Abstract: A wireless communication method in a wireless communication system which includes a radio transmitting station apparatus having a plurality of antennas and a radio receiving station apparatus having an antenna and which performs transmission and reception of a radio signal with a single carrier. The wireless communication method includes: estimating a communication path matrix based on a training signal; transforming the estimated communication path matrix into a frequency domain, transforming a complex conjugate transposed matrix of each of a unitary matrix and an adjoint matrix obtained by performing singular value decomposition for each frequency with respect to the transformed frequency domain communication path matrix into a time domain, and adopting each as a reception weight matrix and a transmission weight matrix; performing transmission beam formation based on the transmission weight matrix; and performing reception beam formation based on the reception weight matrix.

Abstract: In a wireless communication system for performing single-carrier MIMO transmission, a transmitting station apparatus includes a training signal generation unit and a transmit beamforming unit that performs transmit beamforming processing using transmit weights and a receiving station apparatus includes a communication path estimation unit, an interference amount determination unit that determines whether or not a residual inter-stream interference exceeds a predetermined threshold value, a receive weight calculation unit that calculates a receive weight used for receive beamforming processing when the residual inter-stream interference exceeds the threshold value, and a receive beamforming unit that performs receive beamforming processing for suppressing residual inter-stream interferences using the receive weight.

Abstract: A system including a plurality of base stations and terminal stations. A base station includes a transmission signal amplifier enabled to vary transmission power, provides a specification regarding an input-output characteristic of the transmission signal amplifier to a terminal station, and provides transmission power to the terminal station. The terminal station estimates a constellation of a signal points on the basis of the transmission power and the specification, detects a coordinate point on constellation coordinates, of a reception signal, and detects interference power received from base stations and that are not communication partners. Further, a reception point is calculated in which an influence of the interference power is reflected on the coordinate point, and a likelihood with the signal points is calculated for the reception point. Then, a symbol intended by the reception signal is specified on the basis of a calculation result of the likelihood.

Abstract: A radio communication method including detecting an SNR of a line performing radio communication, and determining whether or not there is a margin of a predetermined value or more in the detected SNR for each line with respect to a required SNR of the line performing radio communication. Further, there is a changing of a frame configuration for each line to shorten a frame length within a range of the required SNR or more even when the SNR is degraded for the line determined to have a margin of a predetermined value or more, and executing processing to perform radio communication by the frame configuration changed for each line via the line determined to have a margin of a predetermined value or more.

Abstract: Provided is a wireless communication system using a single-carrier multi-value modulation scheme, the wireless communication system aiming at preventing erroneous transmission of data and securing a high data rate while utilizing a non-linear region of an amplifier. A reception apparatus acquires, from a transmission apparatus, a specification related to an input/output characteristic of a transmission signal amplifier and transmission power of data transmission. On the basis of the specification and the transmission power, a constellation of signal points is estimated. A reception point, which is a point in constellation coordinates, of a reception signal is detected, and likelihood calculation for the reception point is performed with respect to the signal points. A symbol intended by the reception point is identified on the basis of a result of the likelihood calculation.

Abstract: A wireless communication method according to an embodiment includes precoding a stream of a transmission signal in a time domain by using an FIR filter, controlling a transmission power of the precoded stream, amplifying the precoded stream such that the controlled transmission power is obtained; and performing control for changing a tap length in precoding such that the tap length is decreased in a case where a magnitude of a last tap coefficient in precoding is small and the tap length is increased in a case where the magnitude is large, with respect to a threshold value calculated on the basis of quality information of a received signal fed back from a reception device that has received the amplified stream or quality information of a received signal calculated by using at least characteristics of an amplifier.

Abstract: A communication system capable of continuing communication even when the communication quality of a specific wireless channel is poor, with wireless channels used by each set of station apparatuses fixed. The communication system includes a first line switching apparatus that switches a first communication line connected to a first station apparatus, a second line switching apparatus that switches a second communication line connected to a second station apparatus, and a wireless channel allocation means that performs allocation from among a plurality of wireless communication channels to communication between the first communication line and the second communication line. The first line switching apparatus transmits, to the second line switching apparatus, a port number signal indicating a port number at which a signal is input from the first communication line to the first line switching apparatus. The second line switching apparatus specifies the port number of the second line switching apparatus.

Abstract: The present disclosure relates to a wireless communication system using a quadrature amplitude modulation scheme. A transmission device includes: a transmission signal amplifier enabled to vary transmission power; a transmission power control unit that controls the transmission power; and an approximate pattern information notification unit that generates pattern information on an approximate constellation. In a case where 64 QAM is used as the modulation scheme, a 64 QAM distortion constellation is generated in the non-linear region of the transmission signal amplifier. In this case, a 64 APSK approximate constellation is generated, and pattern information on the 64 APSK approximate constellation is transmitted to a reception device. The reception device performs likelihood calculation for a reception point indicated by a data signal by using the approximate constellation corresponding to the pattern information.

Abstract: A radio communication system according to one embodiment is a radio communication system that performs MIMO transmission, the radio communication system including: a precoding unit that precodes multi-streams of transmission signals in a time domain; a plurality of transmission power control units that controls transmission power of each multi-stream precoded by the precoding unit; a plurality of amplification units that amplifies each multi-stream precoded by the precoding unit in accordance with control of the plurality of transmission power control units; and a number-of-taps control unit that performs control to change the number of taps of the precoding unit to improve communication quality of the multi-streams on the basis of quality information of a received signal fed back from a reception device that has received the multi-stream amplified by each of the plurality of amplification units or quality information of a received signal calculated using at least characteristics of the plurality of amplifica

Abstract: An accompanying matrix adjH(z, t) of a transfer function matrix H(z, t) established between a transmission station and a reception station is defined as a transmission weight WT(z). An M sequence part is divided into two blocks to obtain an M sequence first half part and an M sequence second half part. A training symbol #1 having the M sequence second half part and the M sequence first half part in that order and a training symbol #2 having the M sequence first half part and the M sequence second half part in that order are processed by the transmission weight WT(z). In the receiving station, a virtual training signal block having the M sequence part S and the M sequence first half part is generated. A communication path response R(m) is calculated by a slide correlation method for the virtual training signal block.

Abstract: A transmission station device includes a training signal generation unit, a CP addition unit, and a transmission beamforming unit that performs transmission beamforming processing in a time domain using a transmission weight for removing inter-antenna interference. A reception station device includes a CP removal unit, a channel estimation unit, and an equalization unit that performs equalization processing for removing inter-symbol interference in a frequency domain using a reception weight. Either of the transmission station device or the reception station device is provided with a weight calculation unit that calculates the transmission weight and the reception weight based on the channel response, an effective CIR length calculation unit that calculates an effective CIR length between antennas, and a CP length setting unit that sets, to the CP length, a maximum CIR length among the CIR lengths of respective items of the reception weight.

Abstract: A radio wave arrival direction estimation device according to an embodiment includes an antenna angle acquisition unit that acquires each of antenna angles indicating a plurality of different directions in which antennas having non-uniform antenna patterns are sequentially directed, a reception intensity measurement unit that measures reception intensities at which the antenna has received a radio wave at each of the antenna angles acquired by the antenna angle acquisition unit, a matching degree Calculation unit that calculates a matching degree between the antenna angle acquired by the antenna angle acquisition unit and the reception intensity measured by the reception intensity measurement unit, and an antenna pattern of the antenna for each antenna angle acquired by the antenna angle acquisition unit, and an estimation unit that estimates an antenna angle at which the matching degree Calculated by the matching degree Calculation unit is the maximum as an arrival direction of the radio wave.

Abstract: A wireless communication system according to an embodiment is a wireless communication system, in which a transmission device transmits the training signal to a reception device such that a plurality of signal points having different amplitudes on a constellation is included, and the reception device includes: an estimation unit that estimates the signal points included in the training signal of a case where it is assumed that, an input-output characteristic in a non-linear region of an amplifier is also linear; an equalization unit that performs initial equalization on a received signal; a correction unit that corrects a signal subjected to initial equalization by the equalization unit on the basis of the signal points estimated by the estimation unit; a likelihood calculation unit that calculates, with respect to a constellation before the amplifier amplifies a signal, a likelihood of a signal corrected by the correction unit.

Abstract: A transmission apparatus including the number of antennas different from a reception apparatus and performing transmission by SC-MIMO to and from the reception apparatus includes a training signal generation unit that generates a known signal predetermined, a CP addition unit that adds a CP to each symbol of a transmission signal including the known signal, a weight generation unit that generates a transmission weight based on a transposed adjugate matrix that is a product of a channel matrix estimated based on the known signal by the reception apparatus and a complex conjugate transpose of the channel matrix, and a transmission beam formation unit that uses the transmission weight to form a transmission beam for the transmission signal where the CP is added.

Abstract: A transmission apparatus including the number of antennas different from a reception apparatus and performing transmission by SC-MIMO to and from the reception apparatus includes a training signal generation unit that generates a known signal predetermined, a CP addition unit that adds a CP to each symbol of a transmission signal including the known signal, a weight generation unit that multiplies a channel matrix estimated based on the known signal by the reception apparatus by a pseudo-inverse matrix obtained by a predetermined number of iterative calculations to generate a transmission weight that is diagonalizable, and a transmission beam formation unit that uses the transmission weight to form a transmission beam for the transmission signal where the CP is added.

Abstract: A channel estimation method in which a reception device performs channel estimation on the basis of a known signal transmitted by a transmission device divides and arranges a known signal having a predetermined length in frames, transmits the known signal divided and arranged in the frames together with a data signal as a radio frame, receives the transmitted radio frame, calculates a data signal component including a delay wave component from the received radio frame, extracts a plurality of known signal components each including a delay wave component of the divided and arranged known signal by subtracting the data signal component from the received radio frame, concatenates the plurality of extracted known signal components to restore a known signal having a predetermined length, and performs channel estimation on the basis of the restored known signal having a predetermined length.

Abstract: An aggregation station: receives, from each of the base stations, communication path information with each of accommodated user terminals, for each user terminal; in a case where it is determined that the two of the base stations and the two user terminals are arranged on the straight line, generates first information for performing setting such that a transmission beam of any one of the base stations arranged on the straight line is stopped and another of the base stations non-orthogonally superimposes and multiplexes pieces of transmission data for the two respective user terminals with a predetermined power difference or power ratio; and controls the transmission beam of each of the two of the base stations arranged on the straight line on the basis of the first information.

Abstract: An adjoint matrix adjH(z, t) of a transfer function matrix H(z, t) established between a transmission station and a reception station is defined as a transmission weight WT(z). A training signal multiplied by the transmission weight WT(z) is transmitted from transmission antennas toward a reception station. M sequence portions S included in the received training signals #1 and #2 are connected in series to generate a virtual training signal block. A communication path response R(m) implemented by using the transmission weight WT(z) is calculated by calculating a correlation between both an M sequence portion S and a comparison sequence portion at each position while sliding the comparison sequence portion with respect to the virtual training signal block. Based on the communication path response R(m), a reception equalization weight WR(z) corresponding to an inverse response det{H(z, t)}?1 of a determinant det{H(z, t)} of the transfer function matrix H(z, t) is calculated.

Abstract: An aggregation station receives, from each of the base stations, communication path information with each of accommodated user terminals, for each user terminal; transmission weights of respective transmission beams transmitted by the plurality of the respective base stations are calculated such that the transmission beams transmitted by the plurality of the respective base stations arranged on the straight line to the plurality of respective user terminals are shifted by a half wavelength or more for the respective user terminals, on the basis of the communication path information for each user terminal received, in a case where it is determined that the plurality of the base stations and the plurality of user terminals are arranged on the straight line; and the base stations transmit the respective transmission beams on the basis of the respective transmission weights calculated.

Abstract: A wireless communication method in a wireless communication system which includes a radio transmitting station apparatus having a plurality of antennas and a radio receiving station apparatus having an antenna and which performs transmission and reception of a radio signal with a single carrier, the wireless communication method including: the radio receiving station apparatus or the radio transmitting station apparatus estimating a communication path matrix based on a training signal; the radio receiving station apparatus or the radio transmitting station apparatus transforming the communication path matrix into a frequency domain, calculating a pseudo inverse matrix for each frequency with respect to the transformed frequency domain communication path matrix, and transforming the calculated pseudo inverse matrix into a time domain and adopting as a transmission weight matrix; and the radio transmitting station apparatus forming a transmission beam based on the transmission weight matrix.