Abstract: A small base station executes radio communication using multiple antennas. There are set multiple antenna groups that each include all or a portion of the antennas and multiple antenna group patterns that each include at least one of the antenna groups. The small base station transmits reference signals with sequences that differ from one another between antenna groups that are included in the same antenna group pattern. A user apparatus receives the reference signals. Based on a reception result of the reference signals, a use antenna group pattern and at least one use antenna group that are to be used for transmission of a radio signal from the small base station are determined.

Abstract: The present invention is designed to provide highly efficient local area radio access.

Abstract: The present invention is designed to provide a communication system, a local area base station apparatus, a mobile terminal apparatus and a communication method that can provide highly efficient local area radio access. In a communication system in which a mobile terminal apparatus performs radio communication with a wide area base station apparatus that covers a wide area, using a first carrier frequency, and performs radio communication with a local area base station apparatus that covers a local area, using a second carrier frequency, the wide area base station apparatus allocates different frequencies between the uplink and the downlink in the first carrier frequency and communicates with the mobile terminal apparatus, and the local area base station apparatus dynamically switches between the uplink and the downlink in the second carrier frequency on a per time basis based on the communication environment, and communicates with the mobile terminal apparatus.

Abstract: A radio base station applies non-orthogonal multiple access to a plurality of user terminals and transmits downlink signals, and this radio base station has a scheduling section that selects a user set to apply non-orthogonal multiple access to from candidate user sets, and selects a combination of a modulation and coding scheme and transmission power based on combinations of candidate transmission power. The radio base station includes a control section that decides whether or not the combination of the modulation and coding scheme and transmission power selected in the scheduling section is included in combinations that are stipulated in advance, and controls the scheduling section in accordance with the decision. A transmission section applies the combination of the modulation and coding scheme and transmission power to user terminals that are included in the user set selected in the scheduling section, and transmits the downlink signals.

Abstract: The present invention is designed to enable uplink signal transmission power control that is suitable when non-orthogonal multiple access (NOMA) is used on the uplink.

Abstract: The present invention is designed to expand the coverage of reference signals in small cells that are arranged to overlap a macro cell, and, furthermore, reduce the interference between the small cells and improve the received quality of the reference signals in user terminals. The radio communication method of the present invention provides a radio communication method in a radio base station forming a small cell that is placed to overlap a macro cell, and includes the steps of generating a reference signal for measuring received quality, in a first transmission period in which beamforming is not executed, transmitting the reference signal in a narrower transmission bandwidth and with greater transmission power than in a second transmission period in which beamforming is executed, and allocating the reference signal to a band associated with information that is specific to each radio base station forming a small cell, and transmitting the reference signal.

Abstract: The present invention is designed to increase the capacity of backhaul links between radio base stations and relay stations.

Abstract: The present invention is designed to provide a radio communication system, an interference measurement method, a radio base station apparatus, and a user terminal whereby highly accurate interference measurement is possible.

Abstract: Techniques for providing codebooks extended by gain information that can be transmitted in a reduced amount of signaling are disclosed. A user equipment includes a transmission and reception unit communicating a radio signal with a base station in accordance with MIMO (Multiple Input Multiple Output) transmission and a codebook storage unit stores predefined codebooks to specify precoding matrices for use in the MIMO transmission. The codebooks are arranged to represent phase information and gain information and a channel measurement unit measures channel conditions based on reference signals transmitted from multiple antennas in the base station. A codebook selection unit selects a codebook to be indicated to the base station from the stored codebooks based on the measured channel conditions and instructs the transmission and reception unit to indicate feedback information to the base station and the feedback information includes a codebook index for identifying the selected codebook.

Abstract: There is provided a communication system capable of achieving a high usage efficiency of frequencies without the need for cooperation of multiplexed users. A communication system communicates over frequency channels set by dividing a frequency bandwidth assigned to the system allows interference between channels by overlapping the adjacent frequency channels with each other in the frequency domain, or a transmitting and receiving device, which transmits and receives a signal by allowing the interference between symbols at a waveform level for each channel to decrease the occupied bandwidth, is provided with ICI removal and ISI compensation filter 111 serving as either an ICI removal filter for removing the interference between channels or an ISI compensation filter for compensating the interference between symbols.

Abstract: To provide a mobile terminal apparatus, radio base station apparatus and radio communication method that enable accurate precoding weights to be generated in coordinated multipoint transmission, a radio communication method of the invention is characterized in that a mobile terminal apparatus (10) performs channel estimation using a downlink reference signal, selects a PMI using the obtained channel estimation value, measures an IQI using at least the channel estimation value and the PMI, and transmits at least the PMI and IQI to a radio base station apparatus, and that the radio base station apparatus generates precoding weights using the PMI and IQI, and performs coordinated multipoint transmission utilizing MIMO transmission using the precoding weights.

Abstract: The present invention is designed to improve the received quality of reference signals in user terminals, in small cells that are placed to overlap a macro cell. The reference signal transmission method according to the present invention is a reference signal transmission method in a radio base station that forms a small cell, which is placed to overlap a macro cell, and that has a plurality of antenna ports, and includes the steps of generating a plurality of reference signals that vary per antenna port, and in a reference signal transmission period in which beamforming is not executed, transmitting the plurality of reference signals in a transmission bandwidth that is narrower than in a second transmission period in which beamforming is executed, the reference signals of each antenna port are spread in at least one of the time direction and the frequency direction and transmitted.

Abstract: To provide a radio communication method when a macro-base station and micro-base station are regarded as a plurality of transmission points and the plurality of transmission points performs downlink communications using a plurality of carriers, in the radio communication method of the invention, a macro-base station (10) forming a macro-cell determines whether or not a micro-base station transmits a non-data signal that is at least one of a synchronization signal, broadcast signal, measurement reference signal and downlink control signal using a capacity carrier (ST102), and transmits instruction information for instructing the micro-base station (20) to start transmission of the non-data signal using the capacity carrier to the micro-base station when it is determined that the micro-base station transmits the non-data signal (ST103), and the micro-base station (20) starts transmission of the non-data signal using the capacity carrier based on the instruction information from the macro-base station (10) (ST10

Abstract: The present invention is designed to realize link adaptation that is optimal for future radio communication systems. A radio base station is configured to select user terminals from user groups that are determined based on the channel gain of each user terminal, determine a user set to non-orthogonal-multiplex over an arbitrary radio resource, with transmission power that is allocated to each user group on a fixed basis, and transmit downlink signals to the user terminals of the user set, with the transmission power that is allocated to each user group.

Abstract: To increase the number of CSI-RSs for interference measurement to improve interference measurement accuracy, a first reference signal for channel state measurement and a second reference signal for interference measurement are assigned to reference signal resources defined for transmission of the first reference signal, and a mobile terminal apparatus that supports both the first reference signal and the second reference signal is notified of pattern information to identify an assignment pattern of the first reference signal and the second reference signal. A second mobile terminal apparatus that supports the first reference signal and that does not support the second reference signal is notified of pattern information to identify an assignment pattern of the first reference signal, and of assignment information indicating that resources assigned the second reference signal are assigned a third reference signal of zero power for channel state measurement.

Abstract: The present invention is designed to realize non-orthogonal multiple access while reducing the decrease of throughput. A radio base station selects a predetermined decoding pattern, based on channel state information of a user terminal, from among a plurality of decoding patterns in which information regarding the order of decoding of the non-orthogonal multiple access signals and/or whether or not SIC (Successive Interference Cancellation) is applied is defined, and transmits information to represent the selected decoding pattern to the user terminal, and the user terminal receives the information to represent the decoding pattern, and cancels interference in accordance with the order of decoding and SIC based on the decoding pattern that is shown in the received information.

Abstract: The present invention is designed to measure interference with high accuracy, without changing the density of CSI-RSs, in a future system that does not reply on CRSs. A base station apparatus (20) allocates CSI-RS to CSI resources that are defined for CSI-RS transmission, changes arbitrary resources in the CSI-RS resources in resource block units or in resource block group units, and determines and reports to a mobile terminal apparatus (10) the resources to be muted, and the mobile terminal apparatus (10) is configured to measure interference using the muted resources.

Abstract: A radio communication system includes a first radio base station having multiple antenna elements, and user equipment, wherein, for initial connection of the user equipment to the first radio base station, the first radio base station applies different precoding vectors to a downlink user common signal transmitted to all users located in or near a serving area of the first radio base station, and transmits the downlink user common signal while changing the applied precoding vector; wherein the user equipment selects a desired one of the precoding vectors applied to the downlink user common signal, and reports a selection result to the first radio base station, and wherein the first radio base station precodes a data signal addressed to the user equipment using the selected precoding vector and transmits the precoded data signal to the user equipment.

Abstract: A transmitting apparatus and a transmitting method are provided. The transmitting apparatus comprises: an encoder configured to encode data for a plurality of user equipments into corresponding encoded signals, respectively; a modulator configured to perform a joint modulation on the encoded signals for the plurality of user equipments to generate modulated signals, wherein the modulator performs the joint modulation by mapping bits of the encoded signals for the plurality of user equipments to a symbol corresponding to each constellation point of a constellation map of the modulated signals so that respective constellation points satisfy a Gray mapping rule; a transmitter configured to transmit the modulated signals.

Abstract: The present invention is designed to make possible link adaptation that is suitable for future radio communication systems. A radio base station according to the present invention has a coding section that encodes downlink data for each of a plurality of user terminals, a modulation section that modulates the downlink data for each of the plurality of user terminals, and a transmission section that multiplexes the downlink data for each of the plurality of user terminals on a per subband basis, and transmits the downlink data for each of the plurality of user terminals by using transmission power that is allocated to each of the plurality of user terminals on a per subband basis.