KR100949973B1 - Broadcast transmitter / receiver and broadcast signal processing method - Google Patents

Abstract

The present invention relates to a digital broadcasting transmission / reception system. In particular, the present invention inserts and transmits predetermined known data known to the transmission / reception side at a specific position of a data area where enhanced data is transmitted. In addition, by using the known data in the demodulation or equalization process, the reception side can improve reception performance in an environment in which channel variation or noise is weak.

EVSB, Base Data, Position Holder

Description

Broadcasting transmitter / receiver and method of processing broadcasting signal}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital communication system, and more particularly, to a digital broadcast transmission / reception system that modulates a VSB (Vestigial Side Band) scheme and transmits and receives it.

In the United States, ATSC 8T-VSB transmission system was adopted as a standard in 1995 for terrestrial digital broadcasting, and broadcasted since the second half of 1998.In Korea, ATSC 8T-VSB transmission system, which is identical to the US method, was adopted as a standard in May 1995. Experimental broadcasting was started, and on August 31, 2000, the test broadcasting system was switched.

1 shows a conventional ATSC 8T-VSB transmission system. The data randomizer randomizes the input MPEG video / audio data, and the Reed-Soloron encoder adds 20 bytes of parity code by reed-solomon encoding the data, and the data interleaver interleaves the data and trellis. The encoder converts data from bytes into symbols and then trellis-codes the data. The mux muxes the symbol strings and sync signals, the pilot inserter adds the pilot signal to the symbol strings, the VSB modulator modulates the symbol strings into an 8 VSB signal in the middle frequency band, and the RF converter converts the middle frequency signal into an RF band signal. Transmit to transmit via antenna.

The 8T-VSB transmission system, adopted as a digital broadcasting standard in North America and Korea, is a system developed for transmission of MPEG video / audio data. However, with the rapid development of digital signal processing technology and the widespread use of the Internet, digital home appliances, computers, and the Internet are being integrated into one big framework. Therefore, in order to meet various needs of users, it is necessary to develop a system capable of transmitting various additional data in addition to video / audio data through a digital broadcasting channel.

Some users of supplementary data broadcasting are expected to use supplementary data broadcasting by using PC card or portable device equipped with simple indoor antenna. Due to the effects of ghosts and noise caused by reflected waves, broadcast reception performance may deteriorate. However, unlike the general video / audio data, the additional data transmission has to have a lower error rate. In the case of video / audio data, errors that the human eye and ears cannot detect are not a problem, while in the case of additional data (eg program executables, stock information, etc.), a bit error may cause serious problems. It may cause a problem. therefore There is a need to develop a system that is more resistant to ghosting and noise in the channel.

The transmission of additional data will usually be done in a time division manner over the same channel as the MPEG video / sound. Since the beginning of digital broadcasting, however, ATSC VSB digital broadcasting receivers that receive only MPEG video / audio have been widely used in the market. Therefore, additional data transmitted on the same channel as MPEG video / audio should not affect the existing ATSC VSB-only receivers that have been used in the market. Such a situation is defined as ATSC VSB compatible, and the additional data broadcasting system should be compatible with the ATSC VSB system. The additional data may also be referred to as enhanced data or EVSB data.

In addition, in a poor channel environment, the reception performance of the conventional ATSC VSB receiving system may be degraded. Especially in the case of portable and mobile receivers, robustness against channel changes and noise is required.

Accordingly, the present invention has been made to solve the above problems, and proposes a new VSB transmission system suitable for additional data transmission and resistant to noise.

Another object of the present invention is to provide a transmission system and a reception system for improving decoding performance of additional data symbols.

It is still another object of the present invention to provide a transmission system and a reception system for improving reception performance by inserting and transmitting data known to a transmission / reception side into a specific area of data.

According to the present invention for achieving the above object, a digital broadcast transmission system determines a position holder into which known data is to be inserted, inserts null data into the known data position holder, and configures and outputs a packet together with enhanced data. A packet formatter; A parity position holder inserter which obtains a plurality of parity position holders for the output of the packet formatter and inserts null data into the parity position holder and outputs the null data; A data interleaver performing interleaving on the output of the parity position holder inserter to output a plurality of information bytes for each segment, and then replacing null data of the parity position holder with calculated parity data to output the parity position holder inserter; A known data generator for generating known data; A symbol processing unit which replaces and outputs the known data generated by the known data generator if the data output from the data interleaver is a known data position holder; And an unstructured RS encoder that performs parity data by performing unsystematic RS coding on the output of the symbol processing unit and outputs the parity data to the data interleaver.

The parity position holder inserter may determine a parity byte position holder such that a parity byte in a segment output from the data interleaver is output later than an information byte.

If the output data of the symbol processing unit is known data and is the beginning of the continuous known data sequence, it may further include a trellis encoding unit capable of performing trellis encoding after outputting the memory.

A digital broadcast reception system for receiving a signal transmitted by the above-described digital broadcast transmission system includes: a demodulation and equalization unit configured to receive a transmitted signal through tuning, and to perform demodulation and channel equalization by applying known data to the received signal; And a known data detection unit for detecting known data inserted by the transmitting side from the demodulated signal and outputting the known data to the demodulation and equalization unit.

The broadcast transmitter / receiver and broadcast signal processing method according to the present invention have the advantage of being resistant to errors and compatible with existing VSB receivers when transmitting enhanced data through a channel. It also has the advantage of receiving error-free data over ghost and noisy channels over traditional VSB systems. In particular, by inserting the known data into a specific position of the data area and transmitting it, it is possible to improve the reception performance of the reception system even in a channel environment in which channel changes are severe.

Therefore, the present invention is more effective when applied to portable and mobile receivers that require severe channel changes and robustness against noise.

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

In a typical VSB transmission frame, one frame consists of two fields, and each field consists of one field sync segment and 312 data segments.

The present invention is to improve the reception performance of a receiver by inserting and transmitting predetermined known data at a specific position in the data segment.

Figure 2 is a block diagram of the overall configuration of a digital transmission system according to the present invention for this purpose. 2 shows an EVSB preprocessor 201, an EVSB packet formatter 202, a packet multiplexer 203, a data randomizer 204, a Reed Solomon encoder and a parity position holder inserter 205, and a data interleaver 206. , Byte-symbol converter 207, EVSB symbol processor 208, known data generator 209, symbol-byte converter 210, unstructured RS encoder 211, trellis encoder 212, frame multiplexing It consists of a firearm 213 and a transmitter 220.

In the present invention configured as described above, the main data packet is output to the packet multiplexer 203, and the enhanced data stream is output to the EVSB preprocessor 201. The EVSB preprocessor 201 performs preprocessing such as additional error correction encoding, interleaving, null data insertion, and the like on the enhanced data stream and outputs the result to the EVSB packet formatter 202.

The EVSB packet formatter 202 determines a known data position holder into which known data known in the packet is to be inserted, inserts a null byte into the determined known data position holder, and then outputs the EVSB preprocessor 201. The packet consists of data and a unit of 184 bytes. Subsequently, a 4-byte MPEG header byte is inserted and output at the beginning of the packet.

 The MPEG header byte is composed of one byte of MPEG sync byte (0x47) and three bytes of packet identification (PID), and the PID is obtained from an existing ATSC VSB receiver using a null packet PID value or a reserved PID value in an existing ATSC system. Enable to discard enhanced data packets.

The output data of the EVSB packet formatter 202 is input to the packet multiplexer 203 in units of 188 byte packets.

The packet multiplexer 203 multiplexes the existing main data packet and the enhanced data packet of the EVSB packet formatter 202 in units of 188 byte packets and outputs the data to the data randomizer 204.

The data randomizer 204 discards MPEG sync bytes and randomly generates the remaining 187 bytes using pseudo random bytes generated therein, and then uses a Reed-Solomon Encoder (RS) and parity. Output to position holder inserter 205.

The RS encoder and parity position holder inserter 205 performs systematic RS coding or non-systematic RS parity holder insertion on randomized data.

That is, the Reed-Solomon encoder / parity position holder inserter 205 performs systematic RS encoding in the same manner as the existing ATSC VSB system when the 187 byte packet output from the data randomizer 204 is the main data packet. 20 bytes of parity bytes are added after 187 bytes of data.

On the other hand, the Reed-Solomon encoder / parity position holder inserter 205 is a data interleaver 206 in which 20 parity bytes are reared when 187 bytes of the packet output from the data randomizer 204 are enhanced data packets. After determining the location of the parity byte in the packet to be output later than 187 information bytes at the output terminal, a null byte is written at the determined parity byte position, and 187 information input from the data randomizer 204 at the remaining 187 byte positions. Write bytes in order from the beginning.

The null byte can be any value, which is later replaced by a parity value calculated by the unstructured RS encoder 211. Thus, the role of the null byte is to secure the position of the parity byte of the unstructured RS code.

The reason for using an unstructured RS code for the enhanced data packet is to calculate the RS parity again when the value of the enhanced data is changed by the EVSB symbol processing unit 208, which will be described later, wherein the data interleaver 206 This is because the parity bytes should be output in time after the data bytes. For example, when RS is encoded by receiving K data bytes and adding P parity bytes, any P bytes among all N (= K + P) bytes may be used as parity bytes.

The parity position holder described above is different for each segment, and the position is determined by the following equation (1).

[Equation 1]

b = ((52 x p) + (s mod 52)) mod 207, p = 187,188, ..., 206

In Equation 1, s represents a segment number after the field sync signal and has a value from 0 to 311. And b indicates the position of the byte in the segment, and has a value from 0 to 206. That is, s and b denote segments and byte positions respectively input to the data interleaver 206. 52 is a constant predetermined by the data interleaver 206. In addition, mod means modulo operation. In general, in an ATSC VSB system, one transport packet is interleaved by the data interleaver and distributed by several data segments. However, since one data segment can transmit one transport packet, the packet before interleaving is a segment concept. Also used.

Therefore, when the position of the segment is determined, the parity position holder is determined by Equation 1 above. For example, in the case of the first segment (s = 0), the parity position holder becomes b = 202, 47, 99, 151, 203, 48, 100, 152, 204, 49, 101, 153, 205, 50, 102, 154, 206, 51, 103, and 155 when p = 187 to 206 in the above mathematical expression.

However, there is a problem when at least one byte of the parity position holder is located in the first three bytes of the segment. This is because the first 3 bytes of each segment are the positions of the MPEG transport header including the PID.

These segments s = 1,2,3,4,5,6,7,53,54,55,56,57,58,59,105,106,107,

108,109,110,111,157,158,159,160,161,162,163,209,210,211,212,213,214,215,261,262,263,264,265,266,267.

In this case, the last 20 bytes (that is, the output of the data interleaver 206) out of the remaining 204 bytes except for the MPEG header 3 bytes are used as the parity position holder. In the case of transmitting the enhanced data, the MPEG header inserts a null packet PID or reserved PID. Since this is a known value, it is not a problem to perform unsystematic RS coding even if it comes later than parity.

As can be seen from the above description, it can be seen that the position of the parity position holder is repeated with a 52 segment period. Figure 3 shows the byte number of the parity position holder for s mod 52 = 1-7 segments.

FIG. 4 shows the position of the unstructured RS parity given by Equations 1 and 3 according to the packet (or segment) number. The figure shows the packet format at the input of the data interleaver 206 (or the output of the RS encoder and the unstructured RS parity inserter 205) of the EVSB transmission system. In FIG. 3, a blue area is a 3-byte MPEG header area, a green area is an area where enhanced data and known data are located, and a purple area is a location of an unstructured RS parity byte. In FIG. 4, the unstructured RS parity bytes, which are the purple areas of each packet, are output later in time at the output of the data interleaver 206 than the enhanced or known data, which is the green area of the packet.

The output of the RS encoder / parity position holder inserter 205 is output to the data interleaver 206, and the data interleaver 206 interleaves it. In this case, the data interleaver 206 receives an RS parity byte newly calculated and output from the unstructured RS encoder 211 and replaces an unstructured RS parity position holder not yet output. That is, the data interleaved 187 information bytes are first outputted, and then 20 parity position holders in which null bytes are inserted are replaced with newly calculated 20 RS parity bytes.

One byte output from the data interleaver 206 is converted into four symbols by the byte-symbol converter 207 and output to the EVSB symbol processor 208. Here, one symbol consists of two bits.

The known data generated by the known data generator 209 is also output to the EVSB symbol processor 208.

The EVSB symbol processor 208 receives data output from the byte-symbol converter 207 and known data symbols generated from the known data generator 209 to perform various processes, and then executes the trellis encoder 212. And a symbol-byte converter 210 for output. That is, the EVSB symbol processing unit 208 outputs the input symbol as it is with respect to the main data symbol without changing the data. In the case of the enhanced data symbol, the EVSB symbol processing unit 208 is additionally connected when used in connection with the trellis encoder 212. Signal processing for obtaining coding gain is performed.

At this time, if the data output from the byte-symbol converter 207 is a known data position holder with null data inserted therein, the data is replaced with the known data generated by the known data generator 209 and then the trellis encoder 212 is used. Output to the symbol-byte converter 210.

The EVSB symbol processor 208 generates a data symbol at the beginning of the known data symbol so that the memory of the trellis encoder 212 is initialized to a predetermined state and outputs the data symbol instead of the received known data symbol. To this end, the EVSB symbol processor 208 receives a memory value in the trellis encoder 212.

The reason why the trellis encoder 212 is initialized when the sequence of the known data is started may be various depending on the memory state of the trellis encoder 212 even if the sequence of the known data is input to the trellis encoder 212. This is because output columns are possible. Therefore, if the known data is input after the memory state of the trellis encoder 212 is initialized to a predetermined value, the known data output string can be obtained from the trellis encoder 212 output.

In this case, two symbols are required to initialize the memory of the trellis encoder 212. Since 12 trellis encoders are used in the VSB transmission system, 24 input symbols are used for initialization. That is, in the ATSC VSB system, since 12 identical trellis encoders are used, 12 EVSB symbol processing units 208 also have 12 identical symbol processing units. The trellis encoder 212 precodes data input with the upper bits among the output symbols of the EVSB symbol processing unit 208, trellis-codes the data input with the lower bits, and outputs the data to the frame multiplexer 213. .

On the other hand, since the EVSB symbol processor 208 receives a symbol composed of 2 bits and performs various processing, and outputs a symbol composed of 2 bits again, the unstructured RS encoder 211 receives an RS from the output of the EVSB symbol processor 208. To recalculate the parity, the symbol-byte converter 210 must convert the bytes into bytes. That is, the symbol-byte converter 210 converts the input symbols into byte units and outputs them to the unstructured RS encoder 211.

The unstructured RS encoder 211 calculates and outputs 20 bytes of RS parity to the data interleaver 206 for an enhanced data packet of 187 information bytes. The data interleaver 206 receives an RS parity byte calculated and output from the unstructured RS encoder 211 and replaces an unstructured RS parity position holder that is not yet output.

Here, the reason for the unsystematic RS coding is that the EVSB symbol processor 208 changes the enhanced data symbol and the known data position holder to different values so that a decoding error does not occur when RS decoding is performed in the existing ATSC VSB receiver. To avoid that. That is, to have backward compatibility with the existing ATSC VSB receiver.

The frame multiplexer 213 inserts four segment sync symbols for each output symbol of the trellis encoder 212 to form 832 data segments, and inserts one field sync segment for every 312 data segments. One data field is configured and output to the transmitter 220.

The transmitter 220 inserts a pilot signal into the output of the frame multiplexer 213 into which the segment synchronization signal and the field synchronization signal are inserted, VSB modulates the signal, and converts the RF signal into an RF signal. To this end, the transmitter 220 includes a pilot inserter 221, a VSB modulator 222, and an RF up converter 223. And a pre-equalizer filter is optional.

As described above, the enhanced data packet according to the present invention includes enhanced data carried by carrying information and known data inserted to improve reception performance of a receiver. The EVSB packet formatter 202 is a known data position holder that secures a position where the output of the EVSB preprocessor 201 and the known data are inserted for 184 bytes except for a 3-byte MPEG header and a 20-byte unstructured RS parity byte. Multiplexes form one packet. There is no restriction on the position and number of bytes where known data is inserted in an area of 184 bytes excluding MPEG header bytes and unstructured RS parity bytes in an enhanced data packet. It depends on the intended use of the receiving system.

The position at which the output of the known data generator 209 is provided may be variable. For example, the EVSB packet formatter 202 may receive and insert the output of the known data generator 209 instead of the null byte. Alternatively, the RS encoder and the unstructured RS parity position holder inserter 205 may receive the known data of the known data generator 209 and replace the known data position holder included in the enhanced data packet.

FIG. 5 is a block diagram illustrating an embodiment of a digital broadcast receiving system for receiving, demodulating, and equalizing data transmitted from a digital broadcast transmitting system as shown in FIG. 2 to restore original data.

5 shows tuner 301, demodulator 302, equalizer 303, known data detector 304, Viterbi decoder 305, data deinterleaver 306, RS decoder and unstructured RS parity remover. 307, the de-randomizer 308 is configured.

The digital broadcast reception system includes a main data packet remover 309, an EVSB packet deformatter 310, and an enhanced data processor 311.

That is, the tuner 301 tunes the frequency of a specific channel, down-converts it, and outputs the demodulator 302.

The demodulator 302 performs carrier recovery and timing recovery on the tuned channel frequency to form a baseband signal and outputs the same to the equalizer 303 and the known data detector 304.

The equalizer 303 compensates for the distortion on the channel included in the demodulated signal and outputs it to a Viterbi decoder 305.

At this time, the known data detection unit 304 detects the known data symbol string inserted at the transmitting side from the output data of the demodulator 302 and outputs it to the demodulator 302 and the equalizer 303.

The demodulation unit 302 can improve demodulation performance by using the known data during timing recovery or carrier recovery, and can equalize performance using the known data in the equalizer 303 as well.

The Viterbi decoder 305 performs Viterbi decoding on the main symbol and the enhanced data symbol output from the equalizer 303, converts the result into bytes, and outputs the result to the deinterleaver 306. The deinterleaver 306 performs an inverse process of the data interleaver on the transmitting side and outputs the decoded data to an RS decoder and a non-systematic RS parity remover 307. The RS decoder and the unstructured RS parity remover 307 perform RS decoding when the received packet is a main data packet, and remove the unstructured RS parity byte when the received packet is an enhanced data packet. Will output The location of the unstructured RS parity byte is given by Equation 1 and FIG.

The derandomizer 308 performs a reverse process of the randomizer on the outputs of the RS decoder and the unstructured RS parity remover 307 and inserts MPEG sync bytes in front of every packet and outputs them in units of 188 byte packets. .

The output of the derandomizer 308 is output to the main MPEG decoder (not shown) and to the main data packet remover 309. The main MPEG decoder decodes only packets corresponding to the main MPEG. If the packet ID is a null packet PID or a reserved PID (ie, an enhanced data packet), no decoding is performed.

The main data packet remover 309 removes the main data packet in units of 188 bytes from the output of the derandomizer 308 and outputs the main data packet to the EVSB packet deformatter 310. The EVSB packet deformatter 310 removes the 4-byte MPEG header and the bytes of the known data position holder from the 188-byte packet output from the main packet remover 309 and outputs the encoded data to the enhanced data processor 311. . The enhanced data processor 311 performs a reverse process of the EVSB preprocessor 201 on the transmitting side with respect to the output of the EVSB packet deformatter 310 and finally outputs the enhanced data.

As described above, those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

1 is a block diagram of a general digital broadcast transmission system

2 is a block diagram of a digital broadcast transmission system according to the present invention.

3 shows an example of an unstructured RS parity position holder for each segment according to the present invention.

4 shows an example of the location of unstructured RS parity in accordance with the present invention.

5 is a block diagram showing the overall configuration of an embodiment of a digital broadcast receiving system according to the present invention.

Explanation of symbols for the main parts of the drawings

201: EVSB preprocessor 202: EVSB packet formatter

203: packet multiplexer 204: data randomizer

205: Reed Solomon Encoder and Parity Position Holder Inserter

206: data interleaver 207: byte to symbol converter

208: EVSB symbol processing unit 209: known data generation unit

210: symbol-byte converter 211: unstructured RS encoder

212: Trellis encoder 213: frame multiplexer

220: transmitter 221: pilot inserter

222: VSB Modulator 223: RF Up Converter

Claims (6)

In the method for processing a DTV broadcast signal transmitted from a broadcast transmitter in a broadcast receiver, Receiving a DTV broadcast signal; And Here, the DTV broadcast signal, the error correction encoding step for the enhanced data in the broadcast transmitter; Generating a first MPEG packet using the error correction encoded enhanced data and known data known to a transmitter / receiver; Multiplexing a first MPEG packet comprising the enhanced data and the known data and a second MPEG packet comprising normal data; Performing systematic RS encoding on normal data among the multiplexed data, and performing unsystematic RS encoding on enhanced data and known data among the multiplexed data; Performing interleaving on the systematic RS coded normal data and the unsystematic RS coded enhanced data and known data; Trellis encoding the interleaved enhanced data and normal data using a trellis encoder; Initializing a memory of the trellis encoder; And trellis encoding the interleaved known data based on the initialized memory. And removing unsystematic RS parity inserted in enhanced data included in the received DTV broadcast signal. The method of claim 1, Removing the normal data from the received DTV broadcast signal; and processing the DTV broadcast signal in a broadcast receiver. The method of claim 1, And post-processing the enhanced data from which the unsystematic RS parity has been removed. A broadcast receiver for processing a DTV broadcast signal transmitted from a broadcast transmitter, A tuner for receiving a DTV broadcast signal; And And an unstructured RS parity remover for removing unsystematic RS parity inserted into enhanced data included in the received DTV broadcast signal. The DTV broadcast signal is error corrected encoded on the enhanced data by the broadcast transmitter, generates the first MPEG packet using the error corrected encoded data and known data known to the transmitter / receiver, and enhances the enhanced data. Multiplexing the first MPEG packet including the decoded data and the known data and the second MPEG packet including the normal data, performing systematic RS encoding on the normal data among the multiplexed data, and enhancing the multiplexed data. Perform unstructured RS encoding on the coded data and known data, interleave the systematic RS encoded normal data and the unstructured RS encoded enhanced data and known data, and use the trellis encoder Trellis interleaved enhanced data and normal data And encoding and initializing a memory of the trellis encoder, and trellis encoding the interleaved known data based on the initialized memory. The method of claim 4, wherein And a normal data remover for removing the normal data from the received DTV broadcast signal. The method of claim 4, wherein And an enhanced data processor for post-processing the enhanced data from which the unsystematic RS parity has been removed.

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