Abstract: Provided are a mobile terminal apparatus, a radio base station apparatus and a radio communication method capable of making the most of the effects of the MIMO technique and the CoMP technique, when employing both of the techniques. According to the radio communication method of the present invention, a mobile terminal apparatus estimates downlink channel states using respective reference signals included in downlink signals from plural cells; selects PMIs using a codebook based on the channel states; estimates a phase difference between the cells based on the selected PMIs or the channel states; and transmits information of the phase difference and the selected PMIs to radio base station apparatuses of the respective cells.

Abstract: The present invention provides a mobile terminal apparatus, a base station apparatus, and a communication control method, which allow control suitable for interference reduction in a layered network such as HetNet, and which support a next-generation mobile communication system. A mobile terminal apparatus has a receiving section (103) that receives radio frames of a pico cell, in which a protected subframe, the transmission of which by a macro cell is suppressed, and a non-protected subframe, the transmission of which by the macro cell is not suppressed, coexist, a measurement section (112) that measures reception quality from the reference signals multiplexed individually on the protected subframe and the non-protected subframe, and a transmission section (103) that notifies two types of reception quality information of the protected subframe and the non-protected subframe, measured in the measurement section (112), to a base station apparatus (20B).

Abstract: Provided are a radio base station apparatus, a mobile terminal apparatus and a radio communication method capable of taking other-cell interference mitigation measures even in consideration of inter-cell coordination like CoMP. The radio communication method according to the present invention is characterized by, in a radio base station apparatus, generating notification information including subframe information of a serving cell and subframe information of another cell; and transmitting the notification information to a mobile terminal apparatus connected to the serving cell as a connected cell; and in the mobile terminal apparatus, receiving the notification information including the subframe information of the connected cell and the subframe information of another cell; and measuring channel quality of the connected cell with use of the subframe information of the connected cell and measuring channel quality of another cell with use of the subframe information of another cell.

Abstract: To efficiently detect feedback control information on downlink shared data channel signals transmitted with a plurality of base frequency blocks also in the case of performing radio communications with a system band comprised of a plurality of base frequency blocks, it is a feature to have detecting sections (208, 210) configured to detect a correlation value between an ACK/NACK signal received in uplink and each of ACK/NACK candidate replicas associated with ACK and NACK in response to a downlink shared data channel signal of a particular base frequency block assigned to the mobile terminal apparatus among a plurality of base frequency blocks or of each of a plurality of base frequency blocks, and an A/N·DTX determining section (211) configured to determine feedback control information on the downlink shared data channel signal of the particular base frequency block or of each of the plurality of base frequency blocks, based on the detected correlation value and a DTX determination threshold value.

Abstract: The present invention provides a mobile terminal apparatus, a base station apparatus, and a communication control method, which allow control suitable for interference reduction in a layered network such as HetNet, and which support a next-generation mobile communication system.

Abstract: To prevent a situation that communication operation becomes unstable resulting from erroneous detection of a PDCCH in a mobile communication system having a system band comprised of a plurality of base frequency blocks, in a mobile terminal apparatus (10) provided with a downlink control signal decoding section (104) configured to determine radio resources designated by ARI (ACK/NACK Resource Indicator) fields of PDSCHs assigned to a plurality of base frequency blocks (CCs), and a retransmission response signal transmission control section (105) configured to control transmission of retransmission response signals in response to PDSCHs assigned to a plurality of base frequency blocks (CCs) based on the radio resources designated by the ARI fields, the retransmission response signal transmission control section (105) limits transmission of retransmission response signals in response to PDSCHs assigned to all the base frequency blocks (CCs) when the radio resources designated by a plurality of the ARI fields in

Abstract: The present invention provides a base station apparatus, a mobile terminal apparatus and a communication control method which can improve the accuracy of channel quality estimation. A communication control method includes the steps of: allocating a CSI-RS (Channel State Information-Reference Signal), which is a reference signal for downlink channel estimation, in resources for the CSI-RS that are defined for CSI-RS transmission; setting to muting resources in the resources for the CSI-RS; and reporting parameters to specify the CSI-RS, including at least a transmitting subframe cycle, a subframe offset and transmission power, to a mobile terminal apparatus.

Abstract: A mobile communication method according to the present invention includes a step A of transmitting, by a mobile station UE#1 and a mobile station UE#2, information required for scheduling to a radio base station eNB, a step B of transmitting, by the radio base station eNB, scheduling information instructing to perform direct communication between the mobile station UE#1 and the mobile station UE#2 without passing through the radio base station eNB to the mobile station UE#1 and the mobile station UE#2 on the basis of the received information required for scheduling, and a step C of transmitting and receiving, by the mobile station UE#1 and the mobile station UE#2, data signals without passing through the radio base station eNB on the basis of the scheduling information.

Abstract: A mobile communication method according to the present invention includes a step A of notifying, by a radio base station eNB, a mobile station UE during communication in a subordinate cell #1 of “CSI-RS/Muting configuration information” indicating a transmission method of CSI-RS; and a step B of performing, by the mobile station UE, a reception process on the basis of the “CSI-RS/Muting configuration information”.

Abstract: The present invention provides a base station apparatus, a mobile terminal apparatus and a communication control method which can improve the accuracy of channel quality estimation. A communication control method includes the steps of: arranging a CSI-RS, which is a reference signal for downlink channel estimation, in resources of subframes for CSI-RS transmission; setting, in the subframes for CSI-RS transmission, resources to which the CSI-RS is allocated in neighboring areas, to be muting resources; and reporting transmission interval information, which indicates a transmission interval of subframes that are set at the same timing in a transmission cycle of a subframe for CSI-RS transmission in a subject area and in a transmission cycle of a subframe for CSI-RS transmission in the neighboring areas, to a mobile terminal apparatus.

Abstract: Provided is a radio communication system using a relay transmission technique capable of optimizing use of radio resources in a radio base station and preventing reduction in capacity of the whole system. The relay frequency allocation method of the present invention has the steps of: radio base stations (10a) and (10b) transmitting downlink data to a relay station (30) using respective backhaul links established between the relay station (30) and the radio base stations (10a) and (10b); and the relay station (30) transmitting the downlink data received from the radio base stations (10a) and (10b), to a relay terminal (20b) by using an access link established between the relay station (30) and the relay terminal (20b).

Abstract: With this transmission power control method, in a radio base station apparatus (10) of a macro cell, registration information as to whether or not a mobile terminal apparatus is a non-member mobile terminal apparatus, which is not a mobile terminal apparatus having registered access to a radio base station apparatus (20) of a femto cell, a received quality measurement result, and cell information, are received, whether or not a non-member mobile terminal apparatus has come near the femto cell is determined from the registration information, the received quality measurement result, and the cell information, and neighbor information, which indicates that a non-member mobile terminal apparatus has come near the femto cell, is reported to the radio base station apparatus (20) of the femto cell, by a backhaul link, and in the radio base station apparatus (20) of the femto cell, transmission power is reduced based on the neighbor information.

Abstract: It is an object of the present invention to adequately report the SRS transmission timing and SRS parameters to a mobile terminal apparatus, when an aperiodic SRS is adopted, and efficiently use radio resources to be used for SRS transmission. A radio base station apparatus that reports SRS transmission control information to a mobile terminal apparatus and controls transmission of an SRS by the mobile terminal apparatus, and the radio base station apparatus has an SRS setting section that selects bit information to report to the mobile terminal apparatus, from a table having bit information to indicate not to trigger the SRS and bit information to indicate to trigger the SRS using a default SRS parameter, and a reporting section that reports the bit information for the mobile terminal apparatus using a downlink control channel.

Abstract: To provide a signaling method for enabling position information of muting resources to be signaled with a simplified configuration, base station apparatus and mobile terminal apparatus, the signaling method is characterized by having the steps of setting blank resources for a CSI-RS (Channel State Information-Reference Signal) that is a reference signal for downlink channel estimation, and transmitting a bitmap indicative of a position of the blank resources to a mobile terminal apparatus.

Abstract: In each Mobile terminal, channel impulse characteristics from radio base stations to the mobile terminal is calculated. In a radio communication system, under the assumption that each of the mobile terminals performs optimum receiving beamforming in order to receive a data signal from a radio base station that actually sends the data signal to the mobile terminal, optimum receiving beamforming characteristics are estimated for each mobile terminal. Each of radio base stations that share optimum receiving beamforming characteristics calculates precoding characteristics for each mobile terminal according to the optimum receiving beamforming characteristics such that main beams are directed to mobile terminals to which the radio base station sends data signals and null beams are directed to mobile terminals to which the radio base station does not send data signals.

Abstract: To signal CSI-RS location indexes indicative of CSI-RS location positions in a resource block with high efficiency, a signaling method of CSI-RS is characterized by having the steps of locating a CSI-RS that is a reference signal for downlink channel estimation in resources for CSI-RS reserved to transmit the CSI-RS, generating a CSI-RS location index indicative of a location position of the CSI-RS located in the resources for CSI-RS, in the CSI-RS location index an index pattern varies corresponding to the number of CSI-RS ports so that an index pattern of the relatively low number of CSI-RS ports is a subset of an index pattern of the relatively high number of CSI-RS ports, and transmitting the generated CSI-RS location index to a mobile terminal apparatus.

Abstract: In a radio communication system in which a micro cell is provided in a macro cell, when a user terminal that is connected to the macro base station is located in the micro cell, interference signals which the user terminal receives from the micro base station are reduced.

Abstract: A decrease in a transmission capacity is suppressed even when CSI is not fed back from a mobile station apparatus to all cooperating base station apparatuses. A base station apparatus (BS2) decides, according to the presence/absence of CSI fed back from a plurality of mobile station apparatuses (MS (MS1, MS2)), a cooperation target mobile station apparatus (MS2) to which the base station apparatus transmits a signal in cooperation with another base station apparatus (BS1) and a non-cooperation target mobile station apparatus (MS1) to which a specific base station apparatus (BS1) transmits a signal, and generates a precoding weight for the signal transmitted to the cooperation target and non-cooperation target mobile station apparatuses (MSs) based on the channel state information.

Abstract: To cancel interference from the other cells and improve throughput characteristics without needing complicated processing, provided are a reception section that receives a reception signal including signal components from a plurality of base station apparatuses (BSs), and a signal detection and channel estimation section (61) that performs signal detection and channel estimation processing based on a factor graph on the reception signal, where the signal detection and channel estimation section (61) estimates interfering components from base station apparatuses of the other cells except a desired base station apparatus included in the reception signal at a symbol level, and reuses the interfering components in the signal detection and channel estimation processing based on the factor graph.

Abstract: Provided are a base station apparatus, a mobile terminal apparatus and a communication control method capable of selecting a CSI-RS arrangement flexibly in accordance with a system configuration. The base station apparatus has a CSI-RS arrangement section (211) configured to arrange a CSI-RS in a resource reserved for broadcasting when a mobile terminal apparatus (10) is notified of position information of the CSI-RS by broadcasting or in a resource associated with an cell ID of a serving area when the mobile terminal apparatus (10) obtains the position of the CSI-RS based on the cell ID; an identification information generating section (212) configured to generate an identification bit for identifying whether the CSI-RS is arranged in the resource reserved for broadcasting or in the resource associated with the cell ID; and a transmission/reception section (203) configured to transmit the identification information to the mobile terminal apparatus.