KR101162213B1 - Digital broadcasting system and processing method - Google Patents

Abstract

The present invention relates to a digital broadcasting system. In particular, the present invention collects K (K is a natural number) rows consisting of A (A is a natural number) data bytes to form a frame for error correction, and corrects the error for the frame. At least one of encoding, error detection encoding, and row mixing is performed and transmitted. As a result, the present invention enables robust response to fast channel changes while giving robustness to the transmitted data.

Enhanced data, known data, encoding

Description

Digital broadcasting system and processing method

1 is a block diagram showing an embodiment of a digital broadcast transmission system according to the present invention;

2A to 2D are diagrams illustrating an embodiment of an error correction encoding process according to the present invention.

Figure 3 (a), (b) is a view showing an embodiment of a row mixing process according to the present invention

4A to 4C illustrate an embodiment of an error detection encoding process according to the present invention.

5A and 5B are diagrams showing an example of data configuration before and after the data deinterleaver in the digital broadcast transmission system according to the present invention.

6 (a) to (c) are diagrams illustrating an embodiment of a packet multiplexing process in a digital broadcast transmission system according to the present invention.

7 is a block diagram showing an embodiment of a digital broadcast receiving system according to the present invention;

DESCRIPTION OF THE REFERENCE NUMERALS

110: E-VSB preprocessor 111: RS frame encoder

112: randomizer / byte expander 113: group formatter

114: data deinterleaver 115: packet formatter

121: packet multiplexer 122: data randomizer

130: E-VSB post-processing unit 131: RS parity position holder inserter

132: data interleaver 133: E-VSB block processing unit

134: data deinterleaver 135: RS parity position holder remover

TECHNICAL FIELD The present invention relates to digital broadcasting systems, and more particularly, to a method for transmitting and receiving digital broadcasting.

The 8T-VSB (Vestigial Sideband) transmission system, which is adopted as a digital broadcasting standard in North America and Korea, is a system developed for transmission of MPEG video / audio data. However, with the rapid development of digital signal processing technology and the widespread use of the Internet, digital home appliances, computers, and the Internet are being integrated into one big framework. Therefore, in order to meet various needs of users, it is necessary to develop a system capable of transmitting various additional data in addition to video / audio data through a digital broadcasting channel.

Some users of supplementary data broadcasting are expected to use supplementary data broadcasting by using PC card or portable device with simple indoor antenna. In the room, signal strength is greatly reduced due to wall blocking and influence of nearby moving objects. Due to the effects of ghosts and noise caused by reflected waves, broadcast reception performance may deteriorate. However, unlike general video / audio data, the additional data transmission should have a lower error rate. In the case of video / audio data, errors that the human eye and ears cannot detect are not a problem, while in the case of additional data (eg program executables, stock information, etc.), a bit error may cause serious problems. It can cause problems. therefore There is a need to develop a system that is more resistant to ghosting and noise in the channel.

The transmission of additional data will usually be done in a time division manner over the same channel as the MPEG video / sound. Since the beginning of digital broadcasting, however, ATSC VSB digital broadcasting receivers that receive only MPEG video / audio have been widely used in the market. Therefore, additional data transmitted on the same channel as MPEG video / audio should not affect the existing ATSC VSB-only receivers that have been used in the market. Such a situation is defined as ATSC VSB compatible, and the additional data broadcasting system should be compatible with the ATSC VSB system. The additional data may also be referred to as enhanced data or E-VSB data.

In addition, in a poor channel environment, the reception performance of the conventional ATSC VSB receiving system may be degraded. Especially in the case of portable and mobile receivers, robustness against channel changes and noise is required.

Accordingly, an object of the present invention is to provide a new digital broadcasting system and processing method suitable for additional data transmission and resistant to noise.

Another object of the present invention is to provide a digital broadcasting system and a processing method for improving reception performance of a receiver by performing additional encoding on enhanced data and transmitting the same.

Another object of the present invention is to provide a digital broadcasting system and a processing method for improving reception performance of a receiver by multiplexing known data and enhanced data known to the transmitting / receiving side with main data.

In order to achieve the above object, a transmission method according to an embodiment of the present invention, a frame for error correction by collecting a row consisting of A (A is a natural number) enhanced data bytes with information (K is a natural number) Forming a; And performing at least one of error correction encoding, error detection encoding, and row mixing on the frame.

The error correction encoding of the above step is characterized by being (N, K) -RS encoding for generating N-K parity.

The error detection encoding of the above step is characterized in that the CRC encoding to generate a CRC checksum.

Row mixing of the step comprises the steps of forming a frame group with G (G is a natural number) frames; And performing row mixing on the frame group basis.

According to another aspect of the present invention, there is provided a transmission method comprising: forming a frame for error correction by collecting K (K is a natural number) rows of A (A is a natural number) enhanced data bytes having information; Performing error correction encoding on the frame; Collecting G (G is a natural number) of the error correcting encoded frames to form a frame group, and performing row mixing on a frame group basis; And performing error detection encoding on the rows of the frames on which the row mixing is performed.

Transmission method according to another embodiment of the present invention,

(a) performing at least one of error correction encoding, row shuffling, and error detection encoding when enhanced data having information is input;

(b) performing randomization and byte expansion on the enhanced data output in the step;

(c) constructing an enhanced data packet by adding header data to data output in the step; And

and (d) multiplexing and outputting the main data packet and the enhanced data packet.

The transmitting method may include forming an enhanced data group including a plurality of packets, and inserting the enhanced data output in step (b) into a corresponding region of the enhanced data group; And deinterleaving the enhanced data group into which the enhanced data is inserted and outputting the deinterleaved data to the step (c).

The step (d) may include distinguishing an enhanced data burst section from a main data section; Transmitting at least one enhanced data group in the enhanced data burst period; And transmitting only a main data packet in the main data section.

The main data packet may be transmitted in the enhanced data burst period.

The transmission system according to the present invention includes a frame encoder for performing at least one of error correction encoding, row mixing, and error detection encoding when enhanced data having information is input; A randomizer / byte expander for performing randomization and byte expansion on the encoded data; A group formatter / deinterleaver for forming an enhanced data group including a plurality of packets, allocating the byte extended enhanced data to a corresponding region within the enhanced data group, and performing deinterleaving; And a packet formatter for inserting header data into the deinterleaved enhanced data and outputting the enhanced data packet as an enhanced data packet.

The transmission system according to the present invention comprises: a packet multiplexer for multiplexing and outputting a main data packet and an enhanced data packet output from the packet formatter on a packet basis; And a data randomizer for performing randomization only on the header data in the packet when the data output from the packet multiplexer is an enhanced data packet.

The packet multiplexer distinguishes an enhanced data burst section from a main data section, transmits at least one enhanced data group in the enhanced data burst section, and transmits only a main data packet in the main data section. .

The packet multiplexer transmits at least one main data packet in the enhanced data burst period.

The transmission system according to the present invention is characterized in that it further comprises a block processing unit for performing additional encoding at the M / N (where M <N) code rate for the enhanced data that bypasses the data randomizer as it is do.

The reception method according to the present invention comprises the steps of performing trellis decoding and block decoding if the demodulated data is enhanced data; Performing de-randing on the enhanced data on which the decoding has been performed; And performing at least one of error detection decoding, inverse row mixing, and error correction decoding on the de-randomized data.

The reception system according to the present invention includes a block decoder for performing trellis decoding and block decoding if the demodulated data is enhanced data; A data deformatter for performing de-randomizing on the decoded enhanced data; And a frame decoder configured to perform at least one of error detection decoding, inverse row mixing, and error correction decoding on the de-randomized data.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. At this time, the configuration and operation of the present invention shown in the drawings and described by it will be described as at least one embodiment, by which the technical spirit of the present invention and its core configuration and operation is not limited.

In addition, the terminology used in the present invention is a general term that is currently widely used as much as possible, but in some cases, the term is arbitrarily selected by the applicant. It is intended that the present invention be understood as the meaning of the term rather than the name.

In the present invention, the enhanced data may be data having information such as a program execution file, stock information, or the like, or may be video / audio data. Known data is data known in advance by an appointment of the transmitting / receiving side. In addition, the main data is data that can be received by the existing receiving system, and includes video / audio data.

According to the present invention, additional encoding is performed on the enhanced data to be transmitted, thereby providing robustness to the enhanced data and strongly responding to a rapidly changing channel environment.

In an embodiment, the present invention performs at least one of error correction encoding and error detection encoding on the enhanced data. In addition, a process of mixing the encoded data into a predetermined size may be further performed.

1 is a block diagram showing an embodiment of a digital broadcast transmission system according to the present invention.

The digital broadcast transmission system of FIG. 1 includes an E-VSB preprocessor 110, a packet multiplexer 121, a data randomizer 122, an E-VSB post processor 130, and an RS encoder. RS encoder / Non-systematic RS encoder 141, data interleaver 142, parity substituent 143, unsystematic RS encoder 144, trellis encoder 145, frame multiplexing The firearm 146 and the transmitter 150 are comprised.

The E-VSB preprocessor 110 includes an RS frame encoder 111, a randomizer / byte expander 112, a group formatter 113, a data deinterleaver 114, and a packet formatter 115.

The E-VSB post processor 130 may include an RS parity position holder inserter 131, a data interleaver 132, an E-VSB block processor 133, a data deinterleaver 134, and an RS parity position holder remover 135. It is configured to include).

The transmitter 150 includes a pilot inserter 151, a VSB modulator 152, and an RS up converter 153.

In the present invention configured as described above, the main data is input to the packet multiplexer 121, and the enhanced data E-VSB preprocessor 110 performs additional encoding to quickly and powerfully respond to noise and channel changes. Is entered.

The RS frame encoder 111 of the E-VSB preprocessor 110 receives the enhanced data, constructs a frame for further encoding, performs encoding, and outputs the encoded data to the randomizer / byte expander 112. do.

The following is a detailed operation of the RS frame encoder 111.

In an embodiment, the RS frame encoder 111 performs robustness on the data by performing at least one of error correction encoding and error detection encoding on the input enhanced data. In addition, the RS frame encoder 111 includes a process of mixing enhanced data of a predetermined size in order to cope with an extremely poor and rapidly changing propagation environment by distracting a cluster error that may occur due to the propagation environment change. .

In one embodiment, the RS frame encoder 111 performs error correction encoding on the input enhanced data, adds data for error correction, and mixes them in row units. After performing the step 1), error detection encoding is performed to add data for error detection.

In this case, the error correction coding is applied with RS coding, and the error detection coding is applied with cyclic redundancy check (CRC) coding. Parity data to be used for error correction is generated when the RS encoding is performed, and CRC data to be used for error detection is generated when CRC encoding is performed.

2 is a diagram illustrating an RS encoding process according to an embodiment of the present invention. The input enhanced data is divided into units of a predetermined length (A), and a plurality of enhanced data having a predetermined length (A) are collected to form a frame. RS coding is performed in the row or column direction for the configured frame.

In the present invention, the predetermined length (A) unit is called a row for convenience of description, and the A value is determined by the system designer.

For example, if the input enhanced data is an MPEG transport stream (TS) packet composed of 188 byte units, the first MPEG sync byte is removed as shown in FIG. 2 (a) and 187 bytes as shown in FIG. This constitutes one row (A). The reason for removing the MPEG sync byte is that all enhanced packets have the same value.

If there is no fixed byte that can be removed from the input enhanced data or if the length of the input packet is not 187 bytes, the input data is divided by 187 bytes, and the row is divided into 187 bytes. Configure

When row A is determined by the above process, a plurality of rows A are collected to form an RS frame. According to an embodiment of the present invention, as shown in FIG. 2C, 67 rows are collected to form one RS frame.

In addition, after performing (N, K) -RS encoding on each column of the RS frame, NK parity bytes are generated and added to the last part of the corresponding column (ie, after the 67th row of the corresponding column). . In this embodiment, N is 85 and K is 67. Then, as shown in (d) of FIG. 6, the parity data added to each column becomes 18 bytes.

When the (85,67) -RS encoding process is performed for all 187 columns in an RS frame, one row is composed of 187 bytes, and one column is composed of 85 bytes of RS frames. That is, an RS-coded RS frame is equivalent to 85 rows of 187 bytes.

As such, the number of bytes constituting the one row, the number of rows constituting the RS frame, and the N and K values used for RS encoding are values that may vary depending on the system design and the situation. It will not be limited.

3 is a diagram illustrating an embodiment of a row mixing process according to the present invention, and shows an example of performing row mixing on RS-coded data.

That is, a plurality of RS-coded RS frames are collected to form a group, and then row mixing is performed in group units.

Assuming that one row is 187 bytes in FIG. 2 and (85,67) -RS coding is performed, as shown in FIG. Configure an RS frame group composed of rows.

When the row mixing process is performed in a predetermined manner with respect to the RS frame group configured in this way, the positions of the rows before and after row mixing in the RS frame group are changed. That is, the i-th row of the RS frame group before row mixing of FIG. 3 (a) is located in the j-th row of the RS frame group of FIG. 3 (b) after the row mixing process is performed. This relationship between i and j can be seen through Equation 1 below.

Even after the row mixing process is performed, each row of the RS frame group is composed of 187 bytes.

In this case, the size of the RS frame before and after row mixing does not necessarily need to be the same, and only the number of all rows in the RS frame group before and after row mixing need to match.

For example, assuming that the number of RS frames constituting the RS frame group before row mixing is G and the number of rows of one RS frame is 84, the number of RS frames constituting the RS frame group after row mixing is 2G, Even if the number of rows in one RS frame is 42, this is not a problem for row shuffling. That is, the size of each RS frame before and after row mixing may be determined by the system designer as an arbitrary size.

4 is a diagram illustrating an embodiment of a CRC encoding process according to the present invention, and shows an example of performing CRC encoding on data on which row mixing is performed.

The CRC data generated by the CRC encoding is used to inform whether enhanced data is damaged by an error while being transmitted through a channel.

The present invention may use other error detection encoding methods in addition to CRC encoding, or may increase the overall error correction capability at the receiving end by using an error correction encoding method.

4A to 4C illustrate embodiments of CRC encoding methods performed in the present invention.

4A shows an example of using an 8-bit CRC checksum as CRC data, which generates a 1 byte (i.e. 8 bit) CRC checksum for 187 bytes of each row and adds it to the row.

Equation 2 below shows an example of a polynomial that generates a one-byte CRC checksum for 187 bytes.

g (x) = x ⁸ + x ² + x ¹ + 1

In this case, the position of adding the 1-byte CRC checksum may be any position in the row. In an embodiment of the present invention, the row is configured to be 188 bytes in addition to the end of the row.

4B and 4C show an example of using a 16-bit CRC checksum as CRC data. A 2 byte (ie, 16-bit) CRC checksum is generated in units of two rows and added to the row.

Equation 3 below shows an example of a polynomial that generates a 2-byte CRC checksum for two rows, 374 bytes.

g (x) = x ¹⁶ + x ¹² + x ⁵ + 1

In this case, the position of adding the 2-byte CRC checksum may be any position in the two rows. The 2-byte CRC checksum may be added to a predetermined position in the two rows, and then divided into two rows of 188 bytes.

4B shows an example of configuring two rows of 188 bytes by adding a 1 byte CRC checksum to each end of each of the two rows.

4C shows an example of configuring two rows of 188 bytes after adding a 2-byte CRC checksum to the end of the second of the two rows.

The CRC coded data as described above is output to the randomizer / byte expander 112.

The randomizer / byte expander 112 receives and enhances the enhanced data having increased robustness through encoding and row mixing, and performs byte expansion on the randomized data through null data insertion and repetition.

In this case, by performing the randomization on the enhanced data in the randomizer / byte expander 112, the subsequent randomizer 122 may omit the randomizing process on the enhanced data. The enhanced data generator may use the same as the conventional ATSC's renderer, or may use another renderer. That is, the input 187 bytes of enhanced data are randomized using pseudo random bytes generated internally.

In addition, the rendering process and the byte expansion process may be performed in a reversed order. That is, as described above, the byte expansion may be performed after rendering, and conversely, after the byte expansion, the rendering may be performed, which may be selected in consideration of the overall system.

The byte expansion may vary depending on the code rate of the E-VSB block processor 133 of the E-VSB post processor 130. That is, if the code rate is M / N code rate, M bytes are extended to N bytes. For example, if the code rate is 1/2 code rate, 1 byte is extended to 2 bytes, and if the code rate is 1/4, 1 byte is extended to 4 bytes. Accordingly, if the code rate is 1/2 code rate, the 85 RS encoded 188 bytes are extended to 150 188 bytes.

The enhanced data output from the randomizer / byte expander 112 is input to the group formatter 113.

The group formatter 113 forms an enhanced data group according to a predefined rule, and inserts the enhanced data input in a corresponding region in the formed enhanced data group.

In this case, the enhanced data group may be divided into at least one or more layered areas, and the type of enhanced data allocated to each area may vary according to characteristics of each layered area.

FIG. 5A illustrates a form in which data before data deinterleaving is listed separately, and FIG. 5B illustrates a form in which data after data deinterleaving is classified and listed.

In other words, FIG. 5A is a form of data after data interleaving, and FIG. 5B is a form of data before data interleaving.

FIG. 5A illustrates an example of dividing an enhanced data group into three layered areas, that is, a head, a body, and a tail area in a data configuration before data deinterleaving. As a result, the first output part is the head, the middle output part is the body, and the last output part is the tail, based on the enhanced data group that is data interleaved and output.

5A and 5B show an example in which 260 packets form an enhanced data group. This shows that the data interleaver operates periodically in units of 52 packets so that five multiples of 52 packets form an enhanced data group.

In addition, as shown in FIG. 5A, the body region has a quadrangular shape, since the body region has a quadrangular shape as shown in FIG. 5A, and thus the body region is composed of fully enhanced data without being mixed with the main data region in the middle. In this case, the head, body, and tail regions are set in the enhanced data group.

In this case, the body region may be allocated to include at least a part or all of the region where the enhanced data in the enhanced data group is continuously output based on the enhanced data group input to the data deinterleaver. have. In this case, the body region may include a region in which enhanced data is discontinuously output.

Dividing the enhanced data group into three parts is for different purposes. That is, in FIG. 5, the area corresponding to the body is an area that can show more robust reception performance because it is composed of enhanced data without interference of main data in the middle, and the enhanced data of the head and tail areas is the main data and the interleaver output order. This is because the reception performance is lower than that of the body area because it is mixed between phases.

In addition, in the case of applying a system for inserting and transmitting known data into an enhanced data group, when the long data is periodically inserted into the enhanced data periodically, the enhanced data is mainly based on the order of the data interleaver output terminal. It is possible to insert in areas that are not mixed with the data. That is, it is possible to periodically insert known data of a predetermined length into the body region of FIG. 5. However, it is difficult to periodically insert known data into the head and tail regions, and also to insert long known data continuously.

Accordingly, the group formatter 113 inserts the input enhanced data into a corresponding region in the enhanced data group formed as described above.

In one embodiment, the group formatter 113 allocates the received enhanced data to the body region. In addition, the group formatter 113 allocates signaling information indicating overall transmission information to the body region separately from the enhanced data. That is, the signaling information is information necessary for receiving and processing data included in the enhanced data group in a receiving system, and may include enhanced data group information, multiplexing information, and the like.

In addition, the group formatter 113 inserts an MPEG header position holder, an unstructured RS parity position holder, and a main data position holder in relation to data deinterleaving as shown in FIG. 5A. The reason for allocating the main data position is that the enhanced data and the main data are mixed between the head and tail regions based on the input of the data deinterleaver as shown in FIG. 5A. The position holder for the MPEG header is assigned to the beginning of each packet, based on the output data after the data deinterleaving.

The group formatter 113 inserts the known data generated by the predetermined method into the corresponding area, or inserts the known data position holder into the corresponding area for inserting the known data later. Also, the position holder for initializing the trellis encoder 145 is inserted into the corresponding region. In one embodiment, the initialization data location holder may be inserted before the known data stream.

As described above, the enhanced data group into which the data or position holder is inserted in the group formatter 113 is input to the data deinterleaver 114.

In FIG. 5A, the head and tail regions may be used for enhanced data, another information data, or data for assisting the enhanced data as needed.

The data deinterleaver 114 deinterleaves the input enhanced data group in a reverse process of data interleaving and outputs the deinterleaved data to the packet formatter 115. That is, when the enhanced data group of the type shown in FIG. 5A is input, it is deinterleaved as shown in FIG. 5B and output to the packet formatter 115. 5B shows only the parts related to the enhanced data group.

The packet formatter 115 removes the main data position holder and the RS parity position holder, which have been allocated for deinterleaving among the deinterleaved input data, collects the remaining portions, and then stores an MPEG header in a 4-byte MPEG header position holder. Replace it.

In addition, the packet formatter 115 may insert and replace the known data in the known data position holder when the known data position holder is inserted in the group formatter 113 or in the E-VSB post-processing unit 130. The known data position holder may be output as is without adjustment for replacement insertion.

Then, the packet formatter 115 configures the data in the packet-formatted enhanced data group as MPEG TS packets in units of 188 bytes as described above, and provides them to the packet multiplexer 121.

The packet multiplexer 121 multiplexes the enhanced data packet and the main data packet in units of 188 bytes output from the packet formatter 115 and outputs the multiplexed data data to the data randomizer 122. The packet multiplexer 121 will be described in detail later.

If the input data is a main data packet, the data randomizer 122 performs rendering in the same manner as the existing one. That is, the MPEG sync byte in the main data packet is discarded and the remaining 187 bytes are randomly generated using pseudo random bytes generated therein and then output to the E-VSB post-processing unit 130.

However, if the input data is an enhanced data packet, the MPEG sync byte is discarded among the 4 byte MPEG headers included in the enhanced data packet, and only the remaining 3 bytes are rendered, and the rest of the enhanced data except the MPEG header is performed. For the output to the E-VSB post-processing unit 130 without performing the rendering. This is because the randomizer / byte expander 112 has previously rendered the enhanced data. Rendering may or may not be performed on the known data (or known data location holder) and the initialization data location holder included in the enhanced data packet, and only information about the known data is transmitted to the receiving system.

Data rendered or bypassed by the data randomizer 122 is input to the RS parity position holder inserter 131 of the E-VSB post-processing unit 130.

The RS parity position holder inserter 131 inserts a 20-byte RS parity position holder after 187 bytes of data and outputs the data to the data interleaver 132 when the input data is a main data packet of 187 bytes. If the input data is an 187 byte enhanced data packet, a 20-byte RS parity position holder is inserted into the packet for unsystematic RS encoding to be performed later, and the bytes of the enhanced data packet are inserted into the remaining 187 byte positions. Output to the data interleaver 132.

The data interleaver 132 performs data interleaving on the output of the RS parity position holder inserter 131 and outputs the data to the E-VSB block processor 133.

The E-VSB block processor 133 performs additional encoding only on the enhanced data output from the data interleaver 132. As an example, if the randomizer / byte expander 112 performs 2-byte expansion, the E-VSB block processor 133 encodes the enhanced data at a 1/2 code rate and performs 4-byte expansion. If so, encoding is performed at a 1/4 code rate. The main data or RS parity position holder is bypassed as it is. In addition, the known data (or known data position holder) and the initialization data position holder may be bypassed as they are or may be replaced with known data generated by the E-VSB block processor 133 and output.

The data encoded, substituted, and bypassed by the E-VSB block processor 133 is input to the data deinterleaver 134, and the data deinterleaver 134 is inversely processed by the data interleaver 132 to input data. After performing data deinterleaving, the RS outputs the RS parity position holder remover 135.

The RS parity position holder remover 135 removes the 20-byte RS parity position holder added by the RS parity position holder inserter 131 for the operation of the data interleaver 132 and the data deinterleaver 134. Output to encoder / unstructured RS encoder 141. At this time, if the input data is the main data packet, the RS parity position holders of the last 20 bytes of the 207 bytes are removed, and if the enhanced data packet is the 20-byte RS parity position inserted to perform unsystematic RS encoding of the 207 bytes, Remove the holders.

The main data sequentially passes through the RS parity position holder inserter 131, the data interleaver 132, the E-VSB block processor 133, the data deinterleaver 134, and the RS parity position holder remover 135. This is the same as the main data when the RS parity position holder inserter 131 is input.

The RS encoder / unstructured RS encoder 141 performs RS coding on input data, adds 20 bytes of RS parity, and outputs the RS to the data interleaver 142. In this case, the RS encoder / unstructured RS encoder 141 performs systematic RS encoding in the same way as the existing ATSC VSB system when the input data is a main data packet, and adds 20 bytes of RS parity to 187 bytes of data. In the case of an enhanced data packet, 20 parity byte positions are determined in a packet, and 20-byte RS parity obtained by performing unsystematic RS encoding is inserted into the determined parity byte position.

The data interleaver 142 is a convolutional interleaver in bytes, and the same interleaving rule as the data interleaver 132 is applied.

The data interleaver 132 and the data interleaver 142 play the same role, and are separated for convenience of description according to the location. Similarly, the data deinterleaver 114 and the data deinterleaver 134 also perform perfectly the same role, and are separated for convenience of description. The data deinterleaver performs the reverse process of the data interleaver. Therefore, the result obtained by inputting the output string obtained by inserting a specific input string into the data interleaver again to the data deinterleaver is the same as the specific input string input to the data interleaver.

The output of the data interleaver 142 is input to the parity substituent 143 and the unstructured RS encoder 144.

On the other hand, in order to make the output data of the trellis encoder 145 located at the rear end of the parity substituent 143 into known data defined by appointment on the transmitting / receiving side, the memory in the trellis encoder 145 is first initialized. Is needed. That is, before the input known data string is trellis encoded, the memory of the trellis encoder 145 must be initialized.

At this time, the start of the known data string input is not the actual known data but the initialization data position holder included in the group formatter 113. Therefore, a process of generating initialization data immediately before the input known data string is trellis encoded and replacing the corresponding trellis memory initialization data position holder is required. This is to ensure backward compatibility with existing receiving systems.

The trellis memory initialization data is generated by determining a value of the memory of the trellis encoder 145 according to a past memory state. In addition, a process of recalculating RS parity under the influence of the replaced initialization data and substituting the RS parity output from the data interleaver 142 is required.

Accordingly, the unstructured RS encoder 144 receives an enhanced packet including an initialization data position holder to be replaced with initialization data from the data interleaver 142, and receives initialization data from the trellis encoder 145. The new unstructured RS parity is calculated and then output to the parity substituent 143. The parity substituent 143 then selects the output of the data interleaver 142 for the data in the enhanced data packet and the trellis encoder 145 for the RS parity by selecting the output of the unstructured RS encoder 144. )

Meanwhile, when the main data packet is input or an enhanced data packet including an initialization data position holder to be replaced is input, the parity substituent 143 selects data and RS parity output from the data interleaver 142 and transmits the same. Output to the release encoder 145.

The trellis encoder 145 converts data in units of bytes into symbol units, performs 12-way interleaving, trellis-encodes them, and outputs them to the frame multiplexer 146.

The frame multiplexer 146 inserts field synchronization and segment synchronization into the output of the trellis encoder 145 and outputs them to the transmitter 150. The transmitter 150 includes a pilot inserter 151, a VSB modulator 152, and an RF up-converter 153, and thus detailed description thereof will be omitted.

Packet multiplexer

The packet multiplexer 121 performs a function of multiplexing an enhanced data packet and a main data packet in units of 188 bytes output from the packet formatter 115. The multiplexing method can be adjusted by various variables of the system design.

FIG. 6 illustrates an embodiment of multiplexing an enhanced data packet and a main data packet, in which enhanced data is transmitted in burst units.

Referring to FIG. 6A, the enhanced data burst section occupying the N field and the main data section occupying the M field are repeated.

The enhanced data packet and the main data packet in the enhanced data group are multiplexed and output in the N field section, and only the main data packet is output in the M field section.

6 (b) and 6 (c) show an enlarged enhanced data burst section having an N field in the time axis. 6 (b) shows an enlarged enhanced data burst section on the time axis based on the input of the data interleaver 132 or the data interleaver 142. FIG. 6 (c) shows the output of the data interleaver. As a reference, the enhanced data burst section is enlarged on the time axis.

Referring to FIG. 6C, the enhanced data group and the main data of one field are repeatedly transmitted. Here, the enhanced data of the head and tail regions of the enhanced data group are mixed between the main data and the interleaver output order, so that the main data may be included in a field section in which the enhanced data group is transmitted.

As shown in FIG. 6, the first and last fields in the enhanced data burst section locate a field occupied by the enhanced data group and position a field occupied by main data between two fields occupied by the enhanced data group. In this case, the total number N of fields included in the enhanced data burst period becomes odd. In this case, the enhanced data burst period and the main data period do not necessarily need to be in a VSB data field unit but may be set in segment units. The enhanced data burst period and the main data period need not be repeated in a periodic form. In addition, the amount of main data sandwiched between two adjacent enhanced data groups within an enhanced data burst period can be changed according to system design and constraints.

When the enhanced data is transmitted in the burst structure as described above, the receiving system receiving only the enhanced data turns on the power only in the burst period to receive the data, and turns off the power in the main data section in which only the main data is transmitted. By not receiving data, power consumption of the receiving system can be reduced.

As described above, the packet multiplexer 121 receives a main data packet and an enhanced data group output from the packet formatter 115 and transmits the burst data as shown in FIG. In this case, the enhanced data group and the main data packet are multiplexed and output as shown in FIG. 6B within one enhanced data burst period.

The output of the packet multiplexer 121 has an enhanced data burst form as shown in (c) of FIG. 6 at a point of time input to the frame multiplexer 146 after a series of processes including data interleaving. In this case, one enhanced data group is composed of a head of the first 52 segments in which the enhanced data and the main data are mixed, a body of 208 segments composed of only the enhanced data, and a 52 segment tail region in which the enhanced data and the main data are mixed. .

FIG. 7 is a block diagram illustrating an embodiment of a digital broadcast reception system for receiving, demodulating, and equalizing data transmitted from a digital broadcast transmission system to restore original data.

The digital broadcast receiving system of FIG. 7 includes a tuner 701, a demodulator 702, an equalizer 703, a known data detector 704, an E-VSB block decoder 705, and an E-VSB data deformatter 706. And an RS frame decoder 707, a data deinterleaver 708, an RS decoder 709, and a derandomizer 710.

That is, the tuner 701 tunes the frequency of a specific channel, down-converts the intermediate frequency (IF) signal, and outputs the demodulator 702 and the known data detector 704.

The demodulator 702 performs automatic gain control, carrier recovery, and timing recovery on the input IF signal to generate a baseband signal and outputs the same to the equalizer 703 and the known data detector 704.

The equalizer 703 compensates for the distortion on the channel included in the demodulated signal and outputs it to the E-VSB block decoder 705.

At this time, the known data detector 704 detects the position of the known data inserted by the transmitter from the input / output data of the demodulator 702, that is, the data before the demodulation is performed or the data after the demodulation. The symbol string of the known data generated at the position is output to the demodulator 702, the equalizer 703, and the E-VSB block decoder 705. In addition, the known data detection unit 704 enhances the data by the E-VSB block decoder 705 of the receiving side to distinguish the enhanced data that has been further encoded from the transmitting side and the main data that has not been further encoded. The E-VSB block decoder 705 outputs information for knowing the starting point of the block of the DE coder. Although the connection state is not illustrated in the diagram of FIG. 7, the information detected by the known data detector 704 may be generally used in the reception system, and may be used in the E-VSB deformatter 706 and the RS frame decoder 707. Can also be used.

The demodulator 702 can improve demodulation performance by using the known data symbol string during timing recovery or carrier recovery. The equalizer 703 can use the known data to improve equalization performance. have. In addition, the equalization performance may be improved by feeding back the decoding result of the E-VSB block decoder 705 to the equalizer 703.

On the other hand, if the data input from the equalizer 703 to the E-VSB block decoder 705 is enhanced data in which both additional encoding and trellis encoding are performed at the transmitting side, trellis decoding and additionally at the reverse side of the transmitting side are performed. Decoding is performed and only trellis decoding is performed if additional data is not performed and only trellis encoding is performed. The enhanced data group decoded by the E-VSB block decoder 705 is input to the E-VSB data deformatter 706, and the main data packet is input to the data deinterleaver 708.

That is, if the input data is main data, the E-VSB block decoder 705 may perform Viterbi decoding on the input data to output a hard decision value, or hard decision the soft decision value and output the result.

If the input data is enhanced data, the E-VSB block decoder 705 outputs a hard decision value or a soft decision value with respect to the input enhanced data.

If the input data is enhanced data, the E-VSB block decoder 705 decodes the data encoded by the E-VSB block processor 133 and the trellis encoder 145 of the transmission system. At this time, the RS frame encoder 111 of the E-VSB preprocessor 110 of the transmitting side becomes an external code, and the E-VSB block processor 133 and the trellis encoder 145 can be regarded as one internal code. .

In order to maximize the performance of the outer code at the time of decoding the concatenated code, the soft decision value should be output from the decoder of the inner code.

Accordingly, the E-VSB block decoder 705 may output a hard decision value for the enhanced data, and output a soft decision value if necessary.

In other words, the E-VSB block decoder 705 outputs one of the soft decision value and the hard decision value for the enhanced data, and the hard decision value for the main data.

Meanwhile, the data deinterleaver 708, the RS decoder 709, and the derandomizer 710 are blocks necessary for receiving main data, and may not be necessary in a receiving system structure for receiving only enhanced data. .

The data deinterleaver 708 deinterleaves the main data in the reverse process of the data interleaver on the transmitting side and outputs the main data to the RS decoder 709.

The RS decoder 709 performs systematic RS decoding on the deinterleaved data and outputs the deserializer 710.

The derandomizer 710 receives the output of the RS decoder 709 to generate the same pseudo random byte as the transmitter's renderer, bitwise XORs the MPEG sync byte, Insert it before and output in 188 byte main data packet unit.

The data output from the E-VSB block decoder 705 to the E-VSB data deformatter 706 is input in the form of an enhanced data group as shown in FIG. 5A. At this time, since the E-VSB data deformatter 706 already knows the input data configuration, the E-VSB data deformatter 706 distinguishes the signaling information having the system information from the enhanced data group and the enhanced data. At this time, the E-VSB data deformatter 706 uses known data, trellis initialization data, MPEG header, and RS encoder / unsystematic RS encoder 141 or unsystematic system, which have been inserted into the main data and the enhanced data group. RS parity added by RS encoder 144 is removed and output.

Then, de-randomizing is performed in the reverse process of the sender's randomizer / byte expander on the enhanced data. At this time, the null data used for expansion in the byte expander may or may not be necessary. That is, according to the design method of the receiving system, a part for removing the expanded byte by the byte expander of the transmitting system may be needed, but the null data inserted during the byte expansion may be removed and output by the E-VSB block decoder 705. In that case there is no need for extended byte removal. If extended bytes need to be removed, the order of extended byte removal and derandomization depends on the configuration of the sending system. In other words, if a byte expansion after rendering is performed in the transmitting system, de-rendering is performed after removing bytes from the receiving system. If the transmitting system is performed in reverse, the receiving system is also performed in reverse.

In the de-rendering process, if a soft decision is required in the RS frame decoder 707 at the next stage and a soft decision value is input from the E-VSB block decoder 705, the soft decision value is de-randomized. It is difficult to XOR with a pseudo random bit.

Accordingly, the E-VSB data deformatter 706 reverses the sign of the soft decision value when the pseudo random bit to be XORed with respect to the soft decision value of the enhanced data bit is 1, and outputs the soft value when the value is 0. By outputting the sign of the determination value as it is, the soft determination state can be maintained and transmitted to the RS frame decoder 707.

The reason for changing the sign of the soft decision value when the pseudo random bit is 1 in the above description is that the output data bit is reversed when the pseudo random bit XORed to the input data bit in the transmitter's renderer is 1. That is, 0 XOR 1 = 1 and 1 XOR 1 = 0. In other words, when the pseudo-random bit generated by the E-VSB packet deformatter 706 is 1, when the XOR of the hard decision value of the enhanced data bit is reversed, the soft decision value is outputted. The code of the soft decision value is reversed and output.

The RS frame decoder 707 performs an inverse process in the RS frame encoder 111 of the transmitter.

For example, when the E-VSB block processing unit 133 of the transmission system performs encoding at a code rate of 1/2, an RS frame decoder 707 has 85 packets (or rows) of 188 bytes. The frame is input.

In the RS frame decoder 707, G frames are gathered to form 85 * G RS frame groups.

In the case of using a 1 byte (i.e., 8 bit) CRC checksum as shown in FIG. 4A, after checking whether each 188 byte packet is error or not, the 1 byte CRC checksum is removed, leaving only 187 bytes to the error flag corresponding to the packet. Indicates whether an error occurred.

If a 2 byte (i.e. 16 bit) CRC checksum is used as shown in FIGS. 4B and 4C, two 188 byte packets are checked for errors, and then the two byte CRC checksums are removed to make two 187 byte packets. The error flag corresponding to each 187 byte packet indicates whether an error occurs. If a two-byte CRC checksum is used, both packets should be marked as having errors or no errors at the same time.

After checking the error of each row using the CRC checksum as described above, the row mixing process is performed in the transmission system by performing the inverse process of the low mixing process as shown in FIG. 3 for the RS frame group composed of 85 * G 187 bytes. Sort in original order before passing. Then, it is divided into G RS frames consisting of 85 187 bytes. When the reverse row mixing process is performed, an error flag indicating whether each packet (or row) is in error is also converted and inherited. Each RS frame is configured in the form of a 187x85 byte matrix. By decoding the (85,67) -RS encoding applied by the transmitting side to each of the 187 columns in the RS frame, 67 187-byte rows can be obtained with error correction. The enhanced TS packet recovered to 188 bytes is output by adding the MPEG sync byte removed at the beginning of each 187-byte row.

In the RS decoding of each RS frame, RS decoding is performed when the number of rows having an error as a result of CRC error checking is equal to or smaller than the maximum number of errors that can be erased when performing column-oriented RS decoding. Erasure correction maximizes the error correction capability.

The present invention is not limited to the above-described embodiments, and can be modified by those skilled in the art as can be seen from the appended claims, and such modifications are within the scope of the present invention.

As described above, the digital broadcasting system and the processing method according to the present invention have an advantage of being resistant to errors and compatible with existing VSB receivers when transmitting additional data through a channel. In addition, there is an advantage that the additional data can be received without error even in a ghost and noisy channel than the conventional VSB system.

In addition, the present invention is to group the plurality of enhanced data packets having information, and to transmit the group by multiplexing the group with the main data, the grouping of the group into a plurality of areas, the data inserted according to the characteristics of the layered area By dividing the types, processing methods, and the like, the reception performance of the reception system can be improved.

In addition, the present invention performs a row mixing process with at least one of error correction encoding and error detection encoding on the enhanced data, thereby robustly responding to fast channel changes while giving robustness to the enhanced data.

The present invention is more effective when applied to portable and mobile receivers in which channel variation is severe and robustness to noise is required.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (28)

A preprocessor configured to perform at least one of error correction encoding and error detection encoding on enhanced data and to generate an enhanced data packet including the encoded enhanced data; A multiplexer which multiplexes the generated enhanced data packet and a main data packet including main audio and video (AV) data; A first randomizer which performs randomization on main AV data in the multiplexed data packet; A data encoder for adding first parity data for the rendered main AV data and adding second parity data for enhanced data in the multiplexed data packet; An interleaving unit interleaving data of the multiplexed data packet including the first and second parity data; A trellis encoder including at least one memory, initializing the memory before the start of a known data sequence, and trellis encoding the interleaved data; And A data transmitter for transmitting a broadcast signal including the trellis coded data; Digital broadcast transmitter comprising a. The method of claim 1, A parity replacement unit configured to calculate third parity data with respect to data including the initialization data changed in the process of initializing the memory of the trellis encoder, and replace the second parity data with the calculated third parity data; Digital broadcast transmitter further comprising. The method of claim 1, wherein the pretreatment unit, Two randomizers to perform randomizing on the enhanced data; An encoder which generates a data frame including the randomized enhanced data and performs at least one of error correction encoding and error detection encoding on the generated data frame; A group formatter for inserting the enhanced data of the generated data frame into a data group having a plurality of data areas to form a data group; A deinterleaving unit performing de-interleaving on data included in the formed data group; And A packet formatter for adding a header to the deinterleaved data and generating an enhanced data packet; Digital broadcast transmitter comprising a. Performing at least one of error correction encoding and error detection encoding on enhanced data, and generating an enhanced data packet including the encoded enhanced data; Multiplexing the generated enhanced data packet and a main data packet including main audio and video (AV) data; Performing randomizing on main AV data in the multiplexed data packet; Adding first parity data for the rendered main AV data and adding second parity data for enhanced data in the multiplexed data packet; Interleaving data of the multiplexed data packet including the first and second parity data; In a trellis encoder including at least one memory, initializing the memory before the start of a known data sequence and trellis encoding the interleaved data; And Transmitting a broadcast signal including the trellis encoded data; Digital broadcast transmission method comprising a. The method of claim 4, wherein Calculating third parity data with respect to data including the changed initialization data in the process of initializing the memory of the trellis encoder, and replacing the second parity data with the calculated third parity data; Digital broadcast transmission method further comprising. The method of claim 4, wherein generating an enhanced data packet comprises: Performing randomizing on the enhanced data; Generating a data frame including the randomized enhanced data and performing at least one of error correction encoding and error detection encoding on the generated data frame; Inserting the enhanced data of the generated data frame into a data group having a plurality of data regions to form a data group; Performing de-interleaving on data included in the formed data group; And Adding a header to the deinterleaved data and generating an enhanced data packet; Digital broadcast transmission method comprising a. A preprocessor configured to encode enhanced data, and generate an enhanced data packet including the encoded enhanced data to perform pre-processing on the enhanced data; A multiplexer which multiplexes the enhanced data packet with a main data packet including main audio and video (AV) data; And A trellis encoder including at least one memory, initializing the memory before the start of a known data sequence, and trellis encoding data in the multiplexed data packet; Digital broadcast transmitter comprising a. The method of claim 7, wherein An encoder which adds first parity data to the multiplexed data; An interleaving unit interleaving data in the multiplexed data packet including the first parity data; And A parity replacement unit generating second parity data with respect to the data changed in the process of initializing the memory, and replacing the first parity data with the second parity data; Digital broadcast transmitter further comprising. The method of claim 7, wherein the preprocessing unit, A randomization unit for randomizing the enhanced data; A first encoder generating a data frame including the randomized enhanced data and performing at least one of error correction encoding and error detection encoding in units of the data frame; A second encoder which encodes enhanced data in the data frame at a G / H coding rate; A data formatter including data encoded at the G / H coding rate and forming a data group including a plurality of data regions; A deinterleaver for de-interleaving data in the formed data group; And A packet formatter configured to add a header to the deinterleaved data to generate an enhanced data packet; Digital broadcast transmitter comprising a. The method of claim 9, wherein the data formatter, And inserting a header position holder, a main AV data position holder and a parity data position holder into the data group. The method of claim 9, wherein the data formatter, And inserting initialization data for initializing the memory into a data group. Encoding enhanced data, generating an enhanced data packet including the encoded enhanced data, and performing pre-processing on the enhanced data; Multiplexing the enhanced data packet with a main data packet comprising main audio and video (AV) data; And Including at least one memory, initializing the memory before beginning of a known data stream, and trellis encoding data in the multiplexed data packet; Digital broadcast transmission method comprising a. 13. The method of claim 12, Adding first parity data to the multiplexed data; Interleaving data in a multiplexed data packet including the first parity data; And Generating second parity data with respect to the changed data in the process of initializing the memory, and replacing the first parity data with the second parity data; Digital broadcast transmission method further comprising. The method of claim 12, wherein performing the preprocessing on the enhanced data comprises: Randomizing the enhanced data; Generating a data frame including the randomized enhanced data and performing at least one of error correction encoding and error detection encoding in units of the data frame; Performing encoding at a G / H coding rate on the enhanced data in the data frame; Forming a data group including data encoded at the G / H coding rate and including a plurality of data regions; De-interleaving data in the formed data group; And Generating an enhanced data packet by adding a header to the deinterleaved data Digital broadcast transmission method comprising a. The method of claim 14, Inserting a header position holder, a main AV data position holder and a parity data position holder into the data group; Digital broadcast transmission method further comprising. The method of claim 14, Inserting initialization data for initializing the memory into a data group; Digital broadcast transmission method further comprising. delete delete delete delete delete delete delete delete delete delete delete delete

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