame, and if the received MPE-FEC section is not the last section, the burst duration timer is set to the maximum duration. And a controller configured to control whether the received IP datagram is decoded by controlling the Reed-Solomon decoder when the burst duration timer has counted the predetermined time in the burst duration information, and counting the time by the preset duration. Frame boundary detection apparatus in a DV BH receiver, characterized in that. The receiver of claim 9, wherein the controller controls the Reed-Solomon decoder to decode the received IP datagram if the received MPE-FEC section is the last section. Frame boundary detection device. 10. The method of claim 9, wherein if the received MPE section is not the last section, the controller checks whether the burst duration timer has counted by the preset time and controls to transmit the received IP datagram to a higher layer. A frame boundary detection apparatus in a DV receiver. 10. The apparatus of claim 9, wherein the controller controls to transmit the received IP datagram to a higher layer if the received MPE section is the last section.

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