Abstract: A wireless communication apparatus includes a plurality of antennas, transmits a plurality of known symbol sequences each including a plurality of known symbols by using the antennas, each of the known symbols having subcarrier arrangement on which plural known information of the each of the known symbols are carried on, and inversion/non-inversion of a phase of known information on one of two adjacent subcarriers of the subcarrier arrangement being controlled in accordance with the number of the known symbols and time position of the each of the known symbols, and transmits data symbols by using the antennas after the known symbol sequences are transmitted.

Abstract: A wireless communication apparatus having a plurality of antennas for transmitting a known symbol by using a plurality of subcarriers to a receiver, the known symbol including known information, the apparatus includes each of the subcarriers which carries the known information being classified into at least two groups, and a phase control unit configure to control inversion/non-inversion of a phase of the known information carried on two subcarriers which belong to the same group in accordance with notification information to be notified to the receiver.

Abstract: A wireless device, method, and signal for use in communication of a wireless packet between transmitting device and a wireless receiving device via a plurality of antennas, wherein a signal generator generates wireless packet including a short-preamble sequence used for a first automatic gain control (AGC), a first long-preamble sequence, a signal field used for conveying a length of the wireless packet, an AGC preamble sequence used for a second AGC to be performed after the first AGC, a second long-preamble sequence, and a data field conveying data. The AGC preamble sequence is transmitted in parallel by the plurality of antennas.

Abstract: A wireless communication apparatus includes a plurality of antennas, transmits a plurality of known symbol sequences each including a plurality of known symbols by using the antennas, each of the known symbols having subcarrier arrangement on which plural known information of the each of the known symbols are carried on, and inversion/non-inversion of a phase of known information on one of two adjacent subcarriers of the subcarrier arrangement being controlled in accordance with the number of the known symbols and time position of the each of the known symbols, and transmits data symbols by using the antennas after the known symbol sequences are transmitted.

Abstract: An estimation apparatus for estimating a channel response of a radio propagation path using a received signal including a first known signal, comprises a generator which generates a reference signal matrix, a calculator which calculates a generalized inverse matrix of the reference signal matrix including singular values which exceed a preset threshold value, an estimation unit configured to estimate an impulse response of the radio channel modeled using a transversal filter based on the first known signal and the generalized inverse matrix, and a converter which converts the estimated impulse response into a frequency-domain signal to acquire a frequency transfer function of the channel.

Abstract: There is provided with a radio communication apparatus for communicating with a receiver. A transmission rate control unit in the radio communication apparatus specifies a signal having small variation of a metric, which is an index for evaluating a channel of the signal, out of first to nth signals to be transmitted to the receiver. The transmission rate control unit controls a transmission rate of a specified signal based on a channel responses and a transmission weight of the specified signal and controls a transmission rate of each of other signals different from the specified signal out of the first to nth signals based on a relationship between a variation characteristic of a metric of the specified signal and a variation characteristic of a metric of each of the other signals.

Abstract: A wireless communication apparatus generates transmission signal including first and second pilot signal sequences allocated to first and second frequencies symmetrically located in relation to a center frequency, and third and fourth pilot signal sequences allocated to third and fourth frequencies symmetrically located in relation to the center frequency, quadrature-modulates the transmission signal, to obtain a quadrature modulation signal, quadrature-demodulates the quadrature modulation signal, to obtain a reception signal, extracts first to fourth pilot signal sequences from the reception signal, estimates a first transfer characteristic concerning first and second frequency by using first and second pilot signal sequences, estimates a second transfer characteristic concerning third and fourth frequencies using third and the fourth pilot signal sequences, generates a third transfer characteristic from which an influence of transmission IQ imbalance is removed by using first and second transfer characteri

Abstract: A radio communications apparatus executing transmit beam forming includes a receiver which receives an estimate value of a propagation path response, a computer which calculates a weighting matrix to be used for the transmit beam forming, in accordance with the estimate value, a correcting unit which corrects a component, of components of the weighting matrix, and a beam forming unit which executes beam forming using the weighting matrix corrected by the correcting unit and executes radio transmission.

Abstract: The wireless transmission apparatus generates one or a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols for channel estimation, each OFDM symbol including plural subcarriers and having a known signal sequence of known signals which are linearly independent between adjacent subcarriers, and transmits the OFDM symbols.

Abstract: Radio communication apparatus for receiving OFDM signal from base station and transmitting FH signal to base station, using sub-channels, base station comparing hopping pattern information items indicating hopping patterns from radio communication apparatuses including radio communication apparatus, and generating collision information when hopping patterns include colliding hopping patterns, includes estimation unit configured to estimate channel response values of sub-channels based on OFDM signal, selector which selects, from sub-channels, several sub-channels which have higher channel response values than a value, each of channel response values being expressed by power level, signal-to-noise power ratio, or signal-to-interference ratio, determination unit configured to determine hopping pattern from selected sub-channels, transmitter which transmits, to base station, hopping pattern information item indicating determined hopping pattern, receiver which receives collision information from base station, an

Abstract: Before data is transmitted from a plurality of antennas, a plurality of known symbol sequences are transmitted from these antennas. Each known symbol sequence contains a plurality of known symbols having different subcarrier arrangements. Known symbols transmitted from different antennas have different subcarrier arrangements.

Abstract: A wireless communication apparatus receives an quadrature modulated signal, generate a local signal having a frequency different from a center frequency of the quadrature modulated signal, performs quadrature demodulation on the quadrature modulated signal by using the local signal, to obtain an I channel signal and a Q channel signal, performs Fourier transform on the I channel signal and the Q channel signal, to obtain signals in a frequency domain, and calculates a first correction coefficient for correcting phase distortion and amplitude distortion caused by the quadrature demodulation by using pairs of signals among the signals, each of the pairs are located at symmetrical frequency positions with respect to the frequency of the local signal.

Abstract: A receiver of an OFDM signal includes a reception unit to receive an OFDM signal formed by a plurality of OFDM symbols respectively including data subcarriers to which data signals are allocated and pilot subcarriers to which cyclically shifted pilot signals are allocated in frequency domain, an estimator to estimate phase errors of the pilot signals to generate first estimated values related to an offset of the OFDM symbol corresponding to each two or more OFDM symbols in the OFDM signal, a weighting adder to perform weighting additions on the first estimated values to obtain one second estimated value related to the offset, a compensator to compensate the offset by using the second estimated value to obtain a compensated OFDM signal, and a decoder to decode the compensated OFDM signal to reproduce the data signals.

Abstract: A receiving method receiving an OFDM signal including a first OFDM symbol having first and second pilot signals allocated to first and second subcarriers positioned symmetric on the frequency axis, and a second OFDM symbol having third and fourth pilot signals allocated to the first and the second subcarriers, a difference between a product of the first pilot signal and a complex conjugate of the fourth pilot signal and a product of the third pilot signal and a complex conjugate of the second pilot signal being non-zero, estimating a first coefficient representing a change components of an amplitude and a phase, and a second coefficient representing an interference component, using first and second received pilot signals corresponding to the first and third pilot signals, estimating from the first and second coefficients IQ imbalance, and compensating the influence of amplitude and phase errors in accordance with the IQ imbalance.

Abstract: A wireless receiving apparatus includes antennas, a receiving unit configured to receive multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) signals via the antennas, an estimation unit configured to estimate channel response values of subcarriers included in the MIMO-OFDM signals, a first computation unit configured to compute an estimated channel-response error common to the subcarriers based on the estimated channel response values, a response correction unit configured to correct the estimated channel response values using the estimated channel-response error, and a second computation unit configured to perform preprocessing for demodulating the MIMO-OFDM signals, using the corrected channel response values.

Abstract: A wireless communication method includes generating and transmitting an OFDM signal containing a first OFDM symbol possessing a first transmitting pilot signal and a second transmitting pilot signal respectively allocated to a first subcarrier and a second subcarrier being symmetric with respect to a center frequency on a frequency axis, and a second OFDM symbol possessing a third transmitting pilot signal and a fourth transmitting pilot signal respectively allocated to the first subcarrier and the second subcarrier, wherein a difference between a product of a first transmitting pilot signal and a complex conjugate of a fourth transmitting pilot signal and a product of a third transmitting pilot signal and a complex conjugate of a second transmitting pilot signal is non-zero.

Abstract: A transmitting method of OFDM signal includes allocating first and second channel estimation preamble signals for channel response estimation respectively to +kth and ?kth subcarriers from center frequency of first OFDM signal, allocating first and second pilot signals for residual phase offset estimation respectively to +kth and ?kth subcarriers from center frequency of second OFDM signal, transmitting first and second OFDM signals respectively in different time zones using at least one antenna, where, first product of complex conjugate of first channel estimation preamble signal and second pilot signal is equal to second product of second channel estimation preamble signal and complex conjugate of first pilot signal.

Abstract: A radio apparatus includes a first radio-frequency unit configured to receive a reception signal transmitted from a communication partner, and configured to transmit a transmission signal to the communication partner, a second radio-frequency unit configured to receive a reception signal transmitted from the communication partner, configured to transmit a transmission signal to the communication partner, a baseband processing unit configured to be supplied with the reception signal from each of the first and second radio-frequency units, and supply, to each of the first and second radio-frequency units, data to be transmitted to the communication partner, and the baseband processing unit configured to generate a reference signal supplied to each of the first radio-frequency unit and the second radio-frequency unit, and a digital signal supplying unit configured to supply a digital signal containing the reference signal from the baseband processing unit to each of the first and second units.

Abstract: A radio communication system includes a plurality of radio communication terminals each of which includes a plurality of first antennas, and a radio communication apparatus including a plurality of second antennas, an acquisition unit configured to acquire a plurality of channel response values between the first antennas and the second antennas, a setting unit configured to set, based on the channel response values, a plurality of MIMO parameters, and a transmission unit configured to perform multicast transmission to each of the radio communication terminals via the second antennas, based on the MIMO parameters. The multicast transmission is performed based on a multiple-input multiple-output (MIMO) transmission scheme. Each of the radio communication terminals further includes a receiving unit which receives data transmitted from the radio communication apparatus by the multicast transmission.

Abstract: Radio communication apparatus includes unit dividing transmit data into first-and-second streams, unit subjecting first-and-second streams to serial-to-parallel conversion to obtain data signals, unit modulating data signals into OFDM-modulation signals corresponding to first and second streams using subcarriers, unit acquiring channel responses between communication and receiving apparatuses, unit computing singular values ?1(k) and ?2(k) of channel matrix corresponding to kth subcarrier in subcarriers, based on channel responses, unit assigning weights corresponding to singular values ?1(k) and ?2(k) to first-and-second streams where correspondence of weights to streams is different by subcarrier, unit multiplying, by each of assigned weights, OFDM-modulation signals corresponding to each of first and second streams, and acquire first-and-second signals corresponding to first-and-second streams, unit adding first-and-second signals to acquire added signals, unit subjecting added signals to inverse-Fourier t