Abstract: A radio base station includes: an obtaining section that obtains a first communication quality of each of first communication terminals and obtains a second communication quality of each of second communication terminals having a lower communication speed than the first communication terminals; and a scheduler that schedules the first communication terminals based on the first communication qualities and schedules the second communication terminals based on the second communication qualities, and when the scheduler schedules the first communication terminals and the second communication terminals, the scheduler subjects the first communication terminals to space-division multiplexing and subjects the second communication terminals to frequency-division multiplexing or time-division multiplexing.

Abstract: In a radio communication system that performs beamforming in MIMO transmission between a radio base station and at least one user terminal, radio base station (10) includes: weight control section (104) that determines a beamforming weight used for the beamforming, for each of subbands formed by dividing a transmission band; and communication section (109) that transmits a signal to which the beamforming is applied using the beamforming weight.

Abstract: A wireless communication system includes: a plurality of first wireless stations; a plurality of second wireless stations; and a management apparatus configured to manage the plurality of first wireless stations and the plurality of second wireless stations. The management apparatus includes a selection unit that selects a plurality of antennas to be used to transmit reference signals from a plurality of antennas included in the plurality of first wireless stations or a plurality of antennas included in the plurality of second wireless stations, and an instruction unit that instructs the plurality of first wireless stations or the plurality of second wireless stations to transmit reference signals using the plurality of antennas used to transmit the reference signals and selected by the selection unit.

Abstract: In user terminal 20, communication section 202 receives a data signal to which precoding based on first channel information indicating a channel between radio base station 10 and user terminal 20 estimated in first channel estimation and beamforming are applied. The first channel information is an equivalent channel matrix including a beamforming weight. Stage-2 channel estimation section 205 performs second channel estimation for estimating second channel information indicating a channel between radio base station 10 and user terminal 20. The second channel information is an equivalent channel matrix including the beamforming weight and a precoding matrix. Postcoding section 207 performs postcoding on the data signal based on the second channel information.

Abstract: There is provided an estimation device including an acquisition unit that acquires a channel estimation value for each combination of all of a plurality of combinations between a plurality of transmission antenna elements included in a base station and a plurality of reception antenna elements included in a mobile station; and an estimation unit that calculates a channel impulse response for each combination of all of the plurality of combinations between the plurality of transmission antenna elements and the plurality of reception antenna elements using the channel estimation values, and that estimates power delay profile by averaging, over all the combinations of the plurality of combinations between the plurality of transmission antenna elements and the plurality of reception antenna elements, power values for the respective combinations that are calculated from the calculated channel impulse responses for the respective combinations.

Abstract: There is provided a base station of a radio communication system including the base station and one or more mobile stations that communicate with the base station, including a receiver that receives, from each of the one or more mobile stations, a signal of a specific random access sequence of random access sequences; and an identifier that identifies the specific random access sequence of the random access sequences and a receiving direction in which the signal of the specific random access sequence is received, based on absolute values of total values, each of the total values being obtained by calculating correlation values for combinations between signals in respective reception directions to which weights corresponding to the reception directions are applied and the random access sequences, and by adding the correlation values for the combinations corresponding to one random access sequence of the random access sequences.

Abstract: There is provided an estimation device including an acquisition unit that acquires a channel estimation value for each combination of all of a plurality of combinations between a plurality of transmission antenna elements included in a base station and a plurality of reception antenna elements included in a mobile station; and an estimation unit that calculates a channel impulse response for each combination of all of the plurality of combinations between the plurality of transmission antenna elements and the plurality of reception antenna elements using the channel estimation values, and that estimates power delay profile by averaging, over all the combinations of the plurality of combinations between the plurality of transmission antenna elements and the plurality of reception antenna elements, power values for the respective combinations that are calculated from the calculated channel impulse responses for the respective combinations.

Abstract: A management apparatus in a wireless communication system including multiple transmission points transmitting reference signals, the management apparatus managing the transmission points, and a mobile station, includes: a management unit for managing first and second clusters generated by grouping one or more transmission points used to communicate with the mobile station among the multiple transmission points; and a control unit for controlling allocation of the reference signals transmitted from the multiple transmission points in the first and second clusters. The management unit detects that multiple cells formed by the transmission points in the first cluster overlap some of multiple cells formed by the transmission points in the second cluster. When the management unit detects the overlap, the control unit allocates the orthogonal reference signals to the multiple cells formed by the transmission points in the first cluster and the multiple cells formed by the transmission points in the second cluster.

Abstract: A wireless communication system includes: a plurality of first wireless stations; a plurality of second wireless stations; and a management apparatus configured to manage the plurality of first wireless stations and the plurality of second wireless stations. The management apparatus includes a selection unit that selects a plurality of antennas to be used to transmit reference signals from a plurality of antennas included in the plurality of first wireless stations or a plurality of antennas included in the plurality of second wireless stations, and an instruction unit that instructs the plurality of first wireless stations or the plurality of second wireless stations to transmit reference signals using the plurality of antennas used to transmit the reference signals and selected by the selection unit.

Abstract: A base station transmits first discovery signals in different transmission directions from the base station through beamforming; transmits, for one or more first transmission directions corresponding to one or more first discovery signals reported from the mobile station, second discovery signals in second transmission directions within a predetermined range from the first transmission direction; and, for transmitting the second discovery signal, transmits the second discovery signal by multiplying, by a correction precoding vector for adding, to the first transmission direction, a transmission angle difference between the first transmission direction within the predetermined range from the second discovery signal and a second transmission direction of the second discovery signal to be transmitted, and by performing beamforming for the second discovery signal to which the correction precoding vector is multiplied, using a first weight matrix for beamforming in the first transmission direction within the prede

Abstract: There is provided a base station that supports multi-user MIMO and performs communication with a plurality of mobile stations of a radio communication system including the base station and the plurality of mobile stations, the base station including a determination unit that determines a number of a plurality of streams to be transmitted to each of the plurality of mobile stations and parameters to be applied to each of the plurality of streams to be transmitted to each of the plurality of mobile stations based on a channel estimation value for each of the plurality of mobile stations, and a transmitter that generates a determined number of streams according to the parameters determined by the determination unit to be transmitted to the respective plurality of mobile stations.

Abstract: A user equipment UE includes: a measurer that measures, for each of a plurality of candidate beams, a benchmark pertaining to communication quality; a comparer that compares the benchmark with a first threshold value and a second threshold value; and a feedback unit that transmits the benchmark to the base station as feedback information pertaining to an interference beam if the benchmark is the first threshold value or higher and lower than the second threshold value, transmits the benchmark to the base station as feedback information pertaining to a desired beam if the benchmark is the second threshold value or higher, and transmits no feedback information to the base station if the benchmark is lower than the first threshold value, based on the comparison results of the comparer.

Abstract: There is provided a base station of a radio communication system including the base station and one or more mobile stations that communicate with the base station, including a receiver that receives, from each of the one or more mobile stations, a signal of a specific random access sequence of random access sequences; and an identifier that identifies the specific random access sequence of the random access sequences and a receiving direction in which the signal of the specific random access sequence is received, based on absolute values of total values, each of the total values being obtained by calculating correlation values for combinations between signals in respective reception directions to which weights corresponding to the reception directions are applied and the random access sequences, and by adding the correlation values for the combinations corresponding to one random access sequence of the random access sequences.

Abstract: Provided is a base station for communicating with mobile stations of a radio communication system including the base station and mobile stations including an obtaining unit that obtains a channel matrix for each mobile stations; a selector that selects, among the mobile stations, a combination of two or more mobile stations with which communication based on multi-user MIMO is to be performed; and a communication unit that communicates, based on multi-user MIMO, with the two or more mobile stations of the selected combination, wherein the selector calculates, for each of all combinations of two mobile stations of the two or more mobile stations, a correlation value between the channel matrices for the two mobile stations, and selects the combination of the two or more mobile stations, so that, for all the combinations of the two mobile stations, the correlation values is less than or equal to a predetermined value.

Abstract: A communication control method includes: for each of plurality of receivers UE, calculating excluding channel matrices that include a plurality of equivalent channel matrices acquired by multiplying a transmit BF weight matrix corresponding to that receiver UE by each of a plurality of channel matrices corresponding to receivers UE other than that receiver UE, acquiring a first eigenvector that is included in a right-singular matrix obtained from single value decomposition of the excluding channel matrices, the first eigenvector corresponding to a noise subspace of the excluding channel matrices, acquiring a second eigenvector that is included in a right-singular matrix obtained from single value decomposition of a product of an equivalent channel matrix including the transmit BF weight matrix corresponding to that receiver UE and the first eigenvector, the second eigenvector corresponding to a signal subspace of the product, and obtaining a precoding matrix corresponding to that receiver UE by multiplying th

Abstract: A communication control method includes: for each of plurality of receivers UE, calculating excluding channel matrices that include a plurality of equivalent channel matrices acquired by multiplying a transmit BF weight matrix corresponding to that receiver UE by each of a plurality of channel matrices corresponding to receivers UE other than that receiver UE, acquiring a first eigenvector that is included in a right-singular matrix obtained from single value decomposition of the excluding channel matrices, the first eigenvector corresponding to a noise subspace of the excluding channel matrices, acquiring a second eigenvector that is included in a right-singular matrix obtained from single value decomposition of a product of an equivalent channel matrix including the transmit BF weight matrix corresponding to that receiver UE and the first eigenvector, the second eigenvector corresponding to a signal subspace of the product, and obtaining a precoding matrix corresponding to that receiver UE by multiplying th