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: 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: 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 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: 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 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.

Abstract: An Internet Protocol (IP) phone system includes a traffic control device connected to a line. The traffic control device acquires a call duration of each of calls on one line shared by a plurality of IP phones, and sets a packet discard rate of each of the calls in a manner where the packet discard rate is proportional to the call duration until start of a new call so that total call traffic falls within a line capacity of the one line when the total call traffic exceeds the line capacity with the start of the new call.

Abstract: A base station is wirelessly connected to each of a plurality of subscriber stations accommodating one or more terminals and includes a detection unit configured to detect at least one of a change in the number of terminals in communication accommodated by each of the subscriber stations and a change in a radio wave environment with each of the subscriber stations; and a setting unit configured to set a modulation scheme of a minimum modulation order in which a total communication amount of all the terminals that perform communication is accommodatable for each of the subscriber stations in each of the subscriber stations based on the change detected by the detection unit and to set weighting of radio wave intensity in each of the subscriber stations so that communication quality in the modulation scheme of the minimum modulation order is maximized.

Abstract: According to the present invention, in a wireless communication system that performs single carrier MIMO transmission between a transmitting station device and a receiving station device, the transmitting station device includes a time-domain linear equalization unit, a propagation path characteristics estimation unit configured to receive a training signal and estimate a transfer function matrix of propagation path characteristics, a filter tap calculation unit configured to calculate filter tap coefficients for the time-domain linear equalization unit based on the transfer function matrix by a predefined approach, and a transmission mode determination unit configured to make the filter tap calculation unit calculate the filter tap coefficients when the transfer function matrix meets a predefined condition, and to change a transmission mode and determine the transmission mode that meets the predefined condition when the transfer function matrix does not meet the predefined condition.

Abstract: A transmission device includes a training signal generation unit that generates a predetermined existing signal used for a receiving device to estimate a communication channel response and a transmission beam-forming unit that forms a transmission beam for removing interstream interference with a transmission weight calculated based on the communication channel response estimated by the receiving device. The receiving device includes a communication channel estimation unit that receives the existing signal and estimates a communication channel response, a combination unit that combines a plurality of communication channel responses for each stream estimated with the existing signal from which the interstream interference has been removed, and an equalization unit that performs an equalization process of removing intersymbol interference for each stream with the reception weight calculated based on the communication channel responses combined by the combination unit.

Abstract: According to the present invention, in a wireless communication system that performs single carrier MIMO transmission between a transmitting station device and a receiving station device, the transmitting station device including: a time-domain linear equalization unit configured to remove inter-symbol interference and inter-stream interference from a data signal to be transmitted to the receiving station device; a propagation path characteristics estimation unit configured to receive a training signal which is transmitted by the receiving station device and estimate a transfer function matrix of propagation path characteristics; and a filter tap calculation unit configured to calculate filter tap coefficients for the time-domain linear equalization unit by representing the estimated transfer function matrix as a matrix polynomial, taking an inverse response of the matrix polynomial as a transmit weight matrix, and approximating the transmit weight matrix with Neumann series, and the receiving station device

Abstract: A congestion control method in an IP telephone system includes acquiring a number of simultaneous calls in one line shared by a plurality of IP telephones, acquiring a call time order corresponding to length of a call time for each call, and controlling a packet discard rate of each call on the basis of the number of simultaneous calls and the call time order. The packet discard rate of each call is set to a predetermined first upper limit value or less. In addition, the packet discard rate is set higher as the call time is longer, and the packet discard rate is set lower as the call time is shorter. Further, the packet discard rate of the latest call having the shortest call time is set to be equal to or less than a predetermined second upper limit value lower than the predetermined first upper limit value.

Abstract: A congestion control method in an IP telephone system includes processing of acquiring the number of simultaneous calls on one line shared by a plurality of IP telephones, processing of acquiring lengths of call duration of respective calls, and communication parameter setting processing of setting communication parameters that contribute to communication quality of respective calls on the basis of the number of simultaneous calls and the call duration. The call duration of the first call is longer than the call duration of the second call. The communication parameter setting processing includes processing of setting communication parameters such that the communication quality of the first call is worse than the communication quality of the second call in a case where the number of simultaneous calls exceeds a threshold value.