Abstract: To generate a configuration entry in a master codebook. A base station according to one aspect of the present invention includes a codebook generating unit that determines a codebook subset corresponding to a predetermined configuration entry from a plurality of configuration entries in a master codebook, and a transmitter that transmits information of the predetermined configuration entry.

Abstract: A method of Channel State Information Reference Signal (CSI-RS) transmission from a base station (BS) to a user equipment (UE) includes reserving, with the BS, a CSI-RS resource used for aperiodic CSI-RS transmission in subframes transmitted from the BS, transmitting, from the BS to the UE, reservation information indicating the CSI-RS resource via higher layer signaling, and transmitting, from the BS to the UE, the aperiodic CSI-RS using the CSI-RS resource.

Abstract: User equipment for implementing 3D MIMO (3-Dimensional Multiple-Input Multiple-Output) communication includes: a transmission and reception unit configured to transmit and receive radio signals to/from a base station in the 3D MIMO communication; and a codebook management unit configured to have a first codebook and a second codebook. The codebook management unit determines a 3D codebook for the 3D MIMO communication by combining the first codebook with the second codebook, and the transmission and reception unit feeds the first codebook and the second codebook serving as a basis of calculating the determined 3D codebook back to the base station.

Abstract: The present invention provides a mobile station, a base station and a radio communication method. A mobile station pertaining to the present invention is provided, including a receiving section configured to receive information that indicates at least one reference signal resource and measurement window information that indicates an allocation of a measurement window; a measuring section configured to measure a reference signal, to which precoding has been applied, based on the information that indicates the at least one reference signal resource and the measurement window information, and to generate a measurement result; and a transmitting section configured to transmit the measurement result.

Abstract: An information transmission method used in a base station includes: determining mode indication information regarding reference signals to be transmitted; transmitting the mode indication information to a mobile station; and transmitting the reference signals to the mobile station based on the mode indication information.

Abstract: The present disclosure provides a base station, a communication system and a method thereof. The communication system includes three base stations adjacent to each other, and each base station serves at least one UE. The method includes: acquiring, by each base station, a channel matrix of a channel from the base station to an adjacent base station; calculating an interference alignment-based transmission precoding matrix for each base station based on the channel matrices of the channels between the base stations; and precoding, by each base station, data to be transmitted with the interference alignment-based transmission precoding matrix.

Abstract: A beam selection method, a mobile station and a base station are disclosed. A mobile station according to an aspect of the present invention, includes a receiving section configured to receive information for indicating a first quantity of reference signal resources and to receive beams corresponding to reference signals in the first quantity of reference signal resources, based on said information; and a selecting section configured to carry out channel estimation based on the received beams. The mobile station can reduce its workload and signaling overhead by carrying out channel estimation and feedback based on reference signals in the reference signal resources notified by a base station.

Abstract: According to an aspect of the present invention, a mobile station, which carries out communication using a plurality of antenna ports, includes a receiving section configured to receive, from a radio base station, first-amount information that indicates a number of antenna ports in a first dimension, and second-amount information that indicates a number of antenna ports in a second dimension; and a transmitting section configured to transmit, to the radio base station, a precoding matrix codebook index that is obtained using the first-amount information and/or the second-amount information. Accordingly, a mobile station, a radio base station and a radio communication method can be provided in which a precoding matrix for a two-dimensional antenna array can be generated with flexibility.

Abstract: According to an aspect of the present invention, there is provided a radio resource scheduling method, wherein the method includes generating format information, wherein the format information specifies a format of resource allocation information, the format corresponding to a number of a plurality of mobile stations that simultaneously perform communication with the radio base station; generating the resource allocation information provided with the format specified by the format information corresponding to radio resources allocated to the plurality of mobile stations; and transmitting, to the plurality of mobile stations, the resource allocation information.

Abstract: A user equipment used in a mobile communication system that has multiple antenna ports configured to receive a first reference signal from a base station is disclosed. The antenna ports are configured to transmit the first feedback information for the first reference signal. Additionally, the antenna ports are configured to receive a second reference signal from the base station and transmit the second feedback information for the second reference signal.

Abstract: A base station that communicates with a user equipment using multiple antenna ports includes an uplink channel estimation unit that estimates uplink channel states, a downlink channel estimation unit that estimates downlink channel states based on the estimated uplink channel states and channel reciprocity of uplink and downlink, a receiver unit that receives from the user equipment CSI feedback information, and a precoder generating unit that determines a precoding matrix of downlink based on Channel State Information (CSI) indicating the estimated downlink channel states and on the CSI feedback information.

Abstract: A radio base station capable of reducing the impact of interference and improving the efficiency of the use of radio resources even when different DL/UL configurations are employed between neighboring transmitting/receiving points is disclosed. The radio base station can communicate with user terminals via time division duplex and is able to change and control DL/UL configurations, has a subframe type determining section that classifies subframes into fixed subframes or flexible subframes, in accordance with the relationship between the DL/UL configurations that are employed in the radio base station and the DL/UL configurations that are employed in other radio base stations, and a frequency allocation control section that applies mutually different frequency allocation methods to the fixed subframes and the flexible subframes.

Abstract: Techniques for implementing MIMO communication in accordance with reciprocity based precoding are provided. The present disclosure relates to a base station for implementing multi-antenna transmission that includes a communication control unit configured to control multi-antenna transmission with user equipment and a channel state estimation unit configured to estimate a channel state with the user equipment based on an uplink reference signal from the user equipment. The communication control unit causes the user equipment to transmit the uplink reference signal in an uplink shared channel in an uplink subframe.

Abstract: User equipment for implementing 3D MIMO (3-Dimensional Multiple-Input Multiple-Output) communication includes: a transmission and reception unit configured to transmit and receive radio signals to/from a base station in the 3D MIMO communication; and a codebook management unit configured to have a first codebook and a second codebook. The codebook management unit determines a 3D codebook for the 3D MIMO communication by combining the first codebook with the second codebook, and the transmission and reception unit feeds the first codebook and the second codebook serving as a basis of calculating the determined 3D codebook back to the base station.

Abstract: In order to avoid interference efficiently and control the amount of radio resources that are not used for interference avoidance, the present invention provides a radio base station connected to a neighbor radio base station via inter-radio base station interface. The radio base station has: a radio communication section that performs radio communication with a user terminal using a UL/DL configuration indicating a configuration of uplink and downlink subframes in a radio frame; an interference detecting section that measures and detects interference that the radio base station suffers from; and a selecting section that uses an interference detection result as a basis to determine which to apply to each subframe, between a resource allocation-unrestricted scheme and an inter-cell uplink/downlink orthogonalization scheme.

Abstract: Some techniques for implementing estimation of channel states with high accuracy and efficient feedback of the channel states in 3D MIMO are disclosed. One aspect of the present invention relates to user equipment for implementing 3D MIMO (3-Dimensional Multiple-Input Multiple-Output) communication, comprising: a channel state information generation unit configured to measure channel states of antenna ports of 3D MIMO antennas in a base station with reference signals transmitted from the antenna ports and generate channel state information based on the measured channel states; and a channel state information feedback unit configured to use different channel state information feedback means for antenna ports in respective dimensions of the antennas to feed the generated channel state information back to the base station.

Abstract: A beam selection method in a mobile communication system including a base station with multiple antennas and user equipment conducting radio communication with the base station includes the steps of, at the base station, detecting a direction in which the user equipment is located, transmitting precoded reference signals toward the detected direction by spatial multiplexing using same frequency and time resources, and determining a beam for the user equipment based upon feedback information from the user equipment.

Abstract: The present disclosure relates to techniques for implementing efficient beam forming in 3D MIMO. One aspect of the present invention relates to abase station, comprising: a beam forming unit configured to form multiple directional beams in accordance with a predetermined beam arrangement; a transmission and reception unit configured to transmit reference signals in the formed multiple directional beams; and a feedback information acquisition unit configured to acquire feedback information from user equipment receiving the reference signals.

Abstract: In order to avoid interference efficiently and control the amount of radio resources that are not used for interference avoidance, the present invention provides a radio base station connected to a neighbor radio base station via inter-radio base station interface. The radio base station has: a radio communication section that performs radio communication with a user terminal using a UL/DL configuration indicating a configuration of uplink and downlink subframes in a radio frame; an interference detecting section that measures and detects interference that the radio base station suffers from; and a selecting section that uses an interference detection result as a basis to determine which to apply to each subframe, between a resource allocation-unrestricted scheme and an inter-cell uplink/downlink orthogonalization scheme.

Abstract: A method for synchronizing clocks in a communication network includes a first clock of a first network element which is a master element is used for synchronizing second clocks of one or more second network dements which are slave elements. A first sequence of first messages transmitted from the first network element to the second network element and/or a second sequence of second messages transmitted from the second network element to the first network element is recorded. First messages and/or second messages out of those sequences are identified by using an appropriate threshold function with respect to the transmission delays of those messages. Those identified messages have the same constant minimum delay, and based on those messages clock synchronization between the first clock and the second clock is performed.