WO2005109712A1 - Ofdm受信装置及びofdm受信方法 - Google Patents
Ofdm受信装置及びofdm受信方法 Download PDFInfo
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- WO2005109712A1 WO2005109712A1 PCT/JP2005/008431 JP2005008431W WO2005109712A1 WO 2005109712 A1 WO2005109712 A1 WO 2005109712A1 JP 2005008431 W JP2005008431 W JP 2005008431W WO 2005109712 A1 WO2005109712 A1 WO 2005109712A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03159—Arrangements for removing intersymbol interference operating in the frequency domain
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/0224—Channel estimation using sounding signals
- H04L25/0228—Channel estimation using sounding signals with direct estimation from sounding signals
- H04L25/023—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols
- H04L25/0232—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols by interpolation between sounding signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/01—Equalisers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2649—Demodulators
- H04L27/265—Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
- H04L2025/03375—Passband transmission
- H04L2025/03414—Multicarrier
Definitions
- the present invention relates to orthogonal frequency division multiplexing (OFDM).
- the present invention relates to an apparatus and a method for receiving a signal modulated and transmitted by a multiplexing method.
- OFDM is used as a transmission system for digital terrestrial broadcasting in Europe and Japan, wireless LAN, and the like.
- the OFDM system is a transmission system that modulates and demodulates data by allocating data to a plurality of orthogonal carriers.
- the transmitting side performs an inverse fast Fourier transform (IFFT) process
- IFFT fast Fourier transform
- FFT Fast Fourier Transform
- An arbitrary modulation method can be used for each carrier, and a modulation method such as QPSK (Quaternary Phase Shift Keying) QAM (Quadrature Amplitude Modulation) can be selected.
- QPSK Quadrature Phase Shift Keying
- QAM Quadrature Amplitude Modulation
- a frequency characteristic (transmission line characteristic) of a transmission line is estimated based on a pilot signal inserted into a received OFDM signal.
- waveform equalization is performed using the estimated transmission path characteristics.
- Patent Document 1 An example of a technique related to such estimation of transmission path characteristics and waveform equalization is described in Patent Document 1 below.
- Patent Document 1 a transmission path characteristic of a carrier for transmitting a received pilot signal by separating a received pilot signal from an OFDM signal converted into a signal in a frequency domain by an FFT circuit and dividing the received pilot signal by a known pilot signal is disclosed. Seeking.
- the transmission path characteristics are smoothed in the time direction by a symbol filter, that is, interpolation between symbols is performed, and then interpolation between carriers is performed by an interpolation circuit to perform transmission path characteristics H (l, kd) is obtained, and the equalized data X (l, kd) is obtained by dividing the received data signal Y (l, kd) by the transmission path characteristic H (l, kd).
- noise power can be increased by increasing the passband of the filter used to perform interpolation between carriers. It is known that the larger the bandwidth, the smaller the bandwidth. For this reason, it is effective to narrow the pass band width of the filter in order to eliminate the influence of noise and improve the estimation accuracy of the transmission path characteristics.
- the guard period length is TuZ4, TuZ8, TuZl6, or TuZ32 (Tu: effective symbol period length). Then, the OFDM signal is transmitted.
- the delay time of multipath interference that can be eliminated is determined according to the guard period length. For example, when the guard period length is TuZ4, it is possible to receive the signal while eliminating the effect of the delay wave up to TuZ4 on the delay time of the main wave. Therefore, it is effective to widen the passband of the filter in order to eliminate the effects of multipath and improve the estimation accuracy of the transmission path characteristics.
- the interpolation circuit described in Patent Document 1 determines the guard period length of the received OFDM signal power, and performs interpolation between carriers in the interpolation circuit based on the determination result of the guard period length.
- carrier filter By controlling the coefficient of the filter (hereinafter referred to as "carrier filter"), the pass bandwidth of this filter is switched. That is, if the guard period is long, the filter coefficient should be set so that the pass band becomes wider, and if the guard period is short V ⁇ , the filter coefficient should be set so that the pass band becomes narrow. Te ru.
- the bandwidth of the interpolation filter is switched in accordance with the guard period length, thereby suppressing the noise component superimposed on the estimated transmission path characteristic.
- Patent Document 1 JP-A-11-163822
- the present invention provides an OFDM (transmitting a pilot signal having a known amplitude and phase).
- An OFDM receiving apparatus for receiving and demodulating an Orthogonal Frequency Division Multiplexing (OFDM) signal, calculates a transmission path characteristic before interpolation based on the received OFDM signal, and transmits the signal before interpolation.
- the channel characteristics are interpolated using a plurality of filters with different characteristics to obtain a plurality of interpolated transmission line characteristics.
- a high-quality demodulated signal is obtained.
- the demodulated signal is obtained by using the transmission path characteristics obtained as follows.
- the present invention is an OFDM receiving apparatus for receiving and demodulating an OFDM signal transmitting a pilot signal whose amplitude and phase are known, wherein the received OFDM signal is subjected to Fourier transform.
- the transmission path characteristics before interpolation are calculated by an operation between the obtained OFDM signal in the frequency domain and the pilot signal, and interpolation is performed on the transmission path characteristics before interpolation by a plurality of filters having different characteristics.
- a transmission path characteristic estimating unit that outputs a plurality of interpolated transmission path characteristics based on interpolation results obtained by each of the plurality of filters; Equalization unit that performs waveform equalization on the OFDM signal in the wave number domain, and outputs a plurality of demodulated signals based on the waveform equalization results corresponding to the plurality of transmission path characteristics after interpolation. And the plurality A determination unit that determines a signal having the best quality from among the demodulated signals and outputs a determination result; and a selection unit that selects and outputs one of the plurality of demodulated signals according to the determination result. It is provided with.
- the transmission path characteristics obtained from each of the plurality of filters having different characteristics are obtained. That is, it is possible to know a transmission path characteristic that can obtain a high-quality demodulated signal. That is, it is possible to improve the estimation accuracy of the transmission path characteristics, to obtain high quality, and to obtain a demodulated signal.
- the transmission path characteristics are not dependent on the guard period length but are dependent on the interference situation. And the quality of the demodulated signal can be improved. As a result, it is possible to improve the reception performance in the OFDM receiver and the like.
- FIG. 1 is a block diagram showing a configuration example of an OFDM receiving apparatus according to an embodiment of the present invention.
- FIG. 2 is a block diagram showing a configuration example of an OFDM demodulation unit according to the first embodiment of the present invention.
- FIG. 3 is a diagram showing an example of a pilot signal arrangement format in an OFDM signal received by the OFDM receiving apparatus in FIG. 1.
- FIG. 4 is a diagram showing positions where transmission path characteristics interpolated in the symbol direction by the symbol interpolator of FIG. 2 are obtained.
- FIG. 5 is a diagram showing positions where transmission line characteristics interpolated in the carrier direction by the wideband filter and the narrowband filter of FIG. 2 are obtained.
- FIGS. 6 (a) and 6 (b) are diagrams respectively showing a transmission path characteristic obtained by a wideband filter and a transmission path characteristic obtained by a narrowband filter unit under a Gaussian noise disturbance environment.
- FIGS. 7 (a) and 7 (b) are diagrams respectively showing a transmission path characteristic obtained by a wideband filter and a transmission path characteristic obtained by a narrowband filter under a multipath interference environment.
- FIG. 8 is a block diagram showing a configuration example of a quality detection unit in FIG. 1.
- FIG. 9 is a block diagram showing a configuration example of an OFDM demodulation unit according to a second embodiment of the present invention.
- FIG. 10 is a block diagram showing a configuration of an OFDM demodulation unit according to a modification of the second embodiment.
- FIG. 11 is a professional example showing a configuration example of an OFDM demodulation unit according to a third embodiment of the present invention.
- FIG. 1 A first figure.
- FIG. 12 is a block diagram showing a configuration example of an OFDM demodulation unit according to a fourth embodiment of the present invention.
- FIG. 13 is a schematic diagram showing an example of a transmission path characteristic magnitude I HP I of a pilot carrier of this OFDM signal when noise is superimposed on the received OFDM signal.
- FIG. 14 is a diagram showing an impulse response level obtained by the IFFT unit in FIG.
- FIGS. 15 (a) and 15 (b) are diagrams respectively showing impulse responses before and after noise component removal.
- FIG. 16 is a diagram showing transmission path characteristics obtained by the FFT unit in FIG.
- FIG. 17 is a diagram showing transmission path characteristics HP ′ obtained by the noise removing unit in FIG. 12.
- FIG. 18 is a block diagram showing a configuration of an OFDM demodulation unit according to a modification of the fourth embodiment.
- FIG. 1 is a block diagram showing a configuration example of the OFDM receiving apparatus according to the embodiment of the present invention.
- the OFDM receiving apparatus 100 in FIG. 1 includes a tuner 3, an OFDM demodulation unit 4, an error correction unit 5, an information source decoding unit 6, and an output unit 7.
- a signal received by antenna 1 is supplied to tuner 3 in OFDM receiving apparatus 100.
- the tuner 3 extracts the OFDM signal containing the desired service from the supplied received signal, converts the frequency from the RF (Radio Frequency) band to the IF (Intermediate Frequency) band, adjusts the gain, etc. And outputs the processing result to the OFDM demodulation unit 4.
- the OFDM demodulation unit 4 demodulates the signal DI supplied from the tuner unit 3 based on the frequency characteristics of the transmission line (transmission line characteristics), and outputs the demodulation result DO to the error correction unit 5.
- the error correction unit 5 restores the transmitted digital data from the demodulation result DO of the OFDM demodulation unit 4, and performs Viterbi decoding and Reed-Solomon decoding on transmission errors caused by disturbances applied on the transmission path. And outputs the result to the information source decoding unit 6.
- the information source decoding unit 6 separates the output of the error correction unit 5 into data such as video and audio, performs data decompression processing on the separated data, and outputs the data to the output unit 7.
- the output unit 7 displays video information out of the output of the information source decoding unit 6 on a CRT (Cathode Ray Tube: cathode ray tube) or the like, and outputs audio information from a speaker or the like, thereby providing a desired service to the user. To provide.
- the output unit 7 can also output the output of the information source decoding unit to an external device.
- FIG. 2 is a block diagram illustrating a configuration example of the OFDM demodulation unit 4 according to the first embodiment of the present invention.
- the OFDM demodulation unit 4 includes a quadrature detection unit 11, an FFT unit 12, a channel characteristic estimation unit 20, an equalization unit 60, a determination unit 80, delay units 16, 17, and a selection unit 19. ing.
- the quadrature detection section 11 performs quadrature detection to frequency-convert the output of the tuner 3 in FIG. 1 from a signal in the IF band to a signal in a baseband (hereinafter, referred to as a baseband). Output.
- the output of the tuner 3 which is a real number signal is converted into a complex signal including a Kin Phase (in-phase) axis component and a Q (Quadrature Phase) axis component.
- the FFT unit 12 converts the output of the quadrature detection unit 11 from a time-domain OFDM signal to a frequency-domain OFDM signal, and converts the obtained frequency-domain OFDM signal Y into a transmission path characteristic estimation unit 20 and an equalization unit. Output to part 60.
- the OFDM signal Y in the frequency domain output from the FFT unit 12 indicates the phase and amplitude of each carrier of the OFDM signal, and specifically has independent levels in the I-axis direction and the Q-axis direction. It is represented in the form of a complex signal.
- the transmission line characteristic estimating unit 20 estimates a plurality of frequency characteristics (transmission line characteristics) of the transmission line through which the received OFDM signal is transmitted, using a plurality of filters having different characteristics for interpolation. Yes, it includes a transmission path characteristic calculation unit 30, a symbol interpolation unit 42, and a carrier interpolation unit 50.
- the transmission path characteristic calculation unit 30 includes a pilot signal extraction unit 31, a division unit 32, and a pilot signal generation unit 33.
- the carrier interpolation unit 50 has a wideband filter 51 and a narrowband filter 52 as carrier interpolation filters.
- the equalization section 60 includes division sections 61 and 62, and the determination section 80 includes quality detection sections 81 and 82 and a comparison section 83.
- FIG. 3 is a diagram showing an example of an arrangement format of a noise signal in an OFDM signal received by the OFDM receiving apparatus in FIG. Fig. 3 shows the arrangement format of pilot signals such as the terrestrial digital broadcasting system in Europe (DVB-T) and the terrestrial digital broadcasting system in Japan (ISDB-T).
- pilot signals such as the terrestrial digital broadcasting system in Europe (DVB-T) and the terrestrial digital broadcasting system in Japan (ISDB-T).
- k on the horizontal axis represents a carrier index
- 1 on the vertical axis represents a symbol index.
- the black circles indicate pilot signals (SP (Scattered Pilot: distributed pilot)
- a white circle is a data signal (D) including control information and additional information.
- the control information is TPS (Transmission Parameter; signaling) ⁇ in DVB-T, TM (Transmission Multiplexing Configuration Control) in ISi3B-T, and the attached information is AC (Transmission Parameter; Control) in ISDB-T. Auxiliary Channel).
- pilot signals indicated by black circles are arranged for every 12 carriers in each symbol, and are shifted by 3 carriers for each symbol. Further, the pilot signal is modulated based on a pseudo-random code sequence, and its amplitude and phase are determined only by the index k of the arranged carrier, and do not depend on the index 1 of the symbol.
- Pilot signal extraction section 31 extracts a pilot signal included in the OFDM signal in the frequency domain supplied from FFT section 2, and outputs the pilot signal to division section 32.
- the pilot signal generating section 33 is a predetermined pilot signal (the SP signal in ISDB-T and DVB-T) corresponding to the pilot signal supplied from the pilot signal extracting section 31 to the dividing section 32 and having a known amplitude and phase. ) Is generated and output to the division unit 32.
- Dividing section 32 divides the pilot signal supplied from pilot signal extracting section 31 by the pilot signal supplied from pilot signal generating section 33 to generate a carrier for transmitting the pilot signal (hereinafter referred to as a pilot signal). It calculates the frequency characteristic of the transmission path with respect to the carrier, that is, the transmission path characteristic HP, and outputs this to the symbol interpolation unit 42.
- This transmission path characteristic HP is obtained as the transmission path characteristic before interpolation, where the pilot signal SP is inserted in FIG.
- the symbol interpolation unit 42 interpolates between the symbols by performing filtering (band limitation) in the symbol direction (time axis direction) on the channel characteristics HP supplied from the division unit 32.
- the transmission path characteristic HS obtained as a result is output to the wide band filter 51 and the narrow band filter 52.
- FIG. 4 is a diagram showing positions where the channel characteristics interpolated in the symbol direction by the symbol interpolation unit 42 in FIG. 2 are obtained. As shown in Fig. 4, the interpolated channel characteristics HS are obtained for the position of the symbol CT.
- the wideband filter 51 and the narrowband filter 52 of the carrier interpolation unit 50 have different characteristics from each other. It has become.
- the wide-band filter 51 and the narrow-band filter 52 perform carrier-direction (frequency-axis direction) filtering (band limitation) on the transmission path characteristics HS supplied from the symbol interpolation unit 42, thereby interpolating between carriers. Is performed respectively.
- Broadband filter 51 outputs the obtained transmission path characteristic HCW to division section 61
- narrowband filter 52 outputs the obtained transmission path characteristic HCN to division section 62.
- FIG. 5 is a diagram showing positions where transmission path characteristics interpolated in the carrier direction by the wide band filter 51 and the narrow band filter 52 of FIG. 2 are obtained. As shown in Fig. 5, the interpolated transmission line characteristics HCW and HCN are obtained for the position of symbol CF.
- the wide band filter 51 and the narrow band filter 52 are configured by FIR filters. However, the characteristics of the two, that is, the pass bands are different from each other.
- the pass band width of the wide band filter 51 is TuZ4
- the pass band width of the narrow band filter 52 is TuZ8.
- FIGS. 6 (a) and 6 (b) show transmission path characteristics obtained by the wideband filter 51 and transmission obtained by the narrowband filter section 52 in a Gaussian noise (hereinafter simply referred to as noise) interference environment. It is a figure which shows a road characteristic, respectively. 6 (a) and 6 (b) show the signal level (signal power) on the vertical axis and the time axis on the horizontal axis, and show the characteristics of the transmission path passing through the wideband filter 51 and the narrowband filter 52, respectively. And the noise are converted to the time axis response.
- noise Gaussian noise
- the narrowband filter 52 can obtain higher transmission path characteristics with higher estimation accuracy than the wideband filter 51.
- FIGS. 7A and 7B are diagrams respectively showing a transmission path characteristic obtained by the wideband filter 51 and a transmission path characteristic obtained by the narrowband filter 52 in a multipath interference environment.
- 7 (a) and 7 (b) also use the signal level on the vertical axis and the time axis on the horizontal axis, and convert the characteristics of the transmission path passing through each of the wideband filter 51 and the narrowband filter 52 into a time axis response. Is shown.
- the delay time of the delayed wave with respect to the main wave is When the passband width exceeds TuZ8, the transmission path characteristics of the main wave and the delayed wave are both blocked by the narrowband filter 52 that can pass through the broadband filter 51 and must pass through both. Can not. Therefore, when receiving an OFDM signal in an environment of multipath interference in which a delayed wave having a long delay time exceeding the pass band width of the filter is received, the estimation accuracy of the wideband filter 51 is higher than that of the narrowband filter 52. High transmission line characteristics can be obtained.
- Dividing section 61 divides OFDM signal Y in the frequency domain supplied from FFT section 12 by transmission path characteristic HCW, and outputs the obtained demodulated signal XCW to delay section 16 and quality detecting section 81.
- Dividing section 62 divides frequency domain OFDM signal Y supplied from FFT section 12 by transmission path characteristic HCN, and outputs obtained demodulated signal XCN to delay section 17 and quality detecting section 82. That is, the division units 61 and 62 equalize the waveform of the OFDM signal Y in the frequency domain to compensate for waveform distortion due to multipath generated in the transmission path.
- the two transmission path characteristics HCW and HCN obtained by the carrier interpolation unit 50 have different estimation accuracy depending on the state of interference (noise, multipath), division is performed based on these transmission path characteristics.
- Demodulated signals XCW and XCN obtained in each of sections 61 and 62 also have different qualities depending on the interference situation.
- Determination section 80 determines which of the demodulated signals XCW and XCN supplied from each of division sections 61 and 62 has higher quality (higher quality).
- the determining unit 80 will be described.
- the quality detection unit 81 detects the quality value QCW of the demodulated signal XCW, and outputs the detection result to the comparison unit 83.
- Quality detection section 82 detects quality value QCN of demodulated signal XCN, and outputs the detection result to comparison section 83.
- the comparing section 83 compares the quality value QCW with the quality value QCN to judge the higher quality, and outputs the judgment result to the selecting section 19.
- FIG. 8 is a block diagram showing a configuration example of the quality detection unit 81 in FIG.
- the quality detection section 81 includes a hard decision section 86, a signal point distance calculation section 87, and an average calculation section 88. It is assumed that the quality detection unit 82 has the same configuration as the quality detection unit 81.
- Hard decision section 86 decides an ideal signal point closest to the signal point on the IQ plane of the carrier of demodulated signal XCW, and uses this as an ideal signal to calculate a signal point distance calculation section.
- Signal point distance calculation section 87 calculates the signal point distance for each carrier based on the ideal signal output from hard decision section 86 and demodulated signal XCW.
- the signal point distance calculation unit 87 calculates the difference value of the I-axis component between the ideal signal point on the IQ plane indicated by the ideal signal and the signal point on the IQ plane indicated by the demodulated signal. Is calculated, and the square of the difference value of the Q-axis component is calculated. The sum of these is calculated as the distance between signal points and output to the average calculation unit 88.
- the average calculation unit 88 calculates an average value over a plurality of carriers for the signal point distance obtained for each carrier by the signal point distance calculation unit 87.
- the period for calculating the average value may be within one symbol, or may be a period over a plurality of symbols. The longer the calculation period, the higher the detection accuracy of the demodulated signal quality. Conversely, if the calculation period is shortened, the time until the judgment result is obtained in the judgment unit 80 is shortened, so that the hardware amount of the delay units in the delay units 16 and 17 can be reduced.
- the quality values QCW and QCN of each signal are calculated from the two demodulated signals XCW and XCN having different qualities depending on the interference situation, and the calculated quality values QCW and QCN are calculated.
- a higher-quality demodulated signal can be determined based on the QCN comparison result.
- Delay sections 16 and 17 delay demodulated signals XCW and XCN, respectively, and output the result to selection section 19.
- the selecting section 19 selects one of the demodulated signals XCW and XCN with good quality according to the judgment result output from the judging section 80, and outputs the selected result to the error correcting section 5 as the demodulated signal DO.
- delay sections 16 and 17 delay demodulated signals XCW and XCN, respectively, by the time required for quality value detection, comparison, and determination in determination section 80, for example.
- delay sections 16 and 17 delay demodulated signals XCW and XCN, respectively, by the time required for quality value detection, comparison, and determination in determination section 80, for example.
- the two transmissions output from the carrier interpolation unit 50 due to a change in the interference situation, etc.
- the OFDM demodulation unit 4 can quickly follow this change and output an appropriate demodulated signal DO.
- the delay units 16 and 17 may not be provided. In this case, the circuit cost required for the delay units 16 and 17 can be reduced.
- the carrier interpolation unit 50 has been described as having two types of filters, but may be provided with more types of filters. Also in this case, waveform equalization based on the transmission path characteristics obtained by each filter may be performed, and the demodulated signal with the highest quality may be selected from the demodulated signals obtained as a result. Since the accuracy of the quality of the demodulated signal can be selected more flexibly in accordance with the interference situation, the reception performance of the OFDM receiver can be improved.
- the carrier interpolation unit 50 has been described as including a plurality of filters having different pass bands (pass band widths).
- a plurality of filters whose bands are shifted from each other may be provided.
- two filters with a pass bandwidth of TuZ4 are provided, one with a passband of 0 to TuZ4 (center position is TuZ2), and the other with a passband of one TuZ8 to + TuZ8 (center position is TuZ8). 0).
- the accuracy of the quality of the demodulated signal can be selected more flexibly even in the case of multipath interference having various delay times, so that the reception performance of the OFDM receiver can be improved.
- a plurality of filters having different passbands and having their passbands shifted may be provided.
- the OFDM receiver performs demodulation of a received OFDM signal based on transmission path characteristics obtained from each of a plurality of filters having different characteristics (passbands). Equalization is performed, and a signal having the best quality is determined and selected from a plurality of demodulated signals obtained as a result. For this reason, it is possible to improve the reception performance of the OFDM receiving apparatus without depending on the guard period length, even in a situation where there is a possibility that a gap of Gaussian noise interference and multipath interference may occur.
- FIG. 9 is a block diagram illustrating a configuration example of the OFDM demodulation unit 204 according to the second embodiment of the present invention.
- an OFDM demodulation section 204 is used instead of the OFDM demodulation section 4 in the OFDM receiving apparatus of FIG.
- the OFDM demodulation section 204 in FIG. 9 includes a transmission path characteristic estimation section 220 instead of the transmission path characteristic estimation section 20 in the OFDM demodulation section 4 in FIG.
- the other components are the same as those described with reference to FIG. 2, and thus the same reference numerals are given and the description will be omitted.
- the channel characteristic estimating unit 220 includes a channel characteristic calculating unit 30, a symbol interpolating unit 40, and carrier interpolating units 53 and 54.
- the transmission line characteristic calculation unit 30 is the same as that described with reference to FIG.
- the symbol interpolation unit 40 includes a wideband filter 43 having different characteristics and a narrowband filter 44. These filters have different passbands.
- the wideband filter 43 and the narrowband filter 44 perform inter-symbol interpolation by filtering the channel characteristics HP supplied from the divider 32 in the symbol direction.
- the wideband filter 43 outputs the obtained transmission path characteristic HSW to the carrier interpolation unit 53, and the narrowband filter 44 outputs the obtained transmission path characteristic HSN to the carrier interpolation unit 54.
- the interpolated transmission path characteristics HSW and HSN are obtained for the position of the symbol CT in FIG.
- each of the wide band filter 43 and the narrow band filter 44 is configured by an FIR filter.
- the wideband filter 43 is configured as a first-order interpolation filter
- the narrow-band filter 44 is configured as a zeroth-order interpolation filter.
- wideband filter 43 performs linear interpolation in accordance with symbol timing, based on transmission path characteristics HP corresponding to pilot signals obtained every four symbols.
- transmission path characteristics HP corresponding to pilot signals obtained every four symbols In the case of large fluctuations in the transmission line characteristics over time during mobile reception, etc. (during fogging disturbance), a relatively high estimation accuracy for the transmission line characteristics can be ensured, but the noise suppression effect is relatively low, so noise At the time of disturbance, estimation accuracy may be degraded.
- the narrowband filter 44 performs interpolation using the average value of the transmission path characteristic HP corresponding to the pilot signal inserted into the symbols before and after the received symbol, and the passband width is wideband. Narrower than filter 43. Therefore, when there is a large variation in the channel characteristics over time, such as when fading occurs, the estimation accuracy for the channel characteristics deteriorates. Since the effect of suppressing power noise is relatively high, a relatively high estimation accuracy can be assured during noise interference.
- Carrier interpolation section 53 performs inter-carrier interpolation on transmission path characteristic HSW, and outputs the obtained interpolated transmission path characteristic HCW to division section 61.
- the carrier interpolation unit 54 interpolates the transmission path characteristics HSN between carriers, and outputs the obtained interpolated transmission path characteristics HCN to the division unit 62.
- the quality values of the two demodulated signals XCW and XCN signals having different qualities depending on the interference situation are calculated, and based on the calculated quality values. ! /, And higher quality demodulated signals can be selected.
- the symbol interpolating unit 40 has the power described above as including two types of filters.
- the symbol interpolating unit 40 may include more types of filters.
- waveform equalization based on the transmission path characteristics obtained by each filter is performed, and the highest quality demodulated signal may be selected from the demodulated signals obtained as a result. Since the accuracy of the quality of the demodulated signal can be selected more flexibly in accordance with the interference situation, the reception performance of the OFDM receiver can be improved.
- FIG. 10 is a block diagram showing a configuration of an OFDM demodulation unit according to a modification of the second embodiment.
- the OFDM demodulation section 304 in FIG. 10 is a transmission path characteristic estimation section instead of the transmission path characteristic estimation section 220, the equalization section 60, the determination section 80, the delay section 17 and the selection section 19 in the OFDM demodulation section 204 in FIG. 320, an equalizing unit 360, a judging unit 380, a delaying unit 17A and a selecting unit 319, respectively, and further including a delaying unit 17B.
- the transmission path characteristic estimating section 320 is connected to the carrier interpolation section 54 in the transmission path characteristic estimating section 220. Instead, a carrier interpolation unit 350 is provided.
- the carrier interpolation unit 350 has a wideband filter 351 and a narrowband filter 352 as carrier interpolation filters.
- the wide band filter 351 and the narrow band filter 352 are similar to the wide band filter 51 and the narrow band filter 52 of FIG. 2, respectively.
- Equalization section 360 includes division sections 61, 62A, and 62B.
- the determination unit 380 includes quality detection units 81, 82A, 82B, and a comparison unit 383.
- the wideband filter 351 and the narrowband filter 352 perform carrier-to-carrier interpolation on the transmission path characteristics HSN supplied from the symbol interpolation unit 42 by performing carrier-direction filtering.
- Broadband filter 351 outputs obtained transmission path characteristic HCW1 to division section 62A
- narrowband filter 352 outputs obtained transmission path characteristic HCN1 to division section 62B.
- Dividing section 62A divides OFDM signal Y in the frequency domain supplied from FFT section 12 by transmission path characteristic HCW1, and outputs demodulated signal XCN1 to delay section 17A and quality detecting section 82A. Output.
- Dividing section 62B divides frequency domain OFDM signal Y supplied from FFT section 12 by transmission path characteristic HCN1, and outputs the obtained demodulated signal XCN2 to delay section 17B and quality detecting section 82B.
- Quality detection section 82A detects quality value QCN1 of demodulated signal XCN1, and outputs the detection result to comparison section 383.
- Quality detecting section 82B detects quality value QCN2 of demodulated signal XCN2, and outputs the detection result to comparing section 383.
- the comparing unit 383 compares the quality values QCW, QCN1 and QCN2, determines the highest quality, and outputs the determination result to the selecting unit 319.
- the delay units 17A and 17B are the same as the delay unit 16, and delay the demodulated signals XCN1 and XCN2, respectively, and output the delayed signals to the selection unit 319.
- Selection section 319 selects one of the demodulated signals XCW, XCN1 and XCN2 having the best quality according to the determination result output from determination section 380, and outputs the selected result to error correction section 5 as demodulated signal DO. .
- OFDM demodulation section 304 in FIG. 10 selection can be made from more demodulated signals according to the situation of noise interference, multipath interference, fading interference, and the like, so that the reception performance can be further improved.
- the carrier interpolation units 53 and 54 in the OFDM demodulation unit 204 in FIG. 9 and the carrier interpolation unit 53 in the OFDM demodulation unit 304 in FIG. Taka It is assumed that both have the same characteristics as the broadband filter 351.
- the OFDM demodulation section 304 sets the amount of noise to be superimposed to be smaller than any of the other transmission path characteristics HCW, HCN, and HCW1. Since characteristic HCN1 can be obtained, reception performance in a noise interference environment can be improved as compared with OFDM demodulation section 204.
- a carrier interpolation section 350 may be provided instead of carrier interpolation section 53. That is, four kinds of transmission path characteristics are calculated, waveform equalization is performed based on each transmission path characteristic to obtain four kinds of demodulated signals, and the highest quality demodulated signal is selected.
- FIG. 11 is a block diagram showing a configuration example of the OFDM demodulation section 404 according to the third embodiment of the present invention.
- an OFDM demodulation section 404 is used instead of the OFDM demodulation section 4 in the OFDM receiving apparatus of FIG.
- OFDM demodulation section 404 in FIG. 11 includes quadrature detection section 11, FFT section 12, transmission path characteristic calculation section 30, symbol interpolation section 40, equalization section 460, determination section 480, delay section 416, 417, a selection unit 419, a carrier interpolation unit 453, and a division unit 463.
- the same components as those described with reference to FIGS. 2 and 9 are denoted by the same reference numerals, and description thereof will be omitted.
- Equalization section 460 includes division sections 461 and 462.
- the division unit 461 divides the frequency-domain OFDM signal Y supplied from the FFT unit 12 by the transmission path characteristic HSW output from the wideband filter 43, and outputs the obtained demodulated signal XSW to the quality detection unit 481. I do.
- Dividing section 462 divides frequency-domain OFDM signal Y supplied from FFT section 12 by transmission path characteristic HSN output from narrowband filter 44, and obtains demodulated signal XSN, which is obtained by quality detecting section 482. Output to
- the division sections 461 and 462 are based on these transmission path characteristics.
- the quality of the demodulated signals XSW and XSN obtained in each of the above will also differ depending on the interference situation.
- the transfer obtained by the symbol interpolation unit 40 is The channel characteristics HSW and HSN are obtained at the position indicated by the symbol CT of the carrier on which the pilot signal is transmitted in FIG. 4, and the demodulated signals XSW and XSN obtained by the equalizer 460 are obtained. Are also in these same positions!
- the determination section 480 includes quality detection sections 481 and 482 and a comparison section 483. These components are configured in the same manner as in the determination unit 80 of FIG. Judging section 480 judges which one of the demodulated signals XSW and XSN has higher quality (has better quality).
- Quality detection section 481 detects quality value QSW of demodulated signal XSW and outputs the detection result to comparison section 483.
- Quality detecting section 482 detects quality value QSN of demodulated signal XSN and outputs the detection result to comparing section 483.
- the comparing section 483 compares the quality value QSW with the quality value QSN to judge the higher quality, and outputs the judgment result to the selecting section 419.
- the determination unit 480 configured as above, the quality values QSW and QSN of the two demodulated signals XSW and XSN having different qualities depending on the interference situation are calculated, and the calculated quality values QSW and QSN are calculated. Based on the QSN comparison result, it is possible to determine the transmission path characteristics with higher estimation accuracy.
- Delay sections 416 and 417 delay transmission path characteristics HSW and HSN, respectively, and output the result to selection section 419.
- Selection section 419 selects one of the transmission path characteristics HSW and HSN having good quality according to the determination result output from determination section 480, and outputs the selected transmission path characteristic HS to carrier interpolation section 453.
- delay sections 416 and 417 delay transmission path characteristics HSW and HSN, respectively, by the time required for processing in equalization section 460 and determination section 480, for example.
- delay sections 416 and 417 delay transmission path characteristics HSW and HSN, respectively, by the time required for processing in equalization section 460 and determination section 480, for example.
- the delay units 416 and 417 may not be provided. In this case, it is possible to reduce the circuit cost required for the delay units 416 and 417.
- Carrier interpolating section 453 provides carrier for transmission path characteristic HS selected by selecting section 419. Interpolation between carriers is performed by filtering in the direction.
- the carrier interpolation unit 453 outputs the interpolated transmission path characteristics HC to the division unit 463. As shown in FIG. 5, the interpolated transmission path characteristic HC is obtained at the position of the symbol CF.
- Dividing section 463 divides frequency-domain OFDM signal Y supplied from FFT section 12 by transmission path characteristic HC, and outputs obtained demodulated signal DO. That is, division section 463 performs waveform equalization of frequency-domain OFDM signal Y, and compensates for waveform distortion due to multipath generated in the transmission path.
- the amount of calculation in the determination unit can be reduced.
- FIG. 12 is a block diagram illustrating a configuration example of the OFDM demodulation section 504 according to the fourth embodiment of the present invention.
- the OFDM demodulation unit 504 includes a quadrature detection unit 11, an FFT unit 12, a transmission path characteristic calculation unit 30, a symbol interpolation unit 42, a carrier interpolation unit 50, a noise removal unit 70, a difference detection unit 583, It includes delay units 516 and 517, a selection unit 519, and a division unit 461.
- the quadrature detection unit 11, FFT unit 12, channel characteristic calculation unit 30, symbol interpolation unit 42, and carrier interpolation unit 50 are the same as those described with reference to FIG. You.
- the noise removal unit 70 calculates the impulse response by performing IFFT on the transmission path characteristic HP, removes a noise component superimposed on the transmission path characteristic HP based on the impulse response, and The channel characteristics HP 'are output to the symbol interpolation unit 42.
- the noise removing section 70 includes an IFFT section 71, a zero substitution section 72, an FFT section 73, and an end substitution section 74.
- FIG. 13 is a schematic diagram showing an example of the magnitude I HP I of the transmission path characteristics of a received OFDM signal with respect to a pilot carrier when noise is superimposed on the OFDM signal.
- the magnitude I HPI of the transmission path characteristics is constant in an ideal case, but in FIG. 13, distortion occurs over the entire band.
- IFFT section 71 performs IFFT for each symbol on transmission path characteristic HP obtained in transmission path characteristic calculation section 30 to convert a frequency domain signal into a time domain signal!
- the obtained time-domain signal that is, the impulse response is output to the zero replacement unit 72.
- This The impulse response of is obtained in the form of a complex signal (vector) having components in each direction of I-axis and Q-axis.
- FIG. 14 is a diagram showing the level (square of magnitude) of the impulse response obtained by IFFT section 71 of FIG. As can be seen in Fig. 14, the level of the transmission path characteristic has a local peak. The noise component is distributed over the floor of the entire area. The zero replacement unit 72 removes this impulse response noise component.
- FIGS. 15A and 15B are diagrams respectively showing impulse responses before and after noise component removal.
- the zero replacement unit 72 sets a threshold to a predetermined level.
- the zero replacement unit 72 calculates the sum of the square value of the I-axis component and the square value of the Q-axis component of the impulse response output from the IFFT unit 71 as the power of the impulse response.
- the comparison with the set threshold value is performed, the impulse response indicating power smaller than the threshold value is replaced with “0 vector”, and the impulse response indicating power smaller than the threshold value! / Is output to the FFT unit 73 as it is.
- the zero substitution unit 72 outputs the impulse response after substitution as shown in FIG.
- FFT section 73 performs FFT on the impulse response after removing the noise component, converts the FFT into a signal in the frequency domain again, and outputs the signal to end replacement section 74.
- FIG. 16 is a diagram illustrating transmission path characteristics obtained by the FFT unit 73 in FIG. As shown in FIG. 16, the characteristics at both ends of the band may be degraded due to the effect of data truncation.
- the end replacement unit 74 is provided to bypass the above-described noise removal processing for the purpose of avoiding characteristic deterioration at both ends of the band.
- the end replacement unit 74 outputs, as it is, the transmission line characteristics within a predetermined frequency band including the center of the band, out of the transmission line characteristics output from the FFT unit 73, In other words, the transmission line characteristics around the band edge (low-band portion and high-band portion) where the characteristic deterioration is large are replaced with the transmission line characteristics HP before removing the noise component and output.
- the end replacement unit 74 outputs the obtained transmission path characteristic HP 'to the symbol interpolation unit 42. At this time, noise was removed from the transmission path characteristic HP 'at the center of the band not subjected to substitution, and noise was removed from the transmission path characteristic HP' at the end of the substituted band. It has not been done.
- FIG. 17 is a diagram showing transmission path characteristics HP ′ obtained by the noise removing unit 70 of FIG. As shown in Fig. 17, the effect of noise is removed at the center of the band, but the noise remains at both ends of the band without being removed.
- the IFFT may be performed by multiplying the transmission path characteristic HP by an appropriate window function.
- the channel characteristics obtained in 73 may be divided by this window function.
- the symbol interpolating unit 42 performs interpolation in the symbol direction by performing inter-symbol filtering on the transmission path characteristic HP 'after noise removal, and performs carrier interpolation on the transmission path characteristic HS after symbol interpolation. It outputs to the wide band filter 51 and the narrow band filter 52 of the section 50.
- the wideband filter 51 and the narrowband filter 52 calculate the transmission path characteristics HCW and HCN, respectively.
- the wideband filter 51 outputs the obtained transmission path characteristics HCW to the delay section 516 and the difference detection section 583, and the narrowband filter 52 outputs the obtained transmission path characteristics HCN to the delay section 517 and the difference detection section 583. I do.
- the transmission path characteristics HS obtained by interpolating the output of the noise removing unit 70 in the symbol direction have noise removed at the center of the band. For this reason, among the transmission path characteristics HCW and HCN obtained from each of the wide band filter 51 and the narrow band filter 52 in the noise disturbance environment, there is almost no difference between the two in the center of the band due to the influence of noise.
- difference detecting section 583 provides transmission path characteristic H at the center (or a part thereof) of the band.
- the presence or absence of a difference between the CW and the transmission path characteristic HCN (or that the value of the difference exceeds a certain range) is detected, and the detection result is output to the selection unit 519.
- the difference value of the I-axis component and the difference value of the Q-axis component are calculated for the transmission path characteristic HCW and the transmission path characteristic HCN at the center of the band.
- the sum of the squares may be calculated as the difference power for each carrier, and the determination may be made based on whether or not the maximum value of the difference power exceeds a predetermined value.
- the magnitude of the difference power between the transmission path characteristic HCW and the transmission path characteristic HCN in the center band is accumulated over the entire carriers belonging to the center band, and it is determined based on whether the accumulation result exceeds a predetermined value. You may.
- the difference detection unit 583 the difference may be detected at the center of the band or a part of the center of the band.
- Delay sections 516 and 517 delay transmission path characteristics HCW and HCN, respectively, and output the result to selection section 519.
- the selection unit 519 selects one of the transmission path characteristics HCW and HCN based on the detection result output from the difference detection unit 583, and outputs the selected transmission path characteristic HC to the division unit 461. .
- the noise suppression effect is obtained.
- the transmission path characteristic HCN obtained from the high and narrow band filter 52 is selected and output as the transmission path characteristic HC for the entire band. As a result, it is possible to obtain transmission path characteristics in which the influence of noise at both ends is reduced.
- delay sections 516 and 517 delay transmission path characteristics HCW and HCN, respectively, by the time required for processing in difference detection section 583, for example. Then, there is a difference between the timing at which the transmission path characteristics HC W and HCN are input to the selection section 519 and the timing at which the detection result of the difference detection section 583 is input to the selection section 519 for these transmission path characteristics. But Disappears. Therefore, even when the estimation accuracy of the two transmission path characteristics HCW and HCN output from the carrier interpolation unit 50 changes, the OFDM demodulation unit 504 can quickly follow the change.
- Dividing section 461 divides OFDM signal Y in the frequency domain by transmission path characteristic HC, and performs waveform equalization of OFDM signal Y in the frequency domain. Thus, division section 461 compensates for waveform distortion caused by multinos interference generated on the transmission path, and outputs demodulated signal DO obtained as a result.
- the transmission path characteristics HC for the entire band obtained in this way are obtained by appropriately selecting from the outputs of a plurality of filters used for estimating the transmission path characteristics in an environment where noise interference or multipath interference exists. Therefore, if waveform equalization is performed using this transmission path characteristic, which has a high estimation accuracy of the transmission path, the reception performance can be improved. Further, since a plurality of filter output powers can be selected for each symbol, the tracking performance under an environment in which the transmission path characteristics fluctuate is very excellent.
- the delay units 516 and 517 may not be provided. In this case, it is possible to reduce the circuit cost required for the delay units 516 and 517.
- the selection section 519 selects the transmission path of the entire band.
- the characteristics either of the transmission path characteristics HCW and HCN may be selected, or the transmission path characteristic HCW is always selected for the center of the band, and the transmission path characteristic HCW is used only for the band end. It is also possible to select from among HCN and HCN! As described above, since the influence of noise is removed from the transmission path characteristics in the center of the band, there is no problem even if the transmission path characteristics HCW are always used in the center of the band.
- one of the transmission path characteristics may be selected for only one edge, for example, only the edge on the high frequency side. In this case, the amount of hardware of the delay units in the delay units 516 and 517 can be reduced.
- FIG. 18 is a block diagram illustrating a configuration of OFDM demodulation section 604 according to a modification of the fourth embodiment.
- the OFDM demodulation unit 604 is similar to the OFDM demodulation unit 504 in FIG.
- a noise removing unit 670 is provided in place of the unit 70, and the noise removing process is performed after the symbol interpolation process.
- the symbol interpolation unit 42 interpolates the transmission path characteristics HP obtained by the transmission path characteristic calculation unit 30 in the symbol direction by performing inter-symbol filtering, and performs transmission path characteristics after symbol interpolation. Is output to the noise removing unit 670.
- the noise removing section 670 includes an IFFT section 671, a zero replacement section 672, an FFT section 673, and an end replacement section 674, and has almost the same configuration as the noise removing section 70 in FIG. I have.
- the noise removing unit 670 removes a noise component superimposed on the transmission path characteristics from the transmission path characteristics output from the symbol interpolation unit 42 in the same manner as the noise removing unit 70, and widens the transmission path characteristics HS after the noise removal. Output to the filter 51 and the narrow band filter 52.
- the present invention does not depend on the interference condition of the transmission path such as Gaussian noise or multipath, and does not depend on the guard period length. Since it can improve the estimation accuracy and improve the quality of the demodulated signal, it is useful as an OFDM receiver that receives OFDM signals for digital broadcasting, wireless LAN, etc.
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- Physics & Mathematics (AREA)
- Discrete Mathematics (AREA)
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- Mathematical Physics (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
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Abstract
Description
Claims
Priority Applications (3)
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US10/570,769 US7519122B2 (en) | 2004-05-07 | 2005-05-09 | OFDM reception apparatus and OFDM reception method |
JP2006513014A JP4728227B2 (ja) | 2004-05-07 | 2005-05-09 | Ofdm受信装置及びofdm受信方法 |
EP05737201A EP1744480A1 (en) | 2004-05-07 | 2005-05-09 | Ofdm receiver apparatus and ofdm receiving method |
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JP2004138195 | 2004-05-07 | ||
JP2004-138195 | 2004-05-07 |
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EP (1) | EP1744480A1 (ja) |
JP (1) | JP4728227B2 (ja) |
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CN (1) | CN1842982A (ja) |
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Cited By (21)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
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JP2008124964A (ja) * | 2006-11-15 | 2008-05-29 | Fujitsu Ltd | チャネル推定装置 |
JP2008131309A (ja) * | 2006-11-20 | 2008-06-05 | Sharp Corp | Ofdm復調装置及びofdm復調方法 |
JP2008167088A (ja) * | 2006-12-27 | 2008-07-17 | Matsushita Electric Ind Co Ltd | Ofdm受信装置 |
JP2008236716A (ja) * | 2007-02-22 | 2008-10-02 | Oki Electric Ind Co Ltd | Ofdm受信機とドップラー周波数推定回路 |
WO2008129825A1 (ja) * | 2007-03-27 | 2008-10-30 | Panasonic Corporation | Ofdm受信装置、ofdm受信方法、ofdm受信回路、集積回路、及びプログラム |
WO2009069420A1 (ja) * | 2007-11-27 | 2009-06-04 | Panasonic Corporation | 信号復調装置、信号復調方法、半導体集積回路および受信装置 |
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JP2012178635A (ja) * | 2011-02-25 | 2012-09-13 | Kyocera Corp | チャネル推定装置およびチャネル推定方法 |
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Families Citing this family (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8027508B2 (en) * | 2003-07-09 | 2011-09-27 | Digimarc Corporation | Interactive gaming objects |
FR2897998A1 (fr) * | 2006-02-27 | 2007-08-31 | St Microelectronics Sa | Procede et dispositif d'estimation de la fonction de transfert du canal de transmission pour demodulateur cofdm |
FR2897999A1 (fr) * | 2006-02-27 | 2007-08-31 | St Microelectronics Sa | Procede et dispositif d'estimation de la fonction de transfert du canal de transmission pour demodulateur cofdm |
CN101455015A (zh) * | 2006-05-25 | 2009-06-10 | 夏普株式会社 | 接收机和传送路径推断方法 |
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US7830994B2 (en) * | 2006-10-18 | 2010-11-09 | Analog Devices, Inc. | Channel estimation system and method |
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US7979032B2 (en) * | 2007-12-18 | 2011-07-12 | Intel Corporation | Estimating statistical properties of noise in modulated data carrier signals |
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US8325790B2 (en) * | 2009-08-03 | 2012-12-04 | Analog Devices, Inc. | Equalization for OFDM communication |
KR101065590B1 (ko) * | 2009-08-21 | 2011-09-20 | 한국전기연구원 | 임펄스성 잡음의 영향을 감소시키기 위한 다중 반송파 기반의 데이터 복조 방법 및 그 장치 |
US8917799B2 (en) * | 2009-10-27 | 2014-12-23 | Maxlinear, Inc. | Edge equalizer |
JP5275304B2 (ja) * | 2010-08-30 | 2013-08-28 | 株式会社東芝 | Ofdm受信装置 |
US8823806B2 (en) * | 2011-02-18 | 2014-09-02 | Wi-Lan, Inc. | Method and apparatus for television band pilot sensing |
TWI551064B (zh) * | 2012-12-27 | 2016-09-21 | 晨星半導體股份有限公司 | 無線接收系統及其頻道效應估計方法 |
CN103929380B (zh) * | 2013-01-10 | 2017-04-26 | 晨星软件研发(深圳)有限公司 | 无线接收系统及其频道效应估计方法 |
WO2015107677A1 (ja) * | 2014-01-17 | 2015-07-23 | 三菱電機株式会社 | 受信装置および受信方法 |
US9691378B1 (en) * | 2015-11-05 | 2017-06-27 | Amazon Technologies, Inc. | Methods and devices for selectively ignoring captured audio data |
US11146422B1 (en) * | 2020-07-29 | 2021-10-12 | U-Blox Ag | Method and system for adjusting the bandwidth of a frequency domain smoothing filter for channel tracking loop in an OFDM communication system |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH1075226A (ja) * | 1996-08-30 | 1998-03-17 | Jisedai Digital Television Hoso Syst Kenkyusho:Kk | 直交周波数分割多重信号復調装置 |
JPH10257013A (ja) * | 1997-03-14 | 1998-09-25 | Toshiba Corp | 受信装置 |
JPH11163822A (ja) * | 1997-11-26 | 1999-06-18 | Jisedai Digital Television Hoso System Kenkyusho | Ofdm用受信装置 |
JP2000059267A (ja) * | 1998-06-02 | 2000-02-25 | Canon Inc | 通信方法及び装置並びに記憶媒体 |
JP2001189768A (ja) * | 1999-12-28 | 2001-07-10 | Matsushita Electric Ind Co Ltd | 同期検波装置 |
JP2005045628A (ja) * | 2003-07-24 | 2005-02-17 | Fujitsu Ltd | Ofdm通信方式の受信装置 |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5519730A (en) * | 1990-06-12 | 1996-05-21 | Jasper; Steven C. | Communication signal having a time domain pilot component |
JP3006679B2 (ja) * | 1997-01-16 | 2000-02-07 | 日本電気株式会社 | セルラー移動電話システム |
JP3842614B2 (ja) * | 2001-10-30 | 2006-11-08 | 日本放送協会 | 周波数特性算出回路およびそれを用いたキャンセラならびに装置 |
US7209433B2 (en) * | 2002-01-07 | 2007-04-24 | Hitachi, Ltd. | Channel estimation and compensation techniques for use in frequency division multiplexed systems |
JP3955594B2 (ja) * | 2002-05-17 | 2007-08-08 | 松下電器産業株式会社 | 受信装置及び受信方法 |
DE60321401D1 (de) * | 2003-05-12 | 2008-07-10 | Mitsubishi Electric Corp | Demodulationseinrichtung und demodulationsverfahren |
US7433433B2 (en) * | 2003-11-13 | 2008-10-07 | Telefonaktiebolaget L M Ericsson (Publ) | Channel estimation by adaptive interpolation |
US7693227B2 (en) * | 2005-03-31 | 2010-04-06 | Texas Instruments Incorporated | Channel length estimation and accurate FFT window placement for high-mobility OFDM receivers in single frequency networks |
-
2005
- 2005-05-09 CN CNA200580000838XA patent/CN1842982A/zh active Pending
- 2005-05-09 KR KR1020067004597A patent/KR20070006662A/ko not_active Application Discontinuation
- 2005-05-09 TW TW094114954A patent/TW200608723A/zh unknown
- 2005-05-09 WO PCT/JP2005/008431 patent/WO2005109712A1/ja not_active Application Discontinuation
- 2005-05-09 JP JP2006513014A patent/JP4728227B2/ja not_active Expired - Fee Related
- 2005-05-09 US US10/570,769 patent/US7519122B2/en not_active Expired - Fee Related
- 2005-05-09 EP EP05737201A patent/EP1744480A1/en not_active Withdrawn
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH1075226A (ja) * | 1996-08-30 | 1998-03-17 | Jisedai Digital Television Hoso Syst Kenkyusho:Kk | 直交周波数分割多重信号復調装置 |
JPH10257013A (ja) * | 1997-03-14 | 1998-09-25 | Toshiba Corp | 受信装置 |
JPH11163822A (ja) * | 1997-11-26 | 1999-06-18 | Jisedai Digital Television Hoso System Kenkyusho | Ofdm用受信装置 |
JP2000059267A (ja) * | 1998-06-02 | 2000-02-25 | Canon Inc | 通信方法及び装置並びに記憶媒体 |
JP2001189768A (ja) * | 1999-12-28 | 2001-07-10 | Matsushita Electric Ind Co Ltd | 同期検波装置 |
JP2005045628A (ja) * | 2003-07-24 | 2005-02-17 | Fujitsu Ltd | Ofdm通信方式の受信装置 |
Non-Patent Citations (1)
Title |
---|
FUJITA C ET AL: "MC-CDMA Nobori Kaisen ni Okeru MMSE Gosei o Mochiita Multi User Kansho Yokuatsu.", THE INSTITUTE OF ELECTRONICS, INFORMATION AND COMMUNICATION ENGINEERS., 20 November 2001 (2001-11-20), pages 1 - 66, XP008114991 * |
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Also Published As
Publication number | Publication date |
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JPWO2005109712A1 (ja) | 2008-03-21 |
CN1842982A (zh) | 2006-10-04 |
KR20070006662A (ko) | 2007-01-11 |
US20070036232A1 (en) | 2007-02-15 |
JP4728227B2 (ja) | 2011-07-20 |
US7519122B2 (en) | 2009-04-14 |
EP1744480A1 (en) | 2007-01-17 |
TW200608723A (en) | 2006-03-01 |
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