Abstract: A disclosed base station apparatus is capable of communicating with a user equipment terminal in a multi-input multi-output (MIMO) mobile communication system using Pre-coding. The base station apparatus includes a receiving unit receiving a Pre-coding Matrix Indicator (PMI) indicating a specific Pre-coding matrix, a determination unit determining a value of a flag indicator indicating whether the Pre-coding matrix specified in the PMI is to be used for downlink communications, a control signal generation unit generating a downlink control signal including at least the flag indicator, and a transmission unit transmitting a signal including the downlink control signal in downlink.

Abstract: Provided is a radio base station apparatus capable of selecting an optimal modulation and coding scheme for each transmission stream easily. The radio base station apparatus has a CQI information decoder (101) configured to decode CQIs of plural downlink transmission streams and an MCS selector (102) that has an N-dimensional table (two-dimensional reference table (1021)) in accordance with the number N of downlink transmission streams where combinations of modulation and coding scheme between the plural downlink transmission streams are defined in accordance with each of the CQIs of the downlink transmission streams and is configured to select from the combinations of modulation and coding scheme for the downlink transmission streams based on each of the CQIs of the downlink transmission streams decoded by the CQI information decoder (101).

Abstract: A base station communicating using multiple antennas includes a direction-of-arrival (DOA) estimation unit configured to estimate a direction of arrival based on a signal from a mobile station and to output direction-of-arrival information regarding the estimated direction of arrival; a DOA information multiplexing unit configured to multiplex the direction-of-arrival information from the direction-of-arrival estimation unit with a shared data channel to be transmitted to the mobile station; and an antenna weight multiplying unit configured to multiply a signal to be transmitted to the mobile station and including the shared data channel multiplexed with the direction-of-arrival information by antenna weights obtained based on the direction-of-arrival information from the direction-of-arrival estimation unit.

Abstract: A transmitter includes multiple transmit antennas, a conversion unit configured to generate multiple signal sequences corresponding to a predefined frequency bandwidth from one or more transmission streams associated with any of the transmit antennas, a precoding unit configured to weight the signal sequences with a precoding matrix selected from a codebook including multiple predefined precoding matrices, and a transmitting unit configured to convert an output signal from the precoding unit into a number of signals corresponding to the number of transmit antennas and transmit the converted signals from the transmit antennas. The precoding unit applies distinct precoding matrices to different signal sequences, and an association between the distinct precoding matrices and the different signal sequences is determined through open-loop control being independent of a feedback from a receiver.

Abstract: In order to reduce the amount of feedback information for specifying a precoding weight, the mobile station apparatus generates a control signal for specifying the precoding weight using bits representing a rank indicator (RI) and bits representing a precoding matrix indicator (PMI) from a bit space, including a plurality of bits representing the RI and a plurality of bits representing the PMI, in which the same bits representing the RI are allocated to a plurality of ranks equal to or higher than a predetermined rank. The control signal is transmitted in uplink using the antennas.

Abstract: The present invention provides a base station apparatus, a mobile terminal apparatus and a communication control method that can adequately allocate resources of response signals for retransmission for spatially-multiplexed signals respectively corresponding to a plurality of layers via the uplink and that support next-generation mobile communication systems. Discloses is a configuration to receive signals in which a plurality of layers are spatially-multiplexed on the uplink from a mobile terminal apparatus (10), generate HARQ ACK/NACK for signals received in the layers on the uplink, and allocate HARQ ACK/NACK for transport blocks associated with the layers, to PHICH resources, using the offset values that are fixedly defined in advance with the mobile terminal apparatus (10) for every uplink layer.

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: A disclosed base station apparatus is capable of communicating with a user equipment terminal in a multi-input multi-output (MIMO) mobile communication system using Pre-coding. The base station apparatus includes a receiving unit receiving a Pre-coding Matrix Indicator (PMI) indicating a specific Pre-coding matrix, a determination unit determining a value of a flag indicator indicating whether the Pre-coding matrix specified in the PMI is to be used for downlink communications, a control signal generation unit generating a downlink control signal including at least the flag indicator, and a transmission unit transmitting a signal including the downlink control signal in downlink.

Abstract: A data rate in MIMO transmission is increased to a maximum even when the number of transmitting antennas of a mobile station apparatus is different from the number of transmitting antennas of the mobile station apparatus supported by a base station apparatus. The base station apparatus (eNodeB) reports the maximum number of supported antennas of the mobile station apparatus (UE) supported by the base station apparatus (eNodeB) to the mobile station apparatus (UE) (ST11). The mobile station apparatus (UE) compares the number of supported antennas with the number of transmitting antennas of the mobile station apparatus (UE), selects the smaller number of antennas as a number of virtual antennas (ST12), and reports the number of virtual antennas to the base station apparatus (eNodeB) (ST13). The base station apparatus (eNodeB) instructs the mobile station apparatus to transmit a data channel signal in accordance with the number of virtual antennas (ST15).

Abstract: A user apparatus in a mobile communications system is disclosed. The user apparatus includes a unit which receives, from a base station apparatus, a downlink control signal including information for allocating a radio resource; a unit which determines, depending on a channel status, a pre-encoding matrix indicator (PMI) which indicates a pre-encoding matrix to be applied to multiple antennas of the base station apparatus; and a unit which transmits, to the base station apparatus, an uplink signal including the PMI, wherein, if the radio resource is allocated to a physical uplink shared channel of the user apparatus, the PMI is transmitted using a part of the radio resource, and, wherein, if the radio resource is not allocated to the physical uplink shared channel of the user apparatus, the PMI is transmitted in a physical uplink control channel which is allocated, in a fixed manner, to the user apparatus.

Abstract: The data rate in MIMO transmission is increased to a maximum even when a number of transmitting antennas of a base station apparatus is different from the number of transmitting antennas of the base station apparatus supported by a mobile station apparatus. The base station apparatus (eNodeB) reports the number of transmitting antennas provided for the base station apparatus to the mobile station apparatus UE (ST11). The mobile station apparatus UE compares the reported number of transmitting antennas with a maximum number of supported antennas of the base station apparatus (eNodeB) supported by the mobile station apparatus UE, selects the smaller number of antennas as a number of virtual antennas (ST12), and reports the number of virtual antennas to the base station apparatus (eNodeB) (ST13). The base station apparatus (eNodeB) transmits a data channel signal in accordance with the reported number of virtual antennas (ST15).

Abstract: A transmitter includes multiple transmit antennas, a conversion unit configured to generate multiple signal sequences corresponding to a predefined frequency bandwidth from one or more transmission streams associated with any of the transmit antennas, a precoding unit configured to weight the signal sequences with a precoding matrix selected from a codebook including multiple predefined precoding matrices, and a transmitting unit configured to convert an output signal from the precoding unit into a number of signals corresponding to the number of transmit antennas and transmit the converted signals from the transmit antennas. The precoding unit applies distinct precoding matrices to different signal sequences, and an association between the distinct precoding matrices and the different signal sequences is determined through open-loop control being independent of a feedback from a receiver.

Abstract: Wideband transmission is performed efficiently using spectrum aggregation. When performing information transmission using spectrum aggregation that aggregates frequency spectra which are non-contiguous and in different frequency bands, first information requiring communication quality is allocated to an anchor spectrum with small path loss among different frequency spectra used for information transmission and transmitted to a mobile station apparatus (UE), and second information requiring lower communication quality than the first information is allocated to a payload spectrum having large path loss and transmitted to the mobile station apparatus (UE).

Abstract: To reduce interference among mobile station apparatuses even when the CSI is not transmitted from all mobile station apparatuses as feedback in an environment where Joint Transmission is performed, a channel matrix is generated which is comprised of the CSI from a plurality of mobile station apparatuses (UEs) undergoing spatial multiplexing for each of coordinated cells, and based on the channel matrix, precoding weights are generated successively starting from a cell having the highest number of mobile station apparatuses (UEs) that transmit the CSI as feedback.

Abstract: Provided are a mobile terminal apparatus, a radio base station apparatus and a radiocommunication method, capable of saving PHICH resources enough and realizing effective retransmission control of uplink SU-MIMO. The radio communication method of the present invention is characterized in that a radio base station apparatus receives signals of plural codewords, when there is an error in each of the codewords, generates a one-bit negative response physical HARQ indicator channel signal and transmits the physical HARQ indicator channel signal, and a mobile terminal apparatus receives the physical HARQ indicator channel signal and transmits retransmission signals of all the codewords to the radio base station apparatus based on the negative response physical HARQ indicator channel signal.

Abstract: To provide a radio base station apparatus, mobile terminal device and wireless communication method for enabling the SRS to be used efficiently in an LTE-A system, a wireless communication method of the invention is characterized in that a radio base station apparatus performs OFDM modulation on a transmission signal including transmission information on sounding reference signals for each transmission antenna, and transmits the OFDM-modulated transmission signal, and that a mobile terminal device receives the signal including the transmission information, controls a transmission aspect of the sounding reference signals for each transmission antenna based on the transmission information, and transmits the sounding reference signals in the transmission aspect for each transmission antenna.

Abstract: A base station apparatus includes a correction unit for correcting a CQI reported from a user apparatus and a scheduler for scheduling based on the corrected CQI. The correction unit uses a correction table to correct the CQI such that if the reported CQI is poor, the CQI is slightly reduced, and otherwise, the CQI is significantly reduced. One method of generating the correction table includes deriving a first SINR in consideration of the number of interference users less than (n?1) and a second SINR in consideration of the number of interference users equal to (n?1) to explore a distribution of the second SINR to the first SINR. In this method, correspondence between the first SINR and the second SINR is determined based on the distribution to generate the correction table.

Abstract: The present invention provides a radio base station apparatus, a radio terminal apparatus and a radio communication method that can realize highly efficient fallback mode when transmission diversity is adopted in fallback mode in an LTE-A system. With the radio communication method of the present invention, a radio base station apparatus, in fall back mode, performs scheduling for fallback mode, which takes into account the reference signal structures in fallback mode, and transmits a transmission signal after the scheduling by open loop control transmission diversity, and a mobile terminal apparatus receives a downlink signal including mode information, and, in fallback mode, performs channel estimation for fallback mode based on the mode information, and demodulates the downlink signal using the acquired channel estimation value.

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: 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.