Chiharu Yamazaki

Bio: Chiharu Yamazaki is an academic researcher from Kyocera. The author has contributed to research in topics: Base station & Terminal (electronics). The author has an hindex of 18, co-authored 130 publications receiving 1528 citations.

Pico Cell Range Expansion with Interference Mitigation toward LTE-Advanced Heterogeneous Networks

Abstract: Deploying Pico eNodeBs (PeNBs) throughout a Macro cell layout is a promising solution to enhance system capacity and user throughput. However, strong received power from Macro eNodeBs (MeNBs) makes the Pico cell areas narrow. This causes limited cell splitting gain. Cell Range Expansion (CRE), which allows a User Equipment (UE) to be served by a cell with weaker received power, is simple and typical one of alternative cell associations to enhance offloading but it causes downlink (DL) interference issue in not only data and also control channels (CCHs). In this paper, we investigate performance of CRE with various bias settings and show that a moderate bias setting is effective to enhance capacity and user throughput. With respect to the DL interference issue in CCHs, we propose to support coordination of Lightly Loaded CCH transmission Subframe (LLCS) in LTE-Advanced.

Communication control method

Abstract: A communication control method pertaining to an embodiment of the present invention is for controlling dual connectivity communication which uses a master base station that establishes RRC connection with a user terminal and a secondary base station that provides a supplementary wireless resource to the user terminal The communication control method comprises: a step in which the master base station receives, from the user terminal, a measurement report which includes measurement results found for each cell in the user terminal; and a step in which the secondary base station receives, from the master base station, a supplementary request for requesting the allocation of resources to the user terminal In the step for receiving a supplementary request, the master base station includes, in the supplementary request, measurement results for a cell of the secondary base station which is included in the measurement results, and transmits the same

User terminal and base station

Abstract: A user terminal according to an embodiment comprises: a transmitter configured to transmit a message to a base station, the message requesting a gap used to receive or transmit a discovery signal that is a direct terminal-to-terminal radio signal for discovering another user terminal; and a receiver configured to receive configuration information from the base station, the configuration information configuring the gap to the user terminal. The message includes: gap information indicating the gap; and frequency information indicating a frequency associated with the gap information. The gap information includes: a bitmap indicating at least one subframe; and an offset value with reference to “0” of system frame number (SFN).

Mobile communication system and user terminal

Abstract: A first user terminal according to an embodiment comprises: at least one processor and at least one memory coupled to the processor. The processor is configured to perform processes of: determining first radio resources to be used for transmitting control information, the control information indicating location of second radio resources to be used for transmitting data by direct Device-to-Device communication; and directly transmitting the same control information repeatedly to a second user terminal in each resource block included in the first control resources.

Base station and user terminal

Abstract: A user terminal according to an embodiment comprises a receiver; and a controller. The receiver receives, from a base station, a message including first and second information. The first information is information regarding to a configuration for reporting a power measured by the user terminal in the unlicensed band, and includes period information indicating a period of a measurement in the unlicensed band. The second information is information regarding to a configuration of carrier aggregation. The controller periodically measures the power in the unlicensed band according to the period information; reports to the base station on information classified according to the measured power as information indicating the measured power, based on the first information; performs a configuration for using the unlicensed band as a secondary carrier in the carrier aggregation, based on the second information; and communicates a communication with the base station by using the secondary carrier.

User terminal, radio base station and radio communication method

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.

Telecommunications apparatus and methods

Abstract: A wireless telecommunication system comprises base stations for communicating with terminal devices. One or more base stations support a power boost operating mode in which a base station's available transmission power is concentrated in a subset of its available transmission resources to provide enhanced transmission powers as compared to transmission powers on these transmission resources when the base station is not operating in the power boost mode. A base station establishes an extent to which one or more base stations in the wireless telecommunications system support the power boost operating mode conveys an indication of this to a terminal device. The terminal device receives the indication and uses the corresponding information to control its acquisition of a base station of the wireless telecommunication system, for example by taking account of which base stations support power boosting and/or when power boosting is supported during a cell attach procedure.

Terminal device, base station device, communication method, and integrated circuit

Abstract: According to the present invention, there are provided a base station device, a terminal device, a communication method, and an integrated circuit capable of performing communication more efficiently when the terminal device transmits an uplink signal based on scheduling by the base station device. The terminal device includes a setting unit that sets a first uplink-downlink configuration, a second uplink-downlink configuration, and a third uplink-downlink configuration, a reception unit that monitors a physical downlink control channel accompanied with a downlink control information format which is used to schedule a physical downlink shared channel in a downlink subframe based on the third uplink-downlink configuration and includes information making a request for transmitting a sounding reference signal, and a transmission unit that transmits or drops the sounding reference signal and transmit an HARQ-ACK for transmission with the physical downlink shared channel.

User terminal, wireless base station, and wireless communication method

Abstract: In order that a user terminal properly identifies a connection cell in a radio communication system (LTE-U) for operating LTE in an unlicensed band, a user terminal for communicating with a radio base station in an unlicensed band is provided with a detection section that detects a synchronization signal transmitted from a radio base station using a dummy cell ID used in common among a plurality of radio base stations, an estimation section that performs channel estimation using a reference signal, and a reception processing section that performs reception processing of system information transmitted from a radio base station using a channel estimation result.

Method and apparatus for transmitting and receiving data using plurality of carriers in mobile communication system

Abstract: The present invention relates to a method and apparatus for performing a discontinuous reception (DRX) operation while transceiving data using a plurality of carriers in a mobile communication system. The communication method for a terminal according to one embodiment of the present invention comprises the steps of: receiving a control message, including setting information of a secondary serving cell (SCell) to be added and discontinuous reception setting information, from a primary serving cell (PCell); and applying, if the control message includes an indicator indicating that the first base station to which the SCell to be added belongs and the second base station to which the PCell belongs are different from each other, the DRX setting information to the serving cell of a first base station. According to one embodiment of the present invention, a discontinuous reception (DRX) operation is applied upon the occurrence of inter-base-station carrier aggregation, thus reducing the consumption of a battery.