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: To suppress reduction in system performance for mobile communications (group mobility) in a plurality of terminals existing inside the same moving object, a radio communication system for a plurality of user terminals existing inside a moving object and a radio base station is described. The user terminal receives a signal transmitted from the radio base station, and transmits the signal transmitted from the radio base station to a common reception apparatus disposed inside the moving object. The common reception apparatus detects a signal for each user terminal, based on signals transmitted from the plurality of user terminals, and transmits the detected signal to each user terminal. The user terminal receives the signal for the user terminal detected in the common reception apparatus to demodulate. Thus, for group mobility, it is possible to cancel interference among user terminals to improve the multiplexing effect, while suppressing communication overhead.

Abstract: The present invention is designed so that a radio base station controls base station parameters dynamically, in accordance with changes in the surrounding propagation environment. The radio base station according to the present invention has a surrounding environment information acquiring section that acquires surrounding environment information, which is information about the environment in a service area, a propagation environment information extraction section that extracts propagation environment information, which is information about electric wave propagation, based on the surrounding environment information, and a base station parameter generating section that generates base station parameters, which are information about the control of electric waves to transmit and receive, based on the propagation environment information.

Abstract: A radio communication device includes: a full-digital array that has a first antenna element group including multiple antenna elements and that has no analog variable phase shifter; and a hybrid beamformer that has a second antenna element group including multiple antenna elements and that has an analog variable phase shifter.

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 number LR of receive beamforming circuits provided in a receive beamformer execute receive beamforming (NR/LR) times with respect to a received signal vector received by NR reception antennas AR, thereby generating a receive beamforming (BF) output vector having NR receive BF output components. A calculation processor calculates a reception power for each of the NR receive BF output components, selects LR receive BF output components in decreasing order of reception power, and determines a suitable receive BF weight matrix including LR reception orthogonal BF weight vectors corresponding to the selected receive BF output components.

Abstract: To improve system performance for mobile communications (group mobility) in a plurality of terminals existing inside the same moving object, a radio base station, which forms a cell on a moving path of a moving object to communicate with a mobile station provided in the moving object using beam forming, is provided with a transmission section that transmits a plurality of acquisition signals applied with different beam forming weights respectively to at least an edge region of the cell formed on the moving path of the moving object, and a control section that controls a beam forming weight to apply to a data signal transmitted to the mobile station, based on information notified from the mobile station receiving an acquisition signal.

Abstract: To suppress complication of transmission/reception processing even in the case where a user terminal supports a plurality of bandwidths, or the case where the terminal concurrently connects to a plurality of radio communication systems with different usage frequencies, a user terminal, which communicates with a radio base station for forming a wide-area cell and anther radio base station for forming a narrow-area cell in a radio communication system where the narrow-area cell is provided inside the wide-area cell, is provided with a reference signal generating section that generates a sampling frequency of a baseband signal of the wide-area cell as a reference signal, a frequency adjusting section that converts a frequency of the reference signal by n/m times, and a baseband processing section that uses a frequency subjected to frequency conversion as a sampling frequency of a baseband signal of the narrow-area cell.

Abstract: In order to make full use of the performance of a Massive-MIMO-applied communication system, provided is a base station apparatus for controlling a transmission direction of a transmission beam for a synchronization signal used in cell search by beamforming using a plurality of antenna elements. The base station apparatus has a synchronization signal processing section (62) that generates the synchronization signal including information to identify the transmission beam for the synchronization signal and changes a beamforming weight for the synchronization signal at every given time interval; and a transmission section (64) that transmits the synchronization signal generated with the beamforming weight in downlink.

Abstract: A base station performs the combination of digital precoding and analog beamforming. Transceiving antenna elements are classified into antenna groups. The analog beamformer includes branches corresponding to the antenna groups. Each branch includes sub-branches, and each sub-branch is connected to one antenna element. In self-calibration, after pilot signals are transmitted from antenna elements belonging to an antenna group and are received by antenna elements belonging to another antenna group, it is identifiable as to which antenna element transmitted each pilot signal. After pilot signals are received by antenna elements belonging to an antenna group, it is identifiable as to which antenna element received each pilot signal.

Abstract: A mobile communication system that includes a first communication system, which features a user terminal that is present in a moving object, a first radio base station that forms a cell in the moving object, and a first core network that is connected with an external network, and a second communication system, which features a radio mobile station that is provided in the moving object, a second radio base station that forms a cell on the path of the movement of the moving object, and a second core network that is connected with the second radio base station. The first radio base station and the radio mobile station are connected via a user-plane interface and a control-plane interface between the radio base stations and the core networks.

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 number LR of receive beamforming circuits provided in a receive beamformer execute receive beamforming (NR/LR) times with respect to a received signal vector received by NR reception antennas AR, thereby generating a receive beamforming (BF) output vector having NR receive BF output components. A calculation processor calculates a reception power for each of the NR receive BF output components, selects LR receive BF output components in decreasing order of reception power, and determines a suitable receive BF weight matrix including LR reception orthogonal BF weight vectors corresponding to the selected receive BF output components.

Abstract: To suppress deterioration of reception characteristics even in the case where a radio base station performs power multiplexing on downlink signals to transmit, a radio base station according to one aspect of the present invention has a transmission section that performs power multiplexing on downlink signals to a plurality of user terminals each having a MIMO configuration to transmit, and a control section that controls a phase rotation applied to the downlink signal to each user terminal, where the control section controls so as to apply different phase rotations to the downlink signals.

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 base station performs the combination of digital precoding and analog beamforming. Transceiving antenna elements are classified into antenna groups. The analog beamformer includes branches corresponding to the antenna groups. Each branch includes sub-branches, and each sub-branch is connected to one antenna element. In self-calibration, after pilot signals are transmitted from antenna elements belonging to an antenna group and are received by antenna elements belonging to another antenna group, it is identifiable as to which antenna element transmitted each pilot signal. After pilot signals are received by antenna elements belonging to an antenna group, it is identifiable as to which antenna element received each pilot signal.

Abstract: The present invention is designed so that, in a communication system to employ massive MIMO, data signals to which beamforming is applied can be transmitted adequately. A radio base station transmits a data signal to a user terminal by applying beamforming using a plurality of antenna elements, and has a determining section that determines the type of a weight to apply to the data signal for beamforming, a generating section that generates a reference signal which the user terminal uses in channel estimation, a weight control section that controls weights to apply to transmitting signals, and a transmitting section that transmits the data signal and the reference signal, and the weight control section determines whether or not to apply a weight to the reference signal based on the type of the weight.

Abstract: A radio relay station is arranged on a moving conveyance. The radio relay station receives downlink radio signals from a stationary base station fixed outside the conveyance, and transmits to destination user equipments in the conveyance downlink radio signals resulting from the downlink radio signals transmitted from the stationary base station. In addition, the radio relay station receives uplink radio signals from multiple user equipments in the conveyance, and transmits to the stationary base station uplink radio signals resulting from the uplink radio signals transmitted from the multiple user equipments. The radio relay station receives from the multiple user equipments auxiliary radio signals indicating a downlink radio signal which the stationary base station has transmitted, detects, within a result of reception of the auxiliary radio signals, a downlink radio signal addressed to a user equipment in the conveyance, and transmits the downlink radio signal to the user equipment.