KR101263004B1 - Digital broadcasting system and method thereof - Google Patents

Abstract

A digital broadcast system is disclosed. The system includes a transport stream generating apparatus for generating a dual transport stream by multiplexing a normal stream and a turbo stream, inserting an additional reference signal into the dual transport stream, and performing signal processing on the turbo stream to reconstruct the dual transport stream. And a transmitter for outputting the reconstructed dual transport stream and a receiver for receiving the reconstructed dual transport stream and decoding the normal stream and the turbo stream, respectively, to restore normal stream data and turbo stream data. Accordingly, the reception performance of the digital broadcast signal can be efficiently improved.

Digital Broadcast, Dual Transport Stream, Turbo Stream, Additional Reference Signal

Description

Digital broadcasting system and method thereof

The present invention relates to a digital broadcasting system using a dual transport stream including a normal stream and a turbo stream for digital broadcasting, and more particularly, to a receiver and a method for improving reception performance of an ATSC VSB system, which is an American terrestrial DTV system. The present invention relates to a digital broadcast system and a method for improving digital broadcast performance by generating and transmitting a dual transport stream including a robust turbo stream.

The US terrestrial digital broadcasting system, ATSC VSB, is a single carrier system, and field sync is used in units of 312 segments. This results in poor reception on poor channels, especially Doppler fading channels.

1 is a block diagram showing a transceiver according to an ATSC DTV standard as a general US terrestrial digital broadcasting system. The digital broadcasting transmitter of FIG. 1 is an EVSB system proposed by Philips, and configured to transmit and form a dual stream in which robust data is added to normal data of a reference ATSC VSB system. to be.

As shown in FIG. 1, the digital broadcasting transmitter includes a randomizer 11 for randomizing a dual stream, a confidential encoder 11 for adding a parity byte to a transport stream to correct an error caused by channel characteristics A Reed-Solomon encoder 12 in the form of a concatenated coder, an interleaver 13 for interleaving the RS encoded data according to a predetermined pattern, and a Trellis encoding at a 2/3 ratio on the interleaved data And a 2/3 rate trellis encoder 14 that performs mapping to an 8 level symbol by performing the error correction coding on the dual stream.

In addition, the digital broadcast transmitter includes a multiplexer 15 for inserting a field sync and a segment sync as well as the data format of FIG. 2 with respect to data subjected to error correction coding, a multiplexer 15 for multiplexing a segment sync signal and a field sync And a modulator 16 for adding a predetermined DC value to a data symbol into which a signal is inserted, inserting a pilot tone, performing pulse shaping, performing VSB modulation, up-converting the signal into an RF channel band signal, .

Accordingly, the digital broadcasting transmitter multiplexes the normal data and the robust data according to the dual stream method of transmitting the normal data and the robust data on one channel, and inputs the multiplexed data to the randomizing unit 11 (not shown). The input data is randomized through the randomization unit 11, and the randomized data is externally encoded through the Reed Solomon encoder 12, which is an outer coder, and the encoded data is interleaved. Disperse. In addition, the interleaved data is internally encoded through the trellis encoding unit 14 in units of 12 symbols, and the interleaved data is mapped into 8-level symbols with respect to internally encoded data, and then a field sync signal and a segment sync signal are inserted. A pilot tone is inserted, VSB modulation is performed, and the signal is converted into an RF signal and transmitted.

1 includes a tuner (not shown) for converting an RF signal received through a channel into a base signal, a demodulator 21 for performing synchronization detection and demodulation on the converted base signal, A Viterbi decoder 23 for correcting an error of the equalized signal and decoding it into symbol data, an interleaver 13 of a digital broadcast transmitter, A deinterleaver 24 for rearranging the distributed data, an RS decoder 25 for correcting errors, and an RS decoder 25 for derandomizing the corrected data to output an MPEG-2 transport stream And a randomizing unit 26.

Accordingly, the digital broadcast receiver of FIG. 1 down-converts an RF signal to a baseband in a reverse process of a digital broadcast transmitter, demodulates and equalizes the converted signal, and then performs channel decoding to recover the original signal.

FIG. 2 shows a VSB data frame in which a segment sync signal and a field sync signal of a digital broadcast (8-VSB) system in the United States are inserted. As shown, one frame is composed of two fields, one field is composed of one field sync field segment (first sync segment) and 312 data segments. Also, one segment in the VSB data frame corresponds to one MPEG-2 packet, and one segment is composed of four symbol segment sync and 828 data symbols.

In FIG. 2, a segment sync signal and a field sync signal, which are sync signals, are used for synchronization and equalization on the digital broadcast receiver side. That is, the field sync signal and the segment sync signal are already known data between the digital broadcast transmitter and the receiver and are used as a reference signal when performing equalization at the receiver side.

The US terrestrial digital broadcasting system of FIG. 1 transmits robust data to existing normal data together with robust data added to normal data of an existing ATSC VSB system to form a dual stream.

However, the US terrestrial digital broadcasting system of FIG. 1 has a problem that there is little effect of improving the poor reception performance in the multipath channel due to the transmission of the normal data stream, despite the dual stream transmission due to the addition of the robust data have. That is, there is a problem that there is almost no improvement in the reception performance due to the improvement of the normal stream. In addition, there is a problem that the reception performance improvement effect in the multi-pass environment is not large for the turbo stream.

Accordingly, there is a need for a broadcast system capable of improving reception performance of a dual transport stream including a turbo stream and a normal stream.

The present invention has been proposed to meet the above-described needs, and an object of the present invention is to provide a digital broadcasting system and a method for improving the reception performance of the ATSC VSB system, which is an American terrestrial DTV system.

A digital broadcasting system according to an embodiment of the present invention for achieving the above object, a transport stream generating apparatus for generating a dual transport stream by multiplexing the normal stream and the turbo stream, inserting an additional reference signal in the dual transport stream And reconstructing the dual transport stream by performing signal processing on the turbo stream, and then receiving the reconstructed dual transport stream and the transmitter for outputting the reconstructed dual transport stream, and receiving the normal stream and the turbo stream. And a receiving apparatus to decode each to recover normal stream data and turbo stream data.

Preferably, the transport stream generating apparatus, a Reed Solomon encoder for receiving a turbo stream from the outside, to perform the Reed Solomon encoding for the turbo stream, a duplicity for providing a parity insertion region for the Reed Solomon encoded turbo stream It may include a mux for receiving a normal stream from the caterer and the outside, and generating a dual transport stream by multiplexing the turbo stream and the normal stream processed by the duplicater.

In this case, the duplexer converts each byte constituting the turbo stream according to one of a half rate conversion method and a quarter rate conversion method, thereby forming the parity insertion region between data bits in the turbo stream. Can be prepared.

Also preferably, the transmission apparatus may further include a randomization unit configured to receive and randomize the dual transport stream from the transport stream generation device and an additional reference signal for inserting an additional reference signal into a stuffing area provided in the randomized dual transport stream. An inserter, a reedsolomon encoder encoding the dual transport stream into which the additional reference signal is inserted, an interleaver interleaving the encoded dual transport stream, and detecting and encoding a turbo stream from the interleaved dual transport stream, and encoding the encoded turbo stream. A turbo processor for stuffing the dual transport stream and compensating parity corresponding to the encoded turbo stream, and a trellis / parity correction unit for trellis encoding the dual transport stream processed by the turbo processor. Can be.

The turbo processor may include a turbo stream detector that detects the turbo stream from the interleaved dual transport stream, an outer encoder that inserts parity of the detected turbo stream into a parity insertion region provided in the turbo stream, and the parity is inserted. An outer interleaver for interleaving the old turbo stream, a turbo stream stuffer for reconstructing the dual transport stream by inserting the interleaved turbo stream into the dual transport stream, and regenerating parity of the reconstructed dual transport stream, It is preferable to include a parity compensation unit added to the transport stream.

More preferably, the turbo processor may be configured to convert the interleaved dual transport stream from a byte unit into a symbol unit, and a dual transport stream to which a parity regenerated by the parity beam is added. The apparatus may further include a symbol-byte conversion unit converting the byte unit.

Also preferably, the transmitting apparatus may include a mux for adding a synchronization signal to the trellis encoded dual transport stream, a pilot insertion unit for inserting a pilot into the dual transport stream to which the synchronization signal is added, and the pilot is inserted. The apparatus may further include a pre-equalizer for equalizing the dual transport stream, a VSB modulator for VSB modulating the equalized dual transport stream, and an RF modulator for modulating and transmitting the VSB modulated dual transport stream into a signal of an RF channel band. .

Meanwhile, the trellis / parity correcting unit may perform initialization before encoding the additional reference signal, and compensate for parity according to a value changed due to initialization.

In this case, the trellis / parity correction unit performs the initialization when an external control signal corresponding to the initialization section is received and outputs a pre-stored stored value as an initial value, corresponding to the initial value. An RS re-encoder for generating parity, an adder for adding the parity generated in the RS re-encoder to the dual transport stream to correct the parity of the dual transport stream, and a dual transport stream having the parity corrected by the adder. A mux provided to the trellis encoder block and a map for symbol mapping a trellis encoded dual transport stream in the trellis encoder block may be output.

The trellis encoder block may include a plurality of trellis encoders, a splitter for sequentially inputting the transmission stream to the plurality of trellis encoders, and a value encoded by the plurality of trellis encoders. It is preferable to include an encoding output unit to detect.

More preferably, the trellis encoder is initialized when an external control signal is input, and is initialized when the external control signal is input, and outputs a first stored value as a first initial value. And a third memory configured to shift the prestored stored value into the second memory and output the prestored stored value in the second memory as a second initial value. In this case, the RS reencoder may generate a parity corresponding to an initial value composed of a combination of the first and second initial values.

Also preferably, the receiving apparatus may include a demodulator for receiving and demodulating the transmitted dual transport stream, an equalizer for equalizing the demodulated dual transport stream, and restoring normal stream data from the equalized dual transport stream. And a second processor for recovering turbo stream data from the equalized dual transport stream.

Here, the first processing unit performs an error correction on the normal stream of the equalized dual transport stream, deinterleaves the dual transport stream output from the Viterbi decoder and the Viterbi decoder to decode the error corrected normal stream. And a first deinterleaver configured to derandomize the Reed Solomon-decoded dual transport stream by restoring the deinterleaved dual transport stream to a reedsolomon decoder, and to reconstruct the normal stream data. Can be.

The second processor may further include a turbo decoder for performing turbo decoding on the turbo stream of the equalized dual transport stream, a second deinterleaver for deinterleaving the dual transport stream including the turbo decoded turbo stream, and the second processor. A parity remover for removing parity from a dual transport stream deinterleaved by a second deinterleaver, a second derandomizer for derandomizing the dual transport stream from which the parity has been removed, and a demultiplexing of the derandomized dual transport stream It may include a turbo demux for restoring the turbo stream data.

The turbo decoder may further include a trellis decoder for trellis decoding a turbo stream of the equalized dual transport stream, an outer deinterleaver for deinterleaving the trellis decoded turbo stream, and the deinterleaved turbo stream. An outer map decoder for decoding the outer map decoder, an outer interleaver for interleaving the turbo stream decoded by the outer map decoder to the trellis decoder when a soft decision is output from the outer map decoder, and a hard decision of the outer map decoder It may include a frame formatter for formatting the output value.

Preferably, the turbo decoder may further include a symbol deinterleaver for converting the frame formatted turbo stream from symbol units to byte units.

On the other hand, the digital broadcast method according to an embodiment of the present invention, a transport stream generation step of generating a dual transport stream by multiplexing the normal stream and the turbo stream, inserting an additional reference signal in the dual transport stream, the turbo stream Reconstruct the dual transport stream by performing a signal processing on the dual transport stream, and output the reconstructed dual transport stream and the reconstructed dual transport stream to decode the normal stream and the turbo stream to decode the normal stream, respectively. And a receiving step of recovering the data and the turbo stream data.

Preferably, the step of generating the transport stream, receiving a turbo stream from the outside, performing Reedsolomon encoding, preparing a parity insertion region for the Reedsolomon-encoded turbo stream and receiving a normal stream from the outside The method may include multiplexing the turbo stream provided with the parity insertion region and the normal stream to generate a dual transport stream.

More preferably, the preparing of the parity insertion region may include converting each byte constituting the turbo stream according to one of a half rate conversion method and a quarter rate conversion method, thereby converting data bits in the turbo stream. The parity insertion region may be provided in between.

Also preferably, the transmitting may include: randomizing the generated dual transport stream, inserting an additional reference signal into a stuffing region provided in the randomized dual transport stream, and receiving the dual with the additional reference signal inserted therein. Encoding a transport stream, interleaving the encoded dual transport stream, detecting and encoding a turbo stream from the interleaved dual transport stream, stuffing an encoded turbo stream with the dual transport stream, and encoding the encoded turbo Turbo processing for compensating parity corresponding to the stream and trellis encoding the turbo-processed dual transmission stream.

The turbo processing may include detecting the turbo stream from the interleaved dual transport stream, inserting parity for the detected turbo stream into a parity insertion region provided in the turbo stream, and inserting the parity. Interleaving a turbo stream, inserting the interleaved turbo stream into the dual transport stream to reconstruct the dual transport stream, and regenerating parity of the reconstructed dual transport stream and adding parity to the dual transport stream. It may include a step.

The turbo processing may include a byte-symbol conversion step of converting the interleaved dual transport stream from a byte unit to a symbol unit and a symbol of converting the dual transport stream to which the regenerated parity is added from symbol unit to byte unit. It may further comprise a byte conversion step.

The transmitting may include adding a synchronization signal to the trellis encoded dual transport stream, inserting a pilot into the dual transport stream to which the synchronization signal is added, and equalizing the dual transport stream into which the pilot is inserted. The method may further include VSB modulating the equalized dual transport stream and modulating and transmitting the VSB modulated dual transport stream to a signal in an RF channel band.

In the trellis encoding, the initialization may be performed before encoding the additional reference signal, and the parity may be compensated according to a value changed due to the initialization.

Also preferably, the receiving may include receiving and demodulating the transmitted dual transport stream, equalizing the demodulated dual transport stream, restoring normal stream data from the equalized dual transport stream, and Recovering turbo stream data from the equalized dual transport stream.

In this case, restoring the normal stream data may include: performing a Viterbi decoding operation on the normal stream of the equalized dual transport stream, decoding the error corrected normal stream, and decoding the decoded dual transport stream. The method may include deinterleaving, decoding the deinterleaved dual transport stream, and derandomizing the reedsolomon decoded dual transport stream to restore the normal stream data.

The restoring of the turbo stream data may include performing turbo decoding on the turbo stream of the equalized dual transport stream, deinterleaving the dual transport stream including the turbo decoded turbo stream, and deinterleaving. Parity from the extracted dual transport stream, derandomizing the dual transport stream from which the parity has been removed, and demultiplexing the derandomized dual transport stream to restore the turbo stream data. have.

The turbo decoding may include: trellis decoding a turbo stream of the equalized dual transport stream using a trellis decoder, deinterleaving the trellis decoded turbo stream; Decoding a deinterleaved turbo stream, if a soft decision is output in the decoding process, interleaving the decoded turbo stream to provide the trellis decoder, and if a hard decision is output in the decoding process, And outputting the dual transport stream by frame-formatting the determination output value.

More preferably, the step of performing the turbo decoding may further include the step of converting the frame-formatted turbo stream from symbol unit to byte unit.

While the above has been shown and described with respect to preferred embodiments of the invention, the invention is not limited to the specific embodiments described above, it is usually in the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

As described above, according to the present invention, a broadcast service is performed using a dual transport stream including a turbo stream and a normal stream. As a result, it is possible to robustly process and transmit specific data, thereby providing efficient service. In addition, by inserting the additional reference signal in the dual transport stream, it is possible to easily check the channel state at the receiving side, thereby determining the degree of compensation. In particular, the above operation can be performed by using a transmitter and a receiver having a simple structure. As a result, according to the present invention, it is possible to efficiently improve the reception performance of the ATSC VSB system, which is an American terrestrial DTV system.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating a configuration of a digital broadcasting system according to an embodiment of the present invention. According to FIG. 3, the digital broadcasting system includes a transport stream generating apparatus 100, a transmitting apparatus 200, and a receiving apparatus 300.

The transport stream generator 100 is a device for generating a dual transport stream by receiving and multiplexing a normal stream and a turbo stream. Here, the turbo stream refers to a stream processed more robustly than the normal stream. 4 is a block diagram showing an example of the configuration of the transport stream generating apparatus 100. As shown in FIG.

Referring to FIG. 4, the dual transport stream generating apparatus includes a Reed Solomon encoder 110, a duplicater 120, and a mux 320.

The ReedSolomon encoder 110 receives the turbo stream, adds parity to encode the encoded stream, and then provides the duplicate stream to the duplicater 120. FIG. 5 is a diagram illustrating an example of a packet structure encoded by the ReedSolomon encoder 110 of FIG. 4. The Reed Solomon encoder 110 of FIG. 4 receives a turbo stream composed of a synchronization signal, a PID (Packet IDentity), and a turbo data region. The entire turbo stream packet may be composed of 188 bytes, of which a synchronization signal (SYNC) may consist of 1 byte, a PID (Packet Identity) of 3 bytes, and turbo data of 184 bytes. The ReedSolomon encoder 110 removes a synchronization signal from the turbo stream, calculates a parity for the turbo data region, and adds a parity having a size of 20 bytes. As a result, one packet of the final encoded turbo stream consists of 207 bytes in total, of which three bytes are assigned to PID (Packet IDentity), 184 bytes to turbo data, and 20 bytes to parity.

Meanwhile, the duplicater 120 prepares a parity insertion region in the encoded turbo stream. A method of providing a parity insertion region will be described in detail. Each byte, which is a structural unit of a turbo stream, is divided into two or four bytes. Each separated byte is filled with part of the bit value of the original byte and null data (for example, 0). The area filled with null data is the parity insertion area.

The operation of the duplicator 120 will be described in more detail as follows. In other words, if the input is doubled, the duplexer assumes that the bits in one byte are represented by MSB through a, b, c, d, e, f, g, h and input in that order. The output of 120 may be expressed as a, a, b, b, c, c, d, d, e, e, f, f, g, g, h, h. In this case, a 1-byte 2-byte output consisting of a 1-byte composed of a, a, b, b, c, c, d and d and e, e, f, f, g, g, h and h is sequentially It can be seen that it is outputted.

If the input is quadrupled, the output of the duplexer 120 is a, a, a, a, b, b, b, b, c, c, c, c, d, d, d, d It can be expressed as, e, e, e, e, f, f, f, f, g, g, g, g, h, h, h, h. Thus, four bytes are output. On the other hand, the duplicator 120 may not necessarily copy the input bits, but may insert any other value, i.e., null data, at locations other than the designated location. E.g. If the duplicator doubles the input, then two consecutive bits, such as a, x, b, x, c, x ... instead of a, a, b, b, c, c, ... output Only the first part can hold the original input and the second part can contain any value. Or, conversely, you can make only the back part retain its original input. Even if you quadruple the output, you can place the original input in only one of the first, second, third, and fourth positions, and put any value in the rest.

6 and 7 are schematic diagrams for explaining an example of a method in which the duplicater 120 provides a parity insertion region. First, FIG. 6 shows a half rate conversion scheme. The duplicater 120 generates two bytes by applying a 1/2 rate conversion method to each byte of the turbo stream. According to FIG. 6, two bit groups D0 to D3 and D4 to D7 are formed by dividing one byte including D0 to D7 bits by four bits. In this state, one bit is placed side by side in each bit of each bit group to expand each bit group into bytes. As a result, a first byte (D7 0 D6 0 D5 0 D4 0) including bits D4 to D7 and a second byte (D3 0 D2 0 D1 0 D0 0) including bits D0 to D3 are generated. The bits between each bit of the first and second bytes are used as parity insertion regions. That is, in the case of the first and second bytes, the second, fourth, sixth, and eighth bits are used as parity insertion regions. The arrangement position of the parity insertion region may be variously changed. That is, the second, third, sixth, seventh bits, or the third, fourth, fifth, sixth bits may be used as the parity insertion region.

7 shows a quarter rate conversion scheme. Duplicator 120 generates four bytes by applying a quarter rate conversion scheme to each byte of the turbo stream. According to FIG. 7, one byte including the bits D0 to D7 is divided into two bits to form a total of four bit groups D0-D1, D2-D3, D4-D5, and D6-D7. In this state, three bit bits are placed side by side on each bit of each bit group to expand each bit group into bytes. Specifically, the first byte containing the bits D6, D7 (D7 0 0 0 D6 0 0 0), the second byte containing the bits D4, D5 (D5 0 0 0 D4 0 0 0), D2, D3 bits And extends to a third byte (D3 0 0 0 D2 0 0 0), including a fourth byte (D1 0 0 0 D0 0 0 0) including D0 and D1 bits. According to FIG. 7, the 2nd, 3rd, 4th, 6th, 7th and 8th bits are used as parity insertion regions in each byte, but are not limited to this structure.

Returning to the description of FIG. 4 again, the mux 130 muxes the normal stream received separately and the turbo stream processed by the duplicater 120. Accordingly, a dual transport stream in which the normal stream and the turbo stream are mixed can be generated. The normal stream and the turbo stream may be received from an external module such as a broadcast photographing apparatus or the like, or from various internal modules such as a compression processing module (eg, an MPEG 2 module), a video encoder, an audio encoder, or the like.

Meanwhile, the MUX 130 provides an adaptation field for each packet of the dual transport stream. The adaptive field means an area provided for inserting a turbo stream or other data. Specifically, in addition to the turbo stream, reset data for initialization, supplementary reference signal (SRS: Supplementary Reference Singal, hereinafter referred to as "SRS"), and the like may be inserted into the adaptive field. On the other hand, the adaptive field may be used as an option field in which various packet information is recorded. Packet information includes the Program Clock Reference (PCR) used to synchronize the receiver's demodulator, the Original Program Clock Reference (OPCR) used to record, schedule, and play the program at the receiver. Splice countdown, which is a contiguous number of macroblocks consisting of one circuit block, each Cr and Cb block, transport private data length, which is the length of character data of a character broadcast, and adaptive field extension An adaptation field extension length. In this case, it is preferable that the area where the turbo stream is recorded and the option field are arranged such that their positions do not overlap each other.

Meanwhile, the transmitting apparatus of FIG. 3 may be implemented as shown in FIG. 8.

According to FIG. 8, the transmitter 200 includes a randomizer 210, an additional reference signal inserter 220, a Reed Solomon encoder 230, an interleaver 240, a turbo processor 250, and a trellis / parity definition. The unit 260 includes a synchronization signal mux 270, a pilot insertion unit 280, a pre-equalization unit 285, a VSB modulator 290, and an RF modulator 295.

The randomization unit 210 randomizes the dual transport stream received from the transport stream generating apparatus 100.

The additional reference signal inserter 220 receives the dual transport stream and inserts an additional reference signal (SRS: Supplementary Reference Singal) into the adaptive field of each packet. The additional reference signal refers to a signal pattern commonly known to the transmitting side and the receiving side. The broadcast reception side can easily check the channel state by comparing the additional reference signal in the received stream with the known additional reference signal. Accordingly, the degree of compensation can be determined.

The Reed Solomon encoder 230 encodes the dual transport stream into which the additional reference signal is inserted.

Interleaver 240 interleaves the encoded dual transport stream.

The turbo processor 250 detects only the turbo stream from the interleaved dual transport stream, and then encodes and interleaves the detected turbo stream to perform robust processing. The robustly processed turbo stream is then stuffed into the dual transport stream to reconstruct the dual transport stream. Then, a task of compensating for the parity changed due to the encoding of the turbo stream is performed. An example of the configuration of the turbo processor 250 is shown in FIGS. 9 and 10.

According to FIG. 9, the turbo processor 250 includes a turbostream detector 251, an outer encoder 252, an outer interleaver 253, a turbo stream stuffer 254, and a parity compensator 255.

The turbo stream detector 251 detects a turbo stream from the dual transport stream.

The outer encoder 252 adds parity to the parity insertion region provided in the detected turbo stream, and serves to encode the turbo stream.

The outer interleaver 253 serves to interleave the encoded turbo stream.

The turbo stream stuffer 254 reconfigures the dual transport stream by multiplexing the interleaved turbo stream and the normal stream. Turbo stream stuffer 254 may be implemented as a multiplexer.

The parity compensator 255 regenerates the parity of the reconstructed dual transport stream and adds the parity to the dual transport stream, thereby compensating for a parity error due to turbo stream encoding.

10 is a block diagram showing the configuration of a turbo processing unit 250 according to another embodiment of the present invention. According to FIG. 10, the turbo processor 250 may perform byte-symbol conversion in addition to the turbo stream detector 251, the outer encoder 252, the outer interleaver 253, the turbo stream stuffer 254, and the parity compensator 255. The unit 256 may further include a symbol-byte converter 257.

The byte-symbol converter 256 converts the dual transport stream interleaved in the interleaver 240 from symbol to byte. The conversion from byte to symbol can be easily seen by referring to Table D5.2 of the US ATSC DTV Standard (A / 53). The turbo stream detector 251 detects the turbo stream from the dual transport streams converted in symbol units, and the outer encoder 252 calculates the parity for the detected turbo stream and inserts the parity into the parity insertion region, thereby encoding the turbo stream. do. In this case, the outer encoder 252 performs encoding in units of bytes of the turbo stream.

The outer interleaver 253 interleaves the encoded turbo stream. In this case, the outer interleaver 253 interleaves in units of bits.

The turbo stream stuffer 254 multiplexes the interleaved turbo stream and the normal stream to form a dual transport stream. Specifically, the turbo stream is stuffed to a position before it is detected by the turbo stream detector 251 to form a dual transport stream.

The symbol-byte converter 257 converts the dual transport stream from symbol units to byte units. The symbol-to-byte conversion can be easily found by referring to Table D5.2 of the US ATSC DTV Standard (A / 53).

11 is a schematic diagram for describing an interleaving process of the outer interleaver 253. According to FIG. 11, the outer interleaver 253 performs interleaving according to a predetermined interleaving rule. For example, when the interleaving rule is {0, 1, 2, 3} => {2, 1, 3, 0}, when ABCD is sequentially input, the interleaving rule is interleaved and output in the form of DBAC.

Returning to the description of FIG. 8 again, the turbo-processed dual transport stream is trellis encoded by the trellis / parity correction unit 260. The trellis / parity correction unit 260 also corrects the parity that is changed due to trellis encoding.

12 is a block diagram illustrating an example of a configuration of the trellis / parity correction unit 260. According to FIG. 12, the trellis / parity correction unit 260 includes a trellis encoder block 410, a Reed Solomon re-encoder 420, an adder 430, a mux 440, and a map. (450).

The MUX 440 may include: i) an operation mode for performing trellis encoding (hereinafter “normal mode”), and ii) an operation mode for trellis encoding the packet added by the adder 430 (hereinafter “parity”). Correction mode "). The operation mode of the mux 440 is determined by a control signal received from the Reed Solomon reencoder 420.

The trellis encoder block 410 trellis encodes the packet received from MUX 440. The trellis encoder block 410 may trellis-encode the packet according to an external control signal, and preferably initializes the trellis-encoded data of the packet immediately before trellis encoding the packet.

The RS reencoder 420 regenerates parity corresponding to the changed packet in the process of initializing the trellis encoder block 410 described above.

The adder (Exclusive OR) 430 adds the re-encoded parity and the packet received from the turbo processor 250 and provides the packet to the mux 440. Here, the method of adding is as follows.

A) Skip previous ... 101001010111 00 1010101011AAAAA ... skip below

B) Omit previous ... 000000000000 01 0000000000BBBBB ... Omit below

C) Skip previous ... 101001010111 01 1010101011CCCCC ... skip below

A) denotes a packet received from the turbo processor 250, B) denotes an RS re-encoded packet, and C) denotes an exclusive OR of A) and B) using the adder 430. It means one result. When the underlined portion in A) is input to the trellis encoder block 410, initialization is performed. In this case, a value corresponding to a value previously stored in the trellis encoder block 410 is provided to the RS re-encoder 420, and the RS re-encoder 420 adds parity to the provided value to output a B) packet. do. B) The underlined portion of the packet means the change value corresponding to the underlined portion of the packet. B) It can be seen that the parity corresponding to the underlined part of the packet is reproduced with BBBBB.

The adder 430 outputs packet C) by performing an exclusive OR on packet A) and packet B). Looking at the packet C), the underlined part of the first packet A) is changed to "01", and the parity is also changed from AAAAA to CCCCC.

The mux 440 operates in the normal operation mode after the initialization and the parity correction are completed to provide the dual transport stream to the trellis encoder block 410.

The map (MAP) 450 symbolically outputs trellis-encoded packets to eight levels. Specifically, the map 450 may be mapped as shown in the following table.

Z2 Z1 Z0 R 0 0 0 -7 0 0 One -5 0 One 0 -3 0 One One -One One 0 0 +1 One 0 One +3 One One 0 +5 One One One +7

In Table 1, Z0, Z1, and Z2 denote trellis encoding values output from the trellis encoder block 410, and R denotes a mapping output value accordingly. That is, when the trellis encoding value is output as 0, 0, 0, the map 450 outputs -7.

13 is a schematic diagram illustrating an example of a configuration of the trellis encoder block 410. The trellis encoder block 410 includes a splitter 411, a plurality of trellis encoders 412-1 to 412-12, and an encoding output unit 413.

The splitter 411 sequentially outputs the stream output from the mux 440 to the plurality of trellis encoders 412-1 to 412-12. In this case, it can be output in units of bytes.

Each trellis encoder 412-1 to 412-12 trellis encodes an input stream and outputs the trellis encoded. In this case, the trellis encoder 1 to the trellis encoder 12 are sequentially selected to output respective trellis encoding values. Meanwhile, during the initialization period, a value previously stored in the trellis encoder internal memory (not shown) is provided as an initial value to the RS reencoder 420. The RS reencoder 420 adds parity to the provided initial value and outputs it to the adder 430 to correct the parity.

The encoding output unit 413 sequentially detects encoding values output from the trellis encoders 412-1 to 412-12 and outputs the encoded values to the map 450.

Meanwhile, each trellis encoder 412-1 to 412-12 includes a plurality of memories, and performs trellis encoding by using the plurality of memories. In this case, initialization is performed immediately before trellis encoding the region into which the additional reference signal is inserted. According to the initialization, each memory is reset, and in this process, a stored value previously stored in each memory is provided to the RS reencoder 420 as an initial value.

Specifically, each trellis encoder may include three memories (first to third memories). Among these, when the initialization proceeds, the first memory outputs a previously stored value (hereinafter, referred to as a first initial value) as an initial value as it is. In addition, the third memory is initialized and simultaneously shifts the previously stored value to the second memory. According to the shift operation, a value (hereinafter referred to as a second initial value) previously stored in the second memory is output as an initial value. The RS reencoder 420 combines the first and second initial values and utilizes the initial values.

On the other hand, since the second and third memories are arranged side by side to perform a shift operation, two symbols of the control signal are required to initialize all of them. In addition, there are eight initial state values (000, 111, 001, 010, 100, 110, 101, and 011) that can be created using all three memories. The X0 and X1 values representing the first and second initial values are provided to the RS reencoder 420 to change the parity.

8, the synchronization signal mux 270 multiplexes the segment synchronization signal and the field synchronization signal to the trellis encoded dual transport stream.

The pilot inserting unit 280 inserts a pilot by adding a predetermined DC value to the dual transport stream to which the synchronization signal is added.

The pre-equalizer 285 equalizes the dual transport stream into which the pilot is inserted, so that inter-symbol interference is minimized.

The VSB modulator 290 VSB modulates the equalized dual transport stream.

The RF modulator 295 modulates the VSB modulated dual transport stream into a signal of an RF channel band and transmits the modulated signal.

FIG. 14 is a block diagram illustrating an example of a configuration of a receiving apparatus 300 in the digital broadcasting system of FIG. 3. According to FIG. 14, the receiver 300 includes a demodulator 310, an equalizer 320, a first processor 330, and a second processor 340.

When the dual transport stream modulated and transmitted in the form of an RF signal is received through an antenna, the demodulator 310 detects and demodulates synchronization according to a synchronization signal added to a baseband signal of the received dual transport stream.

The equalizer 320 equalizes the demodulated dual transport stream to compensate for channel distortion due to multipath of the channel. The dual transport stream equalized by the equalizer 320 is provided to the first processor 330 and the second processor 340.

The first processor 330 recovers normal stream data by processing a normal stream of the dual transport stream. According to FIG. 14, the first processing unit 330 includes a Viterbi decoder 331, a first deinterleaver 332, an RS decoder 333, and a first derandomization unit 334.

The Viterbi decoder 331 performs error correction on the normal stream of the equalized dual transport stream and decodes the error-corrected symbol to output a symbol packet.

The first deinterleaver 332 deinterleaves the decoded packet to reorder the distributed packets.

The RS decoder 333 corrects the error by decoding the deinterleaved normal stream packet by Reed Solomon.

The first derandomizer 334 derandomizes the ReedSolomon decoded normal stream packet to restore normal stream data.

Meanwhile, the second processor 340 recovers the turbo stream data by processing the turbo stream of the dual transport stream. According to FIG. 14, the second processor 340 includes a turbo decoder 510, a second deinterleaver 520, a parity remover 530, a second derandom equalizer 540, and a turbo demux 550. do.

The turbo decoder 510 performs turbo decoding only on the turbo streams among the equalized dual transport streams. Turbo decoding refers to a decoding process for a turbo stream. The turbo decoder 510 may perform turbo decoding by detecting the turbo stream from part or all of the packet adaptation field of the dual transport stream. When the turbo decoding is completed, the turbo decoder 510 reinserts the dual transport stream by inserting the turbo stream back into the dual transport stream.

The second de-interleaver 520 de-interleaves the dual transport stream reconstructed, and reorder the packets.

The parity remover 530 removes parity existing in the deinterleaved dual transport stream.

The second reverse randomizer 540 derandomizes the dual transport stream from which parity has been removed.

Turbo DE-MUX 550 demultiplexes the derandomized dual transport stream to recover turbo stream data.

15 is a block diagram illustrating an example of a configuration of a turbo decoder 510. The turbo decoder 510 of FIG. 15 includes a trellis decoder 511, an outer de-interleaver 512, an outer map decoder 513, an outer interleaver 514, and a frame formatter 515. ), And symbol deinterleaver 516.

The trellis decoder 511 trellis decodes the turbo stream among the equalized dual transport streams and provides the trellis decoder to the outer deinterleaver 512.

The outer deinterleaver 512 deinterleaves the trellis decoded turbo stream.

The outer map decoder 513 may convolutionally decode the deinterleaved turbo stream. The outer map decoder 513 outputs soft decision and hard decision output values according to the convolutional decoding result. Here, the soft decision and the hard decision are determined according to the metric of the turbo stream. For example, when the turbo stream metric is "0.8", a soft decision value of "0.8" is output. When the turbo stream metric is "1", hard decision is output.

The hard decision output value of the outer map decoder 513 is provided to the frame formatter 515. In this case, the hard decision output value means a turbo stream.

The frame formatter 515 reconstructs the dual transport stream by formatting the convolutionally decoded hard decision turbo stream into frames of the dual transport stream.

The symbol deinterleaver 516 may deinterleave the frame-formatted turbo stream from symbol to byte. The deinterleaving in units of symbols in units of symbols can be easily understood by referring to Table D5.2 of the 'ATSC DTV Standard (A / 53) of the United States of America', so a detailed description thereof will be omitted. Although the symbol deinterleaver 516 is illustrated in FIG. 15, the symbol deinterleaver 516 may be omitted.

On the other hand, when the soft decision is output from the outer map decoder 513, the outer interleaver 514 interleaves the turbostream and provides the trellis decoder 511. The trellis decoder 511 performs the trellis decoding on the interleaved turbo stream to the outer deinterleaver 512, and the outer deinterleaver 512 deinterleaves it to the outer map decoder 513. . The operations of the trellis decoder 511, the outer deinterleaver 512, and the outer interleaver 514 may be repeatedly performed until the hard decision is output. Thus, a reliable decryption level can be obtained.

On the other hand, the digital broadcasting method according to an embodiment of the present invention, after generating a dual transport stream including a turbo stream and a normal stream, the turbo step of transmitting the turbo decoding only of these streams, and the dual transport stream And receiving and decoding the normal stream and the turbo stream, respectively, to restore the normal stream data and the turbo stream data.

16 is a flowchart for explaining an example of a method for generating and transmitting a dual transport stream. According to FIG. 16, a dual transport stream is generated (S610). Specifically, a parity insertion region is provided in the turbo stream, an adaptive field is provided in the normal stream, and the two streams are multiplexed to generate a dual transport stream.

Next, after randomizing the generated dual transport stream (S620), an additional reference signal is inserted into a part of the adaptive field (S630).

In this state, after encoding the dual transport stream into which the additional reference signal is inserted (S640), interleaving is performed (S650).

Then, turbo processing is performed (S660). As described above, the turbo processing refers to a processing operation of detecting, encoding, and interleaving only the turbo stream from the dual transport stream and inserting the same into the dual transport stream. In this case, since the turbo operation is performed after the encoding operation S640, the operation of compensating the parity is further performed in order to prevent the parity due to the turbo process from being changed.

In this way, when turbo processing is completed, trellis encoding and parity correction operations are performed (S670). The synchronization signal is then muxed and transmitted after performing operations such as pilot insertion, equalization, and modulation. A detailed description thereof has been given above, so that redundant description and illustration are omitted.

17 is a flowchart illustrating a receiving method according to an embodiment of the present invention. According to FIG. 17, first, a dual transport stream is received and demodulation is performed (S710). Then, the demodulated stream is equalized (S720).

Then, the Viterbi decoding is performed on the normal stream among the equalized streams (S730), deinterleaving (S735), and Reedsolomon decoding is performed (S740). Next, inverse randomization is performed to restore normal stream data (S745).

Meanwhile, turbo decoding is first performed on the turbo stream among the equalized streams (S750) and then deinterleaved (S755). Then, the parity recorded in the turbo stream is removed (S760), and inverse randomization is performed (S765). Next, demultiplexing is performed to detect the turbo stream from the derandomized dual transport stream (S770) to recover the turbo stream data.

18 is a flowchart for explaining a turbo decoding method. According to FIG. 18, trellis decoding is performed on a turbo stream among dual transport streams (S810). Then, after outer deinterleaving the trellis decoded turbo stream (S820), outer decoding is performed (S830).

When the hard decision output value is output through the outer decoding, the hard decision turbo stream is formatted according to the frame of the dual transport stream (S850), and symbol interleaving is performed (S860).

Meanwhile, when the soft decision output value is outputted through outer decoding, outer interleaving (S840) is performed, and the outer interleaved turbo stream is subjected to trellis decoding and outer de-interleaving (S810 and S820). This makes it possible to obtain a lightly-judged turbo stream at a reliable level.

19 is a schematic diagram illustrating an example of a dual transport stream configuration processed in the digital broadcasting system. The dual transport stream according to FIG. 19 is a form in which a turbo stream 78 packet is inserted into a packet of 312 segments of a dual transport stream 1 field. The dual transport stream is configured by repeating four packets at a 1: 3 ratio in the form of a turbo stream 1 packet (188 bytes) and a normal stream 3 packet (188 bytes). On the other hand, when the turbo stream 70 packets are inserted into the 312 segments of the dual transport stream, the dual transport stream is repeated 70 times by 4 packets at a 1: 3 ratio of 1 turbo stream packet and 3 normal stream packets, and the remaining 32 packets are It consists of normal stream packets. Each packet is inserted with an additional reference signal SRS of size S bytes, whereby the size of the turbo stream is 182-S bytes.

1 is a block diagram showing a configuration of a conventional digital broadcasting (ATSC VSB) transmission / reception system,

2 is an exemplary diagram showing a frame structure of conventional ATSC VSB data,

3 is a block diagram showing a configuration of a digital broadcasting system according to an embodiment of the present invention;

4 is a block diagram illustrating an example of a configuration of an apparatus for generating a transport stream in the digital broadcasting system of FIG. 3;

FIG. 5 is a schematic diagram illustrating an example of a stream configuration output from a Reed Solomon encoder in the transport stream generating apparatus of FIG. 4. FIG.

6 and 7 are schematic views for explaining examples of the parity insertion region generation process in the transport stream generating apparatus of FIG.

8 is a block diagram illustrating an example of a configuration of a transmitter in the digital broadcasting system of FIG. 3;

9 and 10 are block diagrams for describing an exemplary configuration of a turbo processor used in the transmission apparatus of FIG. 8;

11 is a schematic view for explaining the operation of the outer interleaver used in the turbo processor;

12 is a block diagram illustrating an example of a configuration of a trellis / parity correction unit used in the transmission apparatus of FIG. 8;

FIG. 13 is a block diagram illustrating an example of a configuration of a trellis encoder block used in the trellis / parity correction unit of FIG. 12;

14 is a block diagram illustrating an example of a configuration of a receiving apparatus used in the digital broadcasting system of FIG. 3.

FIG. 15 is a block diagram illustrating an example of a configuration of a turbo decoder used in FIG. 14;

16 is a flowchart illustrating a dual transport stream transmission process according to an embodiment of the present invention;

17 is a flowchart illustrating a dual transport stream reception process according to an embodiment of the present invention;

18 is a flowchart for explaining a turbo decoding process, and

19 is a schematic diagram illustrating an example of a dual transport stream configuration processed in the digital broadcasting system.

Explanation of symbols on the main parts of the drawing

100: transport stream generator 200: transmitter

300: receiver 110: Reed Solomon encoder

120: Duplicator 130: Mux

210: randomization unit 220: additional reference signal insertion unit

230: Reed Solomon Encoder 240: Interleaver

250: turbo processing unit 260: trellis / parity correction unit

270: mux 280: pilot insertion unit

285: pre-equalizer 290: VSB modulator

295: RF modulator 310: demodulator

320: equalizing unit 330: first processing unit

340: second processing unit

Claims (29)

In the digital broadcast transmission system, A first converter configured to receive and convert a stream processed more robustly than a normal stream in bytes; An outer encoder for encoding the converted stream output from the first converter and outputting a stream in a symbol unit; An outer interleaver for interleaving the symbol unit stream output from the outer encoder; And And a second converter for converting the interleaved symbol unit stream into byte units. The method of claim 1, A Reedsolomon encoder which receives the stream processed more robustly than the normal stream from the outside and performs Reedsolomon encoding; A duplicater for providing a parity insertion region for the ReedSolomon encoded stream; And And a mux configured to receive a normal stream from an external source, and to generate a dual transport stream by multiplexing the stream processed by the duplexer and the normal stream. 3. The method of claim 2, The duplicater, Converting each byte constituting the Reed Solomon encoded stream according to one of a half rate conversion method and a quarter rate conversion method to provide the parity insertion region between data bits in the Reed Solomon encoded stream. Digital broadcast transmission system, characterized in that. 3. The method of claim 2, A randomizer configured to receive and randomize the dual transport stream; A Reedsolomon encoder for encoding the dual transport stream; And And an interleaver for interleaving the encoded dual transport stream. 5. The method of claim 4, And a trellis / parity correction unit for trellis encoding the interleaved dual transport stream. delete The method of claim 5, A mux for adding a synchronization signal to the trellis encoded dual transport stream; A pilot insertion unit for inserting a pilot into the dual transport stream to which the synchronization signal is added; A pre-equalization unit for equalizing the dual transport stream into which the pilot is inserted; A VSB modulator for VSB modulating the equalized dual transport stream; And And an RF modulator for modulating and transmitting the VSB modulated dual transport stream into a signal of an RF channel band. delete The method of claim 5, The trellis / parity correction unit, A trellis encoder block configured to perform the initialization when an external control signal corresponding to an initialization period is received and output a prestored stored value as an initial value; An RS reencoder generating a parity corresponding to the initial value; An adder for adding the parity generated by the RS re-encoder to the dual transport stream to correct the parity of the dual transport stream; A mux for providing a dual transport stream with parity corrected by the adder to the trellis encoder block; And And a map for symbolly mapping the trellis encoded dual transport stream in the trellis encoder block and outputting the trellis encoded dual transport stream. 10. The method of claim 9, The trellis encoder block, A plurality of trellis encoders; A splitter for sequentially inputting the transport stream to the plurality of trellis encoders; And And an encoding output unit which sequentially detects values encoded by the plurality of trellis encoders. The method of claim 10, The trellis encoder, A first memory initialized when an external control signal is input and outputting a pre-stored stored value as a first initial value; Second memory; And And a third memory which is initialized when the external control signal is input, shifts the stored value stored in the second memory into the second memory, and outputs the stored value stored in the second memory as a second initial value. The RS re-encoder, And generating a parity corresponding to an initial value consisting of a combination of the first and second initial values. In a digital broadcast receiving system, A demodulator for receiving and demodulating a dual transport stream; An equalizer for equalizing the demodulated dual transport stream; And And a second processor configured to recover stream data processed more robustly than the normal stream from the equalized dual transport stream. The second processing unit, A turbo decoder for performing turbo decoding on the stream data of the equalized dual transport stream; A second deinterleaver for deinterleaving the dual transport stream comprising the turbo decoded stream data; A parity removal unit for removing parity from the dual transport stream deinterleaved by the second deinterleaver; And And a second inverse randomizer configured to derandomize the dual transport stream from which the parity has been removed. The method of claim 12, Further comprising: a first processing unit for recovering normal stream data from the equalized dual transport stream, The first processing unit, A Viterbi decoder for performing error correction on the normal stream of the equalized dual transport stream and decoding the error corrected normal stream; A first deinterleaver for deinterleaving the dual transport stream output from the Viterbi decoder; A ReedSolomon decoder for decoding the deinterleaved dual transport stream; And And a first inverse randomizer for restoring the normal stream data by derandomizing the ReedSolomon decoded dual transport stream. delete The method of claim 12, The turbo decoder, A trellis decoder for trellis decoding the stream data of the equalized dual transport stream; An outer deinterleaver for deinterleaving the trellis decoded stream data; An outer map decoder for decoding the deinterleaved stream data; An outer interleaver for interleaving the stream data decoded by the outer map decoder to the trellis decoder when a soft decision is output from the outer map decoder; And And a frame formatter configured to frame format the hard decision output value of the outer map decoder. 16. The method of claim 15, The turbo decoder, And a symbol deinterleaver for converting the frame-formatted stream data from a symbol unit to a byte unit. In the stream processing method of the digital broadcast transmission system, Receiving and converting a stream processed more robustly than a normal stream in bytes; Encoding the converted stream to output a symbol unit stream; Interleaving the symbol unit stream; And And converting the interleaved symbol stream into byte units. 18. The method of claim 17, Receiving a stream that is more robustly processed than the normal stream from the outside and performing ReedSolomon encoding; Providing a parity insertion region for the Reed Solomon encoded stream; And Receiving a normal stream from the outside, and multiplexing the normal stream and the stream provided with the parity insertion region to generate a dual transport stream. 19. The method of claim 18, Providing the parity insertion region, Converting each byte constituting the Reed Solomon encoded stream according to one of a half rate conversion method and a quarter rate conversion method, thereby providing the parity insertion region between data bits in the Reed Solomon encoded stream. Stream processing method characterized in that. 19. The method of claim 18, Randomizing the generated dual transport stream; Encoding the randomized dual transport stream; And Interleaving the encoded dual transport stream. 21. The method of claim 20, Trellis encoding the interleaved dual transport stream. delete 22. The method of claim 21, Adding a synchronization signal to the trellis encoded dual transport stream; Inserting a pilot into the dual transport stream to which the synchronization signal is added; Equalizing the dual transport stream into which the pilot is inserted; VSB modulating the equalized dual transport stream; And And modulating and transmitting the VSB modulated dual transport stream into a signal in an RF channel band. delete In the stream processing method of the digital broadcast receiving system, Receiving and demodulating the dual transport stream; Equalizing the demodulated dual transport stream; And Recovering stream data processed more robustly than the normal stream from the equalized dual transport stream; Restoring the stream data, Performing turbo decoding on the stream data of the equalized dual transport stream; Deinterleaving the dual transport stream including the turbo decoded stream data; Removing parity from the deinterleaved dual transport stream; And Inversely randomizing the dual transport stream from which the parity has been removed. 26. The method of claim 25, Restoring normal stream data from the equalized dual transport stream; Restoring the normal stream data, A Viterbi decoding step of performing error correction on the normal stream of the equalized dual transport stream and decoding the error corrected normal stream; Deinterleaving the decoded dual transport stream; Reedsolomon decoding the deinterleaved dual transport stream; And Derandomizing the ReedSolomon decoded dual transport stream to recover the normal stream data. delete 26. The method of claim 25, Performing the turbo decoding, Trellis decoding the stream data of the equalized dual transport stream using a trellis decoder; Deinterleaving the trellis decoded stream data; Decoding the deinterleaved stream data; Interleaving the decoded stream data to provide the trellis decoder when a soft decision is output in the decoding process; And And outputting a dual transport stream by frame-formatting the hard decision output value when the hard decision is output in the decoding process. The method of claim 28, Performing the turbo decoding, And converting the frame-formatted stream data from a symbol unit to a byte unit.

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