KR20040034878A - Apparatus and method for transmission of digital broadcasting system which has the composition error correction encoder - Google Patents

Abstract

PURPOSE: A transmission device and a transmission method of a digital broadcasting system having a complicated error correction coding function are provided to perform an error correction coding process for data transmitted through an HP(High Priority) layer and data transmitted through an LP(Low Priority) layer differently from each other, thereby efficiently transmitting digital broadcasting according to communication environments of a receiving device. CONSTITUTION: First and second coders(112,122) output data coded by the unit of block to enable error correction respectively for first and second TSs(Transport streams). First and second outer interleavers(114,124) respectively re-align the data outputted from the first and the second coders(112,122). A convolution coder(116) performs convolution coding for the data outputted from the first outer interleaver(114) to output the coded data. A TCM(Trellis Coded Modulation) coder(126) performs TCM coding for the data outputted from the second outer interleaver(124) to output the coded data. An inner interleaver(128) respectively re-aligns and outputs the data outputted from the convolution coder(116) and from the TCM coder(126). And a modulation unit(140) modulates the data outputted from the inner interleaver(128) into digital data and transmits the modulated data.

Description

Apparatus and method for transmission of digital broadcasting system which has the composition error correction encoder}

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.

Digital broadcasting, unlike analog broadcasting, has the advantage of system integration and interoperability through digital code system. Accordingly, digital broadcasting has a condition that can be the core of so-called media convergence using a computer and a network, and it is an opportunity to change the analog broadcasting area that has been unilateral and downward with an 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, DVB of Europe based on US Advanced Television Systems Committee (ATSC) method using 8-VSB (Vestigial Side Band) and Coded Orthogonal Frequency Modulation (COFDM) -T (Digital Video Broadcasting-Terrsetrial) method is proposed. In addition, Terrestrial Digital Multimedia Television Broadcasting (DMB-T) based on Time-Domain Synchronous Orthogonal Frequency Modulation (TDS-OFDM), Advanced Digital Television Broadcast-Terrestrial (ADTB-T) with improved VSB, and Synchronized SMCC with COFDM Various transmission methods such as 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 the error, 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 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). When an error is detected at the receiver, ARQ sends a signal to the transmitter to retransmit the data, and then the transmitter retransmits the data. This method allows the receiver to send a signal to retransmit to the transmitter. This is not suitable for digital broadcasting systems because it is necessary. 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 encoded and decoded by dividing the information into blocks, and includes a Hamming code, a BCH code, and a Reed Solomon (RS) code. Among them, RS codes are most commonly used in digital broadcasting systems because of their excellent distance characteristics and efficient encoding and decoding algorithms. Since RS codes detect and correct errors on a block basis, the ability to correct burst errors is excellent.

In contrast, a convolution code is a code whose output bit is affected not only by the current input bit but also by the past input bit, and is effective for correcting a random error. Since most decoders use a Viterbi decoder, a convolutional code is also called a Viterbi code.

In addition, since the error-corrected data must transmit additional information for error correction, the amount of information that can be transmitted per limited bandwidth is reduced. Accordingly, a transmission method that can obtain a large code gain without reducing the data rate or increasing the bandwidth by combining the encoding and the modulation together without a separate one, is typical of TCM (Trellis Coded Modulation) There is.

1 is a block diagram of a transmission apparatus of a digital broadcasting system according to a digital video broadcasting terrsetrial television (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 11, a forward error correction unit 30, and a modulator 40. The FEC unit 30 includes the first and second RS encoders 12 and 22, the first and second external interleavers 14 and 24, the first and second convolution encoders 16 and 26, and the internal interleaver 28. It consists of The modulator 40 includes a pilot / system information inserter 41, a mapping / OFDM modulator 43, a guard interval inserter 45, a D / A converter 47, and an RF section 36. 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 11. Is entered.

The first and second scramblers 10 and 11 change the data values of the first and second TS streams of the MPEG-2 format inputted according to a predetermined pattern and randomize them. This process is reversed in the receiver to restore the original value.

The FEC unit 30 encodes data input through the first and second scramblers 10 and 11 to correct an error that may occur during transmission. That is, the first and second RS encoders 12 and 22 receive data passing through the first and second scramblers 10 and 11 and perform RS encoding on a block basis for error correction. do. By RS coding, a parity for error correction is added, and the number of parities added 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 error correction coded total bytes are 204 bytes.

The first and second outer interleavers 14 and 24 rearrange the data encoded in units of blocks in the first and second RS encoders 12 and 22, respectively, so as to eliminate a possible coherence error. Perform the function of distributing The first and second convolution encoders 16 and 26 convolutionally encode the data rearranged and output in units of blocks from the first and second external interleavers 14 and 24, 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 coded by the first and second convolutional encoders 16 and 26 are rearranged and output again by an inner interleaver 28.

The modulator 40 performs appropriate digital modulation on the transmission method of the digital broadcasting system on the data encoded and output by the FEC unit 30. As shown in FIG. 1, when the OFDM scheme of the DVB-T system is used, the mapping / OFDM modulator 43 performs quadrature phase shift keying (QPSK), 16-QAM, on data output from the internal interleaver 28. 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 41 inserts information on the signal synchronization, the pilot signal for the signal prediction, and the transmission mode. The guard interval inserter 45 inserts a guard interval to prevent inter symbol interference (ISI) in a multipath environment. In addition, the D / A converter 47 performs a D / A (Digital to Analog) conversion on the signal into which the protection interval is inserted, and the RF unit 49 amplifies the D / A converted signal through a high frequency antenna. Send it out.

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 outer encoders, and the first and second encoders are used as inner encoders. The concatenated code system, which uses the convolutional encoders 16 and 26, is mainly used. In addition, in the case of a transmitter of a digital broadcasting system supporting a hierarchical transmission mode such as DVB-T, an encoder using the same coding scheme in the HP layer and the LP layer and an interleaver performing interleaving by the same scheme are used. .

As such, when error correction is performed using an encoder and an interleaver using the same method in the HP layer and the LP layer, the data transmitted through the HP layer and the data transmitted through the LP layer using a receiver having the same structure are used. All can be received.

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 system according to the communication environment of the receiver. . For example, a reception device under a mobile environment may receive a better reception HP signal, and a reception device under a fixed state may receive an LP signal that can receive more data. In this case, reception performance may be improved by performing enhanced error correction encoding on data transmitted through the HP layer, and the LP layer may 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 using an error correction coding scheme differently according to layers 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, the data transmitted through the HP layer and the data transmitted through the LP layer differently complex error in consideration of the communication environment of the receiver. Disclosed are a transmission apparatus and a transmission method of a digital broadcasting system which can be transmitted by correction encoding.

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

FIG. 5 is a flowchart provided to explain an operation method of the transmission apparatus of the digital broadcasting system of FIG. 4.

Explanation of symbols on the main parts of the drawings

110: first scrambler 111: second scrambler

112: first RS encoder 114: first external interleaver

116: convolutional encoder 122: second RS encoder

124: second external interleaver 126: TCM encoder

128: internal interleaver 130: FEC unit

140: modulation unit 141: pilot / system information insertion unit

143: mapping / OFDM modulator 145: protection section insertion unit

147: D / A converter 149: RF unit

In order to achieve the above object, a transmission apparatus of a digital broadcasting system according to the present invention includes a first outputting data encoded in units of blocks so as to enable error correction for input first and second TS streams, respectively. And a convolution encoder for convoluting and outputting a second encoder, first and second external interleavers for rearranging data output from the first and second encoders, and data output from the first external interleaver, An internal TCM encoder for outputting the Trellis Coded Modulation (TCM) encoding for the data output from the second external interleaver, the data output from the convolutional encoder, and the data output from the TCM encoder. And an interleaver, and a modulator for digitally modulating and transmitting data output from the internal interleaver.

The internal interleaver may interleave and rearrange data output from the convolutional encoder and data output from the TCM encoder in the same manner. The internal interleaver may interleave and rearrange the data output from the convolutional encoder and the data output from the TCM encoder in different ways.

Preferably, the first and second encoders are Reed-Solomon encoders encoded using Reed-Solomon codes. At this time, the first and second encoders can be error-corrected encoded by RS codes having different specifications.

Preferably, the modulator digitally modulates by the OFDM modulation method. In this case, the modulation unit is a mapping / OFDM modulation unit for mapping and OFDM-modulated data output from the internal interleaver by a predetermined mapping method, the pilot signal and transmission for signal synchronization and signal prediction unit to the mapping / OFDM modulation unit A system information insertion unit providing information about a mode, a protection interval insertion unit inserting a guard interval into a signal output from the mapping / OFDM modulator, and a D / A conversion to D / A-convert the signal into which the guard interval is inserted It is possible to include a 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 a first scrambler for randomizing the first TS stream and supplying it to the first encoder, and a second scrambler for randomizing the second TS stream and supplying the second TS stream.

On the other hand, in the transmission method of the digital broadcasting system according to the present invention, (a) the first and second encoded data encoded in block units to enable error correction for the first and second TS streams (transport streams), respectively; (B) rearranging the first and second encoded data to output first and second rearranged data, and (c) convolutionally encoding the first rearranged data; (d) trellis coded modulation (TCM) encoding the second rearranged data, (e) rearranging the convolutionally coded data and the TCM coded data, respectively, and (f) each again Digitally modulating and transmitting the rearranged data.

In the step (e), the convolution coded data and the TCM coded data may be interleaved and rearranged in the same manner. In the step (e), the convolution coded data and the TCM coded data may be interleaved and rearranged in different ways.

In the step (a), it is preferable to encode using a Reed-Solomon code. In this case, in step (a), the first and second encoded data may be error corrected encoded by RS codes having different specifications.

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 positive mapping method, and (f2) pilot signals and transmission modes for signal synchronization and signal prediction. Providing information to the OFDM modulation process, (f3) inserting a guard interval into the signal output in step (f2), (f4) D / A converting the signal into which the guard interval is inserted, and (f5) it may be configured to include the step of transmitting the D / A converted signal by high frequency conversion.

Preferably, 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 them to the 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, the transmission apparatus of the digital broadcasting system according to the present embodiment is largely composed of the first and second scramblers 110 and 111, the FCE unit 130, and the modulation unit 140. The FEC unit 130 includes the first and second RS encoders 112 and 122, the first and second external interleavers 114 and 124, the convolution encoder 116, the TCM encoder 126, and the internal interleaver 128. It consists of The modulator 140 includes a pilot / system information inserter 141, a mapping / OFDM modulator 143, a guard interval inserter 145, a D / A converter 147, and an RF unit 149. It consists of.

The transmission apparatus of the digital broadcasting system according to the present embodiment supports a hierarchical transmission mode, and a TS stream of the MPEG-2 format is separated from the HP by a splitter (not shown). The first TS stream, which is divided into a High Priority layer and a Low Priority (LP) layer, and is transmitted to the HP layer, is input to the first scrambler 110, and the second TS stream transmitted through the LP layer is a second scrambler ( 111).

The first and second scramblers 110 and 111 randomize the data values of the input first and second TS streams according to a predetermined pattern. That is, the correlation of the input signal is eliminated by mixing the pseudo random binary sequence with the input TS stream of the MPEG-2 format. 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 130 performs coding for error correction that may occur during transmission on data input through the first and second scramblers 110 and 111. That is, the first and second RS encoders 112 and 122 receive data passing through the first and second scramblers 110 and 111 and perform RS encoding in units of blocks for error correction. By the RS encoding, a parity for error correction is added, and the sizes of the parities added by the first and second RS encoders 112 and 122 may be encoded in the same manner or encoded differently.

The first and second external interleavers 114 and 124 perform interleaving to rearrange the data output from the first and second RS encoders 112 and 122 in units of bytes.

The convolutional encoder 116 convolutionally encodes the data output from the first external interleaver 114, and the TCM encoder 126 performs TCM encoding of the data output from the second external interleaver 124. The convolution coded data or the TCM coded data is rearranged by the inner interleaver 128 and output to the modulator 140. The internal interleaver 128 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 carrier in an OFDM symbol in the OFDM scheme. Interleaving is performed in units of symbols.

The modulator 140 performs appropriate digital modulation on the transmission method of the digital broadcasting system on the data encoded and output by the internal interleaver 128. 2 illustrates a case of performing modulation based on the OFDM scheme of the DVB-T system.

In this case, the mapping / OFDM modulator 143 of the modulator 140 may use Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM), 64-QAM, or the like, for the data output from the internal interleaver 128. OFDM modulation such as mapping and Inverse Fast Fourier Transform (IFFT) are performed with the same symbol. During this process, the pilot / system information insertion unit 141 inserts information on the signal synchronization, the pilot signal for the signal prediction, and the transmission mode. The guard interval insertion unit 145 inserts a guard interval GI to prevent inter symbol interference (ISI) in a multipath environment. In addition, the D / A converter 147 performs a digital-to-analog (D / A) conversion on the signal having the guard interval inserted therein, and the RF unit 149 amplifies the antenna by performing high frequency amplification on 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, the first TS stream in the MPEG-2 format is transmitted through a first TS stream and a low priority (LP) layer transmitted through a high priority (HP) layer by a splitter (not shown). It is divided into the second TS stream transmitted (S300, S302). First, when the TS stream is transmitted through the HP layer, the first TS stream separated by the separator is input to the first scrambler 110, and the first scrambler 110 randomizes the input first TS stream. Scrambling is performed (S304). 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 first RS encoder 112 performs RS encoding on a block-by-block basis for error correction on the scrambled data passing through the first scrambler 110 (S306).

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, when 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 114 performs external interleaving which rearranges the data encoded in units of blocks in the first RS encoder 112 (S308). There are various ways in which the first external interleaver 114 rearranges data, but in general, a convolutional interleaver is used. The interleaver basically does the job of distributing burst errors as large as possible.

The convolution encoder 116 convolutionally encodes the data output from the first external interleaver 114 (S310). 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 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 and 3/4 according to the usage environment. , 5/6, 7/8 and so on.

The internal interleaver 128 interleaves the data convolutionally encoded by the convolutional encoder 116 again (S322) to improve performance degradation due to multipath. As described above, the error-corrected coded data is digitally modulated for data transmission by the modulator 140 and transmitted (S330).

On the other hand, when the input TS stream is transmitted through the LP layer, as described above, the second TS stream separated by the separator is input to the second scrambler 111 and scrambled (S314), and the scrambled data is The RS is encoded by the second RS encoder 122 (S316). At this time, the size of the parity added by error correction encoding by the second RS encoder 122 may be encoded in the same manner as the first RS encoder 112. It may be encoded differently.

The second external interleaver 124 performs interleaving to rearrange the data encoded by the second RS encoder 122 (S318), thereby distributing the coherence error that may occur in the channel.

The TCM encoder 126 performs TCM encoding so that error correction can be performed on data rearranged and output from the second external interleaver 124 (S320).

Trellis Coded Modulation (TCM), proposed by Underboeck, combines code and modulation separately to achieve large code gains without reducing information rates or increasing bandwidth. To make it possible. The reason for using such a TCM code is as follows.

That is, the error correction coding is transmitted by adding an error correction code, thereby reducing the amount of data that can be sent per bandwidth (bandwidth). Therefore, in order to maintain a constant data rate, more bandwidth must be used than when transmitting without encoding, and when a bandwidth is limited, a modulation method that efficiently uses bandwidth should be used. However, in a transmission device with limited bandwidth and power, it is often difficult to obtain desired performance by applying codes and modulation independently. In order to solve this problem, a communication method that combines code and modulation has been studied, and the representative one is TCM. The TCM treats convolutional codes and modulation as a single operation rather than as separate. Therefore, unlike the reception data is first demodulated and then decoded in a general receiver, the TCM receiver performs a combination of demodulation and decoding.

The data encoded by the TCM encoder 126 is transferred to the internal interleaver 128, and the internal interleaver 128 interleaves the transferred data and rearranges the data again (S322). The data rearranged by the internal interleaver 128 is digitally modulated for data transmission by the modulator 140 and transmitted through the antenna (S330).

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

4 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 210 and 211, an FCE unit 230, and a modulator 240. The FEC unit 230 includes the first and second RS encoders 212 and 222, the first and second external interleavers 214 and 224, the convolutional encoder 216 and the TCM encoder 226, and the first and second internal interleavers. 218,228). The modulator 240 includes a pilot / system information inserter 241, a mapping / OFDM modulator 243, a guard interval inserter 245, a D / A converter 247, and an RF unit 249. 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 is that one internal interleaver 128 is used in FIG. And interleaving data encoded and output by the convolutional encoder 216 and the TCM encoder 226 by using the second internal interleaver 218 and 228, respectively. The functions of the remaining blocks are as described in FIG.

FIG. 5 is a flowchart provided to explain an operation method of the transmission apparatus of the digital broadcasting system of FIG. 4.

Referring to the flowchart, unlike the flowchart of FIG. 3, the first internal interleaver 218 interleaves data output from the convolutional encoder 216 (S410 and S412), and outputs data output from the TCM encoder 226. There is a difference in the point of interleaving in the second internal interleaver 228 (S420, S422). That is, there is a difference in that data output from the convolutional encoder 216 and the TCM encoder 226 can be interleaved by different methods, and operations of the remaining steps are as described with reference to FIG. 3.

As described above, the transmitter 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 differently, and the interleaving scheme is also different from each other. It is possible to configure differently. As described above, the error correction coding is performed differently according to the layer to be transmitted, thereby enabling efficient transmission suitable for the communication environment of the receiving apparatus.

In addition, in the above embodiment, a case of modulating using the OFDM scheme has been described as an example. However, the present invention is applicable to a transmission apparatus of various digital broadcasting systems without being limited to the modulation scheme, thereby optimizing for a communication environment of the receiver. Enable the transfer of the data.

As described above, according to the present invention, an error correction encoding process of different methods is performed on data transmitted through the HP layer and data transmitted through the LP layer, thereby enabling efficient digital broadcasting according to a communication environment of a receiver. Can be transmitted.

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 (16)

First and second encoders for outputting data encoded in units of blocks so as to enable error correction on input first and second TS streams, respectively; First and second external interleavers for rearranging data output from the first and second encoders, respectively; A convolution encoder for convolution encoding and outputting data output from the first external interleaver; A TCM encoder for outputting TCM (Trellis Coded Modulation) encoding on the data output from the second external interleaver; An internal interleaver for rearranging and outputting data output from the convolutional encoder and data output from the TCM encoder; And And a modulator for digitally modulating and outputting data output from the internal interleaver. The method of claim 1, The internal interleaver, And the data output from the convolutional encoder and the data output from the TCM encoder are interleaved and rearranged in the same manner. The method of claim 1, The internal interleaver, And the data output from the convolutional encoder and the data output from the TCM encoder are interleaved and rearranged in different ways. The method of claim 1, And the first and second encoders are Reed-Solomon encoders that encode using Reed-Solomon codes. The method of claim 4, wherein And the first and second encoders perform error correction encoding on RS codes having different specifications. The method of claim 1, The modulator, And a digital modulation according to the OFDM modulation method. The method of claim 6, The modulator, A mapping / OFDM modulator for mapping and OFDM-modulating the data output from 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; A first scrambler for randomizing the first TS stream and supplying the first TS stream to the first encoder; And a second scrambler for randomizing the second TS stream and supplying the second TS stream to the second encoder. (a) outputting first and second encoded data encoded on a block-by-block basis so that error correction may be performed on the input first and second TS streams; (b) rearranging the first and second encoded data, respectively, and outputting first and second rearranged data; (c) convolutionally coding the first rearrangement data; (d) trellis coded modulation (TCM) encoding the second rearranged data; (e) reordering the convolution coded data and the TCM coded data, respectively; And and (f) digitally modulating and transmitting the rearranged data. The method of claim 9, In step (e), And transmitting the convolution coded data and the TCM coded data by interleaving and rearranging the same in the same manner. The method of claim 9, In step (e), And transmitting the convolution coded data and the TCM coded data by interleaving and rearranging the data in different ways. The method of claim 9, In the step (a), the Reed-Solomon code is encoded using a transmission method of a digital broadcasting system. The method of claim 12, In the step (a), the first and second coded data, error correction encoding method using a RS code having different specifications. The method of claim 9, In the step (f), the digital broadcasting system is characterized by digital modulation by OFDM modulation. The method of claim 14, Step (f), (f1) mapping and OFDM modulating 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 (f2); (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 9, 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).