摘要:
An OFDM receiver apparatus mounted on a movable object for receiving an OFDM signal, includes a plurality of directional antennas which receive an OFDM signal, an estimator to estimate a center frequency of a spectrum of a Doppler component from one of the received signals or a multiplexed signal obtained by multiplexing the received signals, a shift quantity calculator to calculate a shift quantity from the estimated center frequency of the estimator and directivity information representing directivity directions of the directional antennas, a plurality of frequency shifters to subject the received signals to frequency shift according to the shift quantity to compensate for Doppler shift, a combining unit to diversity-combine frequency shifted signals of the frequency shifters, and a demodulator/decoder to demodulate and decode combining diversity signals of the combining unit.
摘要:
An OFDM receiver apparatus mounted on a movable object for receiving an OFDM signal, includes a plurality of directional antennas which receive an OFDM signal, an estimator to estimate a center frequency of a spectrum of a Doppler component from one of the received signals or a multiplexed signal obtained by multiplexing the received signals, a shift quantity calculator to calculate a shift quantity from the estimated center frequency of the estimator and directivity information representing directivity directions of the directional antennas, a plurality of frequency shifters to subject the received signals to frequency shift according to the shift quantity to compensate for Doppler shift, a combining unit to diversity-combine frequency shifted signals of the frequency shifters, and a demodulator/decoder to demodulate and decode combining diversity signals of the combining unit.
摘要:
An OFDM demodulator that demodulates an OFDM signal includes an antenna that receives a signal including delayed signals, an estimation circuit that estimates the channel response of the received signal, and a control circuit that controls a length of a retention time interval based on the estimated channel response. The retention time interval includes a time period from the head of a delayed signal having a maximum delay time in the delayed signals to the tail of a preceding signal in the delayed signals based on the estimated channel response. The OFDM demodulator also includes a retention memory that retains a portion of the received signal corresponding to the retention time period, and a selection circuit that selects an OFDM symbol based on a calculation of a maximum likelihood that the retained received signal is equivalent to a signal replica based on the channel response.
摘要:
An OFDM demodulator that demodulates an OFDM signal includes an antenna that receives a signal including delayed signals, an estimation circuit that estimates the channel response of the received signal, and a control circuit that controls a length of a retention time interval based on the estimated channel response. The retention time interval includes a time period from the head of a delayed signal having a maximum delay time in the delayed signals to the tail of a preceding signal in the delayed signals based on the estimated channel response. The OFDM demodulator also includes a retention memory that retains a portion of the received signal corresponding to the retention time period, and a selection circuit that selects an OFDM symbol based on a calculation of a maximum likelihood that the retained received signal is equivalent to a signal replica based on the channel response.
摘要:
A diversity receiver device includes N antennas to receive OFDM signals, N digital filters to filter the signals received by the N antennas in order to reduce delay spread, K (K≦N) beamforming units configured to subject the filtered signals to a beamforming process by using combining weights, an eigen-decomposition unit configured to subject the filtered signals to eigen-decomposition to generate N eigenvalues, a weight setting unit configured to select K eigenvalues in descending order from the generated N eigenvalues in order to set eigenvectors corresponding to the K eigenvalues to the beamforming units as the combing weight, respectively, K FFT units configured to subject the output signals of the beamforming units to fast Fourier transformation to output FFT signals, and a diversity combining unit configured to combine the FFT signals.
摘要:
Orthogonal frequency division multiplexing demodulation apparatus includes: antenna to receive signal including holding period including part of period ranging from leading portion of delayed wave of maximum-delay time to trailing portion of preceding wave, unit estimating channel response of signal received by antenna, unit holding, based on channel response, first-signal component contained in holding period, first-signal component including second-signal component which is contained in period of preset length which is included in holding period, unit acquiring filter-bank outputs by subjecting second-signal component to frequency conversion, unit generating replicas for each of filter-bank outputs, based on estimated-channel response, frequency response of each of filter-bank outputs, and candidates for modulation signal corresponding to subcarrier included in each of filter-bank outputs, unit selecting one of replicas which minimizes quantity corresponding to differences between components of each of filter-bank outputs and components of replicas, and unit determining modulation signal based on selected replica.
摘要:
Orthogonal frequency division multiplexing demodulation apparatus includes: antenna to receive signal including holding period including part of period ranging from leading portion of delayed wave of maximum-delay time to trailing portion of preceding wave, unit estimating channel response of signal received by antenna, unit holding, based on channel response, first-signal component contained in holding period, first-signal component including second-signal component which is contained in period of preset length which is included in holding period, unit acquiring filter-bank outputs by subjecting second-signal component to frequency conversion, unit generating replicas for each of filter-bank outputs, based on estimated-channel response, frequency response of each of filter-bank outputs, and candidates for modulation signal corresponding to subcarrier included in each of filter-bank outputs, unit selecting one of replicas which minimizes quantity corresponding to differences between components of each of filter-bank outputs and components of replicas, and unit determining modulation signal based on selected replica.
摘要:
A receiver comprising: an antenna which receives a radio signal including N possible symbols {c1(n), c2(n), . . . cM−1(n), cM(n)}, an N correlation units which are provided corresponding to the N possible symbols, respectively, each correlation unit detecting the degree of correlation with the radio signal received by the antenna, and a symbol determination unit which determines the symbol included in the radio signal received by the antenna based on the degree of correlation detected by the N correlation units. The N correlation units detect the degree of correlation between the radio signal received by the antenna and the N possible symbols represented by M chips {α0c1(n), α0c2(n)+α1c1(n), . . . , α0cM−1(n)+α1cM−2(n), α0cM(n)+α1cM−1(n)}.
摘要:
A receiver comprising: an antenna which receives a radio signal including N possible symbols {c1(n), c2(n), cM−1(n), cM(n)}, an N correlation units which are provided corresponding to the N possible symbols, respectively, each correlation unit detecting the degree of correlation with the radio signal received by the antenna, and a symbol determination unit which determines the symbol included in the radio signal received by the antenna based on the degree of correlation detected by the N correlation units. The N correlation units detect the degree of correlation between the radio signal received by the antenna and the N possible symbols represented by M chips {α0c1(n),α0c2(n)+α1c1(n), . . . ,α0cM−1(n)+α1cM−2(n), α0cM(n)+α1cM−1(n)}.
摘要:
According to an aspect of the present invention, there is provided with an OFDM (Orthogonal Frequency Division Multiplexing) transmission apparatus, including: a subcarrier modulator configured to perform subcarrier modulation on a data sequence to generate subcarrier modulated signals; an IFFT unit configured to perform IFFT (Inverse Fast Fourier Transform) processing on the subcarrier modulated signals to generate a first OFDM symbol having a length corresponding to the number of FFT points at the IFFT processing; a symbol length shortener configured to obtain a part of the generated first OFDM symbol as a second OFDM symbol; and a transmitter configured to transmit the second OFDM symbol obtained to an other communication apparatus.