HK1140080A - Digital broadcasting transmission/reception system having improved receiving performance and signal processing method thereof - Google Patents

Description

Digital broadcast transmitting/receiving system and signal processing method for improving receiving performance

This application is a divisional application of the patent application entitled "digital broadcast transmitting/receiving system and signal processing method for improving receiving performance" filed as 7/15/2005, application No. 200580023761.8.

Technical Field

The present invention relates to a digital broadcasting transmission/reception system, and more particularly, to a digital transmission/reception system and a signal processing method thereof for enhancing the reception performance of a robust stream (robust stream) in a poor channel environment, thereby simultaneously improving the reception performance of a normal stream (normal stream).

Background

The advanced television systems committee vestigial sideband (ATSC VSB) method is an american-oriented terrestrial wave digital broadcasting system, which is a single carrier method and uses one field sync every 312 segment units. Therefore, the reception performance is not good in a poor channel, particularly, in a doppler fading channel.

Fig. 1 is a block diagram of a transmitter/receiver of a general U.S. oriented terrestrial wave digital broadcasting system according to the ATSC Digital Television (DTV) standard. The digital broadcast transmitter of fig. 1 has: a randomizer (110) for randomizing the MPEG-2 TS; a Reed-Solomon (RS) encoder (120) in the form of a concatenated encoder for correcting errors generated by the channel; interleaver (130) (B-52, M-4), and 2/3 rate trellis encoder (140). The encoded data is mapped in 8-level symbols and a field sync and a segment sync are inserted therein as shown in fig. 2. Thereafter, pilot is inserted into the data, the data is VSB-modulated, upconverted to RF, and transmitted.

Meanwhile, the digital broadcasting receiver of fig. 1 lowers the RF signal to the baseband in the reverse order of the digital broadcasting transmitter, demodulates and equalizes the lowered signal, performs channel decoding, and restores the original signal. Fig. 2 illustrates a Vestigial Sideband (VSB) data frame of the DTV system oriented to the united states. In fig. 2, one frame includes two fields and one field has 312 data segments and a field sync segment. A segment has a segment sync of 4 symbols and data symbols of 828 symbols.

As shown in fig. 1, the digital broadcast transmitter randomizes the MPEG-2TS by a randomizer (110). The randomized data is outer-encoded by an RS encoder (120) as an outer encoder, and the outer-encoded data is dispersed by an interleaver (130). The interleaved data is inner-coded in 12 symbol units by the trellis encoder and the inner-coded data is mapped in 8-level symbols and a field sync and a segment sync are inserted therein as shown in fig. 2. Thereafter, the data having a DC offset for generating a pilot is VSB-modulated, up-converted into an RF signal and transmitted.

Meanwhile, the digital broadcasting receiver of fig. 1 converts an RF signal received through a channel into a baseband signal through a tuner/IF (not shown). The baseband signal is synchronously detected and demodulated by a demodulator (210), and distortion caused by channel multipath is compensated for by an equalizer (220). The equalized data is error corrected and decoded into symbol data by a trellis decoder (230). The decoded data scattered by the interleaver (130) of the transmitter is rearranged by a deinterleaver (240), and the deinterleaved data is error-corrected by an RS decoder (250). The error-corrected data is de-randomized by a de-randomizer (260) and output as an MPEG-2 TS.

In the VSB data frame of the u.s-oriented terrestrial waves DTV system of fig. 2, one segment corresponds to one MPEG-2 packet. In fig. 2, one frame includes two fields, one field having 312 data segments and a field sync segment. A segment has a segment sync of 4 symbols and data symbols of 828 symbols. The segment sync and the field sync are sync signals for synchronization and equalization. The field sync and segment sync are known sequences and are used as training data in the equalizer.

The VSB method of the u.s-oriented terrestrial waves digital television system of fig. 1 is a single carrier system and has a disadvantage in that a large output energy is required to improve reception performance in a poor channel environment because the error correction capability of the trellis encoder of fig. 3 is not strong enough.

Disclosure of Invention

Technical problem

An aspect of the present invention is to provide a digital broadcast transmission/reception system for improving reception performance by combining a normal stream of an existing transmission type in a terrestrial wave Digital Television (DTV) system oriented to the united states of america of a VSB method with a robust stream of improved reception performance in a poor channel environment, and a signal processing method thereof.

Technical scheme

The digital broadcast transmitter according to the present invention may include: a robust data preprocessor for processing the robust data and generating a robust data packet of a specific format; a TS stream generator for combining the robust data packets with the normal data packets and generating a TS stream of a specific format; a randomizer for randomizing the TS stream outputted from the TS stream generator; a convolutional encoder for performing convolutional encoding on the robust data of the data output from the randomizer; and an interleaver for interleaving the data output from the convolutional encoder.

Preferably, the transmitter may further include: and an RS encoder for performing RS-encoding on the robust data output from the interleaver and the normal data of the data output from the randomizer.

More preferably, the transmitter may further include: and a convolutional interleaver for interleaving the data output from the RS encoder.

Further, the transmitter may further include: a trellis encoder for performing trellis encoding on the data interleaved by the convolutional interleaver after the RS encoding.

Preferably, the convolutional encoder may perform convolutional encoding on the robust data in a certain method in order to improve the coding gain when the trellis encoder is simultaneously applied.

In addition, the interleaver may perform interleaving on the robust data in a certain method in order to improve coding gain when the convolutional encoder and the trellis encoder are applied at the same time.

In addition, the convolutional encoder may generate a specific parity for the robust data and output the robust data and the parity.

In addition, the convolutional encoder may puncture the parity at a rate of 1/2.

Meanwhile, the convolutional encoder may skip puncturing the parity at the rate of 1/2 and output the robust data and the parity as they are.

Further, the trellis encoder may perform trellis encoding and output a 4-level mapping value in case of inputting the punctured parity.

Meanwhile, a signal processing method of a digital broadcast transmitter according to the present invention includes: generating a robust data packet of a specific format by processing the robust data; combining the generated robust data packets with the normal data packets and generating a TS stream of a specific format; randomizing the TS stream; performing convolutional encoding on the robust data of the randomized data; and interleaving the convolutionally encoded data.

Meanwhile, the digital broadcast receiver according to the present invention may include: a demodulator for receiving and demodulating the encoded signal into which the robust data is inserted at a specific location; a robust position generator for detecting a position of the robust data from the demodulated signal; an equalizer for equalizing the demodulated signal; a turbo decoder for decoding the robust data of the signal output from the equalizer using the detected position of the robust data; a derandomizer for derandomizing the robust data output from the turbo decoder; and a robust data processor for processing and reconstructing the robust data output from the derandomizer.

the turbo decoder may include: a trellis decoder for trellis-decoding the robust data; and a convolutional decoder for convolutional-decoding the trellis-decoded robust data.

The trellis decoder and the convolutional decoder may exchange decoding reliability information with each other upon decoding.

In addition, the turbo decoder may further include an interleaver and a deinterleaver which respectively connect the trellis decoder and the convolutional decoder, and the reliability information may be exchanged with each other through one path from the deinterleaver to the convolutional decoder and another path from the interleaver to the trellis decoder.

Meanwhile, a signal processing method of a digital broadcast receiver according to the present invention may include: receiving and demodulating the encoded signal into which the robust data is inserted at a specific location; detecting a location of the robust data from the demodulated signal; equalizing the demodulated signal; decoding the robust data of the equalized signal using the detected position of the robust data; de-randomizing the decoded robust data; and processing and reconstructing the derandomized robust data.

Advantageous effects

According to the present invention, in order to improve the reception performance of the ATSC VSB method of the u.s-oriented terrestrial waves DTV system, the robust stream and the normal stream are combined to generate an MPEG-2 packet, the MPEG-2 packet is encoded and transmitted, and the receiver detects the position of the robust stream and decodes the stream by exchanging information using two additional decoders, so that the reception performance of the robust stream can be improved.

Accordingly, compatibility with the existing system is maintained, and reception performance in a poor channel environment is improved.

Drawings

Fig. 1 is a block diagram for illustrating a general digital broadcasting (ATSC VSB) transmission/reception system;

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

fig. 3 is a diagram for illustrating the structure of a trellis encoder;

fig. 4 is a diagram for illustrating a structure of an MPEG packet generated from a digital broadcast transmitter according to the present invention;

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

fig. 6 is a diagram for illustrating a digital broadcasting transmitter according to the present invention;

fig. 7 is a diagram for illustrating a structure of a convolutional encoder according to the present invention; and

fig. 8 is a diagram for illustrating a structure of a digital broadcast receiver according to the present invention.

Detailed Description

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

The digital broadcasting transmitter includes: an RS encoder (301) and a first packet formatter (303) for preprocessing robust data to improve reception performance of the robust data; a second packet formatter (305) for processing normal data; and a TS stream generator (307) for combining the robust data output from the first packet formatter (303) with the normal data output from the second packet formatter (305) to output an MPEG packet.

Further, the digital broadcasting transmitter includes: a randomizer (310) for randomizing the MPEG packet generated from the TS stream generator (307); a convolutional encoder (330) for encoding the robust stream part; an interleaver (340); an RS encoder (320) for encoding the robust stream output from the interleaver (340) together with the normal stream; a convolutional interleaver (350), and a trellis encoder (360).

In the digital broadcasting transmitter according to the present invention, data output from the RS encoder (320) is input to the trellis encoder (360) without change. Accordingly, if the convolutional encoder (330) is employed before the RS encoder (320), information exchange with the trellis encoder (360) may be performed using data output from the RS encoder (320). That is, the transmitter may exchange information with the trellis encoder (360) using the convolution-encoded robust stream, so that reception performance in a poor channel environment may be enhanced.

Fig. 4 shows the structure of an MPEG packet generated by the TS stream generator (307). The TS stream generator (307) reconstructs a new MPEG packet having both the input normal stream and robust stream. The robust stream is fixed at a specific position and transmitted, and the AF header can freely adjust the amount of the robust stream.

Fig. 5 shows the format of data output from the trellis encoder (360). If the robust stream is transmitted using a specific position of the MPEG packet, the robust stream passes through the convolutional encoder (330) and the interleaver (340) and is successively aggregated in the format of fig. 5. Accordingly, maximum a posteriori probability (MAP) decoding operating in frame units can be simply performed on the data of such a format, thereby improving the reception performance of the robust stream.

Fig. 7 shows the structure of a convolutional encoder according to the present invention. The structure of the convolutional encoder (330) can be implemented in various forms. The puncturing as shown in fig. 7 may be used according to usage. The input to the systematic recursive convolution is "d 1" which is the input to the encoder differential encoder of the trellis encoder (360), and the parity is input as being in "d 0". At this time, the parity may be output as it is or punctured to include 1 or 0. Since "d 0" becomes Z1, the point inserted with "1" becomes 4VSB having "-3, -1, 5, 7" map values, and the point inserted with "0" becomes 4VSB having "-7, -5, 1, 3" map values. That is, the output value is alternately changed to 8VSB or 4VSB by puncturing, and the coding gain generated by the trellis encoder (360) is enhanced.

Fig. 8 illustrates a structure of a digital broadcasting receiver according to the present invention. The receiver includes: a demodulator (410) for demodulating a signal received over a channel; an equalizer (420) for compensating for distortion caused by channel multipath; a viterbi decoder (430) for correcting errors and performing decoding in the symbol data; a deinterleaver (440) for rearranging scattered data of the decoded data; an RS decoder (450) for error correcting the deinterleaved data; and a de-randomizer (460) for de-randomizing the error corrected data. Normal data of the received signal is processed through the above-described structure.

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

the turbo decoder (480) includes two decoders, a trellis decoder (not shown) and a convolutional decoder (not shown), and enhances reception performance by exchanging decoding reliability information with each other. In the receiver, the output of the convolutional decoder is the same as the input of the RS encoder.

Further, the turbo decoder (480) includes a deinterleaver (not shown) and an interleaver (not shown) between which the trellis decoder and the convolutional decoder are respectively connected. An interleaver (not shown) has a form of combining the interleaver (340) and the convolutional interleaver (350) of the transmitter, performs interleaving of the two interleavers (340, 350), and becomes a path for transmitting decoding reliability information from the trellis decoder to the convolutional decoder. In addition, a deinterleaver (not shown) performs deinterleaving to reverse the operation of the interleaver and becomes a path for transferring decoding reliability information from the convolutional decoder to the trellis decoder.

Subsequently, the output of the convolutional decoder of the turbo decoder (480) reconstructs the robust stream and inputs it to the robust data processor (500) to perform RS decoding.

According to the present invention, in order to improve the reception performance of the VSB method of the u.s-oriented terrestrial waves DTV system, the normal data and the robust data are combined to become an MPEG-2 packet, and the receiver detects the position of the robust data in the packet and decodes the robust data through information exchange between the trellis decoder and the convolutional decoder, so that the reception performance of the robust data can be improved in a poor multipath channel environment.

In addition, the digital broadcasting transmission/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 of the terrestrial waves digital broadcasting system for the united states.

Claims (10)

1. A digital broadcast receiver, comprising:

a demodulator for receiving and demodulating a transport stream including an additional data stream and a normal data stream;

a decoder for decoding a normal data stream in the transport stream; and

a turbo decoder for turbo decoding the additional data stream in the transport stream.

2. The digital broadcast receiver of claim 1, further comprising:

an equalizer for equalizing the demodulated transport stream.

3. The digital broadcast receiver of claim 1, further comprising:

a deinterleaver for deinterleaving the normal data stream decoded by the decoder;

a Reed-Solomon decoder for decoding the deinterleaved normal data stream;

a derandomizer for derandomizing the decoded normal data stream; and

and an additional data processor for performing Reed-Solomon decoding on the additional data stream turbo-decoded by the turbo decoder.

4. The digital broadcast receiver of claim 1, wherein the turbo decoder comprises a plurality of decoders for decoding the additional data stream and exchanging decoding reliability information with each other.

5. The digital broadcast receiver of claim 1, wherein the transport stream is generated by a digital broadcast transmitter by multiplexing an additional data stream with a normal data stream, wherein the additional data stream is robustly processed by preprocessing data.

6. A method for processing a stream in a digital broadcast receiver, the method comprising:

receiving and demodulating a transport stream including an additional data stream and a normal data stream;

decoding a normal data stream in the transport stream; and

turbo decoding an additional data stream in the transport stream.

7. The method of claim 6, further comprising:

the demodulated transport stream is equalized.

8. The method of claim 6, further comprising:

deinterleaving the decoded normal data stream;

performing Reed-Solomon decoding on the deinterleaved normal data stream;

de-randomizing the reed-solomon decoded normal data stream; and

reed-solomon decoding is performed for the turbo decoded additional data stream.

9. The method of claim 6, wherein turbo decoding is performed using a plurality of decoders for decoding the additional data stream and exchanging decoding reliability information with each other.

10. The method as claimed in claim 6, wherein the transport stream is generated by a digital broadcasting transmitter by multiplexing an additional data stream with a normal data stream, wherein the additional data stream is robustly processed by preprocessing data.