KR20070120790A - Digital broadcasting system and processing method - Google Patents

Abstract

A digital broadcasting system and a processing method thereof are provided to transmit additional data such as enhanced data and known data in a first enhanced data packet form after inserting the additional data to a payload region within a TS(Transport Stream) and transmit the additional data in a second enhanced data packet form after inserting the additional data to an adaptation field within the TS so that the digital broadcasting system can be strong against an error during transmission of the additional data through a channel and be compatible with an existing VSB(Vestigial Side Band) receiver. A transmitting method comprises the following steps of: receiving enhanced data with information and performing at least one error correction encoding, interleaving, and bite extension; generating and outputting the outputted enhanced data into one of a first enhanced data packet and a second enhanced data packet; multiplexing and outputting the first and second enhanced data packets and a main data packet according to a predefined multiplexing rule; and performing at least encoding of an N/M coding rate, wherein N and M are natural numbers and N is smaller than M, second error correction encoding, and Trellis encoding for enhanced data within the first and second enhanced data packets multiplexed and outputted.

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.

3A and 3B illustrate data group configurations before and after a data interleaver according to an embodiment of the present invention.

4A and 4B illustrate a data group configuration before and after a data interleaver according to another embodiment of the present invention.

5 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.

Also, in poor channel environment, the reception performance of the existing 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 and outputting the enhanced data output in step (a) as one of a first enhanced data packet and a second enhanced data packet;

(c) multiplexing and outputting the first and second enhanced data packets and the main data packet according to a predefined multiplexing rule; And

(d) encoding at least N / M (where N and M are natural numbers and N < M) code rate for the enhanced data in the multiplexed output first and second enhanced data packets, and correcting the second error And encoding and trellis encoding.

In the step (b), a 4-byte header is inserted into the input enhanced data, and the enhanced data packet is inserted by inserting the enhanced data into the first data region of 184 bytes in the transport stream packet including the header. It characterized in that to generate.

In the step (b), a 4-byte header is inserted into the enhanced data to be input, and the enhanced data is inserted into the second data area of the first and second data areas of 184 bytes in the transport stream packet including the header. And inserting main data into the remaining first data area to generate a second enhanced data packet.

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

The step (b) further includes inserting known data having a predefined pattern in a first data region in the first enhanced data packet or in a second data region in the second enhanced data packet, wherein ( Step d) is characterized in that the encoding of the N / M code rate is not performed for the known data.

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; Inserting a header into the enhanced data output from the E-VSB preprocessor, and inserts the enhanced data into the first data area of the first and second data areas in the transport stream packet including the header to the first A packet generation unit generating an enhanced data packet or inserting the enhanced data into a second data area to generate a second enhanced data packet and then multiplexing the main data packet and outputting the second data packet; And encoding at least interleaving, N / M (where N and M are natural numbers and N < M) code rate for the enhanced data in the first and second enhanced data packets output from the packet generator. And an encoder for performing error correction encoding and trellis encoding.

The interleaved data in the encoder is in the form of a data group divided into hierarchical first, second and third regions, and the packet generator includes first and second enhanced data in the first and third regions of the interleaved data. The first and second enhanced data packets may be generated and multiplexed so that data in the packet is included and only the data in the first enhanced data packet is included in the second area.

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

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 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 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 generally composed of a header, which is an information area, and a payload, which is a data area.

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 determines the priority of a transmission medium having the same PID in the TS transmission path. The TS having the value set to 1 has a high priority.

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.

In the present invention, for convenience of description, a TS packet structure that does not include an adaptation field is called a first TS packet (or a first data format), and a TS packet structure that includes an adaptation field is referred to as a second TS packet (or second data). Format). That is, the data area of the second TS packet is divided into an adaptation field area and a payload area.

The present invention is to insert and transmit the enhanced data and / or known data in the payload region of the first TS packet or inserted into the stuff byte region of the adaptation field in the second TS packet.

If the enhanced and / or known data is inserted into the payload region of the first TS packet and transmitted, the enhanced and / or known data and the main data are distinguished by PID values in the MPEG header. That is, the enhanced data and / or known data use all of the 184 byte payload areas in one TS packet. Similarly, the main data uses all of the 184 byte payload areas in one TS packet. In other words, the enhanced data (or known data) and the main data are not mixed in one TS packet.

On the other hand, when the enhanced and / or known data is inserted into the adaptive field region in the second TS packet and transmitted, the enhanced and / or known data and the main data are distinguished by the adaptive field control value in the MPEG header. In this case, the payload region in the second TS packet may or may not exist depending on the data length inserted into the adaptation field region. If the data length inserted into the adaptation field region is smaller than 182 bytes, the payload region exists in the second TS packet. In this case, main data may be inserted into the payload region. That is, in the case of the second TS packet, enhanced data (or known data) and main data may be multiplexed in one TS packet.

In the present invention, for convenience of description, a first TS packet generated by inserting enhanced data and / or known data into a payload region divided by PID values is called a first enhanced data packet. The second TS packet generated by inserting the enhanced data and / or known data into the adaptive field region divided by the adaptive field control value will be referred to as a second enhanced data packet. A first TS packet generated by inserting main data into a payload region divided by PID values will be referred to as a main data packet.

FIG. 1C illustrates an embodiment of a structure of a first enhanced data packet according to the present invention, in which an adaptation field region does not exist in the data region and enhanced data is inserted into a payload region.

FIG. 1D illustrates an embodiment of a second enhanced data packet structure according to the present invention, in which a data area is divided into an adaptation field and a payload area, and enhanced data is inserted into the adaptation field. The main data is inserted.

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, and the like on the 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. In this case, 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.

That is, the packet generator 112 receives the main data and the output data of the E-VSB preprocessor 111 to generate an enhanced data packet and a main data packet in units of 188 bytes, and in the case of the enhanced data packet The first enhanced data packet having the structure as shown in FIG. 1C is generated or the second enhanced data packet having the structure as shown in FIG. 1D is generated.

In this case, whether to generate the first enhanced data packet or the second enhanced data packet may be determined according to a data type, a multiplexing rule, and characteristics of each region in a data group to be described later. That is, one transmission frame may include only first enhanced data packets, only second enhanced data packets, and may include both first and second enhanced data packets. In this case, the main data packet may or may not be included in the transmission frame.

The first enhanced data packet in units of 188 bytes includes a 4-byte MPEG header and a payload of 184 bytes, and the payload region includes enhanced data, a known data position holder (or known data), and an initialization data position holder. At least one of is inserted.

The second enhanced data packet in units of 188 bytes includes an MPEG header of 4 bytes, an adaptation field of 2 + N (N is stuff byte size) bytes, and a payload of 182-N bytes. In this case, at least one of enhanced data, known data position holder (or known data), and initialization data position holder is inserted into the stuff byte area of the adaptation field, and main data is inserted into the payload area.

When the packet generator 112 inserts the output data of the E-VSB preprocessor 111 into the stuff byte area in the adaptation field to generate the second enhanced data packet, the AF header in the adaptation field corresponds to the corresponding stuff byte. The length of data to be inserted into the area is displayed. In addition, the adaptation field control value in the MPEG header is marked with '10' or '11' according to the presence or absence of the payload region.

In addition, the packet generator 112 may generate a main data packet composed only of main data. The main data packet has the same structure as the first enhanced data packet, and main data is inserted into the payload region instead.

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 first and second enhanced data packets and the main data packet generated by the packet generator 112 are multiplexed in packet units 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.

On the contrary, when the 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 parity at a predetermined position in the packet for unsystematic RS encoding to be performed later. The position holder is inserted, and the bytes of the enhanced data packet are inserted and output in order at 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 unstructured RS encoding instead of systematic or unstructured RS parity position holder insertion.

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 the plurality of 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 data interleaving, the first output part of the data group is called a head, the middle output part is a body, and the last output part is called 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. The body portion may include a region 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.

3 illustrates an example of configuring a data group including 260 first enhanced data packets. FIG. 3A illustrates a data configuration before data interleaving, and FIG. 3B illustrates a data configuration after data interleaving. In this case, unsystematic RS coding is performed on the first enhanced data packets.

Based on each packet (or segment) in FIG. 3A, enhanced data, known data position holder (or known data), initialization data position holder, RS parity position holder (or RS parity) are added after the 3-byte MPEG header. Located. Since Fig. 3A is a data configuration before data interleaving, one byte of the MPEG sync byte has been discarded in the data renderer 113, and 20 bytes of RS parity position holders (or RS parity) are added.

In this case, the positions of the enhanced data, the predetermined known data, the initialization data position holder, and the RS parities are different for each packet in the data group.

FIG. 3B is a data configuration when data interleaving of FIG. 3A. In dividing the data group into three parts, as a result, a head is first outputted from the rear end of the data interleaver, a body is outputted at the middle, and the body is finally outputted. 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. 3B, the region corresponding to the body is composed of enhanced data without interfering with main data in the middle, and thus shows more robust reception performance. The enhanced data of the head and tail regions 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, it is possible to periodically insert known data of a predetermined length into the body region as shown in FIG. 3B. 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.

4 illustrates an example of configuring a data group including 260 first enhanced data packets and a plurality of second enhanced data packets. FIG. 4A illustrates a data configuration before data interleaving, and FIG. 4B illustrates a data configuration after data interleaving. Is showing. In this case, unsystematic RS coding is performed on the first and second enhanced data packets.

4A is broadly divided into 401, 402, and 403 regions based on data packets input to the data interleaver. The 401 area consists of 52-L main data packets and L second enhanced data packets, the 402 area consists only of 260 first enhanced data packets, and the 403 area includes M second enhanced data packets. It consists of a data packet and 52-M main data packets.

It can be seen that known data is inserted into the adaptation field in the second enhanced data packet in the regions 401 and 403, and the length of the adaptation field into which the known data is inserted is different for each packet. In addition, an initialization data position holder is included in the adaptation field when an initialization data position holder is required. The initialization data position holder is not included in the region 401, and the initialization data position holder is included in the 403 region.

As shown in FIG. 4A, when data interleaving is performed by inserting known data into a payload in a first enhanced data region and an adaptation field in a second enhanced data packet, a known period of known data is arranged in the head and tail regions as shown in FIG. 4B. This form is inserted periodically.

That is, when the data configuration of FIG. 4A passes through the data interleaver, the head, body, and tail regions are divided into the head, body, and tail regions, as shown in FIG. 4B. Has mixed main data. In addition, in the case of FIG. 4B, a long known data column is periodically inserted into the body region, and a short known data column is periodically inserted into the head / tail region. In this case, the known data string inserted in the body region is an interleaved known data string inserted in the payload region of the first enhanced data packet, and the short known data string inserted in the head / tail region is included in the first enhanced data packet. A known data sequence inserted and interleaved in the payload region and the adaptation field region in the second enhanced data packet.

Comparing the data configurations of FIGS. 3B and 4B, it can be seen that known data of a certain length is repeatedly inserted in the head / tail region of FIG. 4B. This can be very helpful for receiving data in the head and tail areas using known data at the receiver. Therefore, multiplexing the second enhanced data packet at the front and the rear of the plurality of consecutive first enhanced data packets helps the receiver to receive the enhanced data even in a channel distortion or channel change environment. In particular, it greatly helps to receive enhanced data in the head and tail areas after interleaving.

FIG. 5 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. 5 includes a tuner 501, a demodulator 502, an equalizer 503, a known data detector 504, an E-VSB block decoder 505, a data deinterleaver 506, and an RS decoder. 507, a data de-randomizer 508, a main data processor 509, an enhanced data deformatter 510, and an enhanced data processor 511.

That is, the tuner 501 tunes the frequency of a specific channel, down-converts the intermediate frequency (IF) signal, and outputs the demodulator 502 and the known data detector 504.

The demodulator 502 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 503 and the known data detector 504.

The equalizer 503 compensates for the distortion on the channel included in the demodulated signal and outputs it to the E-VSB block decoder 505.

At this time, the known data detector 504 detects the position of the known data inserted by the transmitter from the input / output data of the demodulator 502, that is, data before demodulation or data after demodulation is performed, and together with the position information. The known data string generated at the position is output to the demodulator 502, the equalizer 503, and the E-VSB block decoder 505. In addition, the known data detection unit 504 enhances the data by the E-VSB block decoder 505 on 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 505 outputs information for knowing the starting point of the block of the DE coder.

The demodulator 502 can improve demodulation performance by using the known data during timing recovery or carrier recovery, and can equalize performance using the known data in the equalizer 503 as well. In addition, the equalization performance may be improved by feeding back the decoding result of the E-VSB block decoder 505 to the equalizer 503.

On the other hand, if the data input from the equalizer 503 to the E-VSB block decoder 505 is enhanced data in which both additional coding and trellis coding are performed on the transmitting side, the E-VSB block decoder 505 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. In the E-VSB block decoder 505, RS parity, known data, and MPEG header data are treated as main data, and only trellis decoding is performed.

In this case, if the input data is main data, the E-VSB block decoder 505 may perform a 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 505 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.

Accordingly, the E-VSB block decoder 505 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 505 outputs one of a soft decision value and a hard decision value for enhanced data according to the overall system design or condition, and outputs the main data, known data, RS parity, and MPEG header. Output a hard decision value.

The output of the E-VSB block decoder 505 is input to the data deinterleaver 506. The data deinterleaver 506 performs an inverse process of the data interleaver on the transmitting side and outputs the data to the RS decoder 507. The RS decoder 507 performs systematic RS decoding if the received packet is a main data packet, and performs systematic RS decoding or unstructured RS decoding if the received 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. If the transmission system performs unsystematic RS encoding, the systematic RS decoding is performed.

After RS decoding is performed in the RS decoder 507, a data packet from which an RS parity byte has been removed is input to the data derandomizer 508.

The data de-randomizer 508 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 507, 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 508 is input to the main data processor 509 and to the enhanced data deformatter 510. At this time, the soft decision value of the enhanced data is difficult to XOR with a pseudo random bit. Therefore, the data to be output to the main data processing unit 509 is hard-determined according to the sign of the soft decision value as described above, and then outputted 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.

The main data processor 509 decodes only the main data packet corresponding to the main MPEG.

In this case, if the input data packet is the first enhanced data packet, the main data processing unit 509 may be configured as the PID in the first enhanced data packet is a PID not used by an existing VSB receiver, or a null PID or a reserved PID. Discard the first enhanced data packet without decoding it. In addition, if the input data packet is the second enhanced data packet, the main data processing unit 509 regards the enhanced data and / or known data inserted in the adaptation field as a stuff byte and discards it without decoding. Accordingly, the main data processor 509 may perform decoding only on the main data.

This means that the existing VSB receiver can discard the first and second enhanced data packets without decoding and receive only main data.

As described above, the enhanced data processor 510 needs a soft decision to improve performance when decoding the error correction code. Thus, the data de-randomizer 508 generates a separate output for the enhanced data and enhances it. Output to the data deformatter 510. In one embodiment, the data derandomizer 508 outputs the sign of the soft decision value in reverse when the pseudo random bit to be XORed with respect to the soft decision value of the enhanced data bit is 1, and in the case of 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 de-randomizer 508 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 enhanced data deformatter 510 does not output to the enhanced data processor 511 if the input data is a main data packet. If the input data is the first enhanced data packet, the MPEG header byte, known data, and the like included in the first enhanced data packet are removed and then output to the enhanced data processor 511. In addition, if the input data is the second enhanced data packet, the MPEG header byte, known data, adaptation field header, main data, etc. included in the second enhanced data packet are removed and then output to the enhanced data processor 511.

The enhanced data processor 511 removes null data inserted in the byte expansion process according to the reverse process of the E-VSB preprocessor 111 on the sender from the input data, and deinterleaves the error correction decoding process. After 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, the additional data such as the enhanced data, known data is a plurality of transport stream (TS) packet In other words, when additional data is transmitted through a channel by inserting into a payload region within a TS packet and transmitting it in the form of a first enhanced data packet or by inserting into an adaptation field within a TS packet and transmitting into a second enhanced packet. It has the advantage of being error-resistant 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 noise channel more than a 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 (23)

(a) receiving enhanced data having information and performing at least first error correction encoding, interleaving, and byte expansion; (b) generating and outputting the enhanced data output in step (a) as one of a first enhanced data packet and a second enhanced data packet; (c) multiplexing and outputting the first and second enhanced data packets and the main data packet according to a predefined multiplexing rule; And (d) encoding at least N / M (where N and M are natural numbers and N < M) code rate for the enhanced data in the multiplexed output first and second enhanced data packets, and correcting the second error And encoding and trellis encoding. The method of claim 1, wherein step (b) Inserting a 4-byte header into input enhanced data and inserting enhanced data into a first data region of 184 bytes in the transport stream packet including the header to generate a first enhanced data packet Transmission method to do. The method of claim 1, wherein step (b) Inserts a 4-byte header into the enhanced data to be input, inserts the enhanced data into a second data area of the first and second data areas of 184 bytes in the transport stream packet including the header, and inserts the remaining data into the remaining first data. And transmitting the main data into the data area to generate a second enhanced data packet. The method of claim 3, wherein The second data area in the second enhanced data packet includes length information and enhanced data of the second data area, and the size of the first data area varies according to the size of the second data area. . The method of claim 1, In the step (c), the main data packet comprises a header of 4 bytes and a first data area of 184 bytes into which main data is inserted. The method of claim 1, In the step (d), the N / M code rate encoding is not performed on the main data in the main data packet and the main data in the second enhanced data packet. The method of claim 1, The step (b) further includes inserting known data having a predetermined pattern into a first data region in the first enhanced data packet or a second data region in the second enhanced data packet. In the step (d), the N / M code rate is not encoded for the known data. The method of claim 1, Step (b) is an initialization data location holder for initializing a memory during trellis encoding of step (d) in a first data area in the first enhanced data packet or a second data area in a second enhanced data packet. Further comprising inserting the In the step (d), the N / M code rate is not encoded for the initialization data position holder. The method of claim 1, wherein step (b) And indicating whether a second data area is included in a header in the first and second enhanced data packets. The method of claim 1, And interleaving the multiplexed first and second enhanced data packets and the main data packet and outputting the data in a data group form divided into first, second, and third regions. Steps (b) and (c) include data in the first and second enhanced data packets in the first and third regions of the interleaved data, and only data in the first enhanced data packets in the second region. And generating and multiplexing the first and second enhanced data packets as much as possible. An E-VSB preprocessor configured to receive enhanced data having information and perform at least first error correction encoding, interleaving, and byte expansion; Inserting a header into the enhanced data output from the E-VSB preprocessor, and inserts the enhanced data into the first data area of the first and second data areas in the transport stream packet including the header to the first A packet generation unit generating an enhanced data packet or inserting the enhanced data into a second data area to generate a second enhanced data packet and then multiplexing the main data packet and outputting the second data packet; And At least interleaving, N / M (where N and M are natural numbers and N < M) code rate encoding and a second error for the enhanced data in the first and second enhanced data packets output from the packet generator And a coding unit for performing corrective coding and trellis coding. The method of claim 11, wherein the packet generation unit Inserting a 4-byte header into input enhanced data and inserting enhanced data into a first data region of 184 bytes in a transport stream packet including the header to generate a first enhanced data packet Transmission system. The method of claim 11, wherein the packet generation unit Inserts a 4-byte header into the enhanced data to be input, inserts the enhanced data into a second data region of the first and second data regions of 184 bytes in the transport stream packet including the header, and adds the remaining first data. And a second enhanced data packet by inserting main data into the data area. The method of claim 13, The second data area in the second enhanced data packet includes length information and enhanced data of the second data area, and the size of the first data area depends on the size of the second data area. . The method of claim 11, The interleaved data in the encoder is in the form of a data group divided into layered first, second, and third regions. The packet generator may include data in the first and second enhanced data packets in the first and third regions of the interleaved data, and include first and second data in the first and second enhanced data packets. A transmission system characterized by generating and multiplexing an enhanced data packet. The method of claim 11, wherein the encoder And N / M code rate encoding is not performed on the main data in the main data packet and the main data in the second enhanced data packet. The method of claim 11, The packet generation unit inserts known data having a predetermined pattern into a first data area in the first enhanced data packet or a second data area in a second enhanced data packet, and the encoding unit is N for the known data. / M code rate is not performed. The method of claim 12, The packet generator inserts an initialization data position holder for initializing a memory during trellis encoding of the encoder into a first data region in the first enhanced data packet or a second data region in the second enhanced data packet, And an encoding unit does not perform encoding of an N / M code rate on the initialization data position holder. If the received, demodulated and equalized data packet is a first enhanced data packet, at least trellis decoding, first error correction decoding, N / N on enhanced data inserted into a first data region in the first enhanced data packet. Performing decoding of M (where N and M are natural numbers and N < M) code rate; If the received, demodulated and equalized data packet is a second enhanced data packet, at least trellis decoding, first error correcting decoding, N / M () for enhanced data inserted into a second data region in the enhanced data packet Where N and M are natural numbers and N < M) decoding the code rate; And And performing at least deinterleaving and second error correction decoding on the enhanced data decoded and output in the step. The method of claim 19, Estimating known data inserted in a first data area in the first enhanced data packet and known data inserted in a second data area in a second enhanced data packet. The method of claim 19, And classifying the first enhanced data packet by the PID of the input data packet and classifying the second enhanced data packet by the presence or absence of the second data area of the input data packet. Way. The method of claim 19, And a data area of the first enhanced data packet includes only a first data area into which at least one of enhanced data and known data is inserted. The method of claim 19, The data area in the second enhanced data packet includes a first data area into which main data is inserted and a second data area into which at least one of enhanced data and known data is inserted. Is dependent on the size of the second data area.

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