KR20050097435A - Digital television transmitter and receiver for using 16 state trellis coding - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

VSB DTV transceiver related to ATSC A / 53 and a method thereof.

2. Technical problem to be solved by the invention

Provided is an 8-VSB DTV transceiver and method for improving the reception performance of a receiver by transmitting and receiving a dual stream consisting of general data and robust data without increasing the average power regardless of its mixing ratio.

3. Summary of the Solution of the Invention

Encoding means for performing 16-state trellis coding on the robust data when the data stream contains robust data.

4. Important uses of the invention

Used for VSB DTV transceiver.

Description

Digital television transceiver using 16-state trellis coding and its method {DIGITAL TELEVISION TRANSMITTER AND RECEIVER FOR USING 16 STATE TRELLIS CODING}

The present invention relates to a residual side band (VSB) DTV transceiver and method related to the Terrestrial Digital Television (DTV) standard (A / 53) of the Advanced Television System Committee (ATSC). More particularly, the present invention relates to a DTV transceiver and its method using 16-state trellis coding.

The ATSC standard for High Definition Television (HDTV) transmission over terrestrial broadcast channels uses 12 independent data streams with trellis encoding and time multiplexing to provide 8-level VSB (8-VSB, {-7, -5, -3, -1, 1, 3, 5, 7}) A signal modulated with a symbol stream is used. This signal is converted to a 6 MHz frequency band corresponding to a standard VHF or UHF terrestrial television channel, and the signal on that channel is broadcast at a data rate of 19.39 Mbps per second. Detailed technical information on the ATSC DTV standard and A / 53 is available at http://www.atsc.org/.

1 is a block diagram showing a conventional DTV transmitter.

As shown, the data input to the transmitter 100 is a serial data stream consisting of 188 bytes of MPEG compatible data packet (including 187 bytes representing sync byte and payload data). . Input data is randomized in the data randomizer 101, and each packet is forward error correction (FEC-RS coding, 1/6 data field interleaving and 2) in the Reed Solomon (RS) encoder 103. / 3 trellis coding) to encode 20 bytes of parity information. That is, according to the ATSC standard, the data randomizer 101 XORs all of the payload data bytes input to a 16-bit maximum length pseudo random binary sequence (PRBS) initialized at the data field start point. do.

In the RS encoder 103 receiving the output randomized data, 20 RS parity bytes for FEC are added to 187 bytes of data to generate a total of 207 bytes of data per data segment.

The randomization and FEC processes are not performed on the sync byte corresponding to the segment sync signal among the input packet data.

Next, data packets included in consecutive segments of each data field are interleaved in the data interleaver 105, and the interleaved data packets are interleaved and encoded again in the trellis encoder 107. The trellis encoder 107 generates a stream of data symbols represented by three bits using a two bit input. One bit of the input two bits is pre-coded, and the remaining one bit is four-state trellis encoded to be two bits. The three bits thus output are mapped to eight-level symbols. The trellis encoder 107 includes twelve parallel trellis encoders and a precoder to generate twelve interleaved / coded data sequences.

An eight-level symbol is generated from a synchronization unit (not shown) in the multiplexer 109 in combination with a synchronization bit sequence 117 of segment sync and field sync to form a data frame for transmission. The pilot signal is then inserted in pilot inserter 111. The symbol stream is VSB suppressed-carrier modulation in the VSB modulator 113. The baseband 8-VSB symbol stream is finally converted into a radio frequency signal by the RF converter 115 and transmitted.

2 is a block diagram showing a conventional DTV receiver.

As shown, the RF signal transmitted from the transmitter 100 is channel-selected by the tuner 201 of the receiver 200. Next, the synchronization frequency is detected after the intermediate band (IF) filtering in the IF filter and the detector 203. The synchronization and timing recovery block 215 detects the synchronization signal and restores the clock signal.

The signal is then removed from the NTSC filter 205 via a comb filter and the NTSC interference signal is removed and equalized and phase tracked by the equalizer and phase tracker 250.

The encoded data symbols from which multipath interference has been removed are trellis decoded in the trellis decoder 209. The decoded data symbols are deinterleaved in the data deinterleaver 211. The data symbol is then RS decoded in the RS decoder 213 and derandomized in the data derandomizer 217. Accordingly, the MPEG compatible data packet transmitted from the transmitter 100 is restored.

3 is a block diagram of a transmission data frame exchanged between the transmitter of FIG. 1 and the receiver of FIG. 2, and as shown in FIG. It consists of segments.

The first data segment of each data field is a data field sync signal, which is a sync signal, and includes a training data sequence used in the receiver 200. The remaining 312 data segments contain 188 byte transport packets and 20 byte data for FEC. The data in each data segment consists of the data contained in several transport packets because of data interleaving. That is, the data of each data segment may correspond to several transport packet data.

Each data segment consists of 832 symbols. The first four symbols are binary and provide data segment sync. The data segment sync signal corresponds to a sync byte, which is the first byte of 188 bytes of an MPEG compatible data packet. Each of the remaining 828 symbols corresponds to 187 bytes of MPEG compatible data packets and 20 bytes for FEC. These 828 symbols are transmitted in eight levels of signal, with each symbol represented by three bits. Thus, 2484 bits (= 828 symbols # 3) are transmitted for each data segment.

However, the transmission signal of the conventional 8-VSB transceiver is distorted in indoor and mobile channel environments due to a variable channel and a multipath phenomenon, resulting in a poor reception performance of the reception device.

That is, the transmitted data is affected by various channel distortion factors. Channel distortion factors include multipath phenomena, frequency offset, phase jitter, and the like. Although the training data sequence is transmitted every 24.2 ms to compensate for the signal distortion caused by the channel distortion factor, the multipath characteristic change and the Doppler interference are not detected even during the 24.2 ms time interval when the training data sequence is transmitted. The receiver cannot perform accurate equalization because the equalizer of the receiver does not have a fast convergence speed enough to compensate for the distortion of the received signal.

For this reason, the 8-VSB type DTV broadcasting reception performance is lower than that of the analog type, and it is impossible to receive in a mobile receiver, and the signal to noise ratio (SNR) that satisfies the threshold of visibility (TOV) even if reception is possible. There is a problem with this increase.

In order to solve the above problem, robust data is disclosed in International Publication No. WO 02/080559, International Publication No. WO 02/100026, United States Patent Publication No. US2002 / 0194570, and the like {-7, -5, 5, 7} or {-7,- A technique for transmitting one of four levels of symbols of 3, 3, 7} is disclosed. According to the related art, since the symbol to which the robust data is mapped is limited, the average power of the symbol representing the robust data increases compared to the conventional 8-VSB scheme. In other words, if the robust data is any one of the four level symbols {-7, -5, 5, 7}, the symbol average power is 37 energy / symbol, and the robust data is {-7, -3, 3, 7}. In the case of any one of the four level symbols, the symbol average power is 29 energy / symbol, and the average power of the symbol representing the robust data increases compared with the conventional 8-VSB method. The average power rise of symbols representing robust data causes an overall average power increase, and when transmitting signals with limited transmit power (typically), the transmit power of normal data is reduced relative to conventional 8-VSB schemes. As a result, in the same channel environment, general data has a poor reception performance than the conventional 8-VSB scheme.

This problem becomes more severe as the ratio of robust data mixed with general data increases, so that the SNR satisfying the TOV increases. Accordingly, even in a good channel environment, the reception performance is deteriorated. There may be situations where no backward compatibility can be provided.

Accordingly, the present invention has been made to solve the above problems, by receiving and transmitting a dual stream consisting of general data and 16 state trellis coded robust data according to the 8-level VSB (8-VSB) scheme, It is an object of the present invention to provide a DTV transceiver and a method for improving the decoding capability of the equalizer and trellis decoder and reducing the SNR that satisfies the TOV by improving the reception performance for robust data as well as general data.

Those skilled in the art to which the present invention pertains can easily recognize other objects and advantages of the present invention from the drawings, the detailed description of the invention, and the claims.

DTV transmission apparatus according to the present invention for achieving the above object is an input means for receiving a digital video data stream including general data and robust data, encoding means for coding the digital video data stream into a data symbol and the And transmission means for modulating and transmitting an output signal of the encoding means, wherein the encoding means performs 16 state trellis coding on the robust data.

In addition, the DTV receiving apparatus according to the present invention includes a receiving means for receiving and converting a transmission signal including general data and robust data into a baseband signal, an equalizing means for determining a symbol level of the transmission signal, and a determined symbol for the determined symbol. Trellis decoding means for performing release decoding, decoding means for outputting a digital image data stream to the trellis decoded signal, wherein the trellis decoding means comprises a 16-state trellis for the robust data; Perform decoding.

In addition, the DTV transmission method according to the present invention modulates an input signal of a digital video data stream including general data and robust data, an encoding step of coding the digital video data stream into data symbols, and an output signal of the encoding step. A transmitting step of transmitting, wherein the encoding step performs 16-state trellis coding on the robust data.

In addition, the DTV reception method according to the present invention includes a receiving step of receiving a transmission signal including general data and robust data and converting it into a baseband signal, an equalizing step of determining a symbol level of the transmission signal, A trellis decoding step of performing a release release, a decoding step of outputting a digital image data stream with respect to the trellis decoded signal, wherein the trellis decoding step is a 16-state trellis for the robust data Perform decoding.

In addition, the present invention is a general data information, 16-state trellis mapped to any one of {-7, -5, -3, -1, 1, 3, 5, 7} as a residual sideband modulated signal Robust data information coded and mapped to data symbols of any one of {-7, -5, -3, -1, 1, 3, 5, and 7} and a robust data flag for distinguishing the general data from the robust data. Contains information.

According to the present invention, general data is transmitted and received via 8-VSB and robust data is 16 state trellis coded. That is, when a trellis coded robust data packet is transmitted in 16 states instead of a normal data packet to some of the 312 data segments of the data field, the receiver receives an error signal for updating the tap coefficient of the equalizer for the transmitted robust data. The accuracy of calculations and trellis decoders improves not only the SNR of robust data but also the performance of receiving normal data.

The following merely illustrates the principles of the invention. Therefore, those skilled in the art, although not explicitly described or illustrated herein, can embody the principles of the present invention and invent various devices that fall within the spirit and scope of the present invention. In addition, all conditional terms and embodiments listed herein are in principle clearly intended to be understood solely for the purpose of understanding the concept of the invention and are not to be limited to the specifically listed embodiments and states. do. In addition, it is to be understood that all detailed descriptions, including the principles, aspects, and embodiments of the present invention, as well as listing specific embodiments, are intended to include structural and functional equivalents of these matters. In addition, these equivalents should be understood to include not only equivalents now known, but also equivalents to be developed in the future, that is, all devices invented to perform the same function regardless of structure. Thus, for example, it should be understood that the block diagrams herein represent a conceptual view of example circuitry embodying the principles of the invention. Similarly, all flowcharts, state transitions, pseudocodes, and the like are understood to represent various processes performed by a computer or processor, whether or not the computer or processor is substantially illustrated on a computer readable medium and whether the computer or processor is clearly shown. Should be.

The functionality of the various elements shown in the figures, including functional blocks represented by a processor or similar concept, can be provided by the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functionality may be provided by a single dedicated processor, by a single shared processor or by a plurality of individual processors, some of which may be shared. In addition, the explicit use of the terms processor, control or similar terminology should not be interpreted exclusively as a citation of hardware capable of executing software, and is not intended to be used to store digital signal processor (DSP) hardware or software without limitation. It should be understood that it implicitly includes ROM, RAM, and non-volatile memory. Other hardware for the governor may also be included. Similarly, the switches shown in the figures may be presented conceptually only. It is to be understood that the action of such a switch can be performed manually or through the interaction of program control and dedicated logic via program logic or dedicated logic. Certain techniques may be selected by a designer with a more detailed understanding of the disclosure.

In the claims of this specification, components expressed as means for performing the functions described in the detailed description include all types of software including, for example, a combination of circuit elements or firmware / microcode, etc. that perform the functions. It is intended to include all methods of performing a function which are combined with appropriate circuitry for executing the software to perform the function. The invention, as defined by these claims, is equivalent to what is understood from this specification, as any means capable of providing such functionality, as the functionality provided by the various enumerated means are combined, and in any manner required by the claims. It should be understood that.

 The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a block diagram showing a DTV transmitter according to an embodiment of the present invention. As shown, the transmitter 400 includes a first multiplexer 401, a data randomizer 403, an RS encoder 405, a robust interleaver / packet formatter 407, a data interleaver 409, and an enhanced encoder 411. And a robust data processor 413, trellis encoder 415, a second multiplexer 417, and a pilot inserter / modulator / RF converter 419.

The data randomizer 403, RS encoder 405, data interleaver 409, trellis encoder 415, second multiplexer 417 and pilot inserter / modulator / RF converter 419 shown in FIG. 1 illustrates a conventional data randomizer 101, an RS encoder 103, a data interleaver 105, a trellis encoder 107, a multiplexer 109, a pilot inserter 111, and a VSB modulator 113. ) And the RF converter 115.

The first multiplexer 401 multiplexes the general data packet 421 and the robust data packet 423 under the control of the robust data flag signal 425.

The generic data packet 421 and the robust data packet 423 have the same attributes as a serial data stream consisting of 188 bytes of MPEG compatible data packet, while the robust data packet includes an information packet and a null packet. A null packet is a packet consisting of any data (eg, "0") with a null packet header that is inserted to secure packet space to be expanded according to the coding rate of robust data. In the present specification, a description will be made based on an embodiment in which a coding rate of robust data is 1/2, but it should be understood that the present invention is not limited to a coding rate of 1/2.

The robust data flag signal 425 is a signal generated from an external device (not shown) according to the ratio information (NRP) of the robust data and the general data in one field and the coding ratio information (1/2 or 1/4) of the robust data. As another component of the transmitter 400 including the first multiplexer 401, the robust data flag signal 425 may determine whether the data currently being processed is a robust data packet.

The first multiplexer 401 multiplexes the general data packet 421, the robust data packet 423, and the robust data flag 425 according to the number of robust data packets per field. As an example, the position of the robust data packet may be defined as shown in Equation 1 according to the number thereof.

0 ≤ NRP / 2 ≤ 39:

{s | s = 4i, i = 0, 1,... , NRP-1}, (0 ≤ s ≤ 156)

40 ≤ NRP / 2 ≤ 78:

{s | s = 4i, i = 0, 1,... , 77} U {s | s = 4i + 2, i = 0, 1,... , NRP-79}

79 ≤ NRP / 2 ≤ 117:

{s | s = 4i, i = 0, 1,... , 77} U {s | s = 4i + 2, i = 0, 1,... , 77} U {s | s = 4i + 1, i = 0, 1,... , NRP-157}

118 ≤ NRP / 2 ≤ 156:

{s | s = 4i, i = 0, 1,... , 77} U {s | s = 4i + 2, i = 0, 1,... , 77} U {s | s = 4i + 1, i = 0, 1,... , 77} U {s | s = 4i, i = 0, 1,... , NRP-235}

In Equation 1, NRP is the number of robust segments occupied by robust data packets per data field, that is, the number of robust data packets in a frame, as described above, and an information packet and a null packet. It is a value including all the numbers and has a range of 0 to 312. Further, "U" means two sets of unions, s means data segment number in the data field, and has a range of 0 to 311.

Another embodiment of determining the location of a robust data packet can be defined as Equation (2).

RPI = 312 / NRP

RPP = floor (RPI x r)

In Equation 2, RPI is a robust data packet interval, and RPP is a robust data packet position. floor (*) represents a decimal cutting operation (rounding off to a decimal point) for converting an arbitrary number * to an integer value. r represents the arbitrary integer of 0-NRP.

According to Equation 2, when the NRP is 162 and the robust data coding ratio is 1/2, the positions of the general data and the robust data in the data field are determined as shown in Table 1 below.

Packet number Packet type 0 Tenacity One Null 2 Normal 3 Tenacity 4 Normal 5 Null 6 Normal 7 Tenacity 8 Normal 9 Null 10 Normal 11 Tenacity 12 Normal 13 Null 14 Normal 15 Tenacity ... ... 297 Normal 298 Tenacity 299 Normal 300 Null 301 Normal 302 Tenacity 303 Normal 304 Null 305 Normal 306 Tenacity 307 Normal 308 Null 309 Normal 310 Null 311 Normal

The general data packet 421 and the robust data packet 423 multiplexed on a packet basis in the first multiplexer 401 are randomized in the data randomizer 403, and each packet is 20 for FEC in the RS encoder 405. It is encoded to include parity information of bytes. In RS encoder 405, 20 RS parity bytes for FEC are added to 187 bytes of data to generate a total of 207 bytes of data transmitted per data segment. The robust data flag is not subjected to randomization and RS encoding. When 20 RS parity bytes are added by RS encoding for a robust data packet, a robust data flag is also displayed for the added RS parity bytes.

Next, the RS-coded generic / strong data packets contained in successive segments of each data field are input to the robust interleaver / packet formatter 407 and interleaved only for robust data (information packets) based on the robust data flag. The interleaved robust data is reconstructed into packets of 207 bytes according to the robust data coding rate, and the reconstructed robust data packets are multiplexed with normal data packets. Normal data packets have a certain delay to be multiplexed with robust data packets.

FIG. 5 is a block diagram illustrating a robust interleaver / packet formatter of FIG. 4. As shown, the robust interleaver / packet formatter 407 includes a robust data interleaver 501, a packet formatter 503, and a third multiplexer 505.

The robust data interleaver 501 interleaves only robust data packets according to the robust data flag signal. 6 is a conceptual diagram illustrating the robust data interleaver of FIG. 5. As shown in the drawing, the robust data interleaver 501 inputs a signal in units of bytes only for a robust data packet among data packets input from the RS encoder 405. Interleaving is performed to transmit robust data to the packet formatter 503. In addition, the robust data interleaver 501 has parameters of M = 3, B = 69, and N = 207 to perform interleaving by inputting 1 byte from up to 69 different packets, and among the robust data packets in the interleaving process. Null packets are discarded and interleaving is performed only on the information packets.

The packet formatter 503 shown in FIG. 5 processes the robust data interleaved by the robust data interleaver 501. The packet formatter 503 receives 184 bytes from the robust data interleaver 501 and then generates two 207-byte data blocks for the 184 byte robust data. Here, four bits, e.g., LSBs (6, 4, 2, 0), in each byte of the generated 207-byte data block correspond to the input robust data. The remaining four bits, for example MSB (7, 5, 3, 1), are set to arbitrary values. On the other hand, in each of the generated 207-byte data blocks, the byte position which does not correspond to the 184-byte robust data is inserted with header byte data and arbitrary information data for RS parity bytes described later.

Next, the packet formatter 503 inserts the rendered value of the header corresponding to the null packet into the first 3 bytes of each generated 207-byte data block. The packet formatter 503 then generates a packet of 207 bytes by inserting 20 bytes of arbitrary information (e.g., "0") into each data block. As described below, the robust data processor 413 replaces the 20 bytes of arbitrary information with RS parity information.

All other remaining byte positions may be filled with bytes of 184 byte robust data in order. The packet formatter 503 checks whether the position corresponds to the parity byte position before inserting a robust data byte into each of the newly created 207 byte data blocks. If the position does not correspond to the position of the parity byte, then the robust data byte is placed in that position. If the position corresponds to a parity byte position, the byte position is skipped and the next byte position is checked. This process is repeated until all robust data bytes are arranged in a newly created 207 byte data block.

Thus, when robust interleaved four packets (4 x 207 bytes) of robust data are input to the packet formatter 503, the packet formatter 503 is composed of nine pieces of random information data bytes for robust data bytes, header bytes and RS parity bytes. Output a packet (9 x 207 bytes). Each of the nine packets output includes 92 bytes of robust data input to the packet formatter 503.

On the other hand, the position of the arbitrary information data byte for the RS parity byte for each packet is determined according to equation (3).

m = (52 x n + (s mod 52)) mod 207

Where m is the output byte number, that is, the parity byte position of the packet extended to 207 bytes, n (= 0 to 206) is the input byte, that is, the byte number of each packet, and s (= 0 to 311) is one data Indicates a segment corresponding to robust data in the field, that is, a packet number. The parity byte position, i.e. m, can be computed for n = 187-206 million only so that the position of 20 parity packets for each packet can always correspond to the last 20 bytes of the packet after data interleaving (this value of n is a packet Corresponding to the last 20 bytes of.

For example, if you substitute s = 0 and n = 187-206, the parity byte positions for packet 0 are 202, 47, 99, 151, 203, 48, 100, 152, 204, 49, 101, 153, 205, 50, 102, 154, 206, 51, 103, 155. This means that the parity byte position after the interleaving of the data interleaver 409 becomes a packet 187 to 206 only when the parity byte position is the 202th byte. Similarly, another parity byte position should be the 47th byte. However, according to Equation 3, the parity byte may be located at the packet header byte position. I.e. m may be 0, 1 and / or 2. Therefore, to avoid the situation where the parity byte is located at the packet header byte position, the range of n may be increased by the number of parity bytes (maximum 3) at the header position. Accordingly, in the process of calculating 20 m values, if the result of s mod 52 is any one of 1 to 7, some of the 20 m values become 0, 1, and / or 2.

For example, when s mod 52 = 0, all 20 m values do not represent the position (0, 1, or 2) of the header byte, and thus all 20 m values may be used as parity byte positions.

On the other hand, when s mod 52 = 1, one of the 20 m values is 0 (header byte position), in which case the n range is increased by 1 to be 186 to 206. Thus, twenty-one m values are computed and m values coming in header byte positions are discarded. The remaining 20 m values are specified as parity byte positions.

Similarly, if s mod 52 = 2, two of the 20 m values are 0 and 1 (header byte position), in which case the n range is increased by 2 to be 185 to 206. Thus, 22 m values are calculated and the m values, which are header byte positions (0 or 1), are discarded. The remaining 20 m values are specified as parity byte positions.

Table 2 shows the range of n according to position in the robust data segment.

s mod 52 M number additionally required range of n 0 0 187-206 One One 186-206 2 2 185-206 3 3 184-206 4 3 184-206 5 3 184-206 6 2 185-206 7 One 186-206 8 to 51 0 187-206

The third multiplexer 505 of FIG. 5 multiplexes the robust data packet and the general data packet output from the packet formatter 503 according to the robust data flag. The operation of the third multiplexer 505 is the same as the operation of the first multiplexer 401.

Referring back to FIG. 4, the data interleaver 409 reconstructs data packets in consecutive segments of each data field to scramble the sequential order of the robust data flag and the normal / strong data stream in accordance with the ATSC A / 53 standard. Interleaving by byte unit outputs scrambled data. At this time, the general / robust data and robust data flags are interleaved through independent interleavers. The structure of the data interleaver 409 has a structure similar to that of the robust data interleaver 501 (see Fig. 6, M = 4, B = 52, N = 208).

FIG. 7 is a diagram showing the structure of the reinforcement encoder of FIG. 4 in detail. As shown in the drawing, a plurality of reinforcement encoders 411 are specifically configured in parallel with, for example, 12 identical reinforcement encoders 411a to 411l. . Enhancement encoder 411 trellis interleaves the interleaved general / robust data and the robust data flag and codes the general / strong data based on the trellis interleaved robust data flag. The general / strong data output from the data interleaver 409 is sequentially input to the 12 enhanced encoders 411a to 411l in byte units, and the general / strong data of 2 bits (X ₁ ′, X ₂ ′) is 2 bits. Create general / strong data represented by (X ₁ , X ₂ ). For example, the input bit X ₂ ′ is an MSB (7, 5, 3, 1) code word, and the bit X ₁ ′ is an LSB (6, 4, 2, 0) code word. As described above, the MSBs (7, 5, 3, 1) and LSBs (6, 4, 2, 0) of the general data all contain information data, but the LSBs (6, 4, 2, 0) contains information data and MSBs (7, 5, 3, 1) contain arbitrary values.

The general / robust data coded in the reinforcement encoders 411a to 411l is again trellis deinterleaved so that the normal data is bypassed by the robust data processor 413 and input to the trellis encoder 415, which is robust data robust data. Input to trellis encoder 415 via processor 413. In this process, the general data and the robust data coded by each of the 12 enhanced encoders 411a to 411l are sequentially input to the trellis encoder 415 or the robust data processor 413.

Referring again to FIG. 4, trellis encoder 415 is identical to trellis encoder as currently defined in the ATSC A / 53 standard. Although not shown in the figure, similarly to the case of the enhanced encoder 411, the trellis encoder 415 is configured in plural, for example, 12 identical trellis encoders in parallel. Toughness input to the trellis encoder 415 via the robust data processor 413 by bypassing the robust data processor 413 and the general data symbols X ₁ , X ₂ input to the trellis encoder 415. The data symbols X ₁ and X ₂ are input to 12 trellis encoders, and the trellis encoder 415 trellis encodes the input symbols X ₁ and X ₂ into 8-level symbols. Eight-level symbols encoded by each of the 12 trellis encoders are sequentially input to the second multiplexer 417 to perform trellis interleaving as a whole.

FIG. 8 is a diagram for describing an enhancement encoder and a trellis encoder of FIG. 4. As described below, Fig. 8 illustrates a conceptual connection relationship between the enhanced encoder # 0 411a and the trellis encoder # 0 415a because the robust data processor 413 processes only the robust data. .

As defined in the current ATSC A / 53 standard, trellis encoder 415 includes a pre-coding block, a trellis encoding block and a symbol mapping block. The precoding block and trellis encoding block include registers D ₁ , D ₂ , D ₃ that store bit delay values (eg, 12 bit delay values).

Enhancement encoder # 0 (411a) encodes two bits (X ₁ ′, X ₂ ′) of general / strong data input from data interleaver 409 into two bits (X ₁ , X ₂ ) of general / strong data symbols. , Trellis encoder # 0 (415a) generates an 8-level signal according to trellis encoded symbols (Z ₀ , Z ₁ , Z ₂ ) corresponding to 2-bit (X ₁ , X ₂ ) general / strong data symbols. The output is output to the second multiplexer 417.

A method of coding robust data using the enhanced encoder 411 and trellis encoder 415 has been proposed by Philips.

Fig. 9 is a trellis coding block diagram of robust data proposed by Philips.

As shown, the reinforcement encoder 911 uses the X ₁ 'value of the input signals X ₁ ′ and X ₂ ′ to determine the coding values Z ₂ , Z ₁ of the trellis encoder 915 after passing through the precoder remover. The trellis encoded symbols Z ₀ , Z ₁ and Z ₂ are output at four levels of {-7, -5, 5, 7}.

In the robust data coding method proposed by Philips, the output power of the trellis encoder 915 uses four levels of {-7, -5, 5, 7} so that the average power of the symbol representing the robust data is 8- There is a problem that increases compared to the VSB method.

That is, when robust data is mapped to any one of four level symbols of {-7, -5, 5, and 7}, the symbol average power becomes 37 energy / symbol, which is increased compared to the conventional 8-VSB scheme. The average power increase of a symbol representing robust data causes an increase in the overall average power, and when transmitting a signal with a limited transmission output, the transmission power of general data is relatively reduced, compared to the conventional 8-VSB scheme in the same channel environment. It has a poor reception performance.

The problem is that as the ratio of robust data mixed with general data increases, the SNR that satisfies the TOV increases. Accordingly, even when the channel environment is good, the reception performance may decrease, and the reception that follows the 8-VSB method may be performed. Situations may arise where it is not possible to provide backward compatibility for the device.

Therefore, the present invention proposes a method of not increasing the symbol average power regardless of the robust data ratio by using the trellis coding scheme of 16 states for the robust data.

10 is a trellis coding block diagram of robust data according to an embodiment of the present invention.

As shown, the input X ₁ ′ is coded by adding registers D ₄ , D ₅ for robust data generation to the reinforcement encoder 1011.

The output signals of the trellis encoder 1015 and the following states according to the input X ₁ ′ are shown in Tables 3 and 4, respectively.

The 16 states of Table 3 are calculated by equation (4).

S = D ₄ × 8 + D ₅ × 4 + D ₂ × 2 + D ₃

On the other hand, the registers D ₄ and D ₅ additionally used for generating robust data do not change their state values when general data is input, and the output signals and the next states according to the inputs are shown in Tables 5 and 6, respectively.

When robust data is generated by using 16-state trellis coding according to the present embodiment, the performance of the receiver can be improved by designing a trellis decoder and a signal level determiner with reference to Tables 3 and 4.

11 is a trellis coding block diagram of robust data according to another embodiment of the present invention.

As shown, the inputs X ₁ ′ are coded by adding registers D ₄ , D ₅ for robust data generation to the enhancement encoder 1111.

The output signal of the trellis encoder 1115 according to the input X ₁ ′ and the following states are shown in Tables 7 and 8, respectively.

The 16 states of Table 7 are calculated by equation (4).

On the other hand, the registers D ₄ and D ₅ additionally used for generating robust data do not change their state values when general data is input, and the output signals and the next states according to the inputs are shown in Tables 5 and 6, respectively.

When robust data is generated using 16-state trellis coding according to the present embodiment, the performance of the receiver can be improved by designing a trellis decoder and a signal level determiner with reference to Tables 7 and 8.

12 is a detailed block diagram of the robust data processor of FIG. As shown in the figure, the robust data processor 413 includes a data deinterleaver 1203, an RS encoder 1205, and a data interleaver 1207. The robust data (X ₁ , X ₂ ) and the robust data flag output from the reinforcement encoder 411 are deinterleaved in the data deinterleaver 1203 and reassembled into a packet form.

As described above, 20 bytes composed of arbitrary information are inserted into the 207-byte data block generated by the packet formatter 503, and the RS encoder 1205 replaces the 20 bytes of arbitrary information with RS parity information. The robust data packet with the RS parity information inserted is interleaved in the data interleaver 1207 and output to the trellis encoder 415 in units of bytes.

Referring back to FIG. 4, the general data and robust data are combined with a segment sync and field sync sync bit sequence from a synchronization unit (not shown) in the second multiplexer 417 to transmit the data frame. Is generated. The pilot signal is then inserted at the pilot inserter. The symbol stream is VSB suppressed carrier modulated in a VSB modulator. The baseband 8-VSB symbol stream is finally converted into a radio frequency signal by the RF converter and transmitted.

FIG. 13 is a diagram showing a field sync segment of a data frame transmitted by the transmitter of FIG. 4 according to the present invention. As shown in the figure, the segment transmitted by the transmitter 400 is basically the same as the segment of the ATSC A / 53 standard. However, in the reserved area corresponding to the last 104 symbols of the segment, 92 symbols except for the precode 12 symbols include information for recovering a robust data packet. The information for recovering the robust data packet includes ratio information (NRP) of robust data and general data in one field and coding rate information (1/2 or 1/4) of robust data. As will be described later, a receiving apparatus according to an embodiment of the present invention generates a robust data flag from information for restoring a robust data packet, and the component of the receiving apparatus uses the robust data flag to robust the current data. You can check whether it is a data packet.

14 is a block diagram showing a DTV receiver according to an embodiment of the present invention. As shown, the receiver 1400 includes a tuner 1401, an IF filter and a detector 1403, an NTSC filter 1405, an equalizer 1407, a trellis decoder 1409, a data deinterleaver 1411, and a packet. Includes a formatter / robust deinterleaver 1413, an RS decoder 1415, a data derandomizer 1417, a demultiplexer 1418, a sync and timing recovery block 1421, a field sync decoder 1423, and a controller 1425. do.

Tuner 1401, IF filter and detector 1403, NTSC filter 1405, data deinterleaver 1411, RS decoder 1415 and sync and timing recovery block 1421 are shown in tuner 201, IF of FIG. It performs the same functions as the filter and detector 203, the NTSC filter 205, the data deinterleaver 211, the RS decoder 213, and the synchronization and timing recovery block 215.

The field synchronization decoder 1423 receives the segment of the data frame shown in Fig. 13 and performs robust data packet reconstruction information in the reserved area (the ratio information of the robust data and the general data in one field and the coding ratio information of the robust data). And the like) to the control unit 1425.

15 is a detailed block diagram of the controller of FIG. As shown, the controller 1425 includes a general / strong data classification flag generator 1501, a data interleaver 1503, a trellis interleaver 1505, a delay buffer 1507, and a delay operator 1509.

The general / robust data classification flag generator 1501 generates a robust data flag by using the robust data packet recovery information received from the field sync decoder 1423.

The generated robust data flag is bitwise data interleaving and trellis interleaving according to ATSC A / 53 in the data interleaver 1503 and the trellis interleaver 1505, respectively, so that the equalizer 1407 and the trellis decoder 1409 are performed. Is sent). Since the robust data flag included in the data frame transmitted from the transmitting device 400 is already interleaved with data interleaving and trellis interleaved, the equalizer 1407 and trellis decoder 1409 have data interleaving and trellis interleaving. Equalization and trellis decoding are performed based on the determined robust data flags.

Meanwhile, the delay buffer 1507 receives the robust data flag generated by the general / strong data classification flag generator 1501 and processes the data in the trellis decoder 1409 and the data deinterleaver 1411. The robust data flag is transmitted to the packet formatter / strong deinterleaver 1413 in consideration of the delay that occurs. In addition, the delay buffer 1507 stores the robust data flag in consideration of the delay caused by processing the data in the packet formatter / robust deinterleaver 1413, the demultiplexer 1417, the demultiplexer 1419, and the delay operator 1509. Transmit each).

The delay operator 1509 receives a robust data flag and field sync decoder 1423 considering the delay for general data generated by processing the robust data in the packet formatter / robust deinterleaver 1413 received from the delay buffer 1507. The delay time of the robust data packet is calculated by using the robust data packet recovery information received from the Rx, and is transmitted to the data de-randomizer 1417. The data de-randomizer 1417 performs de-randomization in synchronization with the field sync signal of the data frame, and the robust data packet recovery information received from the field sync decoder 1423 includes the data packet recovery information that is robust in the data frame. Information about the location is included. However, in the packet formatter / robust deinterleaver 1413, data processing is performed only for robust data packets. In particular, the deinterleaving process performed in the robust deinterleaver causes a delay of several packets for the robust data packet. The delay operator 1509 calculates a delay time for the robust data packet based on the received robust data packet recovery information and the robust data flag to compensate for the delay for the robust data packet and transmits the delay time to the data derandomizer 1417. do. The data derandomizer 1417 performs derandomizing on the general data packet and the robust data packet based on the received robust data flag and the delay time for the robust data packet. For example, if after performing de-randomizing on the nth general data packet, the strong data packet to which the next de-randomizing should be performed is not a strong data packet sent by the transmitter from the n + 1th, but k (k <n) may be the strongest data packet sent. The reason why the robust data packet delay for the general data packet is large is that a delay in recovering the original packet from the packet formatter / strong deinterleaver 1413 is included. Therefore, the data derandomizer 1417 should perform derandomizing in consideration of this delay.

Fig. 16 is a detailed block diagram of the packet formatter / robust deinterleaver of Fig. 14, and Fig. 17 is a conceptual diagram showing the robust data deinterleaver of Fig. 16, showing the robust interleaver / packet formatter of the transmitter 400 shown in Fig. 5. (407) Perform an operation opposite to the operation. That is, a robust data packet containing information data is removed by removing the RS parity byte (20 bytes) and the header byte (3 bytes) included in the robust data segment (207 bytes) input from the data deinterleaver 1411. Create a packet. Therefore, when a robust data segment of nine packets (9 x 207 bytes) is input to the packet formatter 1601, the packet formatter 1601 outputs four robust data packets of information data and five null packets of null data. do. Next, the robust data deinterleaver 1603 receives the robust data packet input from the packet formatter 1601 in byte units and performs deinterleaving to transmit the robust data packet to the multiplexer 1605. In the deinterleaving process, null packets of robust data packets are discarded and deinterleaving is performed only on information packets. Normal data packets have a certain delay to be multiplexed with robust data packets.

Multiplexed generic data packets and robust data packets are sent to the RS decoder 1415. The RS decoder 1415 RS decodes each packet and transmits the RS to the data derandomizer 1417.

Referring back to FIG. 14, the demultiplexer 1418 demultiplexes the normal data packet and the robust data packet according to the robust data flag and outputs them as a serial data stream composed of 188 bytes of MPEG compatible data packets.

The equalizer 1407 may be a known determiner known as a slicer, or a trellis decoder with zero trace back. The equalizer 1407 performs equalization on the received signal based on bit data interleaving transmitted from the controller 1425 and trellis interleaving according to ATSC A / 53.

That is, for the general data signal, the signal level is determined in four states for eight levels of {-7, -5, -3, -1, 1, 3, 5, 7} as in the conventional case, and the robust data signal The signal level is determined for eight levels of trellis coded {-7, -5, -3, -1, 1, 3, 5, 7} in 16 states. That is, for robust data signals, trellis-coded {-7, -5, -3, -1, 1, 3, 16 trellis coded in 16 states as decision data used to update tap coefficients of the equalizer 1407. 8 level signals of 5, 7} are used. For example, the trellis decoder used in the equalizer 1407 determines the signal level based on the 16 states shown in Tables 3 and 4 (or Tables 7 and 8) for the robust data signal. Accurate signal level determination increases the convergence speed of the equalizer, resulting in improved reception for robust data as well as general data in a Doppler environment.

The trellis decoder 1409 may be a trellis decoder that conforms to the ATSC A / 53 standard, and similar to the trellis decoder that may be used in the equalizer 1407, for a general data signal { Four-state trellis decoding is performed on 8-level signals of -7, -5, -3, -1, 1, 3, 5, 7}, and Tables 3 and 4 (or Table 7) for robust data signals. And trellis decoding is performed on the trellis coded 8-level signal shown in Table 8).

According to the present invention, the 8-VSB receiving apparatus conforming to the ATSC A / 53 standard can receive general data packets, and the robust data packets are treated as null packets to provide backward compatibility.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the technical field of the present invention without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

As described above, according to the present invention, a dual stream consisting of trellis coded robust data using 16 states and general data according to the 8-VSB scheme is not increased without increasing the average power regardless of its mixing ratio. It can also transmit and receive, and has the effect of lowering the SNR that satisfies the TOV by improving reception performance for not only robust data but also general data.

1 is a block diagram showing a conventional DTV transmitter;

2 is a block diagram showing a conventional DTV receiver;

3 is a block diagram of a transmission data frame exchanged between the transmitter of FIG. 1 and the receiver of FIG.

4 is a block diagram showing a DTV transmitter according to an embodiment of the present invention;

FIG. 5 is a block diagram showing the robust interleaver / packet formatter of FIG. 4; FIG.

FIG. 6 is a diagram for explaining the robust data interleaver of FIG. 5; FIG.

FIG. 7 is a diagram for explaining the enhanced encoder of FIG. 4; FIG.

FIG. 8 is a diagram for explaining the enhanced encoder and trellis encoder of FIG. 4; FIG.

9 is a trellis coding block diagram of robust data proposed by Philips;

10 is a trellis coding block diagram of robust data according to an embodiment of the present invention;

11 is a trellis coding block diagram of robust data according to another embodiment of the present invention;

12 is a detailed block diagram of the robust data processor of FIG. 4;

FIG. 13 is a diagram showing field sync segments of a data frame transmitted by the transmitter of FIG. 4; FIG.

14 is a block diagram showing a DTV receiver according to an embodiment of the present invention;

15 is a detailed block diagram of the controller of FIG. 14;

16 is a detailed block diagram of the packet formatter / robust deinterleaver of FIG. 14;

FIG. 17 is a detailed block diagram of the robust data deinterleaver of FIG.

Claims (24)

Input means for receiving a digital video data stream including general data and robust data; Encoding means for coding the digital video data stream into data symbols; And Transmitting means for modulating and transmitting an output signal of said encoding means Including, The encoding means Performing 16-state trellis coding on the robust data DTV transmitter. The method of claim 1, The encoding means The general data is mapped to one data symbol of {-7, -5, -3, -1, 1, 3, 5, 7}. DTV transmitter. The method of claim 1, The encoding means comprises a reinforcement encoder for coding the robust data into 2-bit data symbols, and A trellis encoder for outputting a data symbol of any level of a predetermined level represented by 3 bits based on the 2-bit data symbol DTV transmission device comprising a. The method of claim 3, The enhanced encoder Encoding 2-bit data symbols such that the output symbol level and next state of the trellis encoder are as shown in Tables 1 and 2, respectively. DTV transmitter. Table 1 [Table 2] The method of claim 3, The enhanced encoder Encoding 2-bit data symbols such that the output symbol level and next state of the trellis encoder are as shown in Tables 3 and 4, respectively. DTV transmitter. Table 3 Table 4 The method according to any one of claims 3 to 5, The encoding means A data randomizer for performing data randomization on the output signal of the input means; An RS encoder for performing Reed Solomon (RS) encoding on an output signal of the data randomizer; A robust interleaver / packet formatter which interleaves robust data among the output signals of the RS encoder and reconstructs the robust data packet according to the robust data coding ratio; And A data interleaver for performing data interleaving on the output signal of the robust interleaver / packet formatter Containing more DTV transmitter. Receiving means for receiving and converting a transmission signal comprising general data and robust data into a baseband signal; Equalizing means for determining a symbol level of the transmission signal; Trellis decoding means for performing trellis decoding on the determined symbol; Decoding means for outputting a digital video data stream to a trellis decoded signal Including, The trellis decoding means Performing 16 state trellis decoding on the robust data DTV receiver. The method of claim 7, wherein The trellis decoding means Decoding the symbol level determined to have the symbol level and the next state as shown in Tables 5 and 6, respectively, for the robust data as 2-bit data symbols. DTV receiver. Table 5 Table 6 The method of claim 7, wherein The trellis decoding means Decoding the symbol level determined to be the same as the following Table 7 and Table 8, respectively, as a 2-bit data symbol DTV receiver. Table 7 Table 8 The method according to any one of claims 7 to 9, The decoding means A data deinterleaver for performing data deinterleaving on the signal output from the trellis decoding means; A packet formatter / robust deinterleaver for reconstructing robust data packets composed of information data for robust data among the signals output from the data deinterleaver and performing data interleaving on the reconstructed robust data packets; An RS decoder for performing RS decoding on the output signal of the packet formatter / strong deinterleaver; A data de-randomizer for performing data de-randomization on the output signal of the RS decoder; And Demultiplexer for performing demultiplexing on the output signal of the data derandomizer Containing DTV receiver. Inputting a digital video data stream comprising general data and robust data; An encoding step of coding the digital video data stream into data symbols; And A transmission step of modulating and transmitting the output signal of the encoding step Including, The encoding step Performing 16-state trellis coding on the robust data How to send DTV. The method of claim 11, The encoding step The general data is mapped to one data symbol of {-7, -5, -3, -1, 1, 3, 5, 7}. How to send DTV. The method of claim 11, The encoding step comprises an enhancement encoding step of coding the robust data into 2-bit data symbols, and A trellis encoding step of outputting a data symbol of any level of a predetermined level represented by three bits based on the two-bit data symbol Containing How to send DTV. The method of claim 13, The enhanced encoding step Encoding 2-bit data symbols such that the output symbol level and the next state of the trellis encoding step are as shown in Tables 9 and 10, respectively. How to send DTV. Table 9 Table 10 The method of claim 13, The enhanced encoding step Encoding 2-bit data symbols such that the output symbol level and next state of the trellis encoder are as shown in Tables 11 and 12, respectively. How to send DTV. Table 11 Table 12 The method according to any one of claims 13 to 15, The encoding step A data rendering step of performing data rendering on the input signal; An RS encoding step of performing Reed Solomon (RS) encoding on the data randomized output signal; A robust interleaving / packet formatting step of interleaving robust data among RS encoded output signals and reconstructing the robust data packet according to the robust data coding ratio; And Data interleaving step for performing data interleaving on robust interleaving / packet formatted output signals Containing more How to send DTV. A receiving step of receiving a transmission signal comprising general data and robust data and converting the signal into a baseband signal; An equalizing step of determining a symbol level of the transmission signal; A trellis decoding step of performing trellis decoding on the determined symbol; Decoding step of outputting digital video data stream for trellis decoded signal Including, The trellis decoding step Performing 16 state trellis decoding on the robust data How to receive DTV. The method of claim 17, The trellis decoding step Decoding the symbol level determined to be the same as the following Table 13 and Table 14 for the robust data, respectively, as a 2-bit data symbol. How to receive DTV. Table 13 Table 14 The method of claim 17, The trellis decoding step Decoding the symbol level determined to be the same as the following Table 15 and Table 16, respectively, into a 2-bit data symbol How to receive DTV. Table 15 Table 16 The method according to any one of claims 17 to 19, The decoding step A data deinterleaving step of performing data deinterleaving on the signal output from the trellis decoding step; A packet formatting / robust deinterleaving step of reconstructing a robust data packet composed of information data with respect to robust data among the data deinterleaved output signals and performing data interleaving on the reconstructed robust data packet; An RS decoding step of performing RS decoding on the packet formatting / strong deinterleaved output signal; A data de-randomizing step of performing data de-randomization on the RS decoded output signal; And Demultiplexing step of performing demultiplexing on the data de-randomized output signal Containing How to receive DTV. Residual sideband modulated signal, General data information mapped to a data symbol of any one of {-7, -5, -3, -1, 1, 3, 5, and 7}; Robust data information mapped to a data symbol of any one of {-7, -5, -3, -1, 1, 3, 5, 7} in 16 state trellis coded; And Robust data flag information for distinguishing the general data from the robust data Containing DTV transmission signal. The method of claim 21, The robust data information is Trellis coded so that the output symbol level and the next state are as shown in Table 17 and Table 18, respectively. DTV transmission signal. Table 17 Table 18 The method of claim 21, The robust data information is Trellis coded so that the output symbol level and the next state are as shown in Table 19 and Table 20, respectively. DTV transmission signal. Table 19 Table 20 The method according to any one of claims 21 to 24, The general data information and the robust data information are interleaved and mixed with each other, The robust data information includes header information for having backward compatibility. DTV transmission signal.