Abstract: A receiver includes: a correlation value calculation unit calculating a first cross-correlation function between a received signal, having a preamble spread with an up chirp and a down chirp, and the up chirp and calculating a second cross-correlation function between the received signal and the down chirp; a power value calculation unit calculating first and second power values of the first and second cross-correlation functions; a correlation power memory storing the first and second power values at each sample timing for one period of a spread code; a threshold determination unit determining first and second estimated timings from the first and second power values for one period of the spread code, respectively; and an estimation unit estimating a spread code timing of a transmitter using the first and second estimated timings, and performing coarse estimation of a frequency offset with respect to the transmitter.

Abstract: A receiving apparatus that receives a signal modulated by a frequency modulation scheme, using a plurality of receiving antennas includes an FSK modulation-compatible interference extraction unit that extracts, from a plurality of reception signals received by the plurality of receiving antennas, interference signals that are frequency components other than frequency components of desired signals at which power is concentrated, a complex weight calculator that calculates a complex weight of each reception signal, on the basis of the same number of the interference signals as the number of the receiving antennas, and a complex weight multiplication and combining unit that multiplies each of the plurality of reception signals by the corresponding complex weight, and combines the reception signals that have been multiplied by the complex weights.

Abstract: A radio communication device switches a frequency channel to be used by using a predetermined hopping pattern during communication with a counterpart radio communication device, and includes a null determination unit that determines a position of a null symbol included in a received packet received from the counterpart radio communication device and an interference measuring unit that measures an interference amount by using the null symbol included in the received packet.

Abstract: A receiver includes: a correlation value calculation unit calculating a first cross-correlation function between a received signal, having a preamble spread with an up chirp and a down chirp, and the up chirp and calculating a second cross-correlation function between the received signal and the down chirp; a power value calculation unit calculating first and second power values of the first and second cross-correlation functions; a correlation power memory storing the first and second power values at each sample timing for one period of a spread code; a threshold determination unit determining first and second estimated timings from the first and second power values for one period of the spread code, respectively; and an estimation unit estimating a spread code timing of a transmitter using the first and second estimated timings, and performing coarse estimation of a frequency offset with respect to the transmitter.

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 transmitter includes: a phase rotation sequence generation unit that generates, on the basis of transmit bits being input, a phase rotation sequence in which a frequency response has a bandwidth; an up-sampling unit that changes a sample rate of the phase rotation sequence and further replicates the phase rotation sequence; and a frequency shift unit that shifts, by a specified amount of shift on a frequency axis, a frequency component of the phase rotation sequence acquired from the up-sampling unit.

Abstract: A receiving apparatus includes: a receiving module that is a fixed circuit whose internal processing procedure is not able to be changed, the receiving module performing demodulation processing on a reception signal to generate a binary hard decision sequence; and an external reception controller including a receiving module controller to control the receiving module, and a redundancy decoder to redundantly decode the binary hard decision sequence output from the receiving module for conversion into a multilevel sequence, wherein the redundancy decoder redundantly decodes the binary hard decision sequence by combining values weighted based on reliability.

Abstract: A transmission apparatus that transmits a block signal including a plurality of data symbols, includes: a data-symbol generation unit that generates a data symbol; a symbol arrangement unit that arranges the data symbol and a same-quadrant symbol such that one same-quadrant symbol that becomes a signal point in a same quadrant in a complex plane is inserted per block at a predetermined position in each block signal to generate a block symbol; a CP insertion unit that inserts a Cyclic Prefix into the block symbol; and an interpolation unit that performs interpolation processing on the block symbol on which CP insertion has been performed.

Abstract: A system includes: a transmitter including: a coding unit generating a first bit sequence by convolutional coding on information bits based on a code rate; a bit erasing unit generating a second bit sequence by erasing one or more bits from the first bit sequence for every predetermined first number of bits; and a modulation unit generating a symbol by modulation using the second bit sequence; and a receiver including: a demodulation unit calculating first reliabilities that can be derived from the symbol; a likelihood extension unit generating extended bit sequences each composed of bits for the first number of bits, and generating a plurality of second reliabilities by assigning first reliabilities duplicated, as the reliabilities of the extended bit sequences; and a decoding unit creating a trellis diagram using the code rate and the extended bit sequences, and assigning the second reliabilities to branches of the trellis diagram.

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 transmitter includes: a phase rotation sequence generation unit that generates, on the basis of transmit bits being input, a phase rotation sequence in which a frequency response has a bandwidth; an up-sampling unit that changes a sample rate of the phase rotation sequence and further replicates the phase rotation sequence; and a frequency shift unit that shifts, by a specified amount of shift on a frequency axis, a frequency component of the phase rotation sequence acquired from the up-sampling unit.

Abstract: A communication device includes a signal determiner determining whether there is a reception signal, and a period estimator estimating an interruption period of interruption of a signal transmitted from a device as a source of the reception signal, using a determination result from the signal determiner.

Abstract: A communication device includes a signal determiner determining whether there is a reception signal, and a period estimator estimating an interruption period of interruption of a signal transmitted from a device as a source of the reception signal, using a determination result from the signal determiner.

Abstract: A transmission apparatus that transmits a block signal including a plurality of data symbols, includes: a data-symbol generation unit that generates a data symbol; a symbol arrangement unit that arranges the data symbol and a same-quadrant symbol such that one same-quadrant symbol that becomes a signal point in a same quadrant in a complex plane is inserted per block at a predetermined position in each block signal to generate a block symbol; a CP insertion unit that inserts a Cyclic Prefix into the block symbol; and an interpolation unit that performs interpolation processing on the block symbol on which CP insertion has been performed.

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 transmission apparatus that transmits a block signal including a plurality of data symbols, includes: a data-symbol generation unit that generates a data symbol; a symbol arrangement unit that arranges the data symbol and a same-quadrant symbol such that one same-quadrant symbol that becomes a signal point in a same quadrant in a complex plane is inserted per block at a predetermined position in each block signal to generate a block symbol; a CP insertion unit that inserts a Cyclic Prefix into the block symbol; and an interpolation unit that performs interpolation processing on the block symbol on which CP insertion has been performed.

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 transmitter for use in a communication system uses a orthogonal modulation method, and the transmitter includes: an orthogonal sequence prescriber that prescribes association between orthogonal signals and information words determined on the basis of sizes of differences between information words of a plurality of mutually different information words and a probability of occurrence of decision errors between orthogonal signals of a plurality of mutually orthogonal signals; and a symbol mapper that, upon input of any of the information words, generates modulation symbols based on the orthogonal signals associated with the input information word according to the associations prescribed by the orthogonal sequence prescriber.