Abstract: A base station apparatus includes a transmitter configured to generate a plurality of beams by a plurality of antenna elements so as to transmit a data signal addressed to a plurality of terminal devices, a memory, and a processor coupled to the memory and configured to select, for each terminal device, a combination of terminal devices to which the data signal is transmitted by spatially multiplexed, based on information in which a first beam group including a first beam in which a reception quality of each terminal device is maximized among the plurality of beams is associated with a second beam group including a second beam in which a difference from the reception quality of the first beam is equal to or larger than a predetermined value among the plurality of beams.

Abstract: A transmission method includes: selecting, from a cooperative cluster covered by a plurality of transmission points that transmit signals in cooperation with each other, a transmission point positioned in vicinity of a boundary between the cooperative cluster and another cooperative cluster; generating a first transmission weight that causes the selected transmission point to form a directional beam directed in a direction different from a direction of the another cooperative cluster; generating, by using the first transmission weight generated, a second transmission weight that weights transmission signals, such that signals that are transmitted simultaneously from the transmission points and addressed to a plurality of transmission destinations are separately received; generating, by using the second transmission weight generated, streams to be transmitted from the transmission points, the streams respectively corresponding to antennas; and transmitting the streams generated, from the transmission points.

Abstract: A transmitter includes: a plurality of transmission antennas; a channel estimator configured to estimate channels between the plurality of transmission antennas and a plurality of receivers; a scheduler configured to schedule a combination of target receivers of transmitting downlink signals on same radio resource among the plurality of receivers; and a transmitter configured to transmit downlink signals intended for the combination scheduled by the scheduler by beam forming from the plurality of transmission antennas on the same radio resource. The scheduler modifies a selecting rule related to the combination of target receivers in accordance with a delay time of an opportunity of transmitting the downlink signal from a timing of estimating the channels.

Abstract: A base station apparatus includes a transmitter configured to generate a plurality of beams by a plurality of antenna elements so as to transmit a data signal addressed to a plurality of terminal devices, a memory, and a processor coupled to the memory and configured to select, for each terminal device, a combination of terminal devices to which the data signal is transmitted by spatially multiplexed, based on information in which a first beam group including a first beam in which a reception quality of each terminal device is maximized among the plurality of beams is associated with a second beam group including a second beam in which a difference from the reception quality of the first beam is equal to or larger than a predetermined value among the plurality of beams.

Abstract: A transmission method includes: selecting, from a cooperative cluster covered by a plurality of transmission points that transmit signals in cooperation with each other, a transmission point positioned in vicinity of a boundary between the cooperative cluster and another cooperative cluster; generating a first transmission weight that causes the selected transmission point to form a directional beam directed in a direction different from a direction of the another cooperative cluster; generating, by using the first transmission weight generated, a second transmission weight that weights transmission signals, such that signals that are transmitted simultaneously from the transmission points and addressed to a plurality of transmission destinations are separately received; generating, by using the second transmission weight generated, streams to be transmitted from the transmission points, the streams respectively corresponding to antennas; and transmitting the streams generated, from the transmission points.

Abstract: A base station device includes: a processor that executes a process including determining which group of a first group and a second group each of a plurality of terminal devices belongs to, generating a transmission weight to form a transmission beam having a shape considering only a terminal device that belongs to the first group out of the terminal devices, and multiplying a signal addressed to the terminal devices by the generated transmission weight; and a transmitter that transmits the signal multiplied by the transmission weight from a plurality of antennas simultaneously.

Abstract: A transmission control device includes an acquiring unit that acquires propagation delay time for each propagation path between a plurality of terminal devices and a plurality of transmitter stations; a selector that selects, based on the propagation delay time acquired by the acquiring unit, combinations of terminal devices having similar propagation delay differences from the plurality of the transmitter stations; and a controller that controls transmission timing of the plurality of the transmitter stations that transmit signals to the combinations of the terminal devices selected by the selector.

Abstract: A base station includes a processor and a plurality of antennas that transmit, to each of terminals, first and second wireless signals to form first and second beams, respectively, and receive, from each terminal, a third wireless signal including feedback information of the terminal in response to the second wireless signal. The processor selects, from among the terminals, based on the feedback information and a correlation value between the first beam and the second beam, a terminal to which the second beam is optimum, as a first terminal that performs communication via the first beam, or selects a terminal as a second terminal that performs communication via the second beam while communication via the first beam is performed in parallel. The plurality of antennas transmit a fourth wireless signal including data to each terminal apparatus to form the first beam or the second beam.

Abstract: There is provided a wireless base station that stores information on a plurality of different first precodings and information on a plurality of different reception weights; transmits, from antennas, a plurality of downlink reference signals, each of which is obtained by applying one of the first precodings; receives information on reception quality of the downlink reference signals from wireless terminals; selects at least one from the wireless terminals based on the information on reception quality; determines wireless resource allocation for allowing the selected wireless terminal to transmit an uplink reference signal; notifies the selected wireless terminal of the wireless resource allocation; and receives the uplink reference signal transmitted from the selected wireless terminal by applying each of the reception weights to the uplink reference signal.

Abstract: A base station includes a channel estimator, a scheduler, and a controller. The channel estimator estimates a channel matrix with respect to each of a plurality of terminals. The scheduler determines a transmission weight corresponding to each of the plurality of terminals on the basis of the channel matrix that is estimated by the channel estimator such that the transmission weight is orthogonal to a current channel matrix and a past channel matrix of a terminal that is a subject of interference. The controller controls, when the transmission weight is determined by the scheduler, the number of samples of the current channel matrix and the past channel matrix to which the transmission weight is to be orthogonal with respect to each of the terminals.

Abstract: In a multi-carrier cellular system, a second synchronization code (a Walsh code or a GCL series code) mapped on a second synchronization channel is used as a signal for specifying in which cell of the base station a mobile station terminal device itself is. A signal transmitted from the base station to the mobile station terminal device is mapped in a radio frame having two-dimensional extension in frequency and time directions. When mapping a certain series number of the second code for specifying a cell or a cell group on the radio frame as the second synchronization channel, phase rotation or circular shift in which one radio frame is one cycle is applied to the second synchronization code. On the receiving side, the head timing of the radio frame is known by knowing the phase rotation angle or the amount of circular shift of the second synchronization code.

Abstract: A transmitter includes: a plurality of transmission antennas; a channel estimator configured to estimate channels between the plurality of transmission antennas and a plurality of receivers; a scheduler configured to schedule a combination of target receivers of transmitting downlink signals on same radio resource among the plurality of receivers; and a transmitter configured to transmit downlink signals intended for the combination scheduled by the scheduler by beam forming from the plurality of transmission antennas on the same radio resource. The scheduler modifies a selecting rule related to the combination of target receivers in accordance with a delay time of an opportunity of transmitting the downlink signal from a timing of estimating the channels.

Abstract: There is provided a wireless base station that stores information on a plurality of different first precodings and information on a plurality of different reception weights; transmits, from antennas, a plurality of downlink reference signals, each of which is obtained by applying one of the first precodings; receives information on reception quality of the downlink reference signals from wireless terminals; selects at least one from the wireless terminals based on the information on reception quality; determines wireless resource allocation for allowing the selected wireless terminal to transmit an uplink reference signal; notifies the selected wireless terminal of the wireless resource allocation; and receives the uplink reference signal transmitted from the selected wireless terminal by applying each of the reception weights to the uplink reference signal.

Abstract: A base station includes a receiving unit that receives a report of a reception power from a user equipment, and a selecting unit that calculates a first throughput and a second throughput by using the reception power, the first throughput being a throughput when coordinated communication is not performed and a single user equipment occupies an entire band, the second throughput being a throughput when the coordinated communication is performed and the single user equipment occupies the entire band, and selects a coordination candidate cell based on the first throughput, the second throughput, a first resource allocation rate and a second resource allocation rate, the first resource allocation rate being a resource allocation rate when the coordinated communication is not performed, the second resource allocation rate being a resource allocation rate when the coordinated communication is performed.

Abstract: A base station device includes: a processor that executes a process including determining which group of a first group and a second group each of a plurality of terminal devices belongs to, generating a transmission weight to form a transmission beam having a shape considering only a terminal device that belongs to the first group out of the terminal devices, and multiplying a signal addressed to the terminal devices by the generated transmission weight; and a transmitter that transmits the signal multiplied by the transmission weight from a plurality of antennas simultaneously.

Abstract: A transmission control device includes an acquiring unit that acquires propagation delay time for each propagation path between a plurality of terminal devices and a plurality of transmitter stations; a selector that selects, based on the propagation delay time acquired by the acquiring unit, combinations of terminal devices having similar propagation delay differences from the plurality of the transmitter stations; and a controller that controls transmission timing of the plurality of the transmitter stations that transmit signals to the combinations of the terminal devices selected by the selector.

Abstract: A base station including: a memory, and a processor coupled to the memory and configure to: when scheduling a plurality of terminals based on non-orthogonal multiple access in which a same radio resource having a same time and a same frequency is allocable to two or more terminals of the plurality of terminals, calculate each metric of each of selected terminal combinations and each terminals of the plurality of terminals, each of the selected terminal combinations including two or more terminals of the plurality of terminals, and determine to allocate each radio resource to each of the selected terminal combinations and each terminals of the plurality of terminals based on each metric, wherein the selected terminal combinations are obtained by selecting, from among all terminal combinations of the plurality of terminals, each terminal combination that satisfies a first condition.

Abstract: An arithmetic apparatus to calculate an interference suppression parameter for a radio device includes a predictive value calculator, a predictive error calculator, and an interference suppression parameter calculator. The predictive value calculator calculates a predictive value for a radio communication channel between radio devices. The predictive error calculator calculates a predictive error in the radio communication channel based on the predictive value. The interference suppression parameter calculator calculates an interference suppression parameter available to suppress an interference in the radio communication channel, the interference suppression parameter being orthogonal to the predictive value and the predictive error in a vector space.

Abstract: An arithmetic apparatus to calculate an interference suppression parameter for a radio device includes a predictive value calculator, a predictive error calculator, and an interference suppression parameter calculator. The predictive value calculator calculates a predictive value for a radio communication channel between radio devices. The predictive error calculator calculates a predictive error in the radio communication channel based on the predictive value. The interference suppression parameter calculator calculates an interference suppression parameter available to suppress an interference in the radio communication channel, the interference suppression parameter being orthogonal to the predictive value and the predictive error in a vector space.

Abstract: A base station includes a channel estimator, a scheduler, and a controller. The channel estimator estimates a channel matrix with respect to each of a plurality of terminals. The scheduler determines a transmission weight corresponding to each of the plurality of terminals on the basis of the channel matrix that is estimated by the channel estimator such that the transmission weight is orthogonal to a current channel matrix and a past channel matrix of a terminal that is a subject of interference. The controller controls, when the transmission weight is determined by the scheduler, the number of samples of the current channel matrix and the past channel matrix to which the transmission weight is to be orthogonal with respect to each of the terminals.