KR20070119913A - Digital broadcasting system and processing method - Google Patents

Abstract

A digital broadcasting system and a processing method are provided to receive supplementary data without an error even via a ghost and noise-severe channel. An E-VSB(Enhanced-Vestigial Sideband) pre-processing unit receives enhanced data with information and performs the first error correction coding, interleaving and byte extension on the data. A packet generator(112) inserts a header to the enhanced data outputted from the E-VSB pre-processing unit, and inserts the enhanced data to the first data region, among the first and second data regions in a transport stream packet in which the header is included, to create an enhanced data packet. A Trellis encoding unit(135) performs coding, the second error correction coding and trellis coding on the enhanced data of the enhanced data packet outputted from the packet generator(112) at least at an N/M(N and M are natural numbers and N<M) coding rate.

Description

Digital broadcasting system and processing method

FIG. 1A illustrates a structure of a transport stream packet without an adaptation field

FIG. 1B illustrates a structure of a transport stream packet including an adaptation field

1c illustrates a structure of a transport stream packet according to an embodiment of the present invention

1D illustrates a structure of a transport stream packet according to another embodiment of the present invention.

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

3 illustrates an example in which unstructured RS parity is inserted into a transport stream packet including an adaptation field according to the present invention.

4A and 4B illustrate an embodiment of a data structure before and after an interleaver when unsystematic RS coding is applied to an enhanced data packet according to the present invention.

5A and 5B illustrate an embodiment of a data structure before and after an interleaver when systematic RS coding is applied to an enhanced data packet according to the present invention.

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

Explanation of symbols for main parts of the drawings

111: E-VSB preprocessor 112: packet generation unit

113: data randomizer 120: E-VSB post-processing unit

121: RS Parity Position Holder Inserter

122: data interleaver 123: E-VSB block processing unit

124: data deinterleaver 125: RS parity position holder remover

131,134: RS encoder 132: data interleaver

133: parity substituent 135: trellis encoder

136: frame multiplexer 140: transmitter

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 equipped with simple indoor antenna. 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 processing method for transmitting additional data to be compatible with an existing receiver.

In order to achieve the above object, the transmission method according to the present invention,

(a) receiving enhanced data having information and performing at least first error correction encoding, interleaving, and byte expansion;

(b) generating an enhanced data packet by inserting the enhanced data output in step (a) into a first data area in a transport stream packet including at least one of the first and second data areas; And

(c) performing encoding of at least N / M (where N and M are natural numbers and N <M) code rate, second error correction encoding, and trellis encoding on the enhanced data in the enhanced data packet. Characterized in that comprises a step.

The first data area in the enhanced data packet includes length information and enhanced data of the first data area, and the size of the second data area varies according to the size of the first data area.

The step (b) further includes inserting main data into the second data area, and step (c) does not perform encoding of N / M code rate on the main data.

Step (b) further includes inserting known data having a predetermined pattern in the first data area, and step (c) does not perform N / M code rate encoding on the known data. It is characterized by not.

The step (b) further includes inserting an initialization data position holder for memory initialization during the trellis encoding of the step (c) in the first data area, and the step (c) includes the initialization data position. It is characterized in that the holder is not encoded with the N / M code rate.

According to the present invention, there is provided a transmission system comprising: an E-VSB preprocessor configured to receive enhanced data having information and perform at least first error correction encoding, interleaving, and byte expansion; The header is inserted into the enhanced data output from the E-VSB preprocessor and the enhanced data is inserted into the first data area of the first and second data areas in the transport stream packet including the header. A packet generator for generating a data packet; And encoding at least N / M (where N and M are natural numbers and N <M) code rate, second error correction encoding, and trellis for the enhanced data in the enhanced data packet output from the packet generator. Characterized in that the encoder is configured to perform the encoding.

According to the present invention, if the received, demodulated, and equalized data packet is an enhanced data packet, at least trellis decoding and first error correction are performed on the enhanced data inserted into the first data region in the enhanced data packet. Performing decoding, decoding of N / M (where N and M are natural numbers and N < M) code rate; And performing at least deinterleaving and second error correction decoding on the enhanced data decoded and output in the above step.

The receiving method according to the present invention may further include detecting known data inserted into a first data area in the enhanced data packet.

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.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described. 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 certain cases, the term is arbitrarily selected by the applicant. In this case, since the meaning is described in detail in the description of the present invention, It is to be understood that the present invention should 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 receiver, and includes video and sound data.

The present invention is to transmit enhanced data or known data to improve the reception performance of a broadcast receiver while maintaining compatibility with existing VSB receivers.

In general, a transport stream (TS) packet has a fixed length of 188 bytes, and is largely composed of a header and a payload.

In this case, the payload has a variable length of 0 to 184 bytes depending on whether an adaptation field is included in the TS packet.

If no adaptation field is included, the payload of the TS packet is fixed to 184 bytes.

1A shows a structure of a TS packet without an adaptation field, and is composed of a 4-byte MPEG header and a 184-byte payload.

One byte of the 4-byte MPEG header is a sync byte, and a value of 0x47 (= 0100 0111) is assigned to MPEG-2.

The remaining 3 bytes of the MPEG header are 1 bit transport error indicator field, 1 bit payload unit start indicator field, 1 bit transport priority field, 13 bit PID field, 2 bit transport scrambling control field, 2 bit adaptation. It consists of a field control field and a 4-bit continuity counter field.

Here, whether the adaptation field is included in the TS packet can be known through the adaptation field control field.

That is, in FIG. 1A, when a problem occurs in the transport layer part, for example, a value of '1' is displayed when a packet is lost in the middle.

The payload unit start indicator field indicates a start of one packet. The payload unit start indicator field has a TS unit header in the packet when the field value is 1, and the payload size can be obtained to combine the packets.

That is, when the payload unit start indicator field value is '1', this indicates that the payload unit start indicator field is the first part of a packetized elementary stream (PES) packet. When multiple TSs form one PES, the payload unit start indicator field value is '1', and the next TS is found and combined using the continuity counter field value to form one PES packet. It becomes possible. If the payload unit start indicator field value is '0', this means that the payload unit start indicator field is at the middle or the last part of the PES packet.

The transport priority field is used to determine the priority of a transmission medium having the same PID in the same TS transmission path. The priority of a TS having this value set to 1 is high.

The PID field is an identifier for identifying a corresponding packet. For example, if the PID value is 0, the packet is recognized as a PAT.

The Transport scrambling control field indicates whether the corresponding TS is scrambling.

The Adaptation field control field indicates whether an adaptation field is included. For example, if the Adaptation field control field value is 10 or 11, this indicates that an adaptation field is included in the corresponding TS packet. In this case, 10 indicates that the payload region does not exist in the corresponding TS packet, and 11 indicates that the length of the payload region varies according to the length of the adaptation field. A value of the Adaptation field control field of 01 indicates that an adaptation field is not included in a corresponding TS packet, and 00 is a value not used.

The continuity counter field is used for TS packets having the same PID and increases by 1 for each packet. However, if the value of the Adaptation field control field is '00' or '10', this value should not be increased.

FIG. 1B illustrates a structure of a TS packet including an adaptation field, and further includes an adaptation field in the TS packet of FIG. 1A.

The adaptation field is further composed of an AF header of 2 bytes and a Stuff byte of N bytes. The AF header consists of an 8-bit AF length field and an 8-bit indicator flag field to indicate the length of the adaptation field.

That is, if an adaptation field is included in a TS packet, the payload length in the TS packet is 182-N (N is stuff byte length). For example, if the stuff byte length is 182 bytes in the TS packet, there is no payload area. If the byte length is 20 bytes, the payload area is 162 bytes.

The present invention inserts and transmits enhanced data in the stuff byte area of an adaptation field in a TS packet.

FIG. 1C illustrates an embodiment of a TS packet structure according to the present invention, and illustrates an example of inserting enhanced data into a stuff byte area of 182 bytes.

1D illustrates another embodiment of a TS packet structure according to the present invention, in which enhanced data is inserted into an N byte stuff byte area and main data is inserted into a payload area of remaining (182-N) bytes. Is showing.

In the present invention, when the known data is transmitted, the known data is also inserted into the stuff byte area and transmitted.

2 illustrates an embodiment of a digital broadcast transmission system for transmitting enhanced data and known data according to the present invention.

The digital broadcast transmission system of FIG. 2 includes an E-VSB preprocessor 111, a packet generator 112, a data randomizer 113, an E-VSB postprocessor 120, an RS encoder 131, and a data interleaver 132. ), A parity substituent 133, an RS encoder 134, a trellis encoder 135, a frame multiplexer 136, and a transmitter 140.

In the present invention configured as described above, the E-VSB preprocessor 111 performs additional error correction encoding, interleaving, null data insertion for byte expansion, etc. on the input enhanced data.

In addition, the E-VSB preprocessor 111 may insert known data (or known data position holder) having a predetermined pattern. In this case, an initialization data position holder for initializing the trellis encoder 135 may be inserted.

The data output from the E-VSB preprocessor 111 is input to the packet generator 112. The data output from the E-VSB preprocessor 111 includes at least one of preprocessed enhanced data, known data position holder (or known data), and initialization data position holder.

The packet generation unit 112 inserts a 4-byte MPEG header byte and, if necessary, a 2-byte adaptation field header into the main data and the data output from the E-VSB preprocessor 111, and thereby unites 188 bytes. In the form of a TS packet.

For convenience of description, when configuring the TS packet in the packet generation unit 112, a TS packet including data output from the E-VSB preprocessor 111 is called an enhanced data packet, and is composed of only main data. The packet will be referred to as a main data packet. In this case, the enhanced data packet and the main data packet are multiplexed in packet units according to a predefined multiplexing rule and output.

In this case, the 188-byte enhanced data packet consists of a 4-byte MPEG header, an adaptation field of 2 + N (N is stuff byte size) bytes, and a payload of 182-N bytes.

The present invention inserts enhanced data and known data position holders (or known data) into the stuff byte area in the adaptation field. If the initialization data position holder is inserted in the E-VSB preprocessor 111, the initialization data position holder is also inserted into the stuff byte area.

In this case, the payload region may or may not exist in the enhanced data packet according to the size of data inserted into the stuff byte region. For example, if the data size inserted into the stuff byte area is 182 bytes, as shown in FIG. 1C, the payload area does not exist in the enhanced data packet. If 20 bytes, the payload area has 162 bytes.

According to an embodiment of the present invention, when a payload region exists in an enhanced data packet, main data is inserted into the payload region as shown in FIG. 1D.

The data inserted into the stuff byte area may consist only of enhanced data, only known data position holders (or known data), or two data may be multiplexed. The initialization data position holder for the trellis memory described later is also included in the stuff byte area.

As such, when the data output from the E-VSB preprocessor 111 is inserted into the stuff byte area in the adaptation field, the AF header in the adaptation field indicates the length of data to be inserted into the corresponding stuff byte area. In addition, the Adaptation field control field in the MPEG header indicates a value of '10' or '11' according to the presence or absence of a payload region.

In this case, the reason why the data output from the E-VSB preprocessor 111 is inserted into the adaptation field in the TS packet and transmitted is for maintaining compatibility with the existing VSB receiver. In other words, the adaptation field is used to enable the discarding of the enhanced data packet in the existing VSB receiver.

The present invention omits the process of inserting a known data position holder (or known data) and an initialization data position holder in the enhanced data in the E-VSB preprocessor 111 according to a design scheme, and the process is performed by the packet generation unit. May be performed at 112.

The enhanced data packet and the main data packet generated by the packet generator 112 are multiplexed on a packet basis and input to the data randomizer 113. The randomizer 113 discards the MPEG sync bytes from the input data packet and randomly generates the remaining 187 bytes using pseudo random bytes generated therein and outputs them to the E-VSB post-processing unit 120. .

The E-VSB post processor 120 may include an RS parity position holder inserter 121, a data interleaver 122, an E-VSB block processor 123, a data deinterleaver 124, and an RS parity position holder remover 125. It is configured to include).

The RS parity position holder inserter 121 of the E-VSB post-processing unit 120 inserts a systematic RS parity position holder when a data packet of 187 byte units output from the data randomizer 113 is a main data packet. Holder insertion) is performed. That is, a 20-byte RS parity position holder is inserted after the 187-byte main data packet to output the 207-byte main data packet to the data interleaver 122.

On the other hand, the RS parity position holder inserter 121 performs a systematic RS parity holder insertion when the data packet of 187 byte units output from the data randomizer 113 is an enhanced data packet, or Non-systematic RS parity holder insertion is performed.

At this time, when systematic RS parity position holder insertion is performed on the enhanced data packet in the RS parity position holder inserter 121, 20 bytes of the RS parity position holder are inserted after the enhanced data packet of 187 bytes. In this case, the existing VSB receiver removes 20 bytes of RS parity located at the end of the enhanced data packet after RS decoding and discards the data bytes included in the stuff byte area in the adaptation field according to the adaptation field information.

On the other hand, if an unstructured RS parity position holder insertion is performed on the enhanced data packet in the RS parity position holder inserter 121, 20 bytes of RS are stored at a predetermined position in the packet for unstructured RS encoding to be performed later. The parity position holder is inserted, and the bytes of the enhanced data packet are inserted and output sequentially in the remaining 187 byte positions.

In this case, the predefined position of the RS parity position holder is preferably determined as an arbitrary position which is output later than the initialization data position holder among 207 bytes in the data packet as long as it is input to the data interleaver 122 or 132.

It is more preferable to perform unstructured RS parity position holder insertion on an enhanced data packet that does not contain main data at all.

The RS parity position holder inserter 121 may insert a systematic RS parity or an unstructured RS parity by performing systematic or unsystematic RS coding instead of systematic or unsystematic RS parity position holder insertion.

3 illustrates an example in which the RS parity position holder inserter 121 performs unstructured RS encoding on an enhanced data packet in units of 187 bytes.

3 illustrates a configuration of an enhanced data packet composed of 207 bytes in which RS parity is inserted into a predefined position by unstructured RS encoding when main data is not multiplexed in an enhanced data packet.

The enhanced data packet or main data packet of 207 bytes output from the RS parity position holder inserter 121 is interleaved by the data interleaver 122 and input to the E-VSB block processor 123.

The E-VSB block processor 123 performs additional encoding only on the enhanced data output from the data interleaver 122. For example, if the E-VSB preprocessor 111 extends 1 byte to 2 bytes for the enhanced data, the E-VSB block processor 123 encodes the enhanced data at a 1/2 code rate. If one byte is extended to four bytes, encoding is performed at a 1/4 code rate. The main data or the RS parity position holder (or RS parity) are bypassed without further encoding. That is, it outputs as it is without changing data. In addition, the 3-byte MPEG header and 2-byte adaptive field header are output without change. The known data position holder (or known data) and the initialization data position holder are also output as they are without changing the data. In this case, the known data position holder may be replaced with the known data generated by the E-VSB block processor 123 and output.

The data encoded, replaced, and bypassed by the E-VSB block processor 123 is input to the data deinterleaver 124, and the data deinterleaver 124 is inversely processed by the data interleaver 122 to input data. Data deinterleaving is performed on the RS parity position holder remover 125.

The RS parity position holder remover 125 is a 20-byte RS parity position holder (or RS parity) added by the RS parity position holder inserter 121 for operation of the data interleaver 122 and the data deinterleaver 124. ). If the systematic RS parity position holder is inserted into the input data, the last 20 bytes of RS parity position holders are removed from the 207 bytes. If the systematic RS parity position holder is inserted, the unsystematic RS encoding is performed among 207 bytes. To remove the inserted 20 byte RS parity position holders.

The data packet from which the RS parity position holder (or RS parity) has been removed from the RS parity position holder remover 125 is input to the RS encoder 131. The RS encoder 131 performs a systematic RS encoding or an unstructured RS encoding on the input data packet, adds 20 bytes of RS parity, and outputs the RS to the data interleaver 132.

That is, the RS encoder 131 performs systematic RS encoding if the input data is a main data packet, and outputs the data to the data interleaver 132 by performing systematic RS encoding or unsystematic RS encoding if the input data is a main data packet.

The data interleaver 132 outputs the data packet to which the RS parity is added by the systematic RS encoding or the unstructured RS encoding to the parity substituter 133 and the RS encoder 134.

On the other hand, in order to make the output data of the trellis encoder 135 located at the rear end of the parity substituent 133 into known data defined by mutual appointment on the transmitting / receiving side, the memory in the trellis encoder 135 is first changed. Initialization is required. That is, before the input known data string is trellis encoded, the memory in the trellis encoder 135 must be initialized.

At this time, the start of the known data string input is the initialization data position holder, not the actual known data. Accordingly, before the input known data string is trellis encoded, trellis memory initialization data for initializing the input of the trellis encoder 135 to the state of the past memory is generated and replaced with the corresponding initialization data position holder. The process is necessary. This is to ensure backward compatibility with existing VSB receivers.

In this case, the trellis memory initialization data is generated by determining a value thereof according to the memory state of the trellis encoder 135. In addition, it is necessary to recalculate the RS parity due to the influence of the replaced trellis memory initialization data and replace the RS parity output from the data interleaver 132.

Accordingly, the RS encoder 134 receives an enhanced data packet including an initialization data position holder to be replaced with initialization data from the data interleaver 132, and trellis memory initialization data from the trellis encoder 135. Get input. The initialization data position holder of the input enhanced data packet is replaced with the initialization data. Subsequently, after removing the RS parity added to the enhanced data packet replaced with the initialization data, RS encoding is performed to calculate RS parity, and the calculated RS parity is output to the parity substituent 133. Then, the parity substituent 133 selects the output of the data interleaver 132 for the data in the enhanced data packet, and selects the output of the RS encoder 134 for the data in the enhanced data packet to the trellis encoder 135. Output

If the RS encoder 131 performs unsystematic RS encoding on the enhanced data packet, the RS encoder 134 also performs unsystematic RS coding. In contrast, if the RS encoder 131 performs systematic RS encoding on the enhanced data packet, the RS encoder 134 also performs systematic RS encoding.

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 133 selects data and RS parity output from the data interleaver 132 and transmits the same. Output to release release unit 135.

The trellis encoder 135 converts the data in units of bytes into symbol units, performs 12-way interleaving, trellis-encodes the output, and outputs the result to the frame multiplexer 136.

The frame multiplexer 136 inserts field sync and segment sync into the output of the trellis encoder 135 and outputs the sync to the transmitter 140.

The transmitter 140 includes a pilot inserter 141, a VSB modulator 142, and an RF up-converter 143. Since the transmitter 140 has the same role as a conventional VSB transmitter, detailed description thereof will be omitted.

Meanwhile, when the packet generator 112 multiplexes the enhanced data packet and the main data packet and outputs the multiplexed data group and the main data packet including a plurality of consecutive enhanced data packets, the packet generator 112 may output the multiplexed data group and the main data packet.

In the present invention, the data group is layered into three parts, which is called a head, a body, and a tail area. That is, after the data interleaving, the first portion of the enhanced data group is called a head, the middle portion is a body, and the last portion is a tail. In this case, the body part is allocated to include at least a part or all of an area in which enhanced data in the data group is continuously output based on after data interleaving. In this case, the body portion may include an area in which enhanced data is discontinuously output.

In this case, as described above, the enhanced data packet included in the data group may perform unsystematic RS coding or systematic RS coding.

4 illustrates a data structure before and after interleaving to which an unstructured RS encoding is applied to an enhanced data packet. FIG. 4A illustrates a data structure before data interleaving, and FIG. 4B shows a data structure after data interleaving.

That is, since the data interleaver operates periodically in units of 52 packets, FIG. 4 illustrates a case where 52 times five enhanced data packets of 52 form a data group and non-systematic RS encoding is applied to each enhanced data packet in the data group. It is an example.

In this case, based on each enhanced data packet (or segment), enhanced data and RS parities are located after a 3-byte MPEG header and a 2-byte adaptation field header.

FIG. 4B is a data configuration when data interleaving FIG. 4A. In FIG. 4B, the data group is divided into three parts. As a result, the head is first outputted from the rear end of the data interleaver and the body is outputted last. The part is named tail.

At this time, the data group is hierarchized and divided into a plurality of regions, for example, a head, a body, and a tail region, for different purposes. That is, in FIG. 4B, 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, when a system that can insert and transmit known data into the enhanced data and periodically inserts a long known data string continuously into the enhanced data, the enhanced data is not mixed with the main data based on the order of the data interleaver output stage. It is possible to put in the area. That is, as shown in FIG. 4B, it is possible to periodically insert known data of a predetermined length into the body region. However, it is difficult to periodically insert known data into the head / tail area and also to insert long known data continuously. At this time, at the beginning of the known data sequence, an initialization data position holder for initializing the memory in the trellis encoder is allocated.

FIG. 5 illustrates a data structure before and after interleaving to which an enhanced data packet is applied by systematic RS encoding. FIG. 5A shows a data structure before data interleaving, and FIG. 5B shows a data structure after data interleaving.

That is, in FIG. 5, since the data interleaver operates periodically in units of 52 packets, 5 times multiple enhanced data packets of 52 form a data group, and systematic RS encoding is applied to each enhanced data packet in the data group. It is seen.

FIG. 5B is a data structure when data interleaving FIG. 5A. Similarly to FIG. 4B, known data having a predetermined length is inserted into the body region. In this case, the initialization data position holder must be output before the RS parity in the data interleaver, and the position where the known data can be inserted can be limited because the position of the RS parity is fixed.

FIG. 6 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 and restoring original data.

The digital broadcast reception system of FIG. 6 includes a tuner 601, a demodulator 602, an equalizer 603, a known data detector 604, an E-VSB block decoder 605, a data deinterleaver 606, and an RS decoder. 607, a data de-randomizer 608, an E-VSB data deformatter 609, and an E-VSB data processor 610.

That is, the tuner 601 tunes the frequency of a specific channel, down-converts the intermediate frequency (IF) signal, and outputs the demodulator 602 and the known data detector 604.

The demodulator 602 performs automatic gain control, carrier recovery, and timing recovery on the input IF signal to form a baseband signal and outputs the same to the equalizer 603 and the known data detector 604.

The equalizer 603 compensates the distortion on the channel included in the demodulated signal and outputs it to the E-VSB block decoder 605.

At this time, the known data detection unit 604 detects the position of the known data inserted by the transmitting side from the input / output data of the demodulator 602, that is, the data before the demodulation is performed or the data after the demodulation is performed. The known data string generated at the position is outputted to the demodulator 602, the equalizer 603, and the E-VSB block decoder 605. In addition, the known data detection unit 604 enhances the data to be distinguished by the E-VSB block decoder 605 on the receiving side from the enhanced data that has been further encoded and the main data that has not undergone the additional encoding. Information for knowing the starting point of the block of the code encoder is output to the E-VSB block decoder 605.

The demodulator 602 can improve the demodulation performance by using the known data at the time of timing recovery or carrier recovery, and can equalize the equalization performance using the known data in the equalizer 603 as well. In addition, the equalization performance may be improved by feeding back the decoding result of the E-VSB block decoder 605 to the equalizer 603.

On the other hand, if the data input from the equalizer 603 to the E-VSB block decoder 605 is enhanced data in which both additional coding and trellis coding are performed on the transmitting side, the E-VSB block decoder 605 transmits. On the other hand, the trellis decoding and the additional decoding are performed. If the trellis encoding is performed without additional encoding, only trellis decoding is performed.

That is, if the input data is main data, the E-VSB block decoder 605 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 605 decodes the data encoded by the E-VSB block processing unit and the trellis coding unit of the transmission system to perform a hard decision value or a soft decision value. Outputs

In the digital broadcast transmission system shown in FIG. 1, concatenated encoding using a plurality of error correction codes is performed on enhanced data. In this case, an encoder (not shown) in the E-VSB preprocessor 111 may be an external code, and the E-VSB block processor 123 and the trellis encoder 135 may 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.

Therefore, the E-VSB block decoder 605 may output a hard decision value for the enhanced data, and output a soft decision value if necessary.

That is, the E-VSB block decoder 605 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.

The output of the E-VSB block decoder 605 is input to the data deinterleaver 606. The data deinterleaver 606 performs the reverse process of the data interleaver on the transmitting side and outputs the data to the RS decoder 607. The RS decoder 607 performs systematic RS decoding when the received packet is a main data packet, and performs systematic RS decoding or unsystematic RS decoding when the enhanced packet is an enhanced data packet. That is, if the transmission system performs systematic RS encoding on the enhanced data packet and transmits it, systematic RS decoding is performed.

After RS decoding is performed in the RS decoder 607, the data packet from which the RS parity byte has been removed is input to the data de-randomizer 608.

The data de-randomizer 608 generates the same pseudo random bytes as the renderer of the transmission system, performs bitwise XOR (exclusive OR) with the data packet output from the RS decoder 607, and then synchronizes the MPEG. A byte is inserted in front of every packet and output in units of 188 byte packets.

The output of the data derandomizer 608 is input to the main MPEG decoder (not shown) and to the E-VSB data deformatter 609. The main MPEG decoder decodes only packets corresponding to the main MPEG. This is because enhanced data packets are not used for decoding in the main MPEG decoder and are ignored because they have PIDs that are not used by existing VSB receivers, or null or reserved PIDs.

However, the soft decision value of the enhanced data is difficult to XOR with a pseudo random bit. Therefore, data to be output to the main MPEG decoder is hard-determined according to the sign of the soft decision value as described above, and then output by XORing the pseudo random bit. That is, if the sign of the soft decision value is positive, it is determined as 1, and if it is negative, it is determined as 0, and this decision value is XORed with the pseudo random bit.

As described above, the E-VSB data processor 610 needs a soft decision to improve performance when decoding the error correction code, so that the data de-randomizer 608 outputs a separate output for the enhanced data. And output to the E-VSB data deformatter 609. In one embodiment, the data de-randomizer 608 outputs by inverting 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 when 0 Output as is.

The reason for changing the sign of the soft decision value when the pseudo random bit is 1 in the above explanation is that the output data bit is reversed when the pseudo random bit XORed to the input data bit in the randomizer of the transmission system is 1. That is, 0 XOR 1 = 1 and 1 XOR 1 = 0.

In other words, when the pseudo random bit generated by the data derandomizer 608 is 1, when the XOR of the hard decision value of the enhanced data bit is reversed, the soft decision value is output when the soft decision value is output. The sign of the value is reversed.

The E-VSB data deformatter 609 does not output the input data to the E-VSB data processor 610 when the input data is a main data packet. If the input data is an enhanced data packet, the MPEG header byte, known data, adaptation field header, main data, etc. included in the enhanced data packet are removed and then output to the E-VSB data processor 610.

The E-VSB data processor 610 removes null data inserted in the byte expansion process according to the reverse process of the E-VSB preprocessor 111 on the sender side, and deinterleaves the error correction decoding process. After each output.

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.

According to the digital broadcasting system and the processing method according to the present invention as described above, the enhanced data is subjected to an additional encoding process, and such additional data such as the enhanced data and known data are included in the adaptation field in the transport stream packet. In this case, transmission of additional data through a channel is advantageous in that it is resistant to errors and compatible with existing VSB receivers. 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 particular, 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.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present 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 (20)

(a) receiving enhanced data having information and performing at least first error correction encoding, interleaving, and byte expansion; (b) generating an enhanced data packet by inserting the enhanced data output in step (a) into a first data area in a transport stream packet including at least one of the first and second data areas; And (c) performing encoding of at least N / M (where N and M are natural numbers and N <M) code rate, second error correction encoding, and trellis encoding on the enhanced data in the enhanced data packet. The transmission method comprising the step. The method of claim 1, wherein step (b) Inserting a 4-byte header into the input enhanced data and inserting the enhanced data into the first data region of the 184-byte data region in the transport stream packet including the header to generate an enhanced data packet Transmission method. The method of claim 1, wherein step (b) And multiplexing the main data packet into which the main data is inserted into the second data area of 184 bytes and the enhanced data packet. The method of claim 1, And a first data area in the enhanced data packet includes length information of the first data area and enhanced data, and a size of the second data area depends on the size of the first data area. The method of claim 4, wherein Step (b) further includes inserting main data into the second data area, In the step (c), the main data is not encoded with an N / M code rate. The method of claim 4, wherein Step (b) further includes inserting known data having a predefined pattern in the first data area, In the step (c), the N / M code rate is not encoded for the known data. The method of claim 4, wherein The step (b) further includes inserting an initialization data position holder for memory initialization during the trellis encoding of the step (c) in the first data area. And the step (c) does not perform encoding of an N / M code rate on the initialization data position holder. The method of claim 1, wherein step (b) And if the first data area is included in the data area of the transport stream packet, indicating that the first data area is included in a header in the transport stream packet. The method of claim 1, And in the step (c), the second error correction encoding is a systematic RS encoding. The method of claim 1, And the second error correction encoding in step (c) is unsystematic RS encoding. An E-VSB preprocessor that receives enhanced data having information and performs at least first error correction encoding, interleaving, and byte expansion; The header is inserted into the enhanced data output from the E-VSB preprocessor and the enhanced data is inserted into the first data area of the first and second data areas in the transport stream packet including the header. A packet generator for generating a data packet; And Encoding of at least N / M (where N and M are natural numbers and N <M) code rate, second error correction encoding, and trellis encoding for the enhanced data in the enhanced data packet output from the packet generator; And a coding unit configured to perform the encoding. The method of claim 11, And a first data area in the enhanced data packet includes length information and enhanced data of the first data area, and a size of the second data area depends on the size of the first data area. The method of claim 12, And the packet generator inserts main data into the second data area, and the encoder does not perform N / M code rate encoding on the main data. The method of claim 12, And the packet generator inserts known data having a predetermined pattern in the first data area, and the encoder does not perform N / M code rate encoding on the known data. The method of claim 12, The packet generator inserts an initialization data position holder for memory initialization during trellis encoding of the encoder in the first data region, and the encoder does not perform N / M code rate encoding on the initialization data position holder. No transmission system. The method of claim 11, And the second error correction encoding of the encoder is a systematic RS encoding for generating systematic RS parity. The method of claim 11, And the second error correcting encoding of the encoder is unsystematic RS encoding for generating unsystematic RS parity. (a) if the received, demodulated and equalized data packet is an enhanced data packet, at least trellis decoding, first error correcting decoding, N / M on the enhanced data inserted in the first data region in the enhanced data packet; (Where N and M are natural numbers and N < M) performing decoding of a code rate; And and (b) performing at least deinterleaving and second error correction decoding on the enhanced data decoded and output in step (a). The method of claim 18, And detecting known data inserted into a first data area in the enhanced data packet. The method of claim 18, The data area in the enhanced data packet includes a first data area into which at least one of enhanced data and known data is inserted, and a second data area into which main data is inserted. 1 A receiving method, characterized in that it depends on the size of the data area.

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