HK1139264A - A digital multimedia receiver and a receiving method thereof - Google Patents

Description

Digital multimedia receiver and receiving method thereof

The present application is a divisional application of patent application having an application date of 2004, 12/20/2004, and an application number of 200610146800.X entitled "digital multimedia receiver and receiving method thereof".

Technical Field

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

Background

In the age of multimedia communication and broadcasting, analog type broadcasting is being digitalized in various countries of the world, and especially in developed countries such as the united states, europe, japan, and the like, 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.

The Federal Communications Commission (FCC) in the united states proposed the Advanced Television Systems Committee (ATSC) digital television standard as the next generation television broadcast standard 24/12 in 1996. All terrestrial broadcast operators must comply with the ATSC standard with respect to the specifications of video/audio compression, packet data transmission structure, and modulation and transmission systems. The specification regarding only video formats is not specified and is left to the industry.

The ATSC digital TV standard transmits high quality video, audio, and additional data over a bandwidth of 6MHz using a single carrier VSB scheme, and simultaneously supports a terrestrial broadcast mode and a high data rate cable broadcast mode. The main aspect of this approach is the 8-VSB modulation method, which is a modified form of the existing analog VSB approach, with digital signal modulation capability.

In europe, COFDM (coded orthogonal frequency division multiplexing) systems have been applied to DVB-T (digital video broadcasting-terrestrial) for its high frequency utilization and interference rejection capability.

Other data transmission schemes using different modulation methods may be classified into a multi-carrier scheme and a single-carrier scheme. Thus, conventional digital multimedia receivers can be classified into multi-carrier digital multimedia receivers and single-carrier digital multimedia receivers.

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

The conventional multi-carrier digital multimedia receiver includes: a tuner 110 for tuning the received multi-carrier modulated multimedia signal; an ADC (analog-to-digital converter) 120 for converting a signal output from the tuner 110 into a digital signal; a synchronization unit 130 for performing timing recovery and carrier recovery on the signal from the ADC 120; a Fast Fourier Transform (FFT) unit 140 for fast fourier transforming the signal output from the synchronization unit 130; an equalizing unit 150 for equalizing the signal output from the FFT unit 140; a QAM (quadrature amplitude modulation) symbol detection unit 160 for performing symbol detection on the output of the equalizer; a preamble error correction (FEC) unit 170 for performing preamble error correction on the signal output from the symbol detection unit 160; and a descrambler 180 for descrambling the signal output from the FEC unit 170 to obtain an MPEG stream.

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

The conventional single carrier digital multimedia receiver includes: a tuner 210 for receiving a single-carrier modulated multimedia signal; an ADC 220 for converting a signal output from the tuner 210 into a digital signal; a Synchronization (SYNC) unit 230 for performing timing recovery and carrier recovery; an equalizing unit 240 for equalizing the signal output from the synchronizing unit 230; an (offset) QAM symbol detection unit 250 for performing symbol detection on the output of the equalization unit 240; an FEC unit 260, configured to perform forward error correction on the signal output by the symbol detection unit 250; and a descrambler 270 for descrambling the signal output from the FEC unit 260 to obtain an MPEG stream.

There is a long standing debate as to whether the performance of a single carrier transmission system is good or that of a multi-carrier transmission system is good, but there is no specific result. Both of these solutions have advantages and disadvantages, respectively. It is therefore desirable for a broadcast station to allow selection of a transmission scheme from a plurality of transmission schemes that is suitable for its particular needs and broadcast environment. In this case, a receiver capable of receiving and decoding single-carrier and multi-carrier modulated broadcast signals is required to view Digital Television (DTV) programs from broadcast stations using different transmission schemes.

It is known that conventional digital multimedia receivers cannot simultaneously receive a single carrier modulated signal and a multi-carrier modulated signal, which has many inconveniences.

Disclosure of Invention

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

According to an aspect of the present invention, there is provided a digital multimedia receiver for processing a single carrier modulated signal and a multi-carrier modulated signal, comprising: a tuner for down-converting the received multimedia signal; an ADC for converting the signal down-converted by the tuner into a digital signal; a demodulation unit for demodulating the digital signal converted by the ADC according to the modulation mode indication; a deinterleaver for deinterleaving the signal demodulated by the demodulation unit according to the modulation mode indication; and a channel decoder for decoding the signal deinterleaved by the deinterleaver.

Parameters of the deinterleaver are determined based on the modulation mode indication.

The demodulation unit includes: a first demodulator for demodulating the signal from the ADC if the modulation mode indication is a single carrier modulation mode indication; an FFT unit for performing FFT conversion on the signal from the ADC if the modulation mode indication is a multi-carrier modulation mode indication; a second demodulator for demodulating the signal FFT-converted by the FFT unit; and a switch for selecting one of the demodulated signals from the first demodulator and the second demodulator according to the modulation mode indication.

Preferably, the first demodulator is an OQAM demodulator or a QAM demodulator, and the second demodulator is a QAM demodulator.

The demodulation unit further includes another switch for transmitting the digital signal from the ADC to one of the first demodulator and the FFT unit according to the modulation mode indication.

Preferably, the channel decoder is an LDPC decoder.

According to another aspect of the present invention, there is provided a digital multimedia receiving method for processing a single carrier modulated signal and a multi-carrier modulated signal, comprising the steps of: (a) down-converting the received multimedia signal; (b) converting the down-converted signal into a digital signal; (c) demodulating the filtered signal according to the modulation mode indication; (d) deinterleaving the demodulated signal according to the modulation mode indication; and (e) decoding the demodulated signal.

In step (c), if the modulation mode indication is a single carrier modulation mode indication, the digital signal converted in step (b) is demodulated by OQAM or QAM demodulation, and if the modulation mode indication is a multi-carrier modulation mode indication, the digital signal converted in step (b) is demodulated by FFT transformation and QAM demodulation.

In step (d), a parameter for deinterleaving is determined in accordance with the modulation mode indication.

Preferably, in step (e), the deinterleaved signal is LDPC-decoded.

Drawings

The above and other objects and advantages of the present invention will become more apparent from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

fig. 1 is a schematic block diagram illustrating a conventional digital multimedia receiver for processing a multi-carrier modulated signal;

FIG. 2 is a schematic block diagram illustrating a conventional digital multimedia receiver for processing single carrier modulated signals;

fig. 3 is a block diagram illustrating 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;

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

fig. 5 is a block diagram illustrating 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;

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

fig. 7 is a block diagram showing the construction 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;

fig. 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 performed in the digital multimedia receiver shown in fig. 8 according to a fourth embodiment of the present invention;

fig. 10 is a block diagram showing the construction 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;

fig. 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;

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;

fig. 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;

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; and

fig. 15 is a block diagram illustrating 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 Description

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

Fig. 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; an ADC (analog-to-digital converter) 320 for converting the tuned signal from the tuner 310 into a digital signal; a demodulation unit 330 including a demodulator 331 for demodulating and outputting a signal modulated by a single carrier and a demodulator 332 for demodulating and outputting a signal modulated by a multi-carrier, wherein when a digital signal is input to the demodulation unit 330, one or both of the demodulators demodulate and output the digital signal from the ADC 320; a selector 340 for selecting an effective signal among the demodulated signals output from the demodulation unit 330 according to the modulation mode indication; and a common channel decoder 350 for decoding the selected demodulated signal output from the demodulation unit 330 and outputting the resultant signal.

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, demodulator 332 operates and properly outputs the multi-carrier demodulated signal.

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

A common 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 may be used as the common 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 fig. 3 and 4.

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.

The tuner 310 tunes the received signal to a corresponding frequency band at step S410. Then, the ADC320 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 ADC320 and outputs the demodulated signal. Here, one or both of the demodulators in the demodulation unit 330 can process the digital signal. Specifically, if the input signal is a single-carrier modulated signal, the demodulator 331 correctly demodulates and outputs the input digital signal in the single-carrier mode. If the input signal is a multicarrier modulated signal, the demodulator 332 correctly demodulates and outputs the input digital signal in the multicarrier mode.

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 selector 340 knows that the digital signal input to the demodulation unit 330 is a multicarrier modulated signal according to the modulation mode indication, 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 the receiving method having the above-described structure of the present invention, both a single carrier modulated signal and a multi-carrier modulated signal can be processed by determining the modulation mode of the received multimedia signal. Thus, the hardware implementation of the receiver is simplified and the reception performance of the receiver is improved.

Fig. 5 is a block diagram illustrating 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 a modulation mode indication, and a demodulation unit 540 for demodulating the digital signal according to the modulation mode indication.

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 ADC320 in fig. 3, and thus, detailed descriptions thereof are omitted.

The single-carrier modulated signal and the multi-carrier modulated signal have different PAPR (peak to average power ratio) characteristics, and the multi-carrier modulated signal has a relatively large PAPR compared to the single-carrier modulated signal. The AGC algorithms for these two modulation modes are also different. In the above receiver, only one AGC is used, and thus, in a digital multimedia receiver for processing single carrier modulated signals and multi-carrier modulated signals, the AGC 530 should employ a corresponding algorithm according to a modulation mode indication indicating a modulation mode of the multimedia signal.

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

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.

The tuner 510 tunes the received multimedia signal at step S610.

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

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

In step S640, the AGC 530 controls the gain of the signal input from the tuner 510 to the ADC 520 according to the result of the measurement 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-described structures, it is possible to process a single-carrier modulated signal and a multi-carrier modulated signal by determining a modulation mode of a received multimedia signal. In addition, the gain of the tuner of the receiver may be controlled according to the modulation mode of the received multimedia signal. Thus, the hardware implementation of the receiver is simplified, and the reception performance of the receiver is improved.

Fig. 7 is a block diagram showing the construction 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. The ADC 720 converts the tuned analog signal into a digital signal by sampling and quantization.

The synchronization unit 730 synchronizes the digital signal converted by the ADC 720 using the modulation mode indication.

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

The timing recovery block 730T includes a resampling unit 731, a first loop filter 732, and a Timing Error Detector (TED) 733. Here, the TED733 detects an output signal of the resampling unit 731 to calculate a timing error based on the modulation mode indication, an output signal of which is fed to the first loop filter 732. The first loop filter 732 filters the output signal of the TED733, the filtered signal of the first loop filter 732 being fed to the resampling 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 decimating and interpolating, 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 TED733, and the TED733 selects the corresponding algorithm based on the modulation mode indication. In this case, the timing error information is determined by the modulation mode indication.

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

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

According to the receiver architecture of fig. 7, carrier recovery occurs after timing recovery has occurred. In practice, however, the timing recovery block 730T may 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 may 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, the timing offset and the frequency offset can be compensated based on the single carrier modulation mode and the multi-carrier modulation mode. Thus, the receiver can operate correctly for both the single-carrier modulation mode and the multi-carrier modulation mode.

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

Fig. 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) a multimedia signal received via an antenna.

The ADC 820 converts the signal tuned by the tuner 810 into a digital signal by sampling, quantizing, 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 reception filter 840.

The reception filter 840 filters the digital signal from the ADC 820 according to a filter coefficient set corresponding to the single-carrier modulation mode or the multi-carrier modulation mode supplied from the filter coefficient memory 831. The receive filter 840 may be a Square Root Raised Cosine (SRRC) filter. The SRRC filter, which is used as a matching with the SRRC filter of the transmitting end, maximizes the signal-to-noise ratio by matching signals.

Demodulation unit 850 demodulates the digital signal filtered by receive 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 reception filter 840 is a signal of a single carrier modulation mode, the first switch 851 selects the OQAM demodulator 852. The OQAM demodulator 852 demodulates the signal filtered by the reception filter 840. The first switch 851 selects the FFT unit 853 if the modulation mode indication is a multi-carrier modulation mode indication, that is, if the signal filtered by the reception filter 840 is a multi-carrier modulation mode signal. The FFT unit 853 performs FFT on the signal filtered by the reception filter 840, and then the QAM demodulator 854 demodulates the signal FFT-ed by the FFT unit 853.

A 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 of OQAM demodulator 852 and QAM demodulator 854 operate. In detail, the signal filtered by the reception filter 840 is simultaneously input to the OQAM demodulator 852 and the FFT unit 853, and the OQAM demodulator 852 and the FFT unit 853 or one of them is allowed to operate.

In addition, in this embodiment, 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. 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, the filtered signal is demodulated by OQAM demodulation, and if the modulation mode indication is a multi-carrier modulation mode indication, the filtered signal is demodulated by FFT and QAM demodulation.

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

Further, 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 a common filter is used for both 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.

Fig. 10 is a block diagram showing the construction 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 a received multimedia signal to a corresponding band. The ADC 1020 converts the tuned analog signal into a digital signal by sampling and quantization.

The synchronization unit 1030 synchronizes the digital signal converted by the ADC 1020 with the modulation mode indication.

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 demodulate the received single-carrier modulated signal and the multi-carrier modulated signal, respectively. Based on the modulation mode indication, a demodulation block of the two demodulation blocks corresponding to the modulation mode is enabled.

The first demodulation block 1041 includes a first equalization unit 1043 for equalizing the 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 further includes a first equalization filter 1043a and a coefficient updater 1043 b.

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

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 1043 b. The output of the first equalization filter 1043a is input to the OQAM unit 1044 and demodulated therein. The signal demodulated from the OQAM unit 1044 is input to the selector 1050 for selection. The coefficient updater 1043b detects the signal synchronized from the synchronizing unit 1030, the equalizer output, and the reference signal, and updates the equalization coefficient, and supplies equalization coefficient information to the equalization filter 1043 a.

Here, a predetermined signal, such as a PN sequence, is used as a reference signal. If the first equalizing unit 1043 is in the direct-judged mode, the OQAM demodulation output is used as a reference signal.

The equalization coefficients differ depending on the equalization algorithm used. The implementation of the coefficient updater 1043b is therefore determined by the kind of equalization filter used. In existing algorithms for equalization of single carrier modulated signals, such as linear equalization, frequency domain equalization and decision-feedback equalization (decision-feedback equalization), the DFE algorithm is better used. The use of DFE filters provides a better performance of the proposed demodulation apparatus when processing single carrier modulated signals.

OQAM unit 1044 may be replaced by a QAM mode demodulator.

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

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

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

The selector 1050 selects an 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, the LDPC decoder may function as a channel decoder.

Thus, the demodulation section shown in fig. 10 has the capability of equalizing signals, and can demodulate a received single-carrier modulated signal and a received multi-carrier modulated signal.

Channel distortion can be compensated based on a single carrier modulation mode and a multi-carrier modulation mode using the demodulation unit shown in fig. 10. Accordingly, the performance of the digital multimedia receiver for the two modes can be improved and the channel error can be reduced.

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

For example, assume that 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 decimation rate N:1 of the single carrier modulation mode is equal to r1: r2, and the decimation rate M:1 of the multi-carrier modulation mode is equal to r1: r 3. Since r3 is less than r2, M is greater than N.

Fig. 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.

Referring to fig. 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) a multimedia signal received via an antenna.

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

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

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

The demodulation unit 1140 demodulates the signal extracted by the extraction 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 extractor 1132. The FFT unit 1142 performs FFT transformation on the signal extracted by the second extractor 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 a detailed description thereof is omitted.

The channel decoder 1150 decodes the signal demodulated by the demodulation unit 1140. 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 of the digital multimedia receiver shown in fig. 11 will now be described in detail with reference to fig. 12. 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 decimated according to the modulation mode indication. In detail, if the modulation mode indication is a single carrier modulation mode indication, the digital signal is decimated by N:1, and if the modulation mode indication is a multi-carrier modulation mode indication, the digital signal is decimated by M: 1. Here, N and M are predetermined corresponding to the single-carrier modulation mode and the multi-carrier modulation mode, respectively.

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

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

Further, in step S1240, if the modulation mode indication is a single carrier modulation mode indication, the N:1 extracted signal may also be demodulated by QAM demodulation.

Since the decimator converts the sample rate in proportion to the symbol rate of the single carrier modulated signal and the multi-carrier modulated signal, respectively, only one common ADC is used at the digital multimedia receiver. Accordingly, hardware implementation of the digital multimedia receiver is simplified, and a single carrier modulated signal and a multi-carrier modulated signal can be correctly processed.

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

Fig. 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) a multimedia signal received via an antenna.

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

The demodulation unit 1330 demodulates the digital signal from the ADC 1320 according to the modulation mode indication. 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, the first switch 1331 selects the OQAM demodulator 1332. The OQAM demodulator 1332 demodulates the digital signal from the ADC 1320. The first switch 1331 selects the FFT unit 1333 if the modulation mode indication is a multi-carrier modulation mode indication, i.e., if the multimedia signal is a multi-carrier modulation mode. The FFT unit 1333 performs FFT conversion on the digital signal from the ADC 1320. The QAM demodulator 1334 demodulates the signal FFT-converted by the FFT unit 1333.

The deinterleaver 1340 deinterleaves the demodulated signal according to the modulation mode indication. 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 multi-carrier 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.

Thus, only one deinterleaver is used to process both single-carrier modulated signals and multi-carrier modulated signals. Accordingly, 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 may also be replaced by other types of decoders.

In addition, the first switch 1331 may be omitted, similarly to the case of fig. 9.

In addition, in the present 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, the 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, the digital signal is demodulated by OQAM demodulation, and if the modulation mode indication is a multi-carrier modulation mode indication, the digital signal is demodulated by FFT transformation and QAM demodulation.

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

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

Further, in step S1430, if the modulation mode indication is a single carrier modulation mode indication, the digital signal may also be demodulated by QAM demodulation.

The implementation of the digital multimedia receiver is simplified since only one deinterleaver is used for both the single carrier modulated signal and the multi-carrier modulated signal. In addition, since the LDPC decoder having a superior error correction capability is used in the digital multimedia receiver, the processing performance of the digital multimedia receiver is improved.

Fig. 15 is a block diagram illustrating 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 fig. 15, the digital multimedia receiver includes: a tuner 1510 for tuning the received multimedia signal to a corresponding frequency band; an ADC1520 for converting the tuned signal output from the tuner 1510 into a digital signal; a demodulator 1530 for demodulating the digital signal from the ADC 1520; a symbol demapper 1540 for demapping the demodulated signal output from the demodulator 1530; and an LDPC decoder 1550 for decoding the signal from the symbol demapper 1540 and outputting the resultant signal.

In a digital multimedia transmission system requiring transmission of a bit stream of high definition video/audio without errors, it is very important to use a strong error correction code to reduce a bit error rate. The LDPC code has a strong error correction capability as an error correction code, and thus, the LDPC code can be combined with a digital multimedia transmission system corresponding to a single carrier modulation mode or a multi-carrier modulation mode.

In case that the digital multimedia transmitter uses the LDPC encoder to improve the error correction capability, the LDPC decoder should be used in the receiver accordingly. 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 multicarrier modulated signal, the symbol demapper 1540 is a QAM symbol demapper.

By using the above receiver, 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, decoding performance of digital multimedia reception is significantly improved by using the LDPC decoder.

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

Claims (7)

1. A digital multimedia receiver, comprising:

the analog-to-digital converter is used for converting the received analog signal into a digital signal;

a demodulator for demodulating the digital signal;

a deinterleaver for deinterleaving the demodulated digital signal according to the modulation mode indication; and

a channel decoder for decoding the deinterleaved signals.

2. The digital multimedia receiver of claim 1, wherein if the modulation mode indication is a single carrier mode indication, the demodulator demodulates the digital signal output by the analog-to-digital converter as it is, and if the modulation mode indication is a multi-carrier mode indication, the demodulator performs fast fourier transform on the digital signal output by the analog-to-digital converter and demodulates the transformed digital signal.

3. The digital multimedia receiver of claim 2, wherein the demodulator performs OQAM demodulation if the modulation mode indication is a single carrier mode indication, wherein the demodulator performs QAM demodulation if the tune-to mode indication is a multi-carrier mode indication.

4. The digital multimedia receiver of claim 1, wherein the channel decoder performs reed-solomon RS block decoding.

5. A digital multimedia receiver, comprising:

the analog-to-digital converter is used for converting the received analog signal into a digital signal;

a demodulator for demodulating the digital signal;

a deinterleaver for deinterleaving the demodulated digital signal according to the modulation mode indication; and

a low density parity check, LDPC, decoder for decoding the deinterleaved signals.

6. The digital multimedia receiver of claim 5, wherein if the modulation mode indication is a single carrier mode indication, the demodulator demodulates the digital signal output by the analog-to-digital converter as it is, and if the modulation mode indication is a multi-carrier mode indication, the demodulator performs fast fourier transform on the digital signal output by the analog-to-digital converter and demodulates the transformed digital signal.

7. The digital multimedia receiver of claim 6, wherein the demodulator performs OQAM demodulation if the modulation mode indication is a single carrier mode indication, wherein the demodulator performs QAM demodulation if the tune-to mode indication is a multi-carrier mode indication.