Abstract: A user apparatus, for use in a radio communication system including a base station forming a cell, configured to receive a discovery signal of device-to-device communication, including: an information reception unit configured to receive, from a base station of a residing cell, a resource range in which a discovery signal can be transmitted in a neighbor cell; and a discovery signal reception unit configured to receive a discovery signal at a time position that is synchronized with the neighbor cell in response to receiving a synchronization signal that is synchronized with the neighbor cell within the resource range received by the information reception unit.

Abstract: In a radio relay station, the channel quality of relay links is measured with the use of sounding reference signals from mobile terminals. Feedback information including the measurement results of the channel quality of the relay links is transmitted to a radio base station via a backhaul link. In the radio base station, the channel quality of the direct links is measured with the use of sounding reference signals from the mobile terminals. A correction value from the measurement results of the channel quality from the radio relay station is subtracted. Radio resources are allocated to a mobile terminal based on the measurement results of the channel quality of the direct links and the subtraction results.

Abstract: A user apparatus configured to perform transmission of a discovery signal by radio, including: means that determines a resource group pattern to be used by the user apparatus based on information transmitted from a base station, and determines a resource group including one discovery resource or a plurality of discovery resources that can be used for transmitting the discovery signal from among one resource group or a plurality of resource groups included in the resource group pattern; and means that selects a discovery resource to be used for transmitting the discovery signal from among the determined resource group.

Abstract: The present invention is designed to implement radio communication to maintain good communication quality even when the number of antennas provided in a radio base station apparatus is greater than the number of transmission layers of a downlink control channel, a broadcast channel, and cell-specific reference signals. When, from a radio base station apparatus (200) having a plurality of transmitting antennas, at least one of a downlink control channel, a broadcast channel and a cell-specific reference signal is transmitted with fewer transmission layers than the number of all transmitting antennas, a smaller number of antennas than the number of all transmitting antennas are made virtual in a precoding weight multiplication section (205), and also transmission weights that make the average transmission power of the transmitting antennas or transmission streams the same are multiplied, and the signals multiplied by the transmission weights are transmitted from the transmitting antennas on the downlink.

Abstract: The present invention is directed to preventing the load to be required for blind detection in a mobile station apparatus (UE) from increasing and switching between SU-MIMO and MU-MIMO dynamically, even in the event the system bandwidth is expanded. The present invention has a DCI format selection section (209) that selects identification information which identifies between a DCI format for SU-MIMO and a DCI format for MU-MIMO, a control signal generation section (210) that generates control signals including the identification information and including the DCI format for SU-MIMO or MU-MIMO, having the same number of bits, and a transmission section that transmits the control signals to a mobile station apparatus.

Abstract: The present invention makes it possible to feed back PMIs that are required to generate precoding weights, while securing improvement of throughput performance, in downlink MIMO transmission using a plurality of transmitting antennas. With the present invention, in a mode to include a PTI (Precoder Type Indicator) in a PUCCH and feedback the PTI to a radio base station apparatus for downlink MIMO transmission using a plurality of transmitting antennas, the transmission cycle of feedback information corresponding to report 2 and report 3 when the value of the PTI is 0 are made different from the transmission cycle of feedback information corresponding to report 2 and report 3 when PTI=1 and the former feedback information and the latter feedback information are multiplexed, and the multiplexed signal is transmitted to the radio base station apparatus by the PUCCH.

Abstract: The present invention makes it possible to generate precoding weights reliably, even in downlink MIMO transmission using a plurality of transmitting antennas. The present invention includes: a first feedback information selection section (109) that, in a mode to include a PTI in a PUCCH and feed back the PTI to a radio base station apparatus for downlink MIMO transmission using a plurality of transmitting antennas, selects the same RI as the last RI that was fed back, when the value of the PTI is changed from 0 to 1; a multiplexer (115) that multiplexes the RI and the PTI after the change on a subframe; and a transmission section that transmits the multiplex signal to the radio base station apparatus by the PUCCH.

Abstract: To perform feedback of channel information suitable for MU-MIMO transmission while exploiting a codebook that defines precoding matrixes and PMIs suitable for SU-MIMO transmission, it is a feature that a channel matrix corresponding to a channel transmission path is defined using a plurality of precoding matrixes defined in a codebook suitable for SU-MIMO transmission and a plurality of adjustment coefficients to respectively adjust the plurality of precoding matrixes, a channel information selecting section (111) selects a plurality of precoding matrixes and/or a plurality of adjustment coefficients, and that the selected plurality of precoding matrixes and/or the plurality of adjustment coefficients are transmitted to a base station apparatus as channel information in uplink.

Abstract: The present invention reduces the increase of the amount of feedback information, and, regardless of whether the correlation between antennas is high or low, increases the data rate upon MIMO transmission.

Abstract: The present invention is designed to implement radio communication to maintain good communication quality even when the number of antennas provided in a radio base station apparatus is greater than the number of transmission layers of a downlink control channel, a broadcast channel, and cell-specific reference signals. When, from a radio base station apparatus (200) having a plurality of transmitting antennas, at least one of a downlink control channel, a broadcast channel and a cell-specific reference signal is transmitted with fewer transmission layers than the number of all transmitting antennas, a smaller number of antennas than the number of all transmitting antennas are made virtual in a precoding weight multiplication section (205), and also transmission weights that make the average transmission power of the transmitting antennas or transmission streams the same are multiplied, and the signals multiplied by the transmission weights are transmitted from the transmitting antennas on the downlink.

Abstract: The present invention provides a mobile terminal apparatus and a radio communication method which can feed back precoders that are essential to generate precoding weights in downlink MIMO transmission. With the present invention, in the first mode to feed back subband second PMIs that are selected per bandwidth part through a physical uplink control channel, a subband second PMI and a wideband second PMI are selected from a second codebook, the subband second PMI and the wideband second PMI are multiplexed on a subframe, and the multiplex signals is transmitted to a radio base station apparatus through the above physical uplink control channel.

Abstract: In order to suppress deterioration of the throughput performance of the whole system in the MIMO system performing MIMO transmission, the present invention is characterized in that in a codebook in which there are defined a plurality of precoding weights and a plurality of PMIs (Precoding Matrix Indicators) assigned to the precoding weights, bit information of the PMIs assigned to the precoding weights is adjusted in such a manner as to suppress an effect of feedback error from a mobile station apparatus. The bit information of the PMIs assigned to the precoding weights is adjusted in such a manner as to suppress an effect of a transmission beam formed with a PMI in which feedback error is detected.

Abstract: A data transmission method includes, in the mobile station apparatus, selecting a PMI and an RI corresponding to an Hermitian transpose of a channel matrix indicative of channel characteristics and calculating a CQI from the PMI. The method further includes transmitting the PMI, the RI, and the CQI to the base station apparatus as feedback information. The method further includes, in the base station apparatus, calculating a first data rate of a case of performing SU-MIMO transmission based on the PMI transmitted from the mobile station apparatus as feedback and calculating a second data rate of a case of performing ZF MU-MIMO transmission based on the PMI. The method further includes selecting a transmission scheme corresponding to a higher data rate between the first and second data rates.

Abstract: To increase a data rate (spectral efficiency) of the entire system also in the case of dynamically switching between SU-MIMO transmission and MU-MIMO transmission, it is a feature that a mobile station apparatus (10) selects a PMI associated with a precoding matrix including matrix elements corresponding to a stream that most approximates a channel matrix indicative of a channel state in a channel transmission path to transmit to a base station apparatus (20) as feedback, and that the base station apparatus (20) extracts the matrix elements corresponding to the stream that most approximates the channel state in the channel transmission path from the precoding matrix associated with the PMI transmitted from the mobile station apparatus (10) as feedback, and based on the extracted matrix elements, generates precoding weights.

Abstract: A method transmits data from a first terminal of a wireless communication system to a second terminal of the wireless communication system. The wireless communication system has a core network and at least one radio access network coupled to the core network. Data is transmitted from a first terminal of the wireless communication system to a second terminal of the wireless communication system co-located in a common coverage area of the at least one radio access network. The data is transmitted from the first terminal to the second terminal via the entities of the at least one radio access network without going outside the at least one radio access network. Transmitting the data includes connecting, at a node of the radio access network, the uplink channel between the first terminal and the node and the downlink channel between the node and the second terminal.

Abstract: To perform feedback of channel information suitable for MU-MIMO transmission while exploiting a codebook that defines precoding matrixes and PMIs suitable for SU-MIMO transmission, it is a feature that a channel matrix corresponding to a channel transmission path is defined using a plurality of precoding matrixes defined in a codebook suitable for SU-MIMO transmission and a plurality of adjustment coefficients to respectively adjust the plurality of precoding matrixes, a channel information selecting section (111) selects a plurality of precoding matrixes and/or a plurality of adjustment coefficients, and that the selected plurality of precoding matrixes and/or the plurality of adjustment coefficients are transmitted to a base station apparatus as channel information in uplink.

Abstract: To increase a data rate irrespective of whether the spatial correlation between channels is high or low, while ensuring compatibility with the LTE-scheme MIMO system, in a MIMO system in which a base station apparatus (eNode B) switches between SU-MIMO transmission and ZF MU-MIMO transmission based on feedback information from a mobile station apparatus (UE) to perform data transmission, the mobile station apparatus (UE) selects a PMI and an RI corresponding to an Hermitian transpose of a channel matrix indicative of channel characteristics, calculates a CQI from the PMI, and transmits the PMI, RI and CQI as feedback, and the base station apparatus (eNode B) calculates a first data rate of the case of performing SU-MIMO transmission and a second data rate of the case of performing ZF MU-MIMO transmission based on the PMI that is fed back, and selects a transmission scheme corresponding to a higher data rate between the first and second data rates.

Abstract: Provided are a radio relay station apparatus, a radio base station apparatus and a radio communication method capable of improving user throughput and increasing the capacity in type II relay. The radio communication method of the present invention is characterized by, in a radio relay station apparatus, measuring channel quality of relay links with use of sounding reference signals from mobile terminal apparatuses; and transmitting feedback information including measurement results of channel quality of the relay links to a radio base station apparatus via a backhaul link; in the radio base station apparatus, measuring channel quality of direct links with use of sounding reference signals from the mobile terminal apparatuses, subtracting a correction value from the measurement results of the radio relay station apparatus; and allocating radio resources to a mobile terminal apparatus based on measurement results of the channel quality of the direct links and subtraction results.

Abstract: In order to improve user throughout and increase the capacity in type II relay, a radio relay station apparatus according to the present invention has a channel quality information controlling section configured to measure channel quality of a mobile terminal apparatus, calculate a channel quality reduction value to reduce for the mobile terminal apparatus due to interference from other mobile terminal apparatuses, and select a predetermined mobile terminal apparatus from the other mobile terminal apparatuses; and a transmitting section configured to transmit information of the channel quality of the mobile terminal apparatus, information of the predetermined mobile terminal apparatus selected and the channel quality reduction value to a radio base station apparatus.

Abstract: The present invention makes it possible to feed back PMIs that are required to generate precoding weights, while securing improvement of throughput performance, in downlink MIMO transmission using a plurality of transmitting antennas. With the present invention, in a mode to include a PTI (Precoder Type Indicator) in a PUCCH and feedback the PTI to a radio base station apparatus for downlink MIMO transmission using a plurality of transmitting antennas, the transmission cycle of feedback information corresponding to report 2 and report 3 when the value of the PTI is 0 are made different from the transmission cycle of feedback information corresponding to report 2 and report 3 when PTI=1 and the former feedback information and the latter feedback information are multiplexed, and the multiplexed signal is transmitted to the radio base station apparatus by the PUCCH.