Abstract: An interference cancellation device includes a data symbol extraction unit that extracts a data symbol portion from a received signal, a null symbol extraction unit that extracts a null symbol portion from the received signal, a data symbol power calculation unit that calculates a data symbol power estimated value, a null symbol power calculation unit that calculates a null symbol power estimated value, a null symbol spectrum calculation unit that calculates a null symbol spectrum from a null symbol signal, and an interference center frequency estimation unit that eliminates the effect of an image for an interference in calculation of an interference bandwidth when is calculating an interference center frequency estimated value, using a data symbol signal, the data symbol power estimated value, the null symbol power estimated value, and the null symbol spectrum.

Abstract: A radio communication device that receives signals by using a plurality of reception antennas in a radio communication system employing multi-station simultaneous transmission includes: processing circuitry that estimates channel information on the basis of training symbol sequences, which are different depending on the base-station antennas, included in received signals, and outputs a channel information estimation result; performs a channel matrix extending process of extending dimension of a channel matrix on the basis of the channel information estimation result and a coding rule of the received signals, and extending array's degree of freedom; generates an interference suppression weight by using the channel matrix resulting from the channel matrix extending process; and extends dimension of a received signal vector by using a result of observation over symbol duration time for a plurality of symbols, and multiplies the received signal vector resulting from the extension of dimension by the interference

Abstract: A transmission device included in one base station in a radio communication system including communication areas adjacent to each other in which the base station communicates with a plurality of wireless terminals includes: a modulation unit that generates a data symbol sequence; a synchronization signal generating unit that generates a first symbol sequence constituted by two or more continuous repetitions of reference sequence symbols being a reference, generates a second symbol sequence by performing frequency shifting on the first symbol sequence by using a phase rotation sequence so that the reference sequence symbols become orthogonal for each of the wireless terminals, and generates a synchronization signal; and a synchronization signal adding unit that generates a transmission signal by adding the synchronization signal to the data symbol sequence.

Abstract: A reception device includes an interference cancellation unit to extract a symbol from a received signal with a first signal inserted in a time direction of a data symbol, the symbol being a signal during an interval corresponding to the first signal, to reproduce an interference signal during an interval corresponding to the data symbol, and to output a first interference-cancelled signal obtained by extracting the data symbol from a signal obtained by cancelling the interference signal from the received signal, and an interference-power estimation unit to estimate desired signal power by subtracting second average power of a symbol of a first signal, extracted from the received signal, from first average power the data symbol to estimate first noise power by subtracting the desired signal power from third average power of the data symbol, to estimate second noise power from the first noise power, and to estimate interference power by subtracting the second noise power from the second average power.

Abstract: An interference cancellation device includes a data symbol extraction unit that extracts a data symbol portion from a received signal, a null symbol extraction unit that extracts a null symbol portion from the received signal, a data symbol power calculation unit that calculates a data symbol power estimated value, a null symbol power calculation unit that calculates a null symbol power estimated value, a null symbol spectrum calculation unit that calculates a null symbol spectrum from a null symbol signal, and an interference center frequency estimation unit that eliminates the effect of an image for an interference in calculation of an interference bandwidth when is calculating an interference center frequency estimated value, using a data symbol signal, the data symbol power estimated value, the null symbol power estimated value, and the null symbol spectrum.

Abstract: A radio communication system according to the present invention is a radio communication system including a transmission device and a reception device, the transmission device includes a first null insertion unit that inserts a first signal that is a signal having an electric power lower than an amplitude of the data symbols, in a time direction of data symbols, and the reception device includes a null extraction unit that extracts a first symbol that is a signal in a period corresponding to the first signal, from a received signal, a signal interpolation unit that interpolates the first symbol to reproduce interference components in periods corresponding to the data symbols, and a subtraction unit that subtracts the interference components from the received signal.

Abstract: A reception device includes an interference cancellation unit to extract a symbol from a received signal with a first signal inserted in a time direction of a data symbol, the symbol being a signal during an interval corresponding to the first signal, to reproduce an interference signal during an interval corresponding to the data symbol, and to output a first interference-cancelled signal obtained by extracting the data symbol from a signal obtained by cancelling the interference signal from the received signal, and an interference-power estimation unit to estimate desired signal power by subtracting second average power of a symbol of a first signal, extracted from the received signal, from first average power the data symbol to estimate first noise power by subtracting the desired signal power from third average power of the data symbol, to estimate second noise power from the first noise power, and to estimate interference power by subtracting the second noise power from the second average power.

Abstract: A radio communication system according to the present invention is a radio communication system including a transmission device and a reception device, the transmission device includes a first null insertion unit that inserts a first signal that is a signal having an electric power lower than an amplitude of the data symbols, in a time direction of data symbols, and the reception device includes a null extraction unit that extracts a first symbol that is a signal in a period corresponding to the first signal, from a received signal, a signal interpolation unit that interpolates the first symbol to reproduce interference components in periods corresponding to the data symbols, and a subtraction unit that subtracts the interference components from the received signal.

Abstract: A reception device according to the present invention includes: a signal division unit; a maximum-likelihood point search unit; a maximum-likelihood point search unit; a replica-vector calculation unit; a replica-vector calculation unit; and a likelihood calculation unit. Wherein, the signal division unit divides a reception signal including a plurality of multiplexed signals respectively into a real component and an imaginary component; the maximum-likelihood point search unit narrows down candidate signal points; the maximum-likelihood point search unit to narrows down candidate signal points; the a replica-vector calculation unit calculates a first replica vector by using the first candidate signal point; the replica-vector calculation unit calculates a second replica vector by using the second candidate signal point; and the likelihood calculation unit calculates a likelihood of the modulation signal by using the first replica vector and the second replica vector.

Abstract: A timing estimation device according to the present invention includes a received signal memory that outputs a plurality of sample groups each of which is a first number of samples extracted at symbol rate intervals from an oversampled received signal containing a known sequence, with shifting their leading positions by one sample from each other, a reliability calculation unit that calculates a channel impulse response for each of the sample groups, based on the sample group, generates a replica of the received signal using the channel impulse response and the known sequence, and calculates a reliability value based on the sample group, the replica, and the channel impulse response, and a timing estimation unit that estimates a preceding wave arrival timing and a delayed wave arrival timing, based on the reliability value.

Abstract: A maximum likelihood sequence estimation circuit includes: a signal extraction unit that estimates a reception sample signal including a preceding wave component and a reception sample signal including a delayed wave component from a plurality of reception sample signals sampled from a reception signal at sample intervals shorter than symbol intervals, and extracts, based on an estimation result, both first reception sample signals and second reception sample signals from the plurality of reception sample signals at the symbol intervals; and a maximum likelihood sequence estimation unit that estimates a maximum likelihood sequence using the first reception sample signals extracted and the second reception sample signals extracted.

Abstract: A timing estimation device according to the present invention includes a received signal memory that outputs a plurality of sample groups each of which is a first number of samples extracted at symbol rate intervals from an oversampled received signal containing a known sequence, with shifting their leading positions by one sample from each other, a reliability calculation unit that calculates a channel impulse response for each of the sample groups, based on the sample group, generates a replica of the received signal using the channel impulse response and the known sequence, and calculates a reliability value based on the sample group, the replica, and the channel impulse response, and a timing estimation unit that estimates a preceding wave arrival timing and a delayed wave arrival timing, based on the reliability value.

Abstract: A maximum likelihood sequence estimation circuit includes: a signal extraction unit that estimates a reception sample signal including a preceding wave component and a reception sample signal including a delayed wave component from a plurality of reception sample signals sampled from a reception signal at sample intervals shorter than symbol intervals, and extracts, based on an estimation result, both first reception sample signals and second reception sample signals from the plurality of reception sample signals at the symbol intervals; and a maximum likelihood sequence estimation unit that estimates a maximum likelihood sequence using the first reception sample signals extracted and the second reception sample signals extracted.

Abstract: A demodulation apparatus includes: a synchronization detector to extract a reception mapping point from a reception signal transmitted wirelessly and modulated by a modulation scheme associating discrete values with the mapping points on a complex plane; a reception mapping point corrector to correct the extracted reception mapping points and to output post-correction mapping points; a hard-decision determiner to determine that a reference mapping point having a minimum error with the post-correction mapping point is a reference mapping point to be outputted as a demodulation result based on the inputted error vectors; a reference mapping point estimator to update the reference mapping point to be outputted as the demodulation result using the post-correction mapping points; and a correction coefficient updater to update the correction coefficient using the error between the reference mapping point to be outputted as demodulation result and the post-correction mapping point.

Abstract: A signal generating device includes a first digital filter unit outputting a first interpolated signal by interpolating an input signal, a second digital filter unit outputting a second interpolated signal by interpolating the first interpolated signal, a phase calculation unit calculating a phase of a digital signal, a phase-accuracy conversion unit calculating first phase signal and second phase signal, a first memory storing filter coefficients, a first coefficient readout unit reading filter coefficients from the first memory and switching filter coefficients of the first digital filter unit, a phase-error calculation unit calculating a phase error signal, a second memory storing filter coefficients, a second coefficient readout unit reading filter coefficients from the second memory, and a gain normalization unit normalizing a gain of the filter coefficients to maintain a constant sum of the filter coefficients and switching filter coefficients of the second digital filter unit.

Abstract: A signal generating device includes a first digital filter unit outputting a first interpolated signal by interpolating an input signal, a second digital filter unit outputting a second interpolated signal by interpolating the first interpolated signal, a phase calculation unit calculating a phase of a digital signal, a phase-accuracy conversion unit calculating first phase signal and second phase signal, a first memory storing filter coefficients, a first coefficient readout unit reading filter coefficients from the first memory and switching filter coefficients of the first digital filter unit, a phase-error calculation unit calculating a phase error signal, a second memory storing filter coefficients, a second coefficient readout unit reading filter coefficients from the second memory, and a gain normalization unit normalizing a gain of the filter coefficients to maintain a constant sum of the filter coefficients and switching filter coefficients of the second digital filter unit.

Abstract: A transmitter is capable of suppressing a PAPR to be low and efficiently amplifying transmit power. The transmitter generates a transmission signal by oversampling a modulated signal, and includes a modulation unit that performs a modulation process on an information sequence and that generates a constant envelope signal and a phase interpolation unit that inserts a predetermined number of signals identical in amplitude to signal points of the constant envelope signal between the signal points so that signal points including original signal points are located equidistantly.

Abstract: A transmitter is capable of suppressing a PAPR to be low and efficiently amplifying transmit power. The transmitter generates a transmission signal by oversampling a modulated signal, and includes a modulation unit that performs a modulation process on an information sequence and that generates a constant envelope signal and a phase interpolation unit that inserts a predetermined number of signals identical in amplitude to signal points of the constant envelope signal between the signal points so that signal points including original signal points are located equidistantly.

Abstract: A radio communication device which when transmitting both a first information sequence, on which ?/4-shift differential phase shift modulation is performed, as a delayed wave and a second information sequence, on which a differential phase shift modulation is performed, as an advance wave by using a PADM (Per transmit Antenna Differential Mapping) method, interchanges signal points respectively belonging to quadrants which are one of a first quadrant and a third quadrant, a second quadrant and a fourth quadrant, the first quadrant and the second quadrant, the first quadrant and the fourth quadrant, the second quadrant and the third quadrant, and the third quadrant and the fourth quadrant, the signal points being included in signal points mapped onto a complex plane which consists of a real number axis and an imaginary number axis, to change the arrangement of the information sequence.

Abstract: A signal generation device includes: filter banks that perform sampling frequency conversion with respect to an input signal of a predetermined sampling frequency, and generate a signal obtained after the sampling frequency conversion as an output signal; a control-signal generation unit that selects the filter banks to be used based on a sampling-frequency setting value indicating a sampling frequency of the output signal: and a switching unit selects the filter banks based on a result of selection by the control-signal generation unit.