CN1798282B - Digital multimedia receiver - Google Patents

Abstract

A digital multimedia receiver for processing single carrier modulated signals and multi-carrier modulated signals is provided. The digital multimedia receiver includes a tuner, an ADC, a synchronizing unit for synchronizing a digital signal from the ADC with a modulation mode indication to generate a synchronization signal, a demodulating unit for demodulating the synchronization signal with the modulation mode indication, and a channel decoder for decoding the demodulated signal and outputting a resultant signal. The synchronization unit further includes a timing recovery block for compensating for the timing offset and a carrier recovery block for compensating for the frequency error.

Description

digital multimedia receiver

technical field

The present invention relates to a digital multimedia receiver, in particular to a receiver for processing single-carrier modulated signals and multi-carrier modulated signals.

Background technique

In the era of multimedia communication and broadcasting, all countries in the world are digitizing analog broadcasting, especially in developed countries such as the United States, Europe and Japan, where digital broadcasting systems have been developed and put into use. With its rapid development, different standards for digital broadcasting have been proposed in different countries.

On December 24, 1996, the US Federal Communications Commission (FCC) proposed the Advanced Television Systems Committee (ATSC) digital television standard as the next-generation television broadcasting standard. All terrestrial broadcast operators must comply with ATSC standards for the specification of video/audio compression, packet data transmission structures, and modulation and transmission systems. Only the specifications regarding the video format are not specified, but are left to the industry to decide.

The ATSC digital TV standard uses a single carrier VSB method to transmit high-quality video, audio and additional data on a 6MHz bandwidth, and supports both terrestrial broadcast mode and high data rate cable broadcast mode. The main aspect of this method lies in the 8-VSB modulation method which is an improved form of the existing analog type VSB method with digital signal modulation capability.

In Europe, the COFDM (Coded Orthogonal Frequency Division Multiplexing) system has been applied to DVB-T (Terrestrial Digital Video Broadcasting) for its high frequency utilization rate and anti-interference ability.

Other data transmission schemes using different modulation methods can be classified into multi-carrier schemes and single-carrier schemes. Therefore, traditional digital multimedia receivers can be divided into multi-carrier digital multimedia receivers and single-carrier digital multimedia receivers.

Fig. 1 is a schematic block diagram showing a conventional digital multimedia receiver for processing multi-carrier modulated signals.

This conventional multi-carrier digital multimedia receiver includes: a tuner 110 for tuning the received multi-carrier modulated multimedia signal; ADC (analog-to-digital converter) 120 for converting the signal output from the tuner 110 into digital Signal; Synchronization unit 130, is used to carry out timing recovery and carrier recovery to the signal from ADC 120; Fast Fourier transform (FFT) unit 140, is used to carry out Fast Fourier transform to the signal output from synchronization unit 130; Equalization unit 150, uses For equalizing the signal output from the FFT unit 140; QAM (Quadrature Amplitude Modulation) symbol detection unit 160 is used to perform symbol detection on the output of the equalizer; the previous term error correction (FEC) unit 170 is used to The signal output from the symbol detection unit 160 is subjected to preceding error correction; and the descrambler 180 is used to descramble the signal output from the FEC unit 170 to obtain an MPEG stream.

Fig. 2 is a schematic block diagram showing a conventional digital multimedia receiver for processing a signal modulated by a single carrier.

This conventional single carrier digital multimedia receiver comprises: tuner 210, is used to receive the multimedia signal of single carrier modulation; ADC 220, is used for converting the signal output from tuner 210 into a digital signal; Synchronization (SYNC) unit 230, For performing timing recovery and carrier recovery; equalization unit 240, for equalizing the signal output from synchronization unit 230; (offset) QAM symbol detection unit 250, for carrying out symbol detection to the output of equalization unit 240; The FEC unit 260 is used for performing previous error correction on the signal output by the symbol detection unit 250; and the descrambler 270 is used for descrambling the signal output by the FEC unit 260 to obtain an MPEG stream.

There is a long-standing debate on whether the performance of a single-carrier transmission system or a multi-carrier transmission system is better, but there is no concrete result. Both options have their own advantages and disadvantages. Accordingly, it is desirable for a broadcasting station to allow selection from a variety of transmission schemes to suit its particular needs and broadcasting environment. Under such circumstances, receivers capable of receiving and decoding single-carrier and multi-carrier modulated broadcast signals are required to watch digital television (DTV) programs from broadcast stations using different transmission schemes.

As we all know, traditional digital multimedia receivers cannot receive single-carrier modulated signals and multi-carrier modulated signals at the same time, which has many inconveniences.

Contents of the invention

An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages.

The present invention provides a receiver for processing single-carrier modulated signals and multi-carrier modulated signals.

The receiver for processing single-carrier modulated signals and multi-carrier modulated signals includes a tuner for tuning the received multimedia to a corresponding band, an ADC for converting the tuned analog signal into a digital signal, and A synchronization unit for synchronizing a digital signal from the ADC using a modulation mode indication to generate a synchronization signal, a demodulation unit for demodulating a signal synchronized by the synchronization unit using a modulation mode indication, and decoding a signal demodulated by the demodulation unit and output the resulting signal to the channel decoder.

The synchronization unit of the digital multimedia receiver may include a timing recovery block for using the modulation mode indication to compensate for a timing error of a digital signal from the ADC; and for using the modulation mode indication to compensate for a frequency error of an output signal of the timing recovery block to generate Carrier recovery block for synchronization signals.

The timing recovery block includes a resampling unit, a first loop filter, and a timing error detector (TED). The re-sampling unit receives the digital signal from the ADC, the TED detects the output signal of the re-sampling unit to calculate the timing error based on the modulation mode indication, and its output signal is fed to the first loop filter, the output of the first loop filter to the TED The signal is filtered and the resampling unit compensates for the timing offset of the digital signal from the ADC using the timing error estimate filtered by the first loop filter.

The carrier recovery block includes a mixer, an NCO unit, a second loop filter, and a frequency error estimator (FEE). The mixer mixes the output signal of the resampling unit, the FEE detects the output signal of the mixer and estimates the frequency offset and phase offset based on the modulation mode indication, the second loop filter filters the output signal of the FEE, and the NCO unit will be controlled by the second The frequency offset and phase offset filtered by the loop filter are converted into a phase value and output an NC0 value corresponding to the converted phase value, and the mixer uses the NC0 value provided by the NC0 unit to compensate the frequency offset of the output signal of the resampling unit And phase offset to generate a synchronous signal as the input of the demodulation unit.

On the other hand, the synchronization unit of the digital multimedia receiver may include a carrier recovery block for using the modulation mode indication to compensate the frequency error of the output signal of the timing recovery block of the digital signal from the ADC; and a carrier recovery block for using the modulation mode indication to A timing recovery block that compensates the output signal of the carrier recovery block to generate timing errors of the synchronization signal.

The carrier recovery block includes a mixer, an NCO unit, a second loop filter, and a frequency error estimator (FEE). The mixer mixes the digital signals from the ADC, the FEE detects the output signal of the mixer and estimates the frequency offset and phase offset based on the modulation mode indication, the second loop filter filters the output signal of the FEE, and the NC0 unit will be controlled by the second loop The frequency offset and phase offset filtered by the channel filter are converted into a phase value and output the NC0 value corresponding to the converted phase value, and the mixer uses the NC0 value provided by the NC0 unit to compensate the frequency offset and phase of the digital signal from the ADC offset.

The timing recovery block includes a resampling unit, a first loop filter, and a timing error detector (TED). The re-sampling unit receives the output signal of the mixer, the TED detects the output signal of the re-sampling unit to calculate the timing error based on the modulation mode indication, and its output signal is fed to the first loop filter, the output of the first loop filter to the TED The signal is filtered, and the resampling unit uses the timing error filtered by the first loop filter to estimate and compensate the timing offset of the output signal of the mixer to generate a synchronization signal as an input to the demodulation unit.

Preferably, the channel decoder is an LDPC decoder.

Description of drawings

The above and other objects and advantages of the present invention will become more clear through the following description of the embodiments in conjunction with the accompanying drawings, wherein:

1 is a schematic block diagram representing a conventional digital multimedia receiver for processing multi-carrier modulated signals;

2 is a schematic block diagram representing a conventional digital multimedia receiver for processing signals modulated by a single carrier;

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

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

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

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

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

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

FIG. 9 is a flowchart of a digital multimedia receiving method executed in the digital multimedia receiver shown in FIG. 8 according to a fourth embodiment of the present invention;

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

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

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

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

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

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

Detailed ways

Now, embodiments of the present invention will be described in detail, examples of which are illustrated in the accompanying drawings, in which like reference numerals designate like parts throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

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

Referring to Fig. 3, the digital multimedia receiver includes: a tuner 310 for tuning a received multimedia signal to a corresponding frequency band, wherein the multimedia signal is a single carrier modulated signal or a multi-carrier modulated signal; ADC (analog-digital converter) 320, for converting the tuned signal from the tuner 310 into a digital signal; demodulation unit 330, including a demodulator 331 for demodulating and outputting a signal modulated by a single carrier and for converting a multi-carrier A demodulator 332 that demodulates and outputs the modulated signal, wherein, when the digital signal is input to the demodulation unit 330, one or both of the two demodulators demodulate and output the digital signal from the ADC 320; The device 340 is used to select an effective signal from the demodulated signal output from the demodulation unit 330 according to the modulation mode indication; The signal is decoded and the resulting signal is output.

In the demodulation unit 330, one or both of the demodulator 331 and the demodulator 332 operate and process an input digital signal. If the input signal is a single carrier modulated signal, the demodulator 331 operates and correctly outputs a single carrier demodulated signal. If the digital signal is a multi-carrier modulated signal, the demodulator 332 operates and correctly outputs a multi-carrier demodulated signal.

The selector 340 receives a modulation mode indication indicating a modulation mode of a signal input into the demodulation unit 340, and selects one of signals output from the demodulator 331 and the demodulator 332 according to the modulation mode indication. In more detail, the selector 340 selects the demodulated signal output from the demodulator 331 if the digital signal is a single carrier modulated signal. If the digital signal is a multi-carrier modulated signal, the selector 340 selects the demodulated signal output from the demodulator 332 .

The shared channel decoder 350 used for the single-carrier transmission mode and the multi-carrier transmission mode is connected to the demodulation unit 330 through the selector 340 , and an RS block decoder and an LDPC decoder can be used as the shared channel decoder 350 .

Now, the 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.

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

In step S410, the tuner 310 tunes the received signal to a corresponding frequency band. Then, the ADC 320 digitizes the tuned signal from the tuner 310 and outputs a digital signal at step S420.

In step S430, the demodulation unit 330 demodulates the digital signal from the ADC 320 and outputs the demodulated signal. Here, one or both of the demodulators in the demodulation unit 330 can process digital signals. Specifically, if the input signal is a single-carrier modulated signal, the demodulator 331 correctly demodulates the input digital signal in single-carrier mode and outputs it. If the input signal is a multi-carrier modulated signal, the demodulator 332 correctly demodulates the input digital signal in multi-carrier mode and outputs it.

In step S440, the selector 340 selects an effective signal from the signals from the demodulation unit 330 according to the modulation mode indication. If the selector 340 knows from the mode modulation information that the digital signal input to the demodulation unit 330 is a single carrier modulated signal, the selector 340 selects the demodulated signal output from the demodulator 331 . If the selection 340 knows from the modulation mode indication that the digital signal input to the demodulation unit 330 is a multi-carrier modulated signal, the selector 340 selects the demodulated signal output from the demodulator 332 .

In step S450, the shared channel decoder 350 decodes and outputs the demodulated signal from the selector 340.

By using the digital multimedia receiver and receiving method with the above structure of the present invention, both single-carrier modulated signals and multi-carrier modulated signals can be processed by determining the modulation mode of the received multimedia signal. Thus, the hardware implementation of the receiver is simplified, and the receiving performance of the receiver is improved.

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

As shown in FIG. 5, the digital multimedia receiver includes: a tuner 510, an ADC 520, an AGC (Automatic Gain Controller) 530 for controlling the gain of the tuned signal input to the ADC 520 according to the modulation mode indication, and for The demodulation unit 540 that demodulates the digital signal according to the modulation mode instruction.

The structure of the digital multimedia receiver shown in FIG. 5 is similar to that of the receiver shown in FIG. 3 . For simplicity, the selector and decoder are not shown in FIG. 5 . In addition, the tuner 510 and the ADC 520 have the same functions as the tuner 310 and the ADC 320 in FIG. 3, and thus, their detailed descriptions are omitted.

A single-carrier modulated signal and a multi-carrier modulated signal have different PAPR (Peak-to-Average Power Ratio) characteristics, and a multi-carrier modulated signal has a relatively larger PAPR than a single-carrier modulated signal. The AGC algorithms used for these two modulation modes are also different. In the above receiver, only one AGC is used, therefore, in a digital multimedia receiver for processing single-carrier modulated signals and multi-carrier modulated signals, the AGC 530 should be indicated according to the modulation mode indicating the modulation mode of the multimedia signal to use the corresponding algorithm.

The AGC 530 measures signal characteristics such as average power or average magnitude (magnitude) of the digital signal from the ADC 520, and adjusts the gain of the tuned signal that is then input to the ADC 520 from the tuner 510 according to an AGC algorithm corresponding to the modulation mode, thereby , the amplitude of the signal output from the tuner 510 is within the proper operating range of the ADC 520. For example, the target power of the AGC for the multi-carrier mode is set to a lower value than the target power of the AGC for the single-carrier mode due to a difference in PAPR. In this way, ADC 520 operates correctly corresponding to the modulation mode of the multimedia signal.

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

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

In step S610, the tuner 510 tunes the received multimedia signal.

The ADC 520 converts the tuned signal output from the tuner 510 into a digital signal at step S620.

In step S630, the AGC 530 measures signal characteristics of the digital signal from the ADC 520 such as average power and average amplitude.

In step S640, the AGC 530 controls the gain of the signal input from the tuner 510 to the ADC 520 according to the measured result and the modulation mode indication.

By using the digital multimedia receiver and the automatic gain control method according to the present invention having the above structure, it is possible to process a single carrier modulated signal and a multicarrier modulated signal by determining a modulation mode of a received multimedia signal. Furthermore, the gain of the tuner of the receiver can be controlled according to the modulation mode of the received multimedia signal. Thereby, implementation of the hardware of the receiver is simplified, and the receiving performance of the receiver is improved.

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

The digital multimedia receiver shown in FIG. 7 includes a tuner 710, an ADC 720, a synchronization unit 730, a demodulation unit 740, and a channel decoder 750.

The tuner 710 tunes the received multimedia signal to a corresponding band. ADC 720 converts the tuned analog signal to a digital signal by sampling and quantizing.

The synchronization unit 730 uses the modulation mode indication to synchronize the digital signal converted by the ADC 720.

Synchronization unit 730 includes a timing recovery block 730T for compensating for timing offsets of the digital signal from ADC 720 and a carrier recovery block for compensating for frequency and phase offsets.

The timing recovery block 730T includes a resampling unit 731 , a first loop filter 732 , and a timing error detector (TED) 733 . Here, the TED 733 detects the output signal of the resampling unit 731 to calculate the timing error based on the modulation mode indication, and its output signal is fed to the first loop filter 732 . The first loop filter 732 filters the output signal of the TED 733, and the signal filtered by the first loop filter 732 is fed to the re-sampling unit 731. The resampling unit 731 compensates for the timing offset of the digital signal from the ADC 720 using the timing error estimate filtered by the first loop filter 732. Also, the resampling unit 731 may include a decimator and an interpolator for decimation and interpolation, respectively. Since the timing error detection algorithms for the single-carrier modulation mode and the multi-carrier modulation mode are different, the algorithms for the two modes are implemented in the TED 733, and the TED 733 selects a corresponding algorithm based on the modulation mode indication. In this case, the timing error information is determined by the modulation mode indication.

The carrier recovery block 730C includes a mixer 734 , an NCO unit 735 , a second loop filter 736 , and a frequency error estimator (FEE) 737 . Here, the FEE 737 detects that the output of the mixer 734 is and based on the modulation mode indication estimates a frequency offset and a phase offset. The output signal of FEE 737 is filtered by a second loop filter 736 , the output of which is fed to NCO unit 735 . The NCO unit 735 converts the frequency offset and the phase offset into a phase value and outputs an NCO value corresponding to the converted phase value. The mixer 734 uses the NCO value provided by the NCO unit to compensate the frequency offset and phase offset of the output signal of the resampling unit 731 to generate a synchronization signal as an input of the demodulation unit 740 . Similar to the case of timing error detection, frequency error estimation algorithms for single-carrier modulation mode and multi-carrier modulation mode are implemented in FEE, and FEE 737 selects the corresponding algorithm based on the modulation mode indication. That is, the estimated frequency error information is generated according to the modulation mode indication.

The demodulation unit 740 demodulates the signal synchronized from the synchronization unit 730 based on the modulation mode indication.

The channel decoder 750 decodes the demodulated signal and outputs the signal.

It can be seen from the above description that the digital multimedia receiver according to the present invention performs synchronization based on the modulation mode indication.

According to the receiver structure of Fig. 7, carrier recovery occurs as soon as timing recovery occurs. In practice, however, timing recovery block 730T could be placed in a different location as long as timing recovery occurs prior to demodulation. That is, the positions of the timing recovery block 730T and the carrier recovery block 730C can be interchanged.

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

By using the structure of the digital multimedia receiver shown in FIG. 7, timing offset and frequency offset can be compensated based on a single-carrier modulation mode and a multi-carrier modulation mode. Therefore, the receiver can operate correctly for single-carrier modulation mode and multi-carrier modulation mode.

Receive filters are commonly used in digital multimedia receivers to reduce intersymbol interference and additive noise. Systems for single-carrier modulation modes and multi-carrier modulation modes should have different bandwidths due to different spectrum characteristics. In order to use only one common reception filter in a digital multimedia receiver to handle single-carrier modulation mode and multi-carrier modulation mode, the characteristics of the reception filter should be changed by applying different predetermined coefficient sets. For this, the set of filter coefficients of the common receive filter for the single-carrier modulation mode and the multi-carrier modulation mode should be updated according to the modulation mode.

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

Referring to FIG. 8, the digital multimedia receiver includes a tuner 810, an ADC 820, a filter coefficient unit 830, a reception filter 840, a demodulation unit 850, and a channel decoder 860.

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

The ADC 820 converts the signal tuned by the tuner 810 into a digital signal through sampling, quantization, and encoding.

The filter coefficient unit 830 provides a set of filter coefficients according to the modulation mode 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 sets of filter coefficients corresponding to the single-carrier modulation mode and the multi-carrier modulation mode, respectively. The filter coefficient uploader 832 reads out the filter coefficient set from the filter coefficient memory 831 according to the modulation mode instruction and uploads it to the receiving filter 840 .

The receive filter 840 filters the digital signal from the ADC 820 according to the set of filter coefficients provided by the filter coefficient memory 831 corresponding to the single-carrier modulation mode or the multi-carrier modulation mode. Receive filter 840 may be a square root raised cosine (SRRC) filter. The SRRC filter used to match the SRRC filter on the transmit side maximizes the signal-to-noise ratio by matching the signal.

The demodulation unit 850 demodulates the digital signal filtered by the receiving filter 840 according to the modulation mode indication. The demodulation unit 850 includes a first switch 851 , an 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 signal, then the first switch 851 selects the OQAM demodulator 852 . The OQAM demodulator 852 demodulates the signal filtered by the receive filter 840 . If the modulation mode indication is a multi-carrier modulation mode indication, that is, if the signal filtered by the receive filter 840 is a signal of a multi-carrier modulation mode, then the first switch 851 selects the FFT unit 853 . The FFT unit 853 performs FFT transform on the signal filtered by the reception filter 840, and then the QAM demodulator 854 demodulates the signal FFT transformed by 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, if the modulation mode indication is a single carrier modulation mode indication, the second switch 855 selects the output signal of the OQAM demodulator 852 to output it to the channel decoder 860 . If the modulation mode indication is a multi-carrier modulation mode indication, the second switch 855 selects the output signal of the QAM demodulator 854 to output it to the channel decoder 860 .

The channel decoder 860 decodes the signal demodulated by the demodulation unit 850 . Channel decoder 860 may be an LDPC decoder.

In addition, the first switch 851 may be omitted. In this case, either or both OQAM demodulator 852 and QAM demodulator 854 operate. In detail, the signal filtered by the receive filter 840 is simultaneously input to the OQAM demodulator 852 and the FFT unit 853, and either of the OQAM demodulator 852 and the FFT unit 853 is allowed to operate.

In addition, in this embodiment, the demodulator 852 may also be a QAM demodulator.

The operation of the digital multimedia receiver shown in FIG. 8 will now be described in detail with reference to FIG. 9. Referring to FIG. FIG. 9 is a flowchart of a digital multimedia receiving method performed in the digital multimedia receiver shown in FIG. 8 according to a fourth embodiment of the present invention.

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

In step S930, the digital signal is filtered according to the modulation mode indication. More specifically, a set of filter coefficients is provided according to the modulation mode indication, and the digital signal is filtered based on the set of filter coefficients.

In step S940, the filtered digital signal is demodulated according to the modulation mode indication. In detail, if the modulation mode indication is a single carrier modulation mode indication, then the filtered signal is demodulated by OQAM demodulation, and if the modulation mode indication is a multi-carrier modulation mode indication, then the filtered signal is demodulated by FFT and QAM to be demodulated.

Finally, in step S950, the demodulated signal is decoded.

In addition, in step S940, if the modulation mode indication is a single carrier modulation mode indication, the filtered signal may also be demodulated by QAM demodulation.

Since the filters are shared for the single-carrier modulated signal and the multi-carrier modulated signal, the implementation of the digital multimedia receiver is simplified and the processing performance of the digital multimedia receiver is improved.

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

The digital multimedia receiver shown in FIG. 10 includes a tuner 1010, an ADC 1020, a synchronization unit 1030, a demodulation unit 1040, a selector 1050, and a channel decoder 1060.

The tuner 1010 tunes the received multimedia signal to a corresponding band. The ADC 1020 converts the tuned analog signal into a digital signal by sampling and quantizing.

The synchronization unit 1030 uses a modulation mode instruction to synchronize the digital signal converted by the ADC 1020.

The demodulation unit 1040 demodulates the signal synchronized from the synchronization unit 1030 . The demodulation unit 1040 includes a first demodulation block 1041 and a second demodulation block 1042 . The first demodulation block 1041 and the second demodulation block 1042 may respectively demodulate received single-carrier modulated signals and multi-carrier modulated signals. Based on the modulation mode indication, the demodulation block corresponding to the modulation mode of the two demodulation blocks is activated.

The first demodulation block 1041 includes a first equalization unit 1043 for equalizing a single carrier modulated signal synchronized from the synchronization unit 1030 and an OQAM unit 1044 for demodulating the signal equalized from the first equalization unit 1043 . The first equalization unit 1043 also includes a first equalization filter 1043a and a coefficient updater 1043b.

The first equalization filter 1043a equalizes the signal synchronized from the synchronization unit 1030 using the equalization coefficient provided by the coefficient updater 1043b. The coefficient updater 1043b uses the signal synchronized from the synchronization unit 1030, the output of the equalizer, and the reference signal to perform calculation estimation of the equalization coefficient.

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

Here, a predetermined signal such as a PN sequence is used as a reference signal. If the first equalization unit 1043 is in a decision-directed mode, the OQAM demodulated output is used as a reference signal.

The equalization coefficients vary depending on the equalization algorithm used. Therefore, the realization of the coefficient updater 1043b is determined by the type of equalization filter used. Among the existing equalization algorithms for single-carrier modulated signals, such as linear equalization, frequency domain equalization and decision-feedback equalization, it is better to use the DFE algorithm. The use of DFE filters provides better performance of the proposed demodulation device when processing single carrier modulated signals.

The OQAM unit 1044 can be replaced by a QAM mode demodulator.

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

In the multi-carrier modulation mode, the channel estimator 1046b uses a reference signal for estimation, in this case, the PN sequence extracted from the signal synchronized by the synchronization unit 1030 is used as a reference signal, and provides channel estimation information to the second Equalization filter 1046a. The FFT unit 1045 FFT-converts the signal synchronized from the synchronization unit 1030. The second equalization filter 1046a equalizes the FFT transformed signal using the channel estimation information from the channel estimator 1046b. The QAM unit 1047 demodulates the signal equalized by the second equalization filter 1046a in QAM mode to generate a demodulated signal as an input of the selector 1050 for selection according to the modulation mode indication.

In practice, other predetermined signals, such as pilot subcarriers, can be used as reference signals. Pilot subcarriers are detected from the output of FFT unit 1045 .

The selector 1050 selects the output signal corresponding to the modulation mode indication from the outputs of the OQAM unit 1044 and the QAM unit 1047 as an input of the channel decoder 1060 .

The channel decoder 1060 decodes the demodulated signal and outputs the signal. Here, an LDPC decoder can be used as a channel decoder.

Therefore, the demodulation unit shown in FIG. 10 has the ability to equalize signals, and can demodulate received single-carrier modulated signals and multi-carrier modulated signals.

Using the demodulation unit shown in FIG. 10 can compensate channel distortion based on a single-carrier modulation mode and a multi-carrier modulation mode. Thereby, the performance of the digital multimedia receiver for the two modes can be improved and channel errors can be reduced.

In order to reduce the cost of a digital multimedia receiver capable of handling both single-carrier modulated signals and multi-carrier modulated signals, a common ADC can be used. However, due to the unique nature of the single-carrier modulation mode and the multi-carrier modulation mode, the symbol rates of these two modulation modes are different. Therefore, in the processing path of a digital multimedia receiver, the output of the shared ADC should be decimated to different symbol rates suitable for single-carrier modulation mode and multi-carrier modulation mode.

For example, suppose the sampling rate of the ADC is r1, and the symbol rates of the single-carrier modulation mode and the multi-carrier modulation mode are r2 and r3, respectively. The sampling rate N:1 of the single-carrier modulation mode is equal to r1:r2, and the sampling rate M:1 of the multi-carrier modulation mode is equal to r1:r3. Since r3 is smaller than r2, M is larger than N.

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

11, the digital multimedia receiver includes a tuner 1110, an ADC 1120, a decimation unit 1130, a demodulation unit 1140, and a channel decoder 1150.

The tuner 1110 tunes (down-converts) multimedia signals received via the antenna.

The ADC 1120 converts the signal tuned by the tuner 1110 into a digital signal through sampling, quantization, and encoding.

The extraction unit 1130 extracts the digital signal from the ADC 1120 according to the modulation mode indication. The decimation unit 1130 includes a first switch 1131 , a first decimator 1132 , and a second decimator 1133 .

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, then the first switch 1131 selects the first decimator 1132 , and the first decimator 1132 receives the digital signal passing through the first switch 1131 . The first decimator 1132 decimates the digital signal from the ADC 1120 by N:1. If the modulation mode indication is a multi-carrier modulation mode indication, then the first switch 1131 selects the second decimator 1133 , and the second decimator 1133 receives the digital signal passed through the first switch 1131 . The second decimator 1133 decimates the digital signal from the ADC 1120 with M:1. Here, N and M are respectively predetermined corresponding to the single-carrier modulation mode and the multi-carrier modulation mode.

The demodulation unit 1140 demodulates the signal extracted by the decimation unit 1130 . The demodulation unit 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 extracted by the first decimator 1132 . The FFT unit 1142 performs FFT transform on the signal extracted by the second decimator 1133, and the QAM demodulator 1143 demodulates the signal FFT transformed by the FFT unit 1142.

The second switch 1144 selects one of the OQAM demodulator 1141 and the QAM demodulator 1143 according to the modulation mode indication. The function of the second switch 1144 is the same as that of the second switch 855 in FIG. 8, and thus its detailed description is omitted.

The channel decoder 1150 decodes the signal demodulated by the demodulation unit 1140 . The channel decoder 1150 may be an LDPC decoder.

In addition, similar to FIG. 8 , the first switch 1131 may be omitted.

In addition, in this embodiment, the demodulator 1141 may also be a QAM demodulator.

The operation process of the digital multimedia receiver shown in FIG. 11 will now be described in detail with reference to FIG. 12. Referring to FIG. FIG. 12 is a flowchart of a digital multimedia receiving method performed in the digital multimedia receiver shown in FIG. 11 according to a sixth embodiment of the present invention.

Referring to FIG. 12, in step S1210, a received signal is tuned (down-converted). In step S1220, the tuned (down-converted) signal is converted into a digital signal.

In step S1230, the digital signal is extracted according to the modulation mode indication. In detail, if the modulation mode indication is a single-carrier modulation mode indication, then the digital signal is decimated by N:1, and if the modulation mode indication is a multi-carrier modulation mode indication, then the digital signal is decimated by M:1. Here, N and M are respectively predetermined corresponding to the single-carrier modulation mode and the multi-carrier modulation mode.

In step S1240, the extracted signal is demodulated. More specifically, if the modulation mode indication is a single carrier modulation mode indication, then the N:1 decimated signal is demodulated through OQAM demodulation. If the modulation mode indication is a multi-carrier modulation mode indication, then the M:1 extracted signal is demodulated through FFT transformation and QAM demodulation.

Finally, in step S1250, the demodulated signal is decoded.

In addition, in step S1240, if the modulation mode indication is a single carrier modulation mode indication, then the N:1 decimated signal can also be demodulated through QAM demodulation.

Since the decimator converts the sampling rate proportionally to the symbol rate of the single-carrier modulated signal and the multi-carrier modulated signal respectively, only one shared ADC is used in the digital multimedia receiver. Therefore, hardware implementation of the digital multimedia receiver is simplified, and single-carrier modulated signals and multi-carrier modulated signals can be correctly processed.

The efficiency of error correction coding can be improved by using a data interleaver. The data interleaver spreads out burst errors. Since the data frame structure is different according to different modulation modes, the parameters defining the function of the data interleaver may be different for single-carrier modulation mode and multi-carrier modulation mode. Therefore, in a digital multimedia receiver, parameters for deinterleaver should be changed according to different modulation modes. In addition, LDPC codes can be used in single-carrier modulation mode and multi-carrier modulation mode due to its super error correction capability.

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

Referring to FIG. 13 , the digital multimedia receiver includes a tuner 1310, an ADC 1320, a demodulation unit 1330, a deinterleaver 1340, and an LDPC decoder 1350.

The tuner 1310 tunes (down-converts) multimedia signals received via the antenna.

The ADC 1320 converts the signal tuned by the tuner 1310 into a digital signal through sampling and quantization.

The demodulation unit 1330 demodulates the digital signal from the ADC 1320 according to the modulation mode instruction. The demodulation unit 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 1331 selects one of the OQAM demodulator 1332 and the FFT unit 1333 according to the modulation mode indication. More specifically, if the modulation mode indication is a single carrier modulation mode indication, that is, if the multimedia signal is a single carrier modulation mode, then the first switch 1331 selects the OQAM demodulator 1332 . OQAM demodulator 1332 demodulates the digital signal from ADC 1320. If the modulation mode indication is a multi-carrier modulation mode indication, that is, if the multimedia signal is a multi-carrier modulation mode, then the first switch 1331 selects the FFT unit 1333 . The FFT unit 1333 performs FFT transformation on the digital signal from the ADC 1320. The QAM demodulator 1334 demodulates the signal FFT-transformed by the FFT unit 1333.

The deinterleaver 1340 deinterleaves the demodulated signal according to the modulation mode instruction. More specifically, the function of deinterleaving demodulation is determined by its parameters. The deinterleaver 1340 having the same structure can deinterleave the demodulated signal by using different parameters corresponding to the single carrier modulation mode and the multicarrier modulation mode. That is, different parameters corresponding to the above two modulation modes are applied to the interleaver 1340 according to the modulation mode indication.

Therefore, only one deinterleaver is used to process the single-carrier modulated signal and the multi-carrier modulated signal. Therefore, the parameters of the deinterleaver 1340 should be determined according to the modulation mode indication.

The LDPC decoder 1350 decodes the signal deinterleaved by the deinterleaver 1340 . LDPC decoder 1350 can also be replaced by other types of decoders.

In addition, similar to the case of FIG. 9 , the first switch 1331 may be omitted.

In addition, in this embodiment, the demodulator 1332 may also be a QAM demodulator.

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

Referring to FIG. 14, in step S1410, a received signal is down-converted. In step S1420, the down-converted signal is converted into a digital signal.

In step S1430, the digital signal is demodulated according to the modulation mode indication. In detail, if the modulation mode indication is a single-carrier modulation mode indication, then the digital signal is demodulated through OQAM demodulation, and if the modulation mode indication is a multi-carrier modulation mode indication, then the digital signal is demodulated through FFT transformation and QAM demodulation is demodulated.

In step S1440, the demodulated signal is deinterleaved according to the modulation mode indication. In this case, deinterleaving parameters are determined and applied according to the modulation mode indication.

Finally, in step S1450, the demodulated signal is decoded by LDPC.

In addition, in step S1430, if the modulation mode indication is a single carrier modulation mode indication, then the digital signal can also be demodulated through QAM demodulation.

Since there is only one de-interleaver for the single-carrier modulated signal and the multi-carrier modulated signal, the implementation of the digital multimedia receiver is simplified. In addition, the processing performance of the digital multimedia receiver is improved because an LDPC decoder having a superior error correction capability is used in the digital multimedia receiver.

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

Referring to Figure 15, the digital multimedia receiver includes: a tuner 1510 for tuning the received multimedia signal to a corresponding frequency band; ADC 1520 for converting the tuned signal output from the tuner 1510 into a digital signal; a demodulator 1530 for demodulating the digital signal from ADC 1520; symbol demapper 1540 for demapping the demodulated signal output from demodulator 1530; and LDPC decoder 1550 for demapper from symbol The mapper 1540 decodes the signal and outputs the resulting signal.

In digital multimedia transmission systems that require high-definition video/audio bit streams to be transmitted without errors, it is very important to use strong error correction codes to reduce bit error rates. As a kind of error correction code, LDPC code has strong error correction ability, therefore, LDPC code can be combined with digital multimedia transmission system corresponding to single carrier modulation mode or multi-carrier modulation mode.

In case a digital multimedia transmitter uses an LDPC encoder to improve error correction capabilities, an LDPC decoder should be used accordingly in the receiver. In this case, improved reception performance can be obtained.

When the received multimedia signal is a single carrier modulated signal, the symbol demapper 1540 is an OQAM symbol demapper or a QAM symbol demapper.

When the received multimedia signal is a multi-carrier modulated signal, the symbol demapper 1540 is a QAM symbol demapper.

By using the receiver described above, an improved error correction capability can be obtained.

As described above, according to an aspect of the present invention, a digital multimedia receiver can process a single-carrier modulated signal and a multi-carrier modulated signal with a simplified structure and high reception performance.

According to another aspect of the present invention, by using an LDPC decoder, the decoding performance of digital multimedia reception is significantly improved.

While the invention has been shown and described with reference to particular embodiments, it will be understood by those skilled in the art that various forms and modifications may be made thereto without departing from the spirit and scope of the invention as defined by the appended claims. Modification of details.

Claims (6)

1. digital multimedia receiver that is used for the signal of processing single-carrier modulated signals and multi-carrier modulation comprises:

Tuner, the multi-media signal that is used for tuning reception is to corresponding wave band;

ADC, being used for tuning analog signal conversion is digital signal;

Lock unit, be used to use the modulating mode indication synchronously from the digital signal of ADC to produce synchronizing signal;

Demodulating unit is used to use the synchronous signal of modulating mode indication demodulation lock unit; With

Channel decoder is used for through the signal decoding of demodulating unit demodulation and export the signal of gained,

Wherein, lock unit comprises: timing recovery block is used to use modulating mode to indicate and compensates the timing error from the digital signal of ADC; Carrier recovery block, the output signal frequency error that is used to use modulating mode to indicate and compensates timing recovery block is to produce synchronizing signal.

2. digital multimedia receiver as claimed in claim 1, wherein:

Timing recovery block comprises sampling unit, first loop filter and Timing Error Detector (TED) again,

Sampling unit receives the digital signal from ADC again; TED detects the output signal of sampling unit based on modulating mode indication calculating timing error again; Its output signal is fed to first loop filter; First loop filter carries out filtering to the output signal of TED, and sampling unit uses the timing slip of the timing error estimation compensation of the warp first loop filter filtering from the digital signal of ADC again; With

Carrier recovery block comprises blender, NCO unit, second loop filter and frequency error estimator (FEE),

Mixer mixing is the output signal of sampling unit again; The output signal of FEE detection mixer and based on skew of modulating mode indication estimated frequency and phase deviation; Second loop filter carries out filtering to the output signal of FEE; The NCO unit will be converted into the phase value corresponding N CO value of phase value and output and conversion by the frequency shift (FS) of the second loop filter filtering and phase deviation, and the nco value that blender uses the NCO unit to provide compensates output signal frequency skew and the phase deviation of sampling unit with the input of generation synchronizing signal as demodulating unit again.

3. according to claim 1 or claim 2 digital multimedia receiver, wherein, channel decoder is the LDPC decoder.

4. digital multimedia receiver that is used for the signal of processing single-carrier modulated signals and multi-carrier modulation comprises:

Tuner, the multi-media signal that is used for tuning reception is to corresponding wave band;

ADC, being used for tuning analog signal conversion is digital signal;

Lock unit, be used to use the modulating mode indication synchronously from the digital signal of ADC to produce synchronizing signal;

Demodulating unit is used to use the synchronous signal of modulating mode indication demodulation lock unit; With

Channel decoder is used for through the signal decoding of demodulating unit demodulation and export the signal of gained,

Wherein, lock unit comprises: carrier recovery block is used to use modulating mode to indicate and compensates the output signal frequency error from the timing recovery block of the digital signal of ADC; Timing recovery block, the timing error of output signal that is used to use modulating mode to indicate and compensates carrier recovery block is to produce synchronizing signal.

5. digital multimedia receiver as claimed in claim 4, wherein:

Carrier recovery block comprises blender, NCO unit, second loop filter and frequency error estimator (FEE),

Mixer mixing is from the digital signal of ADC; The output signal of FEE detection mixer and based on skew of modulating mode indication estimated frequency and phase deviation; Second loop filter carries out filtering to the output signal of FEE; The NCO unit will convert phase value and output and the phase value corresponding N CO value of changing into by the frequency shift (FS) and the phase deviation of the second loop filter filtering, and the nco value that blender uses the NCO unit to provide compensates frequency shift (FS) and phase deviation from the digital signal of ADC; With

Timing recovery block comprises sampling unit, first loop filter and Timing Error Detector (TED) again,

Sampling unit receives the output signal of blender again; TED detects the output signal of sampling unit based on modulating mode indication calculating timing error again; Its output signal is fed to first loop filter; First loop filter carries out filtering to the output signal of TED, and the timing slip of the output signal of the timing error estimation compensation blender of the sampling unit use warp first loop filter filtering is to produce the input of synchronizing signal as demodulating unit again.

6. like claim 4 or 5 described digital multimedia receivers, wherein, channel decoder is the LDPC decoder.

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