KR20040035289A - Apparatus and method for transmission of digital broadcasting system having the composition error correction coding function - Google Patents

Abstract

PURPOSE: A transmission method of a transmission device in a digital broadcasting system having a complex ECC(Error Correction Coding) function is provided to perform different ECC processes for data transmitted through an HP(High Priority) layer and data transmitted through an LP(Low Priority) layer, thereby enabling an optimized ECC process under communication environment. CONSTITUTION: A splitter separates MPEG-2 format TSs(Transport Streams) into the first TS and the second TS(S700). In case of the first TS, the first scrambler inputs the first TS and performs a scrambling process for randomizing the first TS(S702,S704). An RS encoder performs an RS encoding process in block unit to conduct an ECC process for scrambled data(S706). The first outer interleaver re-arrays the encoded data(S708). The first convolution encoder convolution-encodes the data outputted from the first outer interleaver(S710). An inner interleaver re-interleaves the convolution-encoded data(S722). A modulator portion digitally modulates the data, and transmits the modulated data(S730).

Description

Apparatus and method for transmission of digital broadcasting system having the composition error correction coding function}

The present invention relates to a transmission apparatus and a transmission method of a digital broadcasting system having a complex error correction encoding function. More specifically, in a digital broadcasting system supporting a hierarchical transmission mode, error correction encoding is performed differently for each transmission layer. The present invention relates to a transmission apparatus and a transmission method of a digital broadcasting system having a complex error correction encoding function.

The digital broadcasting system refers to a system that digitally encodes a broadcast signal, transmits it through a phase or terrestrial channel, and views it through a receiving device. Unlike analog broadcasting, digital broadcasting has the advantage of system integration and interoperability through digital coding system, and it is an opportunity to change the analog broadcasting area that has been unilateral and downward due to the interactive function.

In order to ensure the integration and interoperability of digital broadcasting, standardization must precede. In the case of broadcasting method for digital terrestrial DTV (Digital Television) broadcasting, Europe based on Advanced Television Systems Committee (ATSC) method using 8-VSB (Vestigial Side Band) and Coded Orthogonal Frequency Division Multiplexing (COFDM) Digital Video Broadcasting-Terrestrial (DVB-T) has been proposed. In addition, Terrestrial Digital Multimedia Television Broadcasting (DMB-T) based on Time-Domain Synchronous Orthogonal Frequency Division Multiplexing (TDS-OFDM), Advanced Digital Television Broadcast-Terrestrial (ADTB-T) with improved VSB, and SMCC (COFDM) with improved COFDM Synchronized multi-carrier CDMA (CDMA), other CDTB-T (Chinese Digital Television Broadcasting-Terrestrial), and BDB-T have been proposed.

When transmitting digital broadcasting, it is necessary to compress and transmit a signal source to transmit a huge amount of data, so even a small error occurring in a channel has a great effect on the whole system. Therefore, it is necessary to reduce the error in the channel. In order to reduce errors occurring in the channel, the power may be increased to increase the SNR. However, when the power is increased, problems such as power loss, cost increase due to high output of the transmission apparatus, and interference between the channels occur. To overcome this problem, digital broadcasting systems use error correction codes to correct errors occurring in channels without increasing power. The error correcting code can correct an error occurring in a channel without increasing power, thereby reducing the probability of an error occurring in a receiver.

The error correction code can be largely divided into ARQ (Automatic Repeat Request) and FEC (Forward Error Correction). ARQ is a method in which the transmitting side retransmits data when an error is detected at the receiving side, when the transmitting side sends a signal to transmit the data again. This method is not suitable for digital broadcasting systems because the receiver needs a return channel that can send a signal to the transmitter to retransmit. On the other hand, FEC attaches an additional symbol to a signal and transmits it, and when an error occurs in a channel, the receiver uses algebraic properties to detect or correct a channel error.

FEC can be roughly divided into a block code and a convolution code. The block code is a linear block code and a code that satisfies a cyclic code. Such a block code includes a BCH code and a RS (Reed Solomon) code, which is a non-binary code that satisfies a good condition among the BCH codes. In the block code, a certain check symbol (parity) is added to the information data to correct an error, and it is advantageous to correct a burst error.

In contrast, a convolutional code is a code that uses an encoding method based on a correlation between a current input and a past input, and is effective for correcting a random error. Since most decoders use a Viterbi decoder, a convolutional code is also called a Viterbi code.

1 is a block diagram of a transmission apparatus of a digital broadcasting system according to a DVB-T method based on COFDM.

Referring to the drawings, a transmission apparatus of a digital broadcasting system includes first and second scramblers 10 and 12, a forward error correction (FEC) unit 20, and a modulator 30. Here, the FEC unit 20 includes first and second RS encoders 21 and 25, first and second outer interleavers 22 and 26, and first and second convoluts. It consists of a block encoder 23 and 27, and an inner interleaver 24. The modulator 30 includes a pilot / system information inserter 31, a mapping / OFDM modulator 33, a guard interval inserter 35, a D / A converter 37, and an RF unit 39. It consists of.

In the case of the DVB-T scheme, a hierarchical transmission mode is supported, and in this case, the inputted TS-2 transport stream of the MPEG-2 format is separated by a splitter (not shown) by HP (High Priority). ) And a first TS stream transmitted to the HP layer is input to the first scrambler 10, and a second TS stream transmitted to the LP layer is transmitted to the second scrambler 12. Is entered.

The first and second scramblers 10 and 12 change the data values of the input first and second TS streams according to a predetermined pattern and randomize them. This process is reversed in the receiver to restore the original value.

The FEC unit 20 encodes data input through the first and second scramblers 10 and 12 to correct an error that may occur during transmission. That is, the first and second RS encoders 21 and 25 receive data passing through the first and second scramblers 10 and 12 and perform RS encoding in units of blocks to enable error correction. By RS coding, a parity (check symbol) for error correction is added, and the size of the added parity varies depending on the transmission scheme. In the case of the DVB-T system, 16 parities are added per TS stream of 188 bytes, and the total error-correction encoded bytes are 204 bytes.

The first and second external interleavers 22 and 26 rearrange the RS-coded data in units of blocks in the first and second RS encoders 21 and 25, respectively, so as to disperse a likely aggregation error. Perform the function. The first and second convolutional encoders 23 and 27 convolutionally encode the data rearranged and output by the first and second external interleavers 22 and 26, respectively. In the DVB-T scheme, it is common to use a convolutional code having a constraint length of 7 and a code rate of 1/2. The bits convolutionally encoded by the first and second convolutional encoders 23 and 27 are rearranged and output again by the internal interleaver 24.

The modulator 30 performs appropriate digital modulation on the data encoded and output by the FEC unit 20 according to the transmission method of the digital broadcasting system. As shown in FIG. 1, when the OFDM scheme of the DVB-T system is used, the mapping / OFDM modulator 33 performs quadrature phase shift keying (QPSK), 16-QAM, on data output from the internal interleaver 24. OFDM modulation such as mapping to symbols such as Quadrature Amplitude Modulation, 64-QAM, and Inverse Fast Fourier Transform (IFFT). In this process, the pilot / system information insertion unit 31 inserts information on the signal synchronization, the pilot signal for the signal prediction, and the transmission mode. The guard interval inserting part 35 inserts a guard interval to prevent inter symbol interference (ISI) in a multipath environment. In addition, the D / A converter 37 performs a D / A (Digital to Analog) conversion on the signal into which the protection interval is inserted, and the RF unit 39 amplifies the antenna by performing high frequency amplification on the D / A converted signal. Send it through.

As described above, in the transmission apparatus of the conventional digital broadcasting system, the first and second RS encoders 12 and 22 are used as the outer encoder, and the first and second encoders are used as the inner encoder. The concatenated code system, which uses the convolutional encoders 16 and 26, is mainly used. In addition, in the case of a transmission device of a digital broadcasting system supporting a hierarchical transmission mode such as DVB-T, an encoder using an error correction encoding method having the same specification in the HP layer and the LP layer, and interleaving are performed by the same method. Use an interleaver.

As described above, in case of error correction encoding using the encoder and interleaver of the same specification in the HP layer and the LP layer, both the data transmitted through the HP layer and the data transmitted through the LP layer are received using a receiver having the same structure. There is the convenience of doing it.

However, the receiver using the HP layer and the receiver using the LP layer may exist in different communication environments. In this case, separate error correction coding may increase the transmission efficiency of the entire system according to the communication environment of the receiver. have. For example, a receiving device in a mobile communication environment needs to receive a signal having a good reception state, and a fast data transmission amount may be required in a receiving device in a fixed communication environment. In this case, reception performance may be improved by performing enhanced error correction encoding on data transmitted through either the HP layer or the LP layer, and data transmitted through the other layer may have different error correction encoding. It can be configured to have a faster data rate. Accordingly, there is a need for a transmission apparatus and a transmission method of a digital broadcasting system capable of using a combination of error correction coding methods in consideration of a communication environment of a reception apparatus.

The present invention has been made to solve the above problems, an object of the present invention, error correction encoding data transmitted through the HP layer and data transmitted through the LP layer differently in consideration of the communication environment of the receiving device The present invention provides a transmission apparatus and a transmission method of a digital broadcasting system that can be transmitted.

1 is a block diagram of a transmission apparatus of a general digital broadcasting system.

2 is a block diagram of an embodiment of a transmission apparatus of a digital broadcasting system according to the present invention;

3 is a flowchart provided to explain an operation method for a transmission apparatus of the digital broadcasting system of FIG.

4 is a diagram showing a configuration example of a BPC encoder of FIG. 2;

FIG. 5 is a diagram for explaining a data format generated by the BPC encoder of FIG. 2; FIG.

6 is a block diagram of another embodiment of a transmission apparatus of a digital broadcasting system according to the present invention; and

FIG. 7 is a flowchart provided to explain an operation method for the transmission apparatus of the digital broadcasting system of FIG. 6.

Explanation of symbols on the main parts of the drawings

110: first scrambler 120: second scrambler

200: FEC unit 210: first RS encoder

220: first external interleaver 230: first convolutional encoder

240: internal interleaver 250: BPC encoder

260: second external interleaver 270: second convolution encoder

300: modulation unit 310: pilot / system information insertion unit

330: mapping / OFDM modulation unit 350: protection section insertion unit

370: D / A converter 390: RF unit

In order to achieve the above object, a transmission apparatus of a digital broadcasting system according to the present invention includes an RS encoder for reed-solomon (RS) encoding of an input first TS stream and error correction to an input second TS stream. In order to enable the encoding, the first and second external interleavers and the rearranged data in the first and second external interleavers respectively rearrange the external encoder, the data encoded in the RS encoder, and the data encoded in the external encoder. First and second convolutional encoders for convolutionally encoding the data, an internal interleaver for rearranging the data encoded by the first and second convolutional encoders, and digitally modulating and transmitting the rearranged data from the internal interleaver. It includes a modulating unit.

Preferably, the external encoder uses a BPC (Block Product Code) code to encode the BPC coder. In this case, the BPC encoder is a first encoder for error correction encoding the first TS stream, an interleaver for rearranging the data encoded by the first encoder, and a second error correction encoding for the rearranged data in the interleaver. It is possible to configure with two encoders. The first and second encoders may be configured as RS encoders encoded using Reed-Solomon (RS) codes or BCH encoders encoded using BCH encoding.

The internal interleaver may rearrange the data encoded by the first convolutional encoder and the data encoded by the second convolutional encoder in the same manner. The internal interleaver may rearrange the data encoded by the first convolutional encoder and the data encoded by the second convolutional encoder in different ways.

Preferably, the modulator digitally modulates by an OFDM modulation method. In this case, the modulator may include a mapping / OFDM modulator for mapping and OFDM modulating data rearranged by the internal interleaver using a predetermined mapping method, a pilot signal for signal synchronization and a signal prediction unit for the mapping / OFDM modulator, System information insertion unit for providing information about the transmission mode, the guard interval insertion unit for inserting the guard interval to the signal output from the mapping / OFDM modulation unit, D / A for D / A conversion of the signal inserted into the guard interval It is possible to constitute a conversion unit, and an RF unit for transmitting the D / A converted signal by high frequency conversion.

Preferably, a separator for separating the input TS stream of the MPEG-2 format into the first TS stream transmitted through the HP (High Priority) layer and the second TS stream transmitted through the LP (High Priority) layer. And first and second scramblers each of which randomizes the first and second TS streams to provide the RS encoder and the external encoder.

On the other hand, the transmission method of the digital broadcasting system according to the present invention comprises the steps of: (a) outputting the first encoded data that is RS (Reed-Solomon) coded for the first transport stream (TS), (b) input Outputting encoded second coded data to enable error correction on the second TS stream; (c) rearranging the first and second encoded data, respectively, and outputting the first and second rearranged data, respectively; (D) convolutionally encoding the first and second rearranged data, respectively, (e) rearranging the respective convolutional coded data, and (f) rearranging the respective rearranged data. Digitally modulating and transmitting the data.

In the step (b), it is preferable to encode using a BPC code. In this case, the step (b) may include (b1) error correcting encoding of the first TS stream, (b2) rearranging the encoded data, and (b3) erroring the rearranged data again. It is possible to comprise a step of corrective encoding. In addition, the steps (b1) and (b3) may be encoded using a Reed-Solomon (RS) code or may be encoded using a Block Product Code (BCH) code.

In the step (e), it is possible to rearrange the respective convolutionally encoded data in the same manner. Further, in the step (e), it is also possible to rearrange the respective convolutionally encoded data in different ways.

In the step (f), it is preferable to perform digital modulation by the OFDM modulation method. In this case, step (f) may include: (f1) mapping and OFDM modulating the rearranged data by a predetermined mapping method, and (f2) the pilot signal and the transmission mode for signal synchronization and signal prediction. Providing information about the OFDM modulation process, (f3) inserting a guard interval into the signal output in step (f1), (f4) D / A converting the signal having the guard interval inserted therein, And (f5) converting the D / A-converted signal into high-frequency conversion.

Separating the input TS stream of the MPEG-2 format into the first TS stream transmitted through the HP (High Priority) layer and the second TS stream transmitted through the Low Priority (LP) layer; and And randomizing the first and second TS streams and supplying them to step (a).

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

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

Referring to the drawings, a transmission apparatus of a digital broadcasting system according to the present embodiment is largely composed of first and second scramblers 110 and 120, an FEC unit 200, and a modulator 300. The FEC unit 200 includes an RS encoder 210, a BPC encoder 250, first and second outer interleavers 220 and 260, first and second convolution encoders 230 and 270, and an inner interleaver. interleaver) 240. The modulator 300 includes a pilot / system information inserter 310, a mapping / OFDM modulator 330, a guard interval inserter 350, a D / A converter 370, and an RF unit 390. It consists of.

The transmission apparatus of the digital broadcasting system according to the present embodiment supports a hierarchical transmission mode, and an input TS stream of an MPEG-2 format is separated by a splitter (not shown). The first TS stream separated into the HP (High Priority) layer and the Low Priority (LP) layer and transmitted to the HP layer is input to the first scrambler 110, and the second TS stream transmitted through the LP layer is the second. It is input to the scrambler 120.

The first and second scramblers 110 and 120 randomize the data values of the input first and second TS streams according to a predetermined pattern. This is to prevent the problem that the same number is repeated, such as 00000000b or 11111111b, and loses the synchronization signal in the synchronous data transmission. This process is reversed in the receiver to restore the original value.

The FEC unit 200 performs encoding for error correction that may occur during transmission on data input through the first and second scramblers 110 and 120.

That is, the RS encoder 210 receives the data passed through the first scrambler 110 and performs RS coding in units of blocks for error correction, and the block product code (BPC) encoder 250 performs the second scrambler 120. BPC-encodes the data passed by The first and second external interleavers 220 and 260 perform interleaving to rearrange data output from the first RS encoder 210 and the BPC encoder 250, respectively. The first and second convolution encoders 230 and 270 convolutionally encode data output from the first and second external interleavers 220 and 260, respectively.

The data encoded by the first and second convolutional encoders 230 and 270 are rearranged by the internal interleaver 240 and output to the modulator 300. The internal interleaver 240 may include a bit interleaver and a symbol interleaver. In this case, the bit interleaver performs interleaving in a data block capable of bit interleaving, and the symbol interleaver uses one effective subcarrier in an OFDM symbol in the OFDM scheme. Interleaving is performed in units of symbols of.

The modulator 300 performs digital modulation appropriate to the transmission method of the digital broadcasting system on the data encoded and output by the internal interleaver 240. 2 illustrates a case where the DVB-T system performs modulation based on the OFDM scheme.

In this case, the mapping / OFDM modulator 330 of the modulator 300 may perform quadrature phase shift keying (QPSK), quadrature amplitude modulation (16-QAM), 64-QAM, and the like on the data output from the internal interleaver 240. Mapping to the same symbol, and performs OFDM modulation such as Inverse Fast Fourier Transform (IFFT). During this process, the pilot / system information inserter 310 inserts information on the signal synchronization, the pilot signal for the signal prediction, and the transmission mode. The guard interval inserting unit 350 inserts a guard interval GI to prevent inter symbol interference (ISI) in a multipath environment. In addition, the D / A converter 370 performs a D / A (Digital to Analog) conversion on the signal into which the protection interval is inserted, and the RF unit 390 amplifies the antenna by applying high frequency amplification to the D / A converted signal. Send through.

3 is a flowchart provided to explain an operation method for a transmission apparatus of a digital broadcasting system according to the present invention shown in FIG.

Referring to the flowchart, a first TS stream in MPEG-2 format is inputted as a first TS stream transmitted through a high priority (HP) layer by a splitter (not shown), and a LP (Low). Priority) is separated into a second TS stream delivered through the layer (S700). As a result of the separation, when the first TS stream is input to the first scrambler 110, the first scrambler 110 performs scrambling to randomize the input first TS stream (S702, S704). MPEG-2 defines two multiplexing methods, namely, program stream and TS stream, to cope with various applications. Multiplexing is the creation of a single bitstream that is combined to transmit individually compressed video, audio, and data streams. Program stream is a multiplexing method defined for media with relatively low error or loss of data such as CD-ROM, and TS stream is a multiplexing method defined for an environment where transmission error or data loss may occur such as a noisy channel. to be. One packet of the multiplexed string is of fixed size of 188 bytes.

The RS encoder 210 performs RS encoding on a block-by-block basis for error correction on the scrambled data passing through the first scrambler 110 (S706).

Unlike other coding schemes, the RS (Reed Solomon) code is a non-binary block code, and the element is not composed of only 0 or 1, but is composed of non-binary elements of 0, 1, ..., 2 ^m-1 . By RS coding, one block composed of k input symbols is encoded into n code symbols larger than k. Therefore, nk redundant symbols are added, which is called Reed Solomon Parity. The number of parities added by RS encoding may vary depending on the transmission scheme, such as 16 or 20 per 188-byte symbol. The receiver uses the added parity to determine the accuracy of the received data. As a result of the accuracy determination, if an error is detected, the receiver locates the error, corrects the distorted data, and restores the original signal. In general, error recovery is possible as many as half of the number of added parity symbols, and more errors cannot be recovered.

The first external interleaver 220 performs external interleaving which rearranges data encoded in units of blocks in the first RS encoder 210 (S708). There are various ways in which the first external interleaver 220 rearranges data, but a convolutional interleaver is generally used. The convolution interleaver cyclically writes each input symbol or bit into one of the predetermined shift registers, and when the shift register is read cyclically, the interleaved symbols are output. The interleaver basically does the job of distributing burst errors as large as possible.

The first convolution encoder 230 convolutionally encodes data output from the first external interleaver 220 (S710). The convolutional code encodes each successive input sequence of k bits into n output bits, and the encoding consists of the convolution of the input bits and the binary impulse response. In the case of the DVB-T transmission method, a convolutional coding method having a constraint length of 7 and a coding rate of 1/2 is used, but the coding rates of the convolution are 2/3, 3 / 4, 5/6, 7/8, etc. can be changed.

The internal interleaver 240 interleaves the data convolutionally encoded by the first convolutional encoder 230 (S722) to improve performance degradation due to multipath. The error correction coded data is transmitted by being subjected to digital modulation suitable for data transmission by the modulator 300 (S730).

Meanwhile, when the input TS stream is the second TS stream transmitted through the LP layer, the second TS stream separated by the separator (not shown) is input to the second scrambler 120 and scrambled (S714). The scrambled data is BPC coded by the BPC encoder 250 (S716).

The BPC encoder 250 can be configured in various ways, and FIG. 4 is one example. In FIG. 4, the BPC encoder 250 is composed of a first encoder 252, an interleaver 254, and a second encoder 256. As the first and second encoders 252 and 256, it is possible to use an RS encoder. When the RS encoder is used as the first and second encoders 252 and 256, the first encoder 252 adds predetermined parity by RS coding the input data. The interleaver 254 rearranges the data coded in units of blocks in the first encoder 252 to distribute a possible coherence error. The second encoder 256 RS encodes the data output from the interleaver 254 again.

FIG. 5 shows an example of a data format generated from the BPC encoder 250 configured as shown in FIG. Referring to FIG. 5, a parity rP of size n1-k1 is added to a data having a block size k1 * k2 and a parity cP size of n2-k2 is added to a column direction. . In the figure, pP denotes parity in the row direction for rP or column direction for cP.

Parity rP is added by the first encoder 252, and after rearrangement by the interleaver 254, parity cP and pP are added by the second encoder 256. On the contrary, cP may be added by the first encoder 252 and interleaved by the block interleaver 254, and then rP and pP may be added by the second encoder 256.

The data that is error-corrected encoded and transmitted in this manner is also decoded by the BPC decoder including two first and second decoders and deinterleavers corresponding to the transmitter. In this case, when an error outside the error correctable range occurs due to parity added in the column direction from the data received by the first decoder, an erasure flag is generated instead of discarding the stream data. After deinterleaving, the data including the erasure flag is transmitted to the second decoder. The second decoder uses the erasure flag and the parity added in the row direction to correct the error again. In this case, since the erasure flag indicates the position of the error, the range of error correction is doubled than when the error is corrected using only parity added in the row direction. Therefore, even when an error outside the error correction range of the first decoder occurs, error correction may be possible in the second decoder.

As described above, the BPC encoder 250 may be configured by using a BCH encoder that uses the BCH code to encode the first and second encoders 252 and 256 instead of using the RS encoder. The BHC code was published by three people, Hocquenghem in 1959 and Bose and Chaudhuri in 1960, and is called the BCH code after the three headings. The BHC code can be generated by dividing the coded polynomial shifted to the left by the generated polynomial, such as a hamming code, and adding a CRC (CyclicRedundancy Check Code). In the case of using the BCH encoder, the above-described operation is performed in units of bits, and in the case of using the RS encoder, the operation is performed in units of symbols.

The data encoded by the BPC encoder 250 is transferred to the second external interleaver 260, and the second external interleaver 260 performs interleaving to rearrange the transferred data (S718), which may occur in the channel. Distribute coherency errors

The second convolutional encoder 270 convolutionally encodes the data rearranged from the second external interleaver 260 so that error correction is possible again (S720). The second convolutional encoder 270 is encoded. The data is transferred to the internal interleaver 240, and the internal interleaver 240 interleaves the transferred data and rearranges the data again (S722). The error correction coded data is digitally modulated for data transmission by the modulator 300 and transmitted through an antenna (S730).

In this manner, data transmitted to the HP layer and data transmitted through the LP layer can be transmitted by error correction encoding differently.

6 is a block diagram showing another embodiment of a transmission apparatus of a digital broadcasting system according to the present invention.

Referring to the drawings, a transmission apparatus of a digital broadcasting system includes first and second scramblers 410 and 420, an FEC unit 500, and a modulator 600. The FEC unit 500 includes an RS encoder 510, a BPC encoder 550, first and second external interleavers 520 and 560, first and second convolutional encoders 530 and 570, and first and second internal interleavers 540 and 580. It is composed of The modulator 600 includes a pilot / system information inserter 610, a mapping / OFDM modulator 630, a guard interval inserter 650, a D / A converter 670, and an RF unit 690. It consists of.

The difference between the transmission apparatus of the digital broadcasting system according to the present embodiment and the transmission apparatus of the digital broadcasting system shown in FIG. 2 uses one internal interleaver 240 in FIG. And interleaving data encoded and output by the first and second convolutional encoders 530 and 570 by using the second internal interleaver 540 and 580, respectively. The functions of the remaining blocks are as described in FIG.

FIG. 7 is a flowchart provided to explain an operation method for the transmission apparatus of the digital broadcasting system of FIG. 6.

Referring to the flowchart, unlike the flowchart of FIG. 3, the first internal interleaver 540 interleaves data output from the first convolution encoder 530 (S810 and S812), and the second convolution encoder 570. There is a difference in interleaving data output from the second internal interleaver 580 (S820 and S822). That is, there is a difference in that data output from the first and second convolutional encoders 530 and 570 may be interleaved by different methods. In the flowchart, the operation of the remaining steps is as described in the flowchart of FIG.

As described above, the transmission apparatus of the digital broadcasting system according to the present invention adds error correction codes to the data transmitted through the HP layer and the data transmitted through the LP layer using external encoders having different specifications. In addition, the interleaving scheme of the error correction coded data may be different. As described above, error correction coding is performed differently according to the transmitted layer, thereby enabling error correction coding suitable for the communication environment of the receiving apparatus.

In addition, in the above-described embodiment, the case in which the error correction coded data is modulated by using the OFDM scheme of the DVB-T system has been described as an example. By applying in, it is possible to transmit data optimized for the communication environment of the receiving device.

As described above, according to the present invention, by performing different error correction encoding process for the data transmitted through the HP layer and the data transmitted through the LP layer, the error correction encoding is optimized according to the communication environment of the receiver It becomes possible. In addition, by using the error correction code optimized according to the communication environment of the receiving apparatus, it is possible to improve the overall transmission efficiency of the system.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the specific embodiments described above, but the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, 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.

Claims (20)

An RS encoder for performing RS (Reed-Solomon) encoding on an input first TS stream; Encoding is performed so that error correction is possible to the input second TS stream; First and second external interleavers for rearranging data encoded by the RS encoder and data encoded by the external encoder; First and second convolutional encoders for convolutionally coding the rearranged data in the first and second external interleavers; An internal interleaver for rearranging data encoded by the first and second convolutional encoders, respectively; And And a modulator for digitally modulating and transmitting rearranged data from the internal interleaver. The method of claim 1, The external encoder is a transmission device of a digital broadcasting system, characterized in that the encoding using the BPC (Block Product Code) code BPC coder. The method of claim 2, The BPC encoder, A first encoder for error correction encoding the first TS stream; An interleaver for rearranging the data encoded by the first encoder; And And a second encoder for error correction encoding the rearranged data in the interleaver. The method of claim 3, And the first and second encoders are RS encoders encoded using Reed-Solomon (RS) codes. The method of claim 3, And the first and second encoders are BCH encoders encoded using BCH encoding. The method of claim 1, The internal interleaver, And the data encoded by the first convolutional encoder and the data encoded by the second convolutional encoder are rearranged in the same manner. The method of claim 1, The internal interleaver, And the data encoded by the first convolutional encoder and the data encoded by the second convolutional encoder are rearranged in different ways. The method of claim 1, The modulator, And a digital modulation system using an OFDM modulation method. The method of claim 8, The modulator, A mapping / OFDM modulator for mapping and OFDM modulating data rearranged by the internal interleaver by a predetermined mapping method; A system information insertion unit for providing information on a signal synchronization, a pilot signal for signal prediction, and a transmission mode to the mapping / OFDM modulation unit; A guard section insertion section for inserting a guard section into a signal output from the mapping / OFDM modulator; A D / A converter configured to D / A convert the signal with the guard interval inserted therein; And And a RF unit for transmitting the D / A-converted signal by high frequency conversion and transmitting the same. The method of claim 1, A separator for separating the input TS stream of the MPEG-2 format into the first TS stream transmitted through the HP (High Priority) layer and the second TS stream transmitted through the High Priority (LP) layer; And And randomizing the first and second TS streams respectively and providing first and second scramblers to the RS encoder and the external encoder, respectively. (a) outputting Reed-Solomon (RS) encoded first encoded data with respect to an input first TS stream; (b) outputting encoded second encoded data to enable error correction on the input second TS stream; (c) rearranging the first and second encoded data, respectively, and outputting first and second rearranged data, respectively; (d) convolutionally encoding the first and second rearranged data, respectively; (e) rearranging the respective convolutional coded data respectively; And and (f) digitally modulating and transmitting the rearranged data. The method of claim 11, In the step (b), the transmission method of the digital broadcasting system, characterized in that the encoding using the BPC code. The method of claim 11, In step (b), (b1) error correcting encoding the first TS stream; (b2) rearranging the encoded data; And (b3) error correcting and coding the rearranged data again. The method of claim 13, In the steps (b1) and (b3), the transmission method of the digital broadcasting system, characterized in that the encoding using a Reed-Solomon (RS) code. The method of claim 13, In the steps (b1) and (b3), a transmission method of a digital broadcasting system, characterized by encoding using a block product code (BCH) code. The method of claim 11, In step (e), And rearranging the respective convolutionally encoded data in the same manner. The method of claim 11, In step (e), And rearranging the convolutionally encoded data in different ways. The method of claim 11, In the step (f), the digital broadcasting system is characterized by digital modulation by OFDM modulation. The method of claim 18, Step (f), (f1) mapping and OFDM modulating each of the rearranged data by a predetermined mapping method; (f2) providing information on a pilot signal and a transmission mode for signal synchronization and signal prediction to the OFDM modulation process; (f3) inserting a guard interval into the signal output in step (f1); (f4) D / A converting the signal into which the guard interval is inserted; And (f5) transmitting the D / A-converted signal by high-frequency conversion; transmitting the digital broadcasting system. The method of claim 11, Separating the input TS stream of the MPEG-2 format into the first TS stream transmitted through the HP (High Priority) layer and the second TS stream transmitted through the Low Priority (LP) layer; And Randomizing the first and second TS streams, and supplying the first and second TS streams to the step (a).