KR20060070387A - Digital multimedia receiver for processing single-carrier modulated signal and multi-carrier modulated signal and receiving method thereof - Google Patents

Abstract

 Disclosed are a digital multimedia receiver and receiving method for processing a single carrier modulated signal and a multicarrier modulated signal. The digital multimedia receiver processing the single carrier modulated signal and the multiple carrier modulated signal includes a tuner for down-converting the received multimedia signal and an AD converter for converting the down-converted signal output from the tuner into a digital signal. ), A decimation unit for decimating the digital signal from the AD converter according to a modulation mode indication, a demodulator for demodulating the decimated signal output from the decimation unit, and a demodulated signal. And a channel decoder for decoding the signal. On the other hand, a digital multimedia receiver which processes both a single carrier modulated signal and a multicarrier modulated signal has a simple structure and high performance, and can significantly improve the decoding performance of the digital multimedia receiver by using an LDPC decoder.

Single carrier modulation, multicarrier modulation, LDPC, modulation method

Description

Digital multimedia receiver for processing single-carrier modulated signal and multi-carrier modulated signal and receiving method

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

2 is a block diagram of a single carrier digital broadcast receiver according to the prior art;

3 is a block diagram of a 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 illustrating a digital multimedia signal receiving method performed in a digital multimedia receiver according to the first embodiment of the present invention shown in FIG.

 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;

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

 7 is a block diagram 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 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 illustrating a digital multimedia reception method performed in the digital multimedia receiver of FIG. 8 according to a fourth embodiment of the present invention;

 10 is a block diagram 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 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 illustrating a digital multimedia reception method performed in the digital multimedia receiver illustrated in FIG. 11 according to a sixth embodiment of the present invention;

 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;

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

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.

Explanation of symbols on the main parts of the drawings

310: tuner 320: AD converter

330: demodulation unit 340: selection unit

360: common channel decoder

The present invention relates to a digital multimedia receiver and a digital multimedia signal receiving method, and more particularly, to a digital multimedia receiver capable of receiving a multiple carrier modulated signal and a single carrier modulated signal.

With the advent of the multimedia communication and broadcasting era, countries around the world are digitizing analog broadcasts. In particular, in advanced countries such as the United States, Europe, and Japan, digital broadcasting systems have already been developed and implemented. With this rapid development, countries are proposing different standards for digital broadcasting.

On December 24, 1996, the US Federal Communications Commission (ATC) approved the Advanced Television System Committee (ATSC) digital TV standard as the next generation TV broadcast standard. Terrestrial broadcasters must comply with the ATSC standard for video / audio compression, packet data transmission structures, and modulation and transmission systems. The protocol for video formats was not specifically defined and was reserved by industry.

The ATSC digital TV standard is for high-quality video, audio, and additional data transmission in the 6 MHz band using a single carrier VSB scheme and simultaneously supports terrestrial broadcast mode and high-speed cable broadcast mode. The key to this approach is the 8-VSB modulation scheme, which modulates the digital signal by complementing the existing analog VSB scheme.

In Europe, the Coded Othogonal Frequency Division Multiplexing (COFDM) system, which has the advantages of high frequency efficiency and interference prevention, has been adopted as the Digital Video Broadcasting Terrestrial (DVD-T) standard.

In addition, digital multimedia broadcasting techniques using various modulation methods have been proposed, and these techniques can be divided into multiple carrier techniques and single carrier techniques. Thus, conventional digital multimedia receivers are divided into multi-carrier digital receivers and single-carrier digital receivers.

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

Conventional multi-carrier digital broadcast receivers include a tuner 110 for receiving a multi-carrier modulated digital multimedia signal, an AD converter 120 for converting an output signal from the tuner 110 into a digital signal, and an AD converter 120. FFT / Equalizer which equalizes by performing Fast Fourier Transform (FFT) on the output signal from the synchronizer 130 including timing recovery and carrier recovery for the digital signal. 140) a quadrature amplitude modulation (QAM) symbol detector 160 that performs symbol detection on the equalized output, and an FEC unit 170 that performs forward error correction (FEC) on an output signal from the symbol detector 160. And a descrambler 180 that descrambles an output signal from the FEC unit 170 to obtain an MPEG stream.

2 is a block diagram of a single carrier digital broadcast receiver according to the prior art.

The conventional single carrier digital broadcast receiver includes a tuner 210 for receiving a single carrier modulated digital multimedia signal, an AD converter 220 for converting an output signal from the tuner 210 into a digital signal, timing recovery and carrier recovery. An equalizer 250 that equalizes the output signal from the synchronizer 240, an offset quadrature amplitude modulation (OQAM) or QAM symbol detector that performs symbol detection on the output from the equalizer 250 150, an FEC unit 260 that performs FEC on the output signal from the equalizer 250, and a descrambler 270 that descrambles the output signal from the FEC unit 260.

The discussion of single carrier and multicarrier transmission systems continues for a long time and the results of the discussion are still unclear. Both transmission methods have advantages and disadvantages. Therefore, it is preferable that each broadcasting station selects a multicasting scheme suitable for a specific situation or broadcasting environment. In such a case, a digital TV receiver capable of decoding a single carrier modulated broadcast signal and a multicarrier modulated broadcast signal is required in order to watch DTV programs from broadcasting stations using different transmission techniques.

As is known, a receiver according to the prior art cannot simultaneously receive a multicarrier modulated signal and a single carrier modulated signal, and a conventional receiver cannot operate in different digital broadcasting systems.

Accordingly, an aspect of the present invention is to provide a digital multimedia receiver and a receiving method for processing a single carrier modulated signal and a multicarrier modulated signal for solving the above problems and disadvantages.

A digital multimedia receiver for processing a single carrier modulated signal and a multiple carrier modulated signal according to the present invention for achieving the above object is a tuner for down-converting the received multimedia signal, the down-converted signal output from the tuner as a digital signal Analog to digital converter to convert, decimation unit for decimating digital signal from AD converter according to modulation mode indication, decimated signal output from decimation unit And a channel decoder for decoding the demodulated signal.

Preferably, the decimation unit comprises: a first decimator for decimating a digital signal from the AD converter to N: 1 to generate a decimated signal when the modulation scheme indication is a single carrier modulation scheme indication; And a second decimator for decimating the output from the AD converter to M: 1 in case of the multi-carrier modulation scheme indication.

Here, N and M are natural numbers respectively set according to a single carrier modulation scheme and a multiple carrier modulation scheme, and M is a number greater than N.

Preferably, the demodulator further includes: a first demodulator for demodulating the decimated signal output from the first decimator when the modulation scheme indication is a single carrier modulation scheme indication, and when the modulation scheme indication is a multiple carrier modulation scheme indication, Fast Fourier Transform unit (FFT) for performing fast Fourier transform on the decimated signal output from the 2 decimator, the second demodulator for demodulating the fast Fourier transformed signal output from the FFT, and the modulation scheme instructions And a switch for selecting any one of demodulated signals from the first demodulator and the second demodulator.

Preferably, the first demodulator is an Offset Quadrature Amplitude Modulation (OQAM) demodulator, and the second demodulator is a Quadrature Amplitude Modulation (QAM) demodulator.

The decimation unit may further include a switch for transmitting a digital signal output from the AD converter to either the first decimator or the second decimator according to the modulation scheme indication.

Here, the decoder is a low density parity check (LDPC) decoder.

On the other hand, the digital multimedia reception method for processing a single carrier modulated signal and multiple carrier modulated signal of the present invention comprises the steps of (a) down-converting the received multimedia signal, (b) converting the down-converted signal to a digital signal (C) decimating the digital signal according to the modulation scheme indication, (d) demodulating the decimated signal according to the modulation scheme instruction, and (e) decoding the demodulated signal. .

Preferably, step (c) decimates the digital signal to N: 1 if the modulation scheme indication is a single carrier modulation scheme indication, and the digital signal is decimated to M: 1 if the modulation scheme indication is a multiple carrier modulation scheme indication. Is mated.

In this case, N and M are natural numbers respectively set according to a single carrier modulation scheme and a multiple carrier modulation scheme, and M is a larger number than N.

Also, preferably, step (d) OQAM demodulates the signal decimated to N: 1 in step (c) when (d1) the modulation scheme indication is a single carrier modulation scheme indication, and the modulation scheme indication is a multiple carrier. In the case of the modulation scheme indication, the method further includes QAM demodulation after fast Fourier transforming the signal decimated to M: 1 in step (c).

Preferably, the method further includes deinterleaving the demodulated signal according to the modulation scheme indication.

In this case, the deinterleaved signal in step (e) is decoded by Low Density Parity Check (LDPC).

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

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

The receiver includes a tuner 310, an analog-to-digital converter 320, a demodulator 330, a selector 340, and a common channel decoder 360.

The tuner 310 tunes the received multimedia signal to a corresponding band. Here, the multimedia signal is a single carrier modulated signal or a multicarrier modulated signal. The AD converter 320 converts the tuned 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 is input to the demodulator 330, only one of the two demodulators operates to demodulate a signal corresponding to the multimedia signal modulation scheme input from the AD converter 320. The selector 340 selects a valid signal from demodulation signals output from the demodulator 330 according to a modulation mode indication. The common channel decoder 360 decodes and outputs a demodulated signal output from the demodulator 330.

In the demodulator 330, the digital signal is processed in both the first demodulator 331 and the second demodulator 332. Either one or both demodulators operate to process the signal, and the appropriate output is then selected according to the process. For example, when the input digital signal is a single carrier modulated signal, the first demodulator 331 operates to output a single carrier demodulated signal. When the input digital signal is a multi-carrier modulated signal, the second demodulator 332 operates to output the multi-carrier demodulated signal.

The selector 340 receives a modulation scheme indication indicating a modulation scheme of a signal input to the demodulator 330 and selects among the signals output from the first demodulator 331 and the second demodulator 332 according to the modulation scheme. Choose one. More specifically, when the input digital signal is a single carrier modulated signal, the selector 340 selects a demodulated signal output from the first demodulator 331. When the input digital signal is a multi-carrier modulated signal, the selector 340 selects a demodulated signal output from the second demodulator 332.

The common channel decoder 360 used in both the single carrier transmission scheme and the multicarrier transmission scheme combines with the demodulators. The common channel decoder may be a Reed-Solomon (RS) block decoder or a Low Density Parity Check (LDPC) 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.

FIG. 4 is a flowchart illustrating a digital multimedia signal receiving method performed in the digital multimedia receiver according to the first embodiment of the present invention shown in FIG. 3.

The tuner 310 tunes the received signal to a corresponding band (S410). Subsequently, the AD converter 320 digitizes the tuned signal output from the tuner 310 and outputs a digital signal (S420).

The demodulator 330 demodulates the digital signal output from the AD converter 320 and outputs demodulated signals (S430). Here, one or both demodulators in the demodulator 330 operate for signal processing, and an appropriate output is selected for post processing. More specifically, when the signal is a single carrier modulated signal, the first demodulator 331 operates to output the single carrier modulated signal. If the signal is a multi-carrier modulated signal, the second demodulator 332 operates to output the multi-carrier demodulated signal.

A valid signal among the demodulated signals output from the demodulator 330 is selected by the selector 340 according to the modulation scheme indication (S440). When the selector 340 is provided with an indication that the signal input to the demodulator 330 is a single carrier modulated signal by the modulation scheme information, the selector 340 receives the demodulated signal output from the first demodulator 331. Choose. When the selector 340 receives an instruction indicating that the signal input to the demodulator 330 is a multi-carrier modulated signal by the modulation scheme indication, the selector 340 selects a demodulated signal output from the second demodulator 332. do.

Subsequently, 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 a single carrier modulated signal and a multicarrier modulated signal can be processed by determining a modulation scheme 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 includes a tuner 510, an AD converter 520, an automatic gain control unit 530 that controls a gain of a tuned signal input according to a modulation scheme indication, and Demodulator 540 is included.

The structure of the digital multimedia receiver shown in FIG. 5 is similar to that of FIG. 5 does not show a selector and a decoder. Also, the tuner 510 and the automatic gain control unit 520 perform the same functions as the tuner 310 and the AD converter 320 of FIG. 3. Therefore, detailed description thereof will be omitted.

The single carrier modulated signal and the multicarrier modulated signal have different Peak to Average Powe Patio (PARR) characteristics. The multicarrier modulated signal has a relatively large PARR characteristic as compared to the single carrier modulated signal. The automatic gain control algorithms for the two modulation schemes are different. Only one automatic gain control is used in the receiver described above. Therefore, in a receiver for processing a single carrier modulated signal and a multicarrier modulated signal, the automatic gain control unit 530 adopts an algorithm according to a modulation scheme indication indicating a modulation scheme of the signal.

The automatic gain control unit 530 measures signal characteristics such as average power or average magnitude of the digital signal output from the AD converter 520, and measures the tuned signal output from the tuner 510 and input to the AD converter 520. Adjust the gain according to the automatic gain control algorithm corresponding to the modulation scheme. As a result, the amplitude of the signal output from the tuner 510 falls within the proper operating range of the automatic gain control unit 520. For example, due to the PARR difference, the target power for the automatic gain control of the multi-carrier type is set to have a smaller value than the target power for the automatic gain control of the single carrier type. In this manner, the AD converter 520 operates appropriately in response to the modulation method of the multimedia signal.

The automatic gain control unit 530 performs radio frequency (RF) automatic gain control or intermediate frequency (IF) automatic gain control.

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

The tuner 510 tunes the received signal (S610).

The automatic gain control unit 520 converts the tuned signal output from the tuner 510 into a digital signal (S620).

The automatic gain control unit 530 measures the average power of the digital signal input from the AD converter 520 (S630).

The automatic gain control unit 530 controls the gain of the signal input from the tuner 510 to the AD converter 520 based on the measurement result and the modulation scheme 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 scheme of the received multimedia signal. In addition, the gain of the tuner of the receiver is controlled according to the modulation scheme of the received multimedia signal. Thus, the receiver can be simply implemented in hardware, and the reception performance of the receiver is improved.

7 is a block diagram 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 AD converter 720, a synchronizer 730, a demodulator 740, and a channel decoder 760.

The tuner 710 tunes the received multimedia signal to an intermediate frequency (IF) signal. The AD converter 720 converts the tuned analog signal into a digital signal through sampling and quantization.

The synchronizer 730 synchronizes the digital signal converted by the AD converter 720 using the modulation scheme information.

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 AD converter 720 and converts the sampling rate.

The timing recovery block 730T includes a resampling unit 731 and a timing error detector 732. Here, the timing error detector 732 detects the output signal of the resampling unit 733 to calculate the timing error based on the modulation scheme indication, and provides timing error information to the resampling unit 731. 731 compensates for the timing offset of the digital signal input from the AD 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 may include a decimator and an interpolator to perform decimation and interpolation operations. The timing error detection algorithm differs according to the single carrier modulation method and the multi-carrier modulation method. Since the algorithms for the two modulation methods can be performed in the timing error detection unit, the timing error detection unit 732 uses the corresponding algorithm based on the modulation scheme indication. Select. In this case, the timing error information depends on the modulation scheme 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 scheme indication, and provides the frequency offset information to the mixer 733. The mixer 733 compensates the frequency offset of the output signal of the resampling unit 731 by using 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 the timing error detection, the frequency error estimation algorithm of the single carrier modulation scheme and the multicarrier modulation scheme is performed in the frequency offset estimator, and the frequency offset estimator 734 selects a corresponding algorithm based on the modulation scheme indication. That is, the estimated frequency error information is generated according to the modulation scheme indication.

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

According to the structure of the receiver of FIG. 7, timing recovery is performed immediately before carrier recovery. However, the timing recovery block 730T position may vary as long as timing recovery is performed before demodulation is performed. That is, the positions of the timing recovery block 730T and the carrier recovery block 730C may be interchanged.

The modulation scheme indication may be received from a mode detector (not shown).

By using the digital multimedia receiver of the structure shown in FIG. 7, timing error and frequency offset can be compensated based on a single carrier modulation scheme and a multicarrier modulation scheme. Therefore, the receiver can operate properly according to the single carrier and the multi-carrier transmission scheme.

Receive filters are commonly used in digital multimedia receivers to reduce inter-symbol interference (ISI) and added noise. Due to the different spectral characteristics, the system for the single carrier modulation scheme and the multicarrier modulation scheme should have a specific bandwidth.

In order to use only one common receive filter in a digital multimedia receiver that handles both a single carrier modulation scheme and a multicarrier modulation scheme, certain different coefficient sets must be applied to the receive filter to change the characteristics of the receive filters. To this end, the filter coefficient set of the common receive filter used in the single carrier modulation scheme and the multicarrier modulation scheme should be updated according to the modulation scheme indication.

8 is a block diagram 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 includes a tuner 810, an AD converter 820, a filter coefficient unit 830, a reception filter 840, a demodulator 850, and a channel decoder 870.

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

The AD 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 a modulation scheme indication. 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 scheme and the multicarrier modulation scheme. The filter coefficient uploader 832 reads the filter coefficient set from the filter coefficient memory 831 and uploads the filter coefficient set read to the reception filter 840 according to the modulation scheme indication.

The reception filter 840 filters the digital signal input from the AD converter 820 according to the filter coefficient set provided by the filter coefficient unit 830 corresponding to the single carrier modulation method or the multicarrier modulation method. The reception filter 840 may be a square rooted cosine (SSRC) filter. SSRC filters used as filters to match the transmit SSRC 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 scheme indication.

The demodulator 850 includes a first switch 851, a first quadrature amplitude modulation (QAM) demodulator 852, an FFT unit 853, and a second switch 855. In this case, the first QAM demodulator 852 may be an Offset Quadrature Amplitude Modulation (OQAM) demodulator.

The first switch 851 selects one of the first QAM demodulator 852 and the FFT unit 853 according to the modulation scheme indication. More specifically, when the modulation scheme indication is a single carrier modulation scheme indication, that is, when the signal filtered by the reception filter 840 is a single carrier modulation scheme, the first switch 851 selects the first QAM demodulator 852. do. The first QAM demodulator 852 demodulates the filtered signal output from the reception filter 840. When the modulation scheme indication is a multicarrier modulation scheme indication, that is, when the filtered signal is a multicarrier modulation scheme, the first switch 851 selects the FFT unit 853. The FFT unit 853 performs fast Fourier transform on the filtered signal input from the reception filter 840. The second QAM demodulator 854 demodulates the fast Fourier transformed signal output from the FFT unit 853.

The second switch 855 selects one of the first QAM demodulator 852 and the second QAM demodulator 854 according to the modulation scheme information, and outputs the selected one to the channel decoder 870.

The channel decoder 870 decodes the demodulated signal input from the demodulator.

In addition, the first switch 851 may be omitted. In this case, one or both of the first QAM demodulator 852 and the second QAM demodulator 854 operate. More specifically, a signal output from the reception filter 840 is simultaneously input to the first QAM demodulator 852 and the FFT unit 853, and one or two of the first QAM demodulator 852 and the FFT unit 853 are provided. Will work.

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

9, the received signal is tuned (down-converted) (S910).

The tuned signal is converted into a digital signal (S920).

The digital signal is filtered according to the modulation scheme indication (S930). More specifically, the digital signal is filtered based on a set of filter coefficients provided according to the modulation scheme indication.

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

Finally, the demodulated signal is decoded (S960).

Since the common filter is used for the single carrier modulated signal method and the multicarrier modulated signal method, 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 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 illustrated in FIG. 10 includes a tuner 1010, an AD converter 1020, a synchronizer 1030, a demodulator 1040, a selector 1050, and a channel decoder 1080.

The tuner 1010 tunes the received multimedia signal to the corresponding band. The AD 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 AD converter 1020 and moves the signal to the baseband by using a modulation scheme indication.

The demodulator 1040 demodulates the synchronization signal output from the synchronizer 1030. The demodulator 1040 includes a first demodulation block 1041 and a second demodulation block 1042. The first demodulation block 1041 and the first demodulation block 1042 demodulate the received single carrier modulated signal and the multicarrier modulated signal, respectively. Based on the modulation scheme indication, one or both of the two demodulation blocks corresponding to the modulation scheme operate, and then an appropriate output is selected according to the procedure.

The first demodulation block 1041 is for demodulating the equalized signal output from the first equalizer 1043 and the first equalizer 1043 that equalizes the synchronized single carrier modulated signal input from the synchronizer 1030. An OQAM unit 1044 is included. 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 output from the synchronization unit 1030 using the equalization coefficients provided by the coefficient updater 1043b. The coefficient updater 1043b calculates and estimates equalization coefficients using the synchronization signal, the equalizer output, and the reference signals output from the synchronization unit 1030. The reference signals may be output of the OAQM unit 1044, a decision value for a predetermined signal or actual data, such as a field synchronization signal or a segment synchronization signal defined in the ATSC standard.

In the single carrier modulation scheme, the first equalization filter 1043a equalizes the synchronization signal output from the synchronization unit 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 demodulation signal output from the OQAM unit 1044 is input to the selection unit 1050. The coefficient updater 1043b updates the equalization coefficients by detecting the synchronization signal, the equalizer output, and the reference signals output from the synchronizer 1030, and provides equalization coefficient information to the equalization filter 1043a.

Equalization coefficients depend 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 equalizing a single carrier modulated signal, a Decision Feedback Equalizer (DFE) algorithm is widely used. When processing a single carrier modulated signal, the performance of the proposed demodulator can be further improved by using a DFE filter.

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

In the multi-carrier modulation scheme, the channel estimator 1046b performs estimation using a synchronization signal output from the synchronization unit 1030 having time domain reference signals, and provides channel estimation information to the second equalization filter 1046b. do. In this case, the time domain reference signals may be an OFDM symbol or a PN (Psuedo Noise) sequence inserted between pilot subcarriers embedded in the OFDM symbol. The FFT unit 1045 converts the synchronization signal output from the synchronization unit 1030 into a fast Fourier transform. The second equalization filter 1046a equalizes the fast Fourier transformed signal using the channel estimation information output from the channel estimator 1046a. The QAM unit 1047 demodulates the equalization signal of the second equalization filter 1046a by the QAM method to generate a demodulation signal input to the selection unit 1050 according to the modulation scheme indication.

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

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

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

In addition to the structure of the demodulator shown in FIG. 10, channel distortion may be compensated based on a single carrier modulation scheme and a multicarrier modulation scheme. Thus, the performance of the digital multimedia receiver for the two modulation schemes can be improved and the 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 AD converter may be used. However, due to the inherent characteristics of the two modulation schemes, the symbol ratios of the single carrier modulation scheme and the multicarrier modulation scheme are different. Therefore, in the signal processing path of the digital multimedia receiver, the output of the common AD converter must be decimated at different sample rates suitable for the single carrier modulation scheme and the multicarrier modulation scheme.

For example, the sample rates of the AD converter are set to r1, the symbol rates of the single carrier transmission scheme and the multicarrier transmission scheme are set to r2 and r3, respectively. The decimating ratio N: 1 of the single carrier transmission method is equal to r1: r2, and the decimating ratio M: 1 of the multicarrier transmission method is equal to r1: r3. r3 will be less than r2, so M is greater than N.

11 is a block diagram 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.

Referring to FIG. 11, the digital multimedia receiver includes a tuner 1110, an AD converter 1120, a decimator 1130, a demodulator 1140, a deinterleaver 1150, and a channel decoder 1160.

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

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

The decimation unit 1130 decimates the digital signal input from the AD converter 1120 according to the modulation scheme indication.

The first switch 1131 selects one of the first switch 1132 and the second switch 1133 according to the modulation scheme indication. More specifically, when the modulation scheme indication is a single carrier modulation scheme 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 AD converter 1120 at a ratio of N: 1. If the modulation scheme indication is a multi-carrier modulation scheme 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. do. The second decimator 1133 decimates the output of the AD converter at a ratio of M: 1. Here, N and M are respectively set in correspondence to a single carrier modulation scheme and a multicarrier modulation scheme.

The demodulator 1140 demodulates the decimated 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 output from the second decimator 1133. The QAM demodulator 1143 demodulates the fast Fourier transform signal output from the FFT unit 1142.

Since the operation 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.

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

An operation of the digital multimedia receiver illustrated in FIG. 11 will be described in detail with reference to FIG. 12. 12 is a flowchart illustrating 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 scheme indication (S1230). More specifically, when the modulation scheme indication is a single carrier modulation scheme indication, the digital signal is decimated at a ratio of N: 1, and when the modulation scheme indication is a multicarrier modulation scheme indication, the digital signal is at a ratio of M: 1. Decimated to Here, N and M correspond to a single carrier modulation scheme and a multicarrier modulation scheme, respectively.

The decimated signal is demodulated according to the modulation scheme indication (S1240). More specifically, when the modulation scheme indication is a single carrier modulation scheme indication, the decimated signal is demodulated by OQAM demodulation, and when the modulation scheme indication is a multicarrier modulation scheme indication, the decimated signal is subjected to FFT and QAM demodulation. Demodulated by

Finally, the demodulated signal is decoded (S1260).

Since the sample rate is converted in proportion to the symbol rate of the single carrier modulated signal by the decimators and the symbol rate of the multicarrier modulated signal, only the AD converter is used in the digital multimedia receiver. Therefore, 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.

The efficiency of error correction coding can be improved by using the data interleaver. The data interleaver generates a burst error. When using a different modulation scheme, the data frame formats are different, and thus, the variables that determine the operation of the data interleaver may vary according to a single carrier modulation scheme and a multicarrier modulation scheme. Therefore, the parameters for the deinterleaver in the DTV receiver must be changed according to different modulation schemes. In addition, the LPDC code may be used in both a single carrier modulation scheme and a multicarrier modulation scheme to improve error correction performance.

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 includes a tuner 1310, an AD converter 1320, a demodulator 1330, a deinterleaver 1340, and an LPDC decoder 1350.

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

The ADC 1320 converts the digital signal from the tuned signal input from the tuner 1310 through sampling and quantization.

The demodulator 1330 demodulates the digital signal input from the AD converter 1320 according to the modulation scheme 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 scheme information. More specifically, when the modulation scheme indication is a single carrier modulation scheme indication, that is, when the multimedia signal is a single carrier modulation scheme signal, the first switch 1351 selects the OQAM demodulator 1352. The OQAM demodulator 1352 demodulates the digital signal input from the AD converter 1320. When the modulation scheme indication is a multicarrier modulation scheme indication, that is, when the multimedia signal is a multicarrier modulation scheme 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 AD 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 scheme indication. More specifically, the operation of the deinterleaver is determined by the deinterleaver variable. The deinterleaver having the same structure may deinterleave the single carrier modulated signal and the multicarrier modulated signal using variables corresponding to the single carrier modulation method and the multicarrier modulation method. That is, different deinterleaving variables corresponding to the two modulation schemes are applied to the deinterleaver 1340 according to the modulation scheme information.

Thus, only one deinterleaver is used to process single carrier modulated signals and multicarrier modulated signals. Therefore, the variables of the deinterleaver 1340 should be determined according to the modulation scheme indication.

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

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

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

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

The digital signal is demodulated according to the modulation scheme indication (S1430). More specifically, when the modulation scheme information is a single carrier modulation scheme indication, the digital signal is demodulated by OQAM demodulation, and when the modulation scheme indication is a multicarrier modulation scheme indication, the digital signal is demodulated by FFT and QAM demodulation. .

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

Finally, the deinterleaved signal is channel decoded (S1450).

Since only one deinterleaver is used for a single carrier modulated signal and a multicarrier modulated signal, a 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.

15, a digital multimedia receiver includes a tuner 1510 for tuning a received signal to a corresponding band, an AD converter 1520 for converting a tuned signal input from the tuner 1510 into a digital signal, and an AD converter ( From a demodulator 1530 for demodulating a digital signal output from 1520, a symbol demapper 1540 for demapping the demodulated signal output from the demodulator 1530, and a symbol demapper 1540. LPDC decoder 1560 for decoding and outputting the output signal.

In a virtually error-free condition, in digital multimedia transmission systems that are required to transmit high quality A / V bit streams, it is important to use robust error correction coding to reduce the bit error rate. LDPC code, which is a form of error correction coding, has excellent error correction performance. Accordingly, the LDPC code can be combined with a digital multimedia transmission system according to a single carrier modulation scheme or a digital multimedia transmission system according to a multicarrier modulation scheme.

If an LDPC encoder is used in the transmitter to improve the error correction capability, the receiver's decoder must use the LPDC decoder correspondingly. In this case, improved decoding performance can be obtained.

The QAM or OQAM symbol demapper is used as the symbol demapper 1540. In this case, the digital multimedia receiver is used for single carrier modulated signal processing.

The QAM symbol demapper is used as the symbol demapper 1540. In this case, the digital multimedia receiver is used for multi-carrier modulated signal processing.

Such a receiver can obtain improved error correction performance.

As described above, according to the present invention, a digital multimedia receiver which processes both a single carrier modulated signal and a multicarrier modulated signal has a simple structure and high performance.

In addition, the decoding performance of the digital multimedia receiver can be remarkably improved by using the LDPC decoder.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the specific embodiments described above, but the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

Claims (13)

A tuner for down-converting the received multimedia signal; An analog-to-digital converter (AD converter) for converting the down-converted signal output from the tuner into a digital signal; A decimation unit for decimating the digital signal from the AD converter according to a modulation mode indication; A demodulator for demodulating the decimated signal output from the decimator; And And a channel decoder for decoding the demodulated signal. The digital multimedia receiver of claim 1, further comprising a single carrier modulated signal and a multiple carrier modulated signal. The method of claim 1, The decimation unit, A first decimator that decimates the digital signal from the AD converter to N: 1 when the modulation scheme indication is a single carrier modulation scheme indication to generate the decimated signal; And And a second decimator for decimating the output from the AD converter to M: 1 to generate the decimated signal when the modulation scheme indication is a multi-carrier modulation scheme indication. N and M are digital multimedia receivers, each of which is a predetermined natural number according to a single carrier modulation scheme and a multiple carrier modulation scheme. The method of claim 2, And wherein M is a number greater than N. 3. The method of claim 3, The demodulation unit, A first demodulator for demodulating the decimated signal output from the first decimator when the modulation scheme indication is a single carrier modulation scheme indication; A Fast Fourier Transform unit (FFT) for performing fast Fourier transform on the decimated signal output from the second decimator when the modulation scheme indication is a multi-carrier modulation scheme indication; A second demodulator for demodulating a fast Fourier transformed signal output from the FFT unit; And And a switch for selecting any one of demodulated signals from the first demodulator and the second demodulator according to the modulation scheme indication. The method of claim 4, wherein And wherein the first demodulator is an Offset Quadrature Amplitude Modulation (OQAM) demodulator, and the second demodulator is a Quadrature Amplitude Modulation (QAM) demodulator. The method of claim 2, The decimation unit may further include a switch for transmitting the digital signal output from the AD converter to any one of the first decimator and the second decimator according to the modulation scheme indication. receiving set. The method of claim 1, And the decoder is a low density parity check (LDPC) decoder. (a) down converting the received multimedia signal; (b) converting the down-converted signal into a digital signal; (c) decimating the digital signal according to a modulation scheme indication; (d) demodulating the decimated signal according to a modulation scheme indication; And (e) decoding the demodulated signal; a digital multimedia receiving method for processing a single carrier modulated signal and a multiple carrier modulated signal. The method of claim 8, In step (c), the digital signal is decimated to N: 1 when the modulation scheme indication is a single carrier modulation scheme indication, and M: 1 when the digital signal is a multiple carrier modulation scheme indication. Decimated to, N and M are digital multimedia reception method, characterized in that the natural number which is respectively set according to the single carrier modulation method and the multiple carrier modulation method. The method of claim 9, The M is a digital multimedia reception method, characterized in that greater than the number N. The method of claim 10, In step (d), (d1) If the modulation scheme indication is a single carrier modulation scheme indication, OQAM demodulates the signal decimated to N: 1 in step (c), and if the modulation scheme indication is a multicarrier modulation scheme indication, and performing QAM demodulation after fast Fourier transforming the signal decimated to M: 1 in step c). The method of claim 8, And deinterleaving the demodulated signal according to the modulation scheme indication. The method of claim 12, In the step (e), the deinterleaved signal is low density parity check (LDPC) decoding, characterized in that the digital multimedia.

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