Abstract: A radio communication system includes a radio base station and a terminal device. The radio base station and the terminal device share correspondence information about subsets of preamble sequences obtained by segmenting preamble sequences available in the radio communication systems into groups, each of the subsets being associated with a received signal level at the terminal device and a number of repetitions for transmitting the preamble sequences of each of the subsets. Based upon a receive level of a signal transmitted from the radio base station, the terminal device selects a subset corresponding to the receive level by referring to the correspondence information and transmits a preamble sequence included in the selected subset at the number of repetitions associated with the selected subset.

Abstract: To optimize operation of a mobile terminal apparatus when a Half-duplex FDD scheme is applied, the mobile terminal apparatus performs radio communications with a base station apparatus by HD-FDD, and when transmission timing of an uplink signal and reception timing of a downlink signal overlaps each other, selectively performs transmission processing of the uplink signal and reception processing of the downlink signal, based on a priority relationship defined between the uplink signal and the downlink signal.

Abstract: The present invention is designed to flexibly report aperiodic channel state information to a plurality of radio base station apparatuses to be coordinated, even when coordinated multiple-point (CoMP) transmission/reception is performed.

Abstract: A radio communication system includes a first base station that is identified by a first cell identity, a second base station that is identified by a second cell identity, and a user device that can perform radio communication with each of the base stations. The user device detects a first transmission timing based on a first synchronization signal from the first base station and establishes synchronization with the first base station. The first base station notifies the user device of synchronization state information related to a synchronization state with the second base station and of frequency information related to an identification signal frequency that is used by the second base station to transmit an identification signal. The user device, based on the synchronization state information, performs identifying processing, on the identification signal frequency indicated by the frequency information, to identify the second cell identity indicated by the identification signal.

Abstract: The present invention is provided to randomize interference between small cells in a radio communication system in which the small cells are located to overlap a macro cell. The radio communication method of the present invention includes the steps of generating, in a small base station forming the small cell, a downlink signal by using a terminal-specific identity that is formed based on a first terminal-specific identity and a second terminal-specific identity, transmitting, in the small base station, the downlink signal to a user terminal, generating, in the user terminal, an uplink signal by using the terminal-specific identity, and transmitting, in the user terminal, the uplink signal to the small base station.

Abstract: To provide a radio base station apparatus and radio communication method capable of performing radio communications using downlink reference signal structures suitable for antenna virtualization, a radio base station apparatus (200) has a plurality of transmission antennas, generates CRSs used in demodulation of at least downlink control information, CQI-RSs generated for each of the transmission antennas used in measurement of channel quality, and DM-RSs generated for each stream used in demodulation of downlink transmission data, and multiplexes the CRSs, CQI-RSs and DM-RSs into a same transmission time unit to transmit from each of the antennas.

Abstract: A radio communication system includes a radio base station having multiple antenna elements arranged two-dimensionally, and a user equipment configured to perform radio communication with the radio base station. The radio base station is configured to transmit a reference signal used for channel estimation in two or more different configurations using a part or all of the antenna elements, and wherein the user equipment is configured to feed back at least one of horizontal channel information, vertical channel information, and inter-polarization channel information to the radio base station.

Abstract: To use CSI feedback information capable of sufficiently supporting MU-MIMO transmission and CoMP transmission in LTE-A systems, in a radio communication method of the invention, a radio base station apparatus (200) generates downlink transmission data including a report mode corresponding to a bandwidth to perform feedback of feedback information including channel quality information and spatial channel information, and an extension level of the feedback information, and multiplexes the downlink transmission data and a reference signal for feedback information to transmit to a mobile terminal apparatus (100), and the mobile terminal apparatus (100) receives a downlink signal including the report mode and the extension level, and generates feedback information associated with the report mode and the extension level to transmit to the radio base station apparatus (200).

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: The present invention is designed to reduce interference between cells even when a plurality of cells are placed at a high density. In a radio base station, a receiving section that receives an uplink signal transmitted from a user terminal, and an interference estimation section that estimates the level of interference received from an other cell based on an uplink signal transmitted from a user terminal of the other cell, are provided, and the interference estimation section estimates the level of interference of each cell based on the uplink signal, and a blank state is assumed in the uplink signal at a resource position that varies on a per cell basis. Furthermore, a control section that controls a predetermined resource position in an uplink signal transmitted from a serving user terminal to assume the blank state, is provided.

Abstract: In order to achieve enough randomization of uplink control signals between a plurality of small cells located in a macro cell and to simplify cell planning of the small cells, the present invention provides a user terminal that is capable of communicating with a macro base station covering a macro cell and a small base station covering a small cell located within the macro cell. The user terminal generates uplink signals using uplink signal sequences of zero autocorrelation except at a synchronization point, and allocates the uplink signals to subframes by using a hopping pattern where a sequence number of an uplink signal sequence is switched per subframe in a predetermined cycle. A hopping cycle of the uplink signal sequences in a hopping pattern for the small base station is longer than a hopping cycle of the uplink signal sequences in a hopping pattern for the macro base station.

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.

Abstract: The present invention is designed to improve spectral efficiency in a radio communication system which can use non-orthogonal multiple access (NOMA). Steps are provided in which a radio base station configures one of a plurality of transmission mode including a first transmission mode, which groups a plurality of transmission methods including a transmission method to employ non-orthogonal multiple access (NOMA) and multiple-user multiple-input and multiple-output (MU-MIMO), and a second transmission mode, which groups a plurality of transmission methods including a transmission method to employ this NOMA and open-loop transmit diversity, and transmits a downlink signal for this user terminal based on the configured transmission mode.

Abstract: The present invention is designed to provide a radio base station, a user terminal, a radio communication system and a radio communication method of novel structures that can improve the efficiency of the use of radio resources sufficiently.

Abstract: In a communication environment where a plurality of operators coexist, in order to minimize interference between the operators and also improve use efficiency of radio resources, a radio base station is disclosed. The radio base station includes an allocation control section that controls allocation to make an UL carrier for uplink transmission and a DL carrier for downlink transmission orthogonal to each other in a frequency direction, and a transmission/reception section that performs transmission or reception of a signal by using either of the UL carrier and the DL carrier for a user terminal in one transmission time interval. The allocation control section controls a carrier adjacent to a carrier used by a different operator to have same transmission direction as the carrier of the different carrier.

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: To provide a radio base station apparatus and mobile terminal for enabling cell selection to be performed in a faster cell switching period in handover, the radio base station apparatus of the invention has a plurality of transmission/reception sections capable of being extended to remote sites, an FCS application determining section that determines whether to apply fast cell selection in handover based on information from the mobile terminal, and a multi-cell scheduling control section that controls transmission/non-transmission of the first and second transmission/reception sections when the FCS application determining section determines that FCS is applied.

Abstract: The present invention is designed to provide a user terminal, a radio base station and a radio communication method of novel structures that can achieve a good communication environment. A radio base station non-orthogonal-multiplexes downlink signals for a plurality of user terminals over a given radio resource, a user terminal having received the downlink signals for the plurality of user terminals decodes downlink signal for another user terminal, judges whether or not the downlink signal for the other user terminal has been successfully received, based on the decoding result of the downlink signal, reports a judgement result as to whether or not the downlink signal for the other user terminal has been successfully received and a judgement result as to whether or not a downlink signal for the user terminal has been successfully received, to the radio base station, and then the radio base station executes retransmission control of downlink signals based on reports from the user terminal.

Abstract: The present invention is designed to establish synchronization between transmission points when downlink signals are transmitted from a plurality of transmission points to a user terminal. A radio communication system has a first radio base station that forms a first cell, a second radio base station that forms a second cell, which is placed on the area of the first cell in an overlapping manner, and a user terminal that is capable of carrying out radio communication with the first radio base station and the second radio base station, and the second radio base station has a receiving section that receives synchronization correction information, which is for establishing synchronization with a synchronization target, from the user terminal, and a synchronization correction section that corrects synchronization based on the synchronization correction information.

Abstract: In order to compensate for frequency errors even when introducing a new carrier, the present invention provides a radio base station having a configuring section that configures a first carrier type subframe in which cell-specific reference signals are mapped at a predetermined density, and a second carrier type subframe in which cell-specific reference signals are mapped at a density that is lower than the density of the first carrier type subframe; a generating section that, when configuring the second carrier type subframe, generates at least a synchronization signal to use for frequency synchronization; and a transmitting section that transmits association information for associating the synchronization signal with an other downlink signal that is transmitted in the second carrier type subframe.