KR20090101421A - Digital broadcasting receiver and stream processing method thereof - Google Patents

Abstract

PURPOSE: A digital broadcasting receiver and a stream processing method thereof are provided to combine a robust stream having improving receiving performance with a normal stream which is in an existing transmitting type in a VSB type American terrestrial DTV system, thereby improving receiving performance. CONSTITUTION: A digital broadcasting receiver includes a robust data pre-processor, a transport stream generating unit(307), an RS encoder(301), an interleaver(340), and a trellis encoder(360). The robust data pre-processor receives and processes robust data. The transport stream generating unit multiplexes robust data outputted from a data pre-processor with normal data. The RS encoder encodes a transport stream. The interleaver interleaves the encoded transport stream. The trellis encoder trellis-encodes the interleaved transport stream.

Description

Digital broadcasting transmitter and stream processing method

The present invention relates to a digital broadcast transmitter and a stream processing method thereof, and more particularly, to a digital broadcast transmitter and a stream processing method capable of improving the reception performance of a normal stream by enhancing the reception performance of a robust stream in a poor channel environment. It is about.

ATSC VSB, a terrestrial digital broadcasting system for the United States, is a single carrier system and field sync signals are used in units of 312 segments. This results in poor reception, especially on poor channels, especially the Doppler fading channel.

1 is a block diagram showing a transceiver according to the ATSC DTV standard as a general US terrestrial digital broadcasting system. The digital broadcast transmitter of FIG. 1 is a randomizer 110 that randomizes an MPEG-2 TS stream, and an RS encoder in the form of a concatenated coder to correct an error generated by a channel. encoder 120, an interleaver 130 (B = 52, M = 4), and a trellis encoder (140). The encoded data is mapped to 8 level symbols, and then the field sink and the segment sink are inserted as shown in the data format of FIG. 2. The pilot is then inserted, VSB modulated and converted to RF for transmission.

Meanwhile, the digital broadcast receiver of FIG. 1 reverses the RF signal to the baseband, demodulates and equalizes it, and decodes the channel to restore the original signal. 2 shows a VSB data frame of an American terrestrial DTV system. In FIG. 2, one frame is composed of two fields, and one field is composed of 312 data segments and a field sync segment. One segment is composed of 4 symbols of segment sync and 828 data symbols.

As shown in FIG. 1, the digital broadcast transmitter randomizes data through the randomization unit 110 for the MPEG-2 TS stream, and the randomized data is an RS encoder (Reed-Solomon encoder) which is an outer coder. The coded data is distributed through the interleaver 130. The interleaved data is internally coded through a trellis encoder (140) in units of 12 symbols. After the internally encoded data is mapped to 8 level symbols, a field sink and a segment sink are inserted as shown in the data format of FIG. 2. After that, DC offset is given for pilot generation, VSB modulation is performed, and converted to RF for transmission.

Meanwhile, the digital broadcast receiver of FIG. 1 converts a signal received through a channel into a baseband signal through a tuner / IF (not shown). The base signal is demodulated through the synchronization detection and demodulation unit 210 and compensates for channel distortion due to the multipath of the channel through the equalizer 220. The equalized signal is corrected by a trellis decoder 230 and decoded into symbol data. The decoded data rearranges the data distributed by the interleaver 130 of the digital broadcast transmitter through the deinterleaver 240. The deinterleaved data corrects an error through an RS decoder 250. The data corrected through the RS decoder 250 is derandomized through a derandomizer 260 to output an MPEG-2 TS stream.

In the VSB data frame of the U.S. terrestrial DTV system of FIG. 2, one segment corresponds to one MPEG-2 packet. In FIG. 2, one frame includes two fields, and one field includes 312 data segments and a field sync segment. In addition, one segment is composed of a segment sync of 4 symbols and 828 data symbols. Here, the segment sync and the field sync, which are sync signals, are used for synchronization and equalization. The field sink and the segment sink are used as training data in the equalizer as a known sequence.

The VSB method of the U.S. terrestrial DTV system of FIG. 1 is a single carrier method, and since the error correction capability of the trellis encoder of FIG. 3 is not strong, high output energy is required to improve reception performance in a poor channel environment. There is a problem.

Accordingly, an object of the present invention is to provide a digital broadcast transmission / reception system for improving reception performance by combining a normal stream, which is a conventional data transmission form, and a robust stream which improves reception performance in a poor channel state in a VSB terrestrial DTV system. A digital broadcast transmitter and a stream processing method thereof are provided.

According to an aspect of the present invention, a digital broadcast transmitter includes: a boost data preprocessor configured to receive and boost boost data, and a boost data output from the boost data preprocessor; A transport stream generator configured to mux normal data to form a transport stream, an RS encoder for encoding the transport stream, an interleaver for interleaving the encoded transport stream, and a trellis encoder for trellis encoding the interleaved transport stream. Include.

Here, the boost data preprocessor includes an encoder for encoding the boost data and a first packet formatter for formatting the encoded boost data.

The transmitter may further include a second packet formatter for formatting the normal data. In this case, the transport stream generator may mux the data formatted in the first packet formatter and the second packet formatter, respectively.

On the other hand, the stream processing method of the digital broadcast transmitter according to an embodiment of the present invention, a pre-processing step of receiving the boost data to boost processing, the boost data and normal data processed in the pre-processing step by muxing the transport stream Constructing a stream, encoding the transport stream, interleaving the encoded transport stream, and trellis encoding the interleaved transport stream.

Here, the preprocessing step may include encoding the low boost data and formatting the encoded low boost data.

The method may further comprise formatting the normal data, in which case configuring the transport stream may mux the formatted normal data and the formatted robust data.

According to the present invention, in order to improve the reception performance of the ATSC VSB scheme, which is an American terrestrial DTV system, a low-stream stream is combined with a normal stream to generate, encode, and transmit an MPEG-2 packet, and a receiving side detects a location of the low-boost stream. Therefore, the decoding performance is improved by using two separate decoders to improve the reception performance of the boost stream.

Therefore, it is compatible with existing systems and improves data reception performance in poor channel environments.

1 is a block diagram showing a general digital broadcast (ATSC VSB) transmission and reception system,

2 is a diagram illustrating a frame structure of ATSC VSB data;

3 is a diagram illustrating a structure of a trellis encoder;

4 is a view showing the structure of an MPEG packet generated in a digital broadcast transmitter according to the present invention;

5 is a diagram illustrating a format of data output from a trellis encoder according to the present invention;

6 is a block diagram showing a digital broadcast transmitter according to the present invention;

7 illustrates a structure of a convolutional encoder according to the present invention; and

8 is a diagram showing the structure of a digital broadcast receiver according to the present invention.

Explanation of symbols on the main parts of the drawings

300: digital broadcast transmitter 307: TS stream generation unit

310: randomization unit 320: RS encoder

330: convolutional encoder 340: interleaver

350: Convolution Interleaver 360: Trellis Encoder

400: digital broadcast receiver 410: demodulator

420: equalizer 470: low-boost data detector

480: turbo decoder 500: Robust data processing unit

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

6 is a block diagram illustrating a digital broadcast transmitter of a dual stream EVBS system according to the present invention.

The digital broadcast transmitter includes a pre-processing RS encoder 301 and a first packet format unit 303, a second packet format unit 305 for normal data processing, and a first packet format unit to improve reception performance of the low boost data. And a stream stream (TS stream generator) 307 for outputting MPEG packets by combining the low boost data and the normal data output from the second packet format unit 305 and 305, respectively.

In addition, the digital broadcast transmitter may include a randomization unit 310 that randomizes data with respect to MPEG packets generated by the TS stream generation unit 307, a convolution encoder 330 and an interleaver 340 that encode a low-boost stream portion. And an RS encoder 320, a convolutional interleaver 350, and a trellis encoder 360, which encode the low-boost stream output from the interleaver 340 together with the normal stream.

4 shows the structure of an MPEG packet generated by the TS stream generation unit 307. The TS stream generation unit 307 reconstructs the new MPEG packet such that the normal stream and the boost stream exist simultaneously in one packet from the input normal MPEG packet and the boost MPEG packet. Here, the low boost stream is fixedly transmitted at a specific position and can be transmitted by arbitrarily adjusting the amount through the AF header.

5 is a diagram illustrating a format of data output from the trellis encoder 360. When the robust stream is transmitted using a specific position of the MPEG packet, the packets input to the convolutional encoder 330 and passed through the interleaver 340 become a continuous form of the robust stream as shown in FIG. 5. Therefore, MAP (maximum a posteriori probability) decoding, which operates in units of frames, can be easily performed on data in this format, thereby improving performance of a low-boost stream.

7 is a diagram illustrating a structure of a convolutional encoder according to the present invention. Increasing the coding gain of the trellis encoder 360 improves the performance of the information exchange of the receiving side decoder. To this end, the convolutional encoder 330 of FIG. 7 punctures the parity at 1/2 rate. The input of the convolutional encoder is input to "d1" which is the input of the differential encoder of the trellis encoder 360, and the parity is input to "d0". At this time, parity is punctured so that 1 or 0 is in the middle. Since "d0" becomes Z1 as "1" is entered, it becomes 4VSB with mapping value of "-3, -1,5,7" and when "0" is entered, "-7, -5,1,3" 4VSB with a mapping value of. That is, the output value alternates with 8VSB and 4VSB by puncturing and the coding gain is improved by the trellis encoder 360.

8 is a diagram showing the structure of a digital broadcast receiver according to the present invention. The receiver includes a demodulator 410 for demodulating a signal received through a channel, an equalizer 420 for compensating for channel distortion due to multipath of a channel, and a Viterbi decoder for correcting an error and decoding the symbol data. 430, a deinterleaver 440 for rearranging the distributed data with respect to the decoded data, an RS decoder 450 for correcting errors for the deinterleaved data, and an inverse randomization of the corrected data. A randomizer 660. Normal data of the received signal is processed through the structure as described above.

Meanwhile, the receiver uses a robust data generator (470) for detecting the location of the boot data from the demodulated data stream demodulated by the demodulator (410) and the detected boost data using the location of the detected boost data. It includes a turbo decoder (480) for decoding the.

The turbo decoder 480 is composed of two decoders including a trellis decoder (not shown) and a convolution decoder (not shown) to improve performance while performing mutual decoding reliability information exchange. The output of the convolutional decoder is the same as the input of the receiving RS encoder. Subsequently, the output of the convolutional decoder of the turbo decoder 480 is input to and processed by the robust data processor 500 which reconstructs the robust stream and performs RS decoding.

According to the present invention, in order to improve the reception performance of the VSB method of the US terrestrial DTV system, the normal data and the boost data are combined to form a single MPEG-2 packet, and the location of the boost data is detected at the receiver to detect the boost data. By using the trellis decoder and the convolutional decoder for information exchange and decoding, the reception performance of the low boost data may be improved in a poor multipath channel environment.

In addition, the digital broadcast transmission and reception method according to the present invention is compatible with the existing receiver proposed by ATSC, and can improve the reception performance of the ATSC VSB method, which is a terrestrial DTV system for the US.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention without departing from the spirit of the present invention as claimed in the claims. Anyone skilled in the art can make various modifications, as well as such modifications are within the scope of the claims.

Claims (6)

A boost data preprocessing unit for receiving the boost data and processing the boost data; A transport stream generator configured to mux the boost data and the normal data output from the low data preprocessor to form a transport stream; An RS encoder for encoding the transport stream; An interleaver for interleaving the encoded transport stream; And, A trellis encoder for trellis encoding the interleaved transport stream. The method of claim 1, The low boost data preprocessing unit, An encoder for encoding the low boost data; And, And a first packet formatter for formatting the encoded robust data. The method of claim 2, A second packet formatter for formatting the normal data; The transport stream generating unit muxes data formatted in the first packet formatter and the second packet formatter, respectively. A preprocessing step of receiving the boost data and performing the boost processing; Muxing the boost data and the normal data processed in the preprocessing step to construct a transport stream; Encoding the transport stream; Interleaving the encoded transport stream; And, Trellis encoding the interleaved transport stream. The method of claim 4, wherein The pretreatment step, Encoding the low boost data; And, Formatting the encoded low boost data. The method of claim 5, Formatting the normal data further; The configuring of the transport stream may include muxing the formatted normal data and the formatted robust data.