Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Takaya Hayashi

Kenichiro Hayashi

Daisuke Hayashi

Tetsuya Yagi

Shigeru Soga

Seiji Sakashita

Toshihiko Fukuoka

Takehiro Kamada

Tomohiko Taniguchi

A time from the start of a reception operation to the output of video, audio or the like is shortened. An OFDM reception apparatus is provided for receiving an OFDM signal composed of a plurality of carriers, comprising a fast Fourier transform section for converting a received time-domain OFDM signal into a frequency-domain OFDM signal, an equalization section for performing waveform equalization with respect to the frequency-domain OFDM signal, and outputting the waveform-equalized OFDM signal, and a modulation scheme estimating section for estimating a modulation scheme for a plurality of carriers constituting the waveform-equalized OFDM signal based on signal points of the plurality of carriers, and outputting an obtained estimation result. The OFDM reception apparatus performs a process for obtaining transmitted information with respect to the received OFDM signal, depending on the estimation result.

OFDM reception apparatus and OFDM reception method

An OFDM reception apparatus for receiving and demodulating an OFDM signal comprising a fast Fourier transform section for converting a received OFDM signal into a frequency-domain OFDM signal, a channel response calculation section for obtaining a channel response with respect to a carrier transmitting a pilot signal, from the frequency-domain OFDM signal, an interpolation section for interpolating the channel response, and outputting the result, a power calculation section for calculating the square of a magnitude of the interpolated channel response, as a carrier power, for each carrier corresponding to the channel response, an interference calculation section for calculating a degree of an influence of interference on the received OFDM signal, as an interference power, for each carrier corresponding to the interpolated channel response, and a carrier quality calculation section for calculating a ratio of the carrier power obtained to the interference power corresponding thereto, for each carrier.

An average power indicating channel characteristics is outputted from a reference value calculation unit as a reference value. An interference level corresponding to the degree of influence by frequency selective interference is outputted from an interference detection unit. A reliability determination unit determines a carrier that has been subjected to interference on the basis of the reference value and the interference level, to decide a reliability level. An error correction unit performs error correction of a demodulation signal on the basis of the reliability level.

Receiving apparatus and receiving method

Precision of channel estimation is improved. An OFDM reception apparatus for receiving and demodulating an OFDM signal which transmits a pilot signal, comprises a channel estimation section for calculating a channel response before interpolation by performing computation between a frequency-domain OFDM signal and the pilot signal, performing interpolation with respect to the before-interpolation channel response using a plurality of filters having different characteristics from each other, and outputting a plurality of interpolated channel responses based on respective results of the interpolation obtained by the plurality of filters, an equalization section for performing waveform equalization with respect to the frequency-domain OFDM signal based on the plurality of interpolated channel responses, and outputting a plurality of demodulated signals based on respective results of the waveform equalization corresponding to the plurality of interpolated channel responses, a determination section for determining one having best quality from the plurality of demodulated signals, and outputting a result of the determination, and a selection section for selecting and outputting one of the plurality of demodulated signals in accordance with the determination result.

A reception apparatus for receiving an OFDM signal having a plurality of pilot carriers that transmit predetermined pilot signals at predetermined symbols. The reception apparatus transforms the received OFDM signal to a frequency-domain OFDM signal, determines channel responses corresponding to the transmitted pilot signals for each of the pilot carriers among a plurality of carriers constituting the frequency-domain OFDM signal, determines, based on channel responses corresponding to first, second and third pilot signals transmitted sequentially in a same carrier, a channel response at a symbol between the second pilot signal and the third pilot signal, compensates a waveform distortion in the frequency-domain OFDM signal according to the channel response at the symbol between the second pilot signal and the third pilot signal and outputs the results.

Reception apparatus and method, and channel response measurement apparatus for receiving an orthogonal frequency divisional multiplexing signal

Integrating AFC/APC function with waveform equalization function for and reducing the circuit size of a signal wave-form equalizer apparatus. A waveform equalization section is divided into an FFE block as an anterior stage and a DFE block as a posterior stage. An AFC/APC block is provided therebetween. In the AFC/APC block, an AFC/APC coefficient update section updates a coefficient used for removing frequency and phase errors in accordance with an LMS algorithm, and a tap multiplies a modulated signal by the updated coefficient. Error data produced by an error estimation block is used by not only FFE and DFE coefficient update sections but also the AFC/APC coefficient update section for updating the coefficients. That is to say, the waveform equalization section and the AFC/APC block use the error estimation block in common, thereby reducing the circuit size considerably.

Signal waveform equalizer apparatus

A demodulation method for tentatively demodulating a modulated input signal by a signal having a fixed frequency to form a tentative complex demodulated signal and then generating a determined complex demodulated signal from the tentative complex demodulated signal. The method includes step (a) of obtaining a determined complex demodulated signal by compensating for the tentative complex demodulated signal based on an optimum phase compensation amount; step (b) of estimating an optimum frequency compensation amount based on a shift in the optimum phase compensation amount during a predetermined cycle; and step (c) of estimating an immediately subsequent optimum phase compensation amount to be used in the steps (a) and (b) performed in repetition, based on the tentative complex demodulated signal, the determined complex demodulated signal, and the optimum frequency compensation amount.

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Kyoto, Japan

Takaya Hayashi