KR20060070389A - A digital multimedia receiver - Google Patents

Abstract

A digital multimedia receiver is disclosed. The digital multimedia receiver according to the present invention includes a tuner for tuning a received signal to a corresponding band, an A / D converter for converting a tuned signal output from the tuner into a digital signal, and a demodulator for demodulating a digital signal output from an A / D converter. And a symbol de-mapper for demapping the demodulated signal output from the demodulator, and an LDPC decoder for decoding and outputting the demapped signal output from the symbol demapper. According to the present invention, it is possible to process both a single carrier modulated signal and a multicarrier modulated signal by a digital multimedia receiver having a simple structure, which has an advantage of having excellent performance.

Digital Multimedia Receiver, Tuner, A / D Converter, Synchronous, Demodulation, Modulation

Description

Digital multimedia receiver

1 is a block diagram showing the configuration of a conventional multi-carrier digital broadcast receiver;

2 is a block diagram showing the configuration of a conventional single carrier digital broadcast receiver;

3 is a block diagram showing the configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a first embodiment of the present invention;

4 is a flowchart provided to explain a digital multimedia reception method performed in a digital multimedia receiver according to the first embodiment of the present invention shown in FIG.

5 is a block diagram showing a configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a second embodiment of the present invention;

6 is a flowchart provided to explain an automatic gain control method performed in the digital multimedia receiver according to the second embodiment of the present invention shown in FIG.

7 is a block diagram showing the structure of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a third embodiment of the present invention;

8 is a block diagram showing a configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a fourth embodiment of the present invention;

9 is a flowchart provided to explain a digital multimedia reception method performed in a digital multimedia receiver according to the fourth embodiment of the present invention shown in FIG. 8;

10 is a block diagram showing the structure of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a fifth embodiment of the present invention;

11 is a block diagram showing the configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a sixth embodiment of the present invention;

12 is a flowchart provided to explain a digital multimedia reception method performed in a digital multimedia receiver according to a sixth embodiment of the present invention shown in FIG. 11;

13 is a block diagram showing the configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a seventh embodiment of the present invention;

14 is a flowchart provided to explain a digital multimedia reception method performed in a digital multimedia receiver according to a seventh embodiment of the present invention shown in FIG. 13;

FIG. 15 is a block diagram illustrating a configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to an eighth embodiment of the present invention.

Brief description of the main parts of the drawing

300,500,700,800,1000,1100,1300,1500: Digital Multimedia Receiver

310,510,710,810,1010,1110,1310,1510: tuner

320,520,720,820,1020,1120,1320,1520: A / D converter

330,540,740,850,1040,1140,1330: demodulator

331,332: first demodulator, second demodulator

340,1050: selector

360,760,870,1070,1160,1350: channel decoder

530: AGC

730, 1030: synchronization unit

730T: Timing Restoration Block 730C: Carrier Restoration Block

731: Resampling unit 732: Timing Error Detector

733: Mixer 734: Frequency Offset Estimator

830: filter coefficient unit 831: filter coefficient memory

832: filter coefficient uploader 840: receiving filter

851,1131,1331: First switch 852,1141,1332: OQAM demodulator

853,1045,1142,1333: FFT unit 854,1143,1334: QAM demodulator

855, 1144, 1335: second switch 1041: first demodulation block

1042: second demodulation block 1043: first equalizer

1043a: first equalization filter 1043b: coefficient updater

1044: OQAM section 1046: second equalizer

1046a: second equalization filter 1047: QAM unit

1130: decimation unit 1132, 1133: first and second decimators

1340 deinterleaver 1530 demodulator

1540: symbol demapper 1560: LDPC decoder

The present invention relates to a digital multimedia receiver, and more particularly, to a digital multimedia receiver capable of processing a multi-carrier modulated signal and a single carrier modulated signal.

In the age of multimedia communications and broadcasting, countries around the world are digitizing analogue forms of broadcasting. In particular, in advanced countries such as the United States, Europe, and Japan, digital broadcasting systems have already been developed and put into practical use. Due to the rapid development of digital broadcasting, the standards of digital broadcasting have been proposed differently in each country.

On December 24, 1996, the Federal Communications Commission (FEC) approved the Digital Television Standard of the Advanced Television System Committee (ATSC) as the next generation television broadcast standard. All terrestrial broadcast operators must comply with the ATSC standard with regard to audio / video compression, packet data transmission structures, and specifications of modulation and transmission systems. Only the video format was not specifically mentioned, but it was left to the industry.

The ATSC digital TV standard is for transmitting high quality audio / video data and additional data with a bandwidth of 6 MHz using a single carrier VSB scheme, and supports simultaneous terrestrial broadcasting mode and high-speed cable broadcasting mode. The main aspect of this approach is the 8-VSB modulation method. This is a variation of the current analog VSB scheme for the modulation of digital signals. In Europe, the Coding Orthogonal Frequency Division Multiplexing (COFDM) system has been adopted for European terrestrial digital video broadcasting (DVB-T) because of its high frequency efficiency and the benefits of interference prevention.

Other digital multimedia broadcasting methods using various modulation methods have been proposed, and these digital multimedia broadcasting methods can be divided into a multi-carrier method and a single carrier method. Therefore, the existing digital multimedia receiver may be divided into a multi-carrier digital receiver and a single carrier digital receiver.

1 is a block diagram of a conventional multi-carrier digital broadcast receiver according to the prior art.

Conventional multi-carrier digital broadcast receivers include a tuner 110 for receiving multi-carrier modulated digital multimedia signals and an analog-to-digital converter 120 for converting signals output from the tuner 110 into digital signals. ), A synchronization unit 130 that performs timing recovery and carrier recovery on the digital signal output from the A / D converter 120, and a fast Fourier transform on the signal output from the synchronization unit 130. FFT unit 140 for performing the following operations, an equalization unit 150 for equalizing the signal output from the FFT unit 140, a symbol detection unit 160 for performing symbol detection on the equalization output, and a symbol detection unit 160. A descrambler which decodes the signal output from the forward error correction unit (FEC unit) 170 and the FEC unit 170, which performs forward error correction on the signal output from Pov The.

2 is a block diagram of a conventional single carrier digital broadcast receiver. The conventional single carrier digital broadcast receiver includes a tuner 210 for receiving a single carrier modulated digital multimedia signal, an A / D converter 220 for converting a signal output from the tuner 210 into a digital signal, and timing recovery and A synchronization unit 230 that performs carrier recovery, an equalizer 240 that equalizes the output signal of the synchronization unit 230, and an OQAM symbol detector 250 that performs symbol detection on the output of the equalizer 240. ) And a signal output from the FEC unit 260 and the FEC unit 260 which perform forward error correction on the signal output from the OQAM symbol detector 250 to obtain an MPEG stream. The descrambler 270 is included.

The debate on whether the performance of either single carrier or multicarrier transmission system is better has long lasted, but the conclusion is still not clear. Single carrier transmission systems and multicarrier transmission systems have advantages and disadvantages for each. Therefore, each broadcasting station should select one of the various transmission methods suitable for the request of the specification or the broadcasting environment.

In this case, we need a digital TV receiver that can decode both single carrier and multicarrier modulated broadcast signals to watch DTV programs transmitted from broadcast stations using different transmission schemes.

As is well known in the art, a receiver cannot receive both a multicarrier modulated signal and a single carrier modulated signal. That is, the conventional receiver has a problem that cannot operate in other digital broadcasting system.

Accordingly, an object of the present invention is to provide a digital multimedia receiver capable of receiving both a single carrier modulated signal and a multicarrier modulated signal.

A digital multimedia receiver according to the present invention for achieving the above object comprises a tuner for tuning a received signal to a corresponding band; An A / D converter for converting the tuned signal output from the tuner into a digital signal; A demodulator for demodulating the digital signal output from the A / D converter; A symbol de-mapper for demapping demodulated signals output from the demodulator; And an LDPC decoder for decoding and outputting a demapped signal output from the symbol demapper.

Here, when the digital multimedia signal is a multicarrier modulated signal, the symbol demapper is preferably an OQAM symbol demapper.

Here, when the digital multimedia signal is a single carrier modulated signal, the symbol demapper is preferably a QAM symbol demapper.

Hereinafter, with reference to the accompanying drawings illustrating the present invention. Like elements are described throughout the specification using like reference numerals.

3 is a block diagram showing the configuration of a receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a first embodiment of the present invention.

Referring to FIG. 3, the receiver 300 includes a tuner 310, an analog-to-digital converter 320, a demodulator 330, a selector 340, and a common channel decoder 360. Include.

The tuner 310 tunes the received multimedia signal to the corresponding band. Here, the multimedia signal is a single carrier modulated signal or a multicarrier modulated signal. The A / D converter 320 converts the tuning signal input from the tuner 310 into a digital signal. The demodulator 330 includes a first demodulator 331 for demodulating and outputting a single carrier modulated signal and a second demodulator 332 for demodulating and outputting a multicarrier modulated signal. When the digital signal output from the A / D converter 320 is input to the demodulator 330, two demodulators for demodulating a signal corresponding to a modulation mode of the multimedia signal input from the A / D converter 320. Only one of 331 and 332 is activated. The selector 340 selects a valid signal from demodulated signals output from the demodulator 330 according to the modulation mode indication. The common channel decoder 360 decodes and outputs a demodulated signal input from the demodulator.

The digital multimedia signal output from the A / D converter 320 is processed by the first demodulator 331 and the second demodulator 332 in the demodulator 330. Either one or both demodulators are activated to process the signal, and the appropriate output is selected for post processing. For example, when the digital signal input to the demodulator 330 is a single carrier modulated signal, the first demodulator 331 operates to output a single carrier demodulated signal. When the digital signal input to the demodulator 330 is a multicarrier modulated signal, the second demodulator 332 operates to output a multicarrier demodulated signal.

The selector 340 receives a modulation mode indication indicating a modulation mode of a signal input to the demodulator 330. The selector 340 selects one of the signals output from the first demodulator 331 and the second demodulator 332 according to the received modulation mode indication. In more detail, when the digital signal input to the demodulator 330 is a single carrier modulated signal, the selector 340 selects a demodulated signal output from the first demodulator 331. Meanwhile, when the digital signal input to the demodulator 330 is a multicarrier modulated signal, the selector 340 selects a demodulated signal output from the second demodulator 332.

The common channel decoder used for both the single carrier transmission mode and the multicarrier transmission mode is connected to the demodulator. An RS block decoder or LDPC decoder can be used as the common channel decoder.

An operation of the digital multimedia receiver according to the first embodiment of the present invention will be described with reference to FIGS. 3 and 4.

4 is a flowchart provided to explain a digital multimedia signal receiving method performed in a digital multimedia receiver according to the first embodiment of the present invention shown in FIG.

First, the tuner 310 tunes the signal received through the antenna to the corresponding band (S410). Subsequently, the A / D converter 320 digitizes the tuning signal output from the tuner 310 and outputs a digital signal (S420).

The demodulator 330 demodulates the digital signal output from the A / D converter 320 and outputs demodulated signals (S430). At this time, only one or all of the plurality of demodulators in the demodulator 330 are operated for signal processing, and an appropriate output is selected for post processing. More specifically, when the digital multimedia signal input to the demodulator 330 is a single carrier modulated signal, the first demodulator 331 operates to output a single carrier demodulated signal. In addition, when the digital multimedia signal input to the demodulator 330 is a multicarrier modulated signal, the second demodulator 332 operates to output a multicarrier demodulated signal.

Next, the selector 340 selects one of the demodulated signals output from the demodulator 330 according to the modulation mode display (S440). When the selector 340 knows that the signal input to the demodulator 330 is a single carrier modulation mode signal by the modulation mode indication, the selector 340 selects a demodulated signal output from the first demodulator 331. . In addition, when the selector 340 learns that the signal input to the demodulator 330 is a multicarrier modulated signal by the modulation mode indication, the selector 340 selects the demodulated signal output from the second demodulator 332. do.

Finally, the demodulated signal output from the selector 340 is decoded by the common channel decoder 360 and output (S460).

According to the multimedia receiver having the above structure and a method of receiving the same, both the single carrier modulated signal and the multicarrier modulated signal can be processed by determining the modulation mode of the received multimedia signal. Therefore, the receiver can be simply implemented in hardware, and the performance of the receiver is improved.

5 is a block diagram of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a second embodiment of the present invention.

As shown in FIG. 5, the receiver 500 controls the gain of the tuned signal input to the tuner 510, the A / D converter 520, and the A / D converter 520 according to the modulation mode indication. automatic gain controller 530 and a demodulator 540.

The structure of the digital multimedia receiver shown in FIG. 5 is similar to that of FIG. However, the selector and decoder are not shown in FIG. Also, the tuner 510 and the A / D converter 520 perform the same functions as the tuner 310 and the A / D converter 320 of FIG. 3. Therefore, detailed description thereof will be omitted.

The single carrier modulated signal and the multicarrier modulated signal have different PERR (Peak to Average Powef Patio) characteristics. The multicarrier modulated signal has a relatively large PARR characteristic compared to the single carrier modulated signal. The AGC algorithms for the two modulation modes are different. In the receiver, only one AGC is used. Thus, in a receiver for processing single carrier modulated signals and multicarrier modulated signals, the AGC 530 employs an algorithm according to the modulation mode indication indicating the modulation mode of the signal.

The AGC 530 measures signal characteristics such as the average power or the average magnitude of the digital signal output from the A / D converter 520, and is output from the tuner 510 according to the AGC algorithm corresponding to the modulation mode. The gain of the tuning signal input to the converter 520 is adjusted. As a result, the amplitude of the signal output from the tuner 510 falls within the proper operating range of the A / D converter 520. For example, due to the PARR difference, the target power for the AGC in the multi-carrier mode is set to have a value less than the target power for the AGC in the single carrier mode. In this manner, the A / D converter 520 operates properly in response to the modulation mode of the multimedia signal.

The AGC 530 is a radio frequency (RF) AGC or intermediate frequency (IF) AGC.

6 is a flowchart provided to explain an automatic gain control method performed in the digital multimedia receiver of FIG. 5 according to the second embodiment of the present invention.

First, the tuner 510 tunes the signal received through the antenna (S610).

Subsequently, the A / D converter 520 converts the tuning signal output from the tuner 510 into a digital signal (S620).

The AGC 530 measures the average power of the digital signal input from the A / D converter 520 (S630).

The AGC 530 controls the gain of the signal input from the tuner 510 to the A / D converter 520 based on the measurement result value and the modulation mode indication (S640).

According to the digital multimedia receiver and the receiving method of the present invention having the above structure, the single carrier modulated signal and the multicarrier modulated signal can be processed by determining the modulation mode of the received multimedia signal. In addition, the gain of the tuner is controlled corresponding to the modulation mode of the received multimedia signal. Therefore, the receiver can be simply implemented in hardware, and the reception performance of the receiver is greatly improved.

FIG. 7 is a block diagram illustrating a structure of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a third embodiment of the present invention.

The digital multimedia receiver illustrated in FIG. 7 includes a tuner 710, an A / D converter 720, a synchronizer 730, a demodulator 740, and a channel decoder 760.

Tuner 710 tunes the received multimedia signal to an intermediate frequency signal. The A / D converter 720 converts the tuned analog signal into a digital signal using sampling and quantization.

The synchronizer 730 synchronizes the digital signal converted by the A / D converter 720 by using the modulation mode indication.

The synchronization unit 730 includes a timing recovery block 730T and a carrier recovery block 730C.

While the carrier recovery block 730C compensates for frequency and phase offsets, the timing recovery block 730T compensates for the timing offset of the digital signal input from the A / D converter 720 and converts the sampling rate. do.

The timing recovery block 730T includes a resampling unit 731 and a timing error detector 732. Here, the timing error detector 732 detects an output signal of the resampling unit 733 to calculate a timing error based on the modulation mode indication, and provides timing error information to the resampling unit 731. The resampling unit 733 compensates for the timing offset of the digital signal input from the A / D converter 720 and converts the sampling rate using the timing error information input from the timing error detector 732. In addition, the resampling unit 731 preferably includes a decimator and an interpolator for decimation and interpolation. Since the timing error detection algorithm is different in the single carrier modulation mode and the multicarrier modulation mode, and the algorithms for the two modulation modes can be implemented in the timing error detector, the timing error detector 732 is a corresponding algorithm based on the modulation mode indication. Select. In this case, the timing error information is determined in accordance with the modulation mode indication.

The carrier recovery block 730C includes a mixer 733 and a frequency offset estimator 734. Here, the frequency offset estimator 734 detects the output signal of the mixer 733, estimates the frequency offset based on the modulation mode indication, and provides the frequency offset information to the mixer 733. The mixer 733 compensates the frequency offset of the signal output from the resampling unit 731 based on the frequency offset information estimated from the frequency offset estimator 734 to generate a signal synchronized with the input of the demodulator 740. do. Similar to timing error detection, the frequency offset estimation algorithms of the single carrier modulation mode and the multicarrier modulation mode are implemented in the frequency offset estimator, and the frequency offset estimator 734 selects the corresponding algorithm based on the modulation mode indication. In other words, estimated frequency offset information is generated according to the modulation mode indication.

The demodulator 740 demodulates the synchronization signal input from the synchronizer 730 based on the modulation mode indication.

The channel decoder 760 decodes and outputs a demodulated signal.

As described above, the digital multimedia receiver according to the present invention performs synchronization based on the modulation mode indication.

According to the structure of the receiver of FIG. 7, timing recovery occurs immediately before carrier recovery. However, timing recovery block 730T can be positioned differently as long as timing recovery occurs before actually demodulation is performed. That is, the positions of the timing recovery block 730T and the carrier recovery block 730C may be exchanged.

The demodulation mode indication can be received from a mode detector (not shown).

By using the digital multimedia receiver of the structure shown in FIG. 7, the timing offset and the frequency offset can be compensated based on the single carrier modulation mode and the multicarrier modulation mode. Thus, the receiver can operate properly for single carrier and multicarrier transmission modes.

Receive filters are commonly used in digital multimedia receivers to reduce internal symbol interference and added noise. Due to the different spectral characteristics, systems for single carrier modulation mode and multicarrier modulation mode should have unique bandwidths. In order to process the single carrier modulation mode and the multicarrier modulation mode using only one common reception filter in the digital multimedia receiver, the characteristics of the reception filter must be changed by applying different predetermined coefficient sets. To this end, the filter coefficient set of the common receive filter used in the single carrier modulation mode and the multicarrier modulation mode should be updated according to the modulation mode.

8 is a block diagram showing the configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a fourth embodiment of the present invention. Referring to FIG. 8, the digital multimedia receiver 800 includes a tuner 810, an A / D converter 820, a filter coefficient unit 830, a reception filter 840, a demodulator 850, and a channel decoder 870. It includes.

The tuner 810 tunes (down-converts) the multimedia signal received via the antenna.

The A / D converter 820 converts the signal output from the tuner 810 into a digital signal through sampling, quantization, and encoding.

The filter coefficient unit 830 provides a coefficient set according to the modulation mode display. The filter coefficient unit 830 includes a filter coefficient memory 831 and a filter coefficient uploader 832.

The filter coefficient memory 831 stores two filter coefficient sets respectively corresponding to the single carrier modulation mode and the multicarrier modulation mode. The filter coefficient uploader 832 reads the filter coefficient set from the filter coefficient memory 831 and uploads the filter coefficient set to the receiving filter 840 according to the modulation mode indication.

The reception filter 840 filters the digital signal input from the A / D converter 820 according to the filter coefficient set provided by the filter coefficient unit 830 corresponding to the single carrier modulation mode or the multicarrier modulation mode. The reception filter 840 may be a square-root raised cosine (SRRC) filter. SSRC filters used as filters to match the transmission SRRC filters maximize the signal-to-noise ratio by matching signals.

The demodulator 850 demodulates the digital signal filtered by the reception filter 840 according to the modulation mode indication.

The demodulator 850 includes a first switch 851, an offset quadrature amplitude modulation (OQAM) demodulator 852, an FFT unit 853, a QAM demodulator 854, and a second switch 855.

The first switch 851 selects one of the OQAM demodulator 852 and the FFT unit 853 according to the modulation mode indication. More specifically, if the modulation mode indication is a single carrier modulation mode indication, that is, if the signal filtered by the receive filter 840 is a single carrier modulation mode indication, the first switch 851 selects the OQAM demodulator 852. The OQAM demodulator 852 demodulates the signal filtered by the reception filter 840. If the modulation mode indication is the multi-carrier modulation mode indication, that is, if the signal filtered by the reception filter 840 is the multi-carrier modulation mode indication, the first switch 851 selects the FFT unit 853. The FFT unit 853 performs Fast Fourier Tansformation on the filtered signal input from the reception filter 840. The QAM demodulator 854 demodulates the converted signal from which the fast Fourier transform is performed from the FFT unit 853.

The second switch 855 selects one of the OQAM demodulator 852 and the QAM demodulator 854 according to the modulation mode indication. More specifically, when the modulation mode indication is a single carrier modulation mode indication, the second switch 855 selects the output signal of the OQAM demodulator 852 and outputs it to the channel decoder 870, where the modulation mode indication is multicarrier modulation. In the mode display, the second switch 855 selects the output signal of the QAM demodulator 854 and outputs it to the channel decoder 870.

The channel decoder 870 decodes the demodulated signal input from the demodulators 852 and 854.

On the other hand, the first switch 851 can be omitted. In this case, only one or both of O demodulator 852 and QAM demodulator 854 operate. In more detail, the signal output from the reception filter is simultaneously input to the OQAM demodulator 852 and the FFT unit 853, and only one or both of the QAM demodulator 852 and the FFT unit 853 are operated. .

An operation procedure of the digital multimedia receiver of FIG. 8 will be described in detail with reference to FIG. 9. 9 is a flowchart provided to explain a digital multimedia reception method performed in the digital multimedia receiver of FIG. 8 according to the fourth embodiment of the present invention.

Referring to FIG. 9, first, a received signal is tuned (down-converted) (S910). Subsequently, the tuned signal is converted into a digital signal (S920).

Subsequently, the digital signal is filtered according to the modulation mode indication (S930). More specifically, a filter coefficient set is provided in accordance with the modulation mode indication, and the digital signal is filtered based on the provided filter coefficient set.

The filtered signal is demodulated according to the modulation mode indication (S940). More specifically, if the modulation mode indication is a single carrier modulation mode indication, then the filtered signal is demodulated by OQAM demodulation, and when the modulation mode indication is a multicarrier modulation mode indication, the filtered signal is subjected to fast Fourier transform and QAM demodulation. Demodulated by

Finally, the demodulated signal is decoded (S960).

Since the common filter is used in the single carrier modulated signal mode and the multicarrier modulated signal mode, the implementation of the digital multimedia receiver is simple, and the processing performance of the digital multimedia receiver is improved.

10 is a block diagram illustrating a structure of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a fifth embodiment of the present invention.

The digital multimedia receiver 1000 shown in FIG. 10 includes a tuner 1010, an A / D converter 1020, a synchronizer 1030, a demodulator 1040, a selector 1050, and a channel decoder 1070. do.

The tuner 1010 tunes the received multimedia signal to the corresponding band. The A / D converter 1020 converts the tuned analog signal into a digital signal through sampling and quantization.

The synchronizer 1030 synchronizes the digital signal converted by the A / D converter 1020 and moves the signal to the baseband using the modulation mode indication.

The demodulator 1040 demodulates the synchronization signal input from the synchronizer. The demodulator 1040 includes a first demodulation block 1041 and a second demodulation block 1042. The first demodulation block 1041 and the second demodulation block 1042 demodulate the received single carrier modulated signal and the multicarrier modulated signal, respectively. Based on the modulation mode indication, one or both of the two demodulation blocks corresponding to the modulation mode are operated and an appropriate output is selected for post processing.

The first demodulation block 1041 demodulates the equalized signal input from the first equalizer 1043 and the first equalizer 1043 for equalizing the synchronized single carrier modulated signal input from the synchronizer 1030. OQAM portion 1044 for. The first equalizer 1043 further includes a first equalization filter 1043a and a coefficient updater 1043b.

The first equalization filter 1043a performs equalization of the synchronization signal input from the synchronizer 1030 using the equalization coefficients provided by the coefficient updater 1043b. The coefficient updater 1043b calculates and estimates equalization coefficients using a synchronization signal input from the synchronization unit 1030, an output of the first equalization filter, and a reference signal. The reference signal may be a predetermined value such as field sync or segment sync defined in the ATSC standard or a decision value for actual data, or may be a signal generated by the OQAM unit 1044.

In the single carrier modulation mode, the first equalization filter 1043a equalizes the synchronization signal input from the synchronizer 1030 using the equalization coefficient provided by the coefficient updater 1043b. The output of the equalization filter 1043a is input to the OQAM unit 1044 and demodulated. The demodulated signal from the OQAM unit 1044 is input to the selector 1050. The coefficient updater 1043b detects the synchronization signal, the output of the first equalization filter, and the reference signal input from the synchronization unit 1030, updates the equalization coefficients, and provides equalization coefficient information to the equalization filter 1043a.

Equalization coefficients vary depending on the equalization algorithm used. Thus, the implementation of the coefficient updater 1043b depends on the type of equalization filter used. Among existing algorithms for equalization of a single carrier modulated signal, a Decision Feedback Equalizer (DFE) algorithm is widely used. When processing a single carrier modulated signal, using a DFE filter improves the performance of the proposed demodulator.

On the other hand, the second demodulation block 1042 includes an FFT unit 1045 for converting the synchronized multicarrier modulated signal from the time domain to the frequency domain, a second equalizer 1046 for equalizing the converted signal, and an equalizer. A QAM unit 1047 for demodulating the equalized signal at 1046. The second equalizer 1046 further includes a second equalization filter 1046a and a channel estimator 1046b.

In the multi-carrier modulation mode, channel estimator 1046b is input from synchronizer 1030 having time domain reference signals, such as Pseudo Noise (PN) sequences inserted between OFDM symbols or pilot subcarriers embedded in OFDM symbols. Estimation using the synchronization signal is performed, and channel estimation information is provided to the second equalization filter 1046a. The FFT unit 1045 converts the synchronization signal input from the synchronization unit 1030. The second equalization filter 1046a equalizes the fast Fourier transformed transform signal using the channel estimation information input from the channel estimator 1046b. The QAM unit 1047 demodulates the equalized signal of the second equalization filter 1046a in the QAM mode to generate a demodulated signal input to the selector 1050.

The selector 1050 selects an output signal corresponding to the modulation mode indication from the output signals of the OQAM unit 1044 and the QAM unit 1047, and outputs the output signal to the channel decoder 1070.

The channel decoder 1070 decodes the demodulated signal and outputs the signal. Here, a low density parity check (LDPC) decoder is used as a channel decoder.

Accordingly, the demodulator shown in FIG. 10 may demodulate the received single carrier modulated signal and the multicarrier modulated signal.

With the structure of the demodulator shown in FIG. 10, channel distortion may be compensated based on the single carrier modulation mode and the multicarrier modulation mode. Thus, the performance of the digital multimedia receiver for two modulation modes can be improved, and channel errors can be reduced.

In order to reduce the cost of a digital multimedia receiver capable of processing single carrier modulated signals and multicarrier modulated signals, a common A / D converter may be used. However, due to the unique characteristics of the two modulation modes, the symbol rates of the single carrier modulation mode and the multicarrier modulation mode are different. Therefore, in the signal processing path of the digital multimedia receiver, the output of the common A / D converter must be decimated at different sample rates to be suitable for the single carrier modulation mode and the multicarrier modulation mode.

For example, it is assumed that the sample rate of the A / D converter is r1, and the symbol rates of the single carrier transmission mode and the multicarrier transmission mode are r2 and r3, respectively. The decimating ratio N: 1 of the single carrier transmission mode is equal to r1: r2, and the decimating ratio M: 1 of the multicarrier transmission mode is equal to r1: r3. Since r3 will be less than r2, M is greater than N.

11 is a block diagram of a digital multimedia receiver for processing a single carrier modulation mode signal and a multicarrier modulation mode signal according to a sixth embodiment of the present invention.

Referring to FIG. 11, the digital multimedia receiver 1100 includes a tuner 1110, an A / D converter 1120, a decimator 1130, a demodulator 1140, and a channel decoder 1160.

The tuner 1110 tunes (down-converts) the multimedia signal received through the antenna.

The A / D converter 1120 converts the signal tuned from the tuner 1110 into a digital signal through sampling, quantization, and encoding.

The decimation unit 1130 decimates the digital signal input from the A / D converter 1120 according to the modulation mode display.

The first switch 1131 selects one of the first decimator 1132 and the second decimator 1133 according to the modulation mode indication. More specifically, if the modulation mode indication is a single carrier modulation mode indication, the first switch 1131 selects the first decimator 1132, and the first decimator 1132 passes through the first switch 1131. Receive a digital signal. The first decimator 1132 decimates the digital signal input from the A / D converter 1120 at a ratio of N: 1. When the modulation mode indication is a multi-carrier modulation mode indication, the first switch 1131 selects the second decimator 1133, and the second decimator 1133 receives the digital signal passing through the first switch 1131. Receive. The second decimator 1133 decimates the output of the A / D converter 1120 at a ratio of M: 1. Here, N and M are predetermined to correspond to the single carrier modulation mode and the multicarrier modulation mode, respectively.

The demodulator 1140 demodulates the decimation signal output from the decimation unit 1130. The demodulator 1140 includes an OQAM demodulator 1141, an FFT unit 1142, a QAM demodulator 1143, and a second switch 1144.

The OQAM demodulator 1141 demodulates the signal decimated by the first decimator 1132. The FFT unit 1142 performs fast Fourier transform on the decimated signal input from the second decimator 1133. The QAM demodulator 1143 demodulates the fast Fourier transformed converted signal input from the FFT unit 1142.

Since the function of the second switch 1144 is the same as that of the second switch 955 of FIG. 9, a detailed description thereof will be omitted.

The channel decoder 1160 decodes a signal input from the demodulator 1140.

In addition, similarly to FIG. 9, the first switch 1131 may be omitted.

Referring to FIG. 12, the operation of the digital multimedia receiver illustrated in FIG. 11 will be described in detail. 12 is a flowchart provided to explain a digital multimedia reception method performed in the digital multimedia receiver shown in FIG. 11 according to the sixth embodiment of the present invention.

Referring to FIG. 12, the received multimedia signal is tuned (down-converted) (S1210). The down-converted signal is converted into a digital signal (S1220). The digital signal is decimated according to the modulation mode indication (S1230). More specifically, if the modulation mode indication is a single carrier modulation mode indication, the digital signal is decimated at a ratio of N: 1, and if the modulation mode indication is a multicarrier modulation mode indication, the digital signal is deciphered at a ratio of M: 1. Is displayed. Here, N and M are predetermined to correspond to the single carrier modulation mode and the multicarrier modulation mode, respectively.

The decimated signal is demodulated according to the modulation mode indication (S1240). More specifically, if the modulation mode indication is a single carrier modulation mode indication, the decimated signal is demodulated by OQAM demodulation, and if the modulation mode indication is a multicarrier modulation mode indication, the decimated signal is subjected to fast Fourier transform and QAM demodulation. Demodulated by

Finally, the demodulated signal is decoded (S1260).

Since the sample rate is converted in proportion to the symbol rates of the single carrier modulated signal and the multicarrier modulated signal by the decimators, only one A / D converter is used in the digital multimedia receiver. Accordingly, the digital multimedia receiver can be simply implemented in hardware, and the single carrier modulated signal and the multicarrier modulated signal can be properly processed.

By using the data interleaver, the efficiency of error correction coding can be improved. The data interleaver spreads burst errors. According to different modulation modes, the data frame formats are different, and therefore, the design variables that define the function of the data interleaver differ according to the single carrier modulation mode and the multicarrier modulation mode. Therefore, in a DTV receiver, the design variables for the deinterleaver must be changed according to different modulation modes. Also, for excellent error correction capability, the LDPC code can be used in single carrier modulation mode and multicarrier modulation mode.

13 is a block diagram of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a seventh embodiment of the present invention.

Referring to FIG. 13, the digital multimedia receiver 1300 includes a tuner 1310, an A / D converter 1320, a demodulator 1330, a deinterleaver 1340, and a channel decoder 1350.

The tuner 1310 tunes (down-converts) the multimedia signal received through the antenna.

The A / D converter 1320 converts the tuning signal input from the tuner 1310 into a digital signal through sampling and quantization.

The demodulator 1330 demodulates the digital signal input from the A / D converter 1320 according to the modulation mode indication. The demodulator 1330 includes a first switch 1331, an OQAM demodulator 1332, an FFT unit 1333, a QAM demodulator 1334, and a second switch 1335.

The first switch 1351 selects one of the OQAM demodulator 1352 and the FFT unit 1353 according to the modulation mode indication. More specifically, when the modulation mode indication is a single carrier modulation mode indication, that is, when the multimedia signal is a single carrier modulation mode signal, the first switch 1351 selects the OQAM demodulator 1352. The OQAM demodulator 1352 demodulates the digital signal input from the A / D converter 1320. When the modulation mode indication is a multicarrier modulation mode indication, that is, when the multimedia signal is a multicarrier modulation mode signal, the first switch 1351 selects the FFT unit 1353. The FFT unit 1353 performs fast Fourier transform on the digital signal input from the A / D converter 1320. The QAM demodulator 1354 demodulates the fast Fourier transformed signal input from the FFT unit 1353.

The deinterleaver 1340 deinterleaves the demodulated signal according to the modulation mode indication. More specifically, the function of the deinterleaver is determined by the design variables of the deinterleaver. By using different design variables corresponding to the single carrier modulation mode and the multi-carrier modulation mode, the deinterleaver having the same structure is used as a single carrier modulation signal. And deinterleaving the multicarrier modulated signal. That is, different deinterleaving design variables corresponding to the two modulation modes are applied to the deinterleaver 1340 according to the modulation mode indication.

As such, only one deinterleaver is used to process single carrier modulated signals and multicarrier modulated signals. Therefore, the design variables of the deinterleaver 1340 must be determined according to the modulation mode indication.

A channel decoder 1350, such as an LDPC decoder or an RS block decoder, decodes the deinterleaving signal input from the deinterleaver 1340.

In addition, similarly to the case of FIG. 9, the first switch 1531 may be omitted.

14 is a flowchart provided to explain a digital multimedia reception method performed in the digital multimedia receiver shown in FIG. 13 according to the seventh embodiment of the present invention.

Referring to FIG. 14, the received signal is down converted (S1410). Subsequently, the down converted signal is converted into a digital signal (S1420).

The digital signal is demodulated according to the modulation mode indication (S1430). More specifically, when the modulation mode indication is a single carrier modulation mode indication, the digital signal is demodulated by OQAM demodulation, and when the modulation mode indication is a multicarrier modulation mode indication, the digital signal is subjected to fast Fourier transform and QAM demodulation. Demodulated

The demodulated signal is deinterleaved according to the modulation mode display (S1440). In this case, the deinterleaving design variables are determined and applied according to the modulation mode indication.

Finally, channel decoding is performed on the deinterleaved signal (S1450).

Since only one deinterleaver is used for the single carrier modulated signal and the multicarrier modulated signal, the digital multimedia receiver can be easily implemented.

15 is a block diagram of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to an eighth embodiment of the present invention.

Referring to FIG. 15, the digital multimedia receiver 1500 is a tuner 1510 for tuning a received signal to a corresponding band, and an A / D converter 1520 for converting a tuned signal input from the tuner 1510 into a digital signal. ), A demodulator 1530 for demodulating a digital signal input from the A / D converter 1520, a symbol demapper 1540 for demapping the demodulated signal input from the demodulator 1530, and a symbol demapper. And an LDPC decoder 1560 that decodes and outputs a signal output from the mapper 1540.

In digital multimedia transmission systems where transmission of a high resolution A / V bit stream is required without substantial error, it is important to use robust error correction coding to reduce the bit error rate. LDPC code, which is a form of error correction code, has excellent error correction capability. Accordingly, the LDPC code can be combined with a digital multimedia transmission system corresponding to a single carrier modulation mode and a multicarrier modulation mode.

In the case where an LDPC encoder is used in a transmitter for improving error correction capability, the decoder of the receiver should use a corresponding LDPC decoder. In this case, improved decoding performance can be obtained.

The OQAM symbol demapper is used as the symbol demapper 1540. In this case, the digital multimedia receiver is used to process single carrier modulated signals.

The QAM symbol demapper is used as the symbol demapper 1540. In this case, the digital multimedia receiver is used to process the multicarrier modulated signal.

As described above, according to the present invention, both the single carrier modulated signal and the multicarrier modulated signal can be processed by the digital multimedia receiver having a simple structure.

Further, according to the present invention, the decoding performance of the digital multimedia receiver is greatly improved by using the LDPC decoder.

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 that fall within the scope of the claims.

Claims (3)

A tuner for tuning the received signal to a corresponding band; An A / D converter for converting the tuned signal output from the tuner into a digital signal; A demodulator for demodulating the digital signal output from the A / D converter; A symbol de-mapper for demapping demodulated signals output from the demodulator; And And a LDPC decoder for decoding and outputting a demapped signal output from the symbol demapper. The method of claim 1, And if the digital multimedia signal is a multi-carrier modulated signal, the symbol demapper is an OQAM symbol demapper. The method of claim 1, And when the digital multimedia signal is a single carrier modulated signal, the symbol demapper is a QAM symbol demapper.

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