Abstract: The present invention is designed to, upon updating CQIs that are fed back, prevent the increase of the overhead of feedback information, and still improve the accuracy of the updated CQIs when CoMP transmission is applied. The radio communication system of the present invention is formed with a plurality of radio base station apparatuses and a user terminal that is configured to be able to perform coordinated multiple point transmission/reception with the plurality of radio base station apparatuses, and the user terminal acquires channel state information of multiple cells, generates feedback information such that the channel state information of multiple cells is allotted and transmitted in a plurality of subframes, and feeds back the generated feedback information to the radio base station apparatus of one of the multiple coordinated points, using a physical uplink shared data channel.

Abstract: The present invention is designed to adequately measure the received quality of small cells on the user terminal side. A radio base station communicates with a user terminal by using a plurality of carriers into which a communication band is divided, and has a generating section that generates reference signals for allowing the user terminal to measure received quality, and an allocation section that controls the allocation of the reference signals, and, when one of the plurality of carriers is made subject to non-transmission, the allocation section configures a zero-power RS in a predetermined resource location of a specific carrier.

Abstract: To reduce overhead of CSI feedback without decreasing throughput in applying CoMP transmission, a radio communication method of the invention is characterized by including, in a user terminal measuring quality information for each of cells to perform Coordinated Multi-Point transmission, and notifying a radio base station apparatus of the quality information, in the radio base station apparatus calculating a quality difference between the cells to perform Coordinated Multi-Point transmission, by using the quality information for each the cells from the user terminal, determining granularity of inter-cell channel state information for each of the cells based on the quality difference, and notifying the user terminal of the granularity, and, in that the user terminal generating inter-cell channel state information for each of the cells according to the granularity from the radio base station apparatus, and transmitting the inter-cell channel state information for each of the cells to radio base station apparatu

Abstract: A radio communication system including a plurality of radio base stations and a user terminal that is capable of coordinated multiple point transmission with the plurality of radio base stations is provided, and, in this radio communication system, a radio base station has a generating section that generates parameter information related to downlink signals, a control information generating section that generates downlink control information that includes an indicator to represent specific parameter information, a control section that controls whether or not to configure a bit field for the indicator of the parameter information in the downlink control information, and a transmission section that transmits information as to whether or not the bit field for the indicator of the parameter information is configured, to the user terminal, by higher layer signaling.

Abstract: In order to signal information that is required in rate matching efficiently, even when CoMP transmission/reception techniques are employed, CoMP transmission is scheduled, in which a plurality of radio base station apparatuses (eNBs) serve as transmission points and carry out coordinated multi-point transmission with respect to a user terminal (UE), downlink control information is generated, in which a rate matching pattern is incorporated, in a physical downlink control channel, based on a table, in which rate matching patterns that are required are mapped to bit data in association with transmission modes in CoMP transmission, a physical downlink control channel is transmitted and also a physical downlink shared data channel is transmitted, to the user terminal (UE), and in the user terminal (UE), the rate matching pattern incorporated in the downlink control information, is specified, based on a table of the same contents as in the radio base station apparatuses (eNBs).

Abstract: In order to recognize a relatively accurate channel state of each UE, a channel of the UE is reconfigured based on channel phase information and channel quality information reported from the UE to obtain a channel matrix of the UE. Besides, a channel of the UE is reconfigured based on channel phase information and channel quality information reported from the UE to obtain a channel matrix of the UE, a precoding matrix of the UE is determined based on the channel matrix of the UE, and precoding is performed on data to transmit to the UE, using the precoding matrix.

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: The present invention is designed to provide a radio communication system, a radio base station apparatus and a radio communication method which can realize high transmission rate while reducing the calculation load involved in CoMP scheduling.

Abstract: The present invention is designed so that it is possible to feed back channel state information (CSI) that is suitable for downlink communication in which 3D beams are used. The radio communication method of the present invention is a radio communication method to allow a radio base station to carry out downlink communication with a user terminal by using a 3D beam that is formed with a horizontal beam having directivity in a horizontal plane and a vertical beam having directivity in a vertical plane, and has the steps in which the radio base station transmits a plurality of measurement reference signals that are pre-coded using different precoding weights between a plurality of vertical beams, and the user terminal transmits channel state information that is generated based on the plurality of measurement reference signals, to the radio base station.

Abstract: The present invention is designed to provide a mobile terminal apparatus, a radio base station apparatus and a radio communication method which, even when a MIMO technique and a CoMP technique are applied together, can optimize the effects of both techniques. The mobile terminal apparatus estimates downlink channel states using reference signals included in downlink signals from a plurality of cells, determines the PMI for each cell and inter-cell phase difference information, from the channel states of the plurality of cells, such that the combinations of the PMI of each cell and inter-cell phase difference information become optimal, measures channel quality from the determined PMIs and inter-cell phase difference information, and transmits the PMI for each cell, the inter-cell phase difference information and channel quality information, to a radio base station apparatus.

Abstract: The present invention is designed to use radio resources effectively and improve the throughput of a radio communication system even when a plurality of small cells are placed densely. A radio base station controls the connecting cell of a user terminal, and has a selection section that selects candidate cells, the received power and/or the received quality of which in the user terminal is equal to or greater than a predetermined value, and a determining section that calculates the amount of data to transmit to serving user terminals, for each candidate cell, by taking into account the frequency band that is used, and determines a candidate cell where the amount of data is small, as the connecting cell of the user terminal.

Abstract: The present invention is designed so that it is possible to feed back channel state information (CSI) that is suitable for downlink communication in which 3D beams are used. The radio communication method of the present invention is a radio communication method to allow a radio base station to carry out downlink communication with a user terminal by using a 3D beam that is formed with a horizontal beam having directivity in a horizontal plane and a vertical beam having directivity in a vertical plane, and has the steps in which the radio base station transmits a plurality of measurement reference signals that are pre-coded using different precoding weights between a plurality of vertical beams, and the user terminal transmits channel state information that is generated based on the plurality of measurement reference signals, to the radio base station.

Abstract: To reduce overhead of CSI feedback without decreasing throughput in applying CoMP transmission, a radio communication method of the invention is characterized in that a radio base station apparatus determines so that content of CSI to transmit to a serving cell to perform CoMP transmission as feedback is different from content of CSI to transmit to a coordinated cell as feedback, and notifies a user terminal of the content of CSI, and that the user terminal generates feedback information based on the content of CSI notified from the radio base station apparatus, and transmits the feedback information to radio base station apparatuses of cells that perform Coordinated Multi-Point transmission.

Abstract: The present invention is designed to prevent the decrease of throughput and also reduce the overhead of CSI feedback when CoMP transmission is applied. In a radio communication system including a plurality of radio base station apparatuses and a user terminal that is configured to be able to carry out coordinated multiple-point transmission/reception with the plurality of radio base station apparatuses, the radio base station apparatus designates a plurality of candidate values of predetermined inter-cell channel state information and reports them to the user terminal, and the user terminal measures inter-cell channel state information of each cell, and also selects a specific candidate value that is close to the measurement value of inter-cell channel state information from the plurality of candidate values that have been reported, and feeds back the specific candidate value to the radio base station apparatus.

Abstract: Techniques for providing codebooks extended by gain information that can be transmitted in a reduced amount of signaling are disclosed.

Abstract: In order to signal information that is required in rate matching efficiently, even when CoMP transmission/reception techniques are employed, CoMP transmission is scheduled, in which a plurality of radio base station apparatuses (eNBs) serve as transmission points and carry out coordinated multi-point transmission with respect to a user terminal (UE), downlink control information is generated, in which a rate matching pattern is incorporated, in a physical downlink control channel, based on a table, in which rate matching patterns that are required are mapped to bit data in association with transmission modes in CoMP transmission, a physical downlink control channel is transmitted and also a physical downlink shared data channel is transmitted, to the user terminal (UE), and in the user terminal (UE), the rate matching pattern incorporated in the downlink control information, is specified, based on a table of the same contents as in the radio base station apparatuses (eNBs).

Abstract: To perform rate matching appropriately even when downlink signals are transmitted from a plurality of transmission points to a user terminal, a radio communication system having a user terminal capable of coordinate multi-point transmission and reception with several radio base stations is provided. A radio base station transmits downlink control information including bit information defining a predetermined rate matching pattern to the user terminal. The user terminal receives the downlink control information and performs rate matching based on the bit information defining the rate matching pattern. A combination of a cell-specific reference signal pattern and an interference measurement reference signal pattern in the case of transmission from several radio base stations each using an MBSFN subframe or NCT is defined in predetermined bits.

Abstract: The present invention is designed so that it is possible to feed back channel state information (CSI) that is suitable for downlink communication in which 3D beams are used. The radio communication method of the present invention is a radio communication method to allow a radio base station to carry out downlink communication with a user terminal by using a 3D beam that is formed with a horizontal beam having directivity in a horizontal plane and a vertical beam having directivity in a vertical plane, and has the steps in which the radio base station transmits a plurality of measurement reference signals that are pre-coded using different precoding weights between a plurality of vertical beams, and the user terminal transmits channel state information that is generated based on the plurality of measurement reference signals, to the radio base station.

Abstract: To make it possible to feed back channel state information adequately even when a plurality of pieces of channel state information are generated in a user terminal, a user terminal that is configured to be able to conduct coordinated multi-point transmission/reception with a plurality of radio base stations has a generating section that generates a plurality of kinds of channel state information using channel state measurement reference signals transmitted from each radio base station, a selection section that selects predetermined channel state information to feed back, from the plurality of kinds of channel state information, and a transmission section that feeds back the predetermined channel state information to the radio base station via an uplink control channel, and the selection section selects the predetermined channel state information based at least on the priorities assigned to the resource indices of channel state measurement reference signals corresponding to each channel state information.

Abstract: The present invention is designed to realize signaling of cell index information that is suitable for CoMP transmission/reception techniques. The radio base station apparatus of a special cell generates downlink control information, in which the indices of CoMP sets are incorporated in a physical downlink control channel that is shared between the multiple cells that carry out joint transmission, based on a table in which indices to represent individual coordinated cells that serve as transmission points in CoMP transmission and indices of CoMP sets to represent combinations of multiple cells that carry out joint transmission in CoMP transmission are mapped to bit data.