Ntt Docomo, Inc.

Nec Corporation

Mitsubishi Electric Corporation

Akihito Morimoto

Mamoru Sawahashi

Nobuhiko Miki

Yoshihisa Kishiyama

Kenichi Higuchi

Motohiro Tanno

Yukihiko Okumura

Masashige Shirakabe

Sadayuki Abeta

Yusuke Ohwatari

Satoshi Nagata

Hiroki Harada

Toshifumi Sato

Hidekazu Taoka

Yousuke Sano

Hiroyuki Kawai

Eiji Nagatake

A radio communication system includes a user device, base stations, and a communication control device. The communication control device generates and reports, to the user device, selection information that is used to select base stations with which the user device should maintain synchronization. The user device selects, based on the selection information, base stations with which the user device should maintain synchronization. The user device reports, to the communication control device, identifiers of the selected base stations and received levels of radio waves transmitted from the base stations corresponding to the identifiers. The user device maintains synchronization with each of the selected base stations.

Radio communication system and communication control method

In a radio communication system including multiple mobile terminals and multiple radio base stations, the mobile terminal has a function of interference rejection combining. The radio base stations share downlink channel characteristics for mobile terminals connected to radio base stations. The radio base station gives weights to radio waves transmitted from multiple transmission antennas to perform in-phase addition of an interfering radio wave beam directed to a mobile terminal for which the desired radio base station is another radio base station to an interfering radio wave beam transmitted from yet another radio base station for limiting the number of interfering radio wave beams that arrive at the mobile terminal. The radio base station does not perform in-phase addition when the number of interfering radio wave beams of which interference can be suppressed by the mobile terminal is equal to or greater than the number of radio base stations that send interfering radio wave beams to the mobile terminal.

Radio communication system, radio base station, and mobile terminal

A radio base station communicates with mobile terminals and is configured to be able to execute radio transmission to the mobile terminals using resources that are the same as resources used by a second radio base station forming a second cell having a smaller area within a first cell formed by the radio base station itself and is configured to collaborate with the second radio base station for inter-cell interference control. The radio base station sets a modulation system having a modulation level that is less than that of the modulation system provisionally determined as the modulation system for mobile terminals to which a resource group having a low transmission power is assigned and adjusts transmission parameters in a case in which the modulation system provisionally determined for the mobile terminals to which the resource group having the low transmission power is assigned, is inappropriate for the low transmission power.

Enhanced inter-cell interference control in a radio communication system

In a radio communication system in which a high-power base station and a low-power base station collaborate for inter-cell interference control, the downlink transmission power at the high-power base station is suitably controlled. The high-power base station executes wireless transmission to the user terminals using resources that are the same as resources used by the low-power radio base station. A transmission power controller of the radio base station uses a first downlink transmission power at first resources and uses a lower second downlink transmission power at second resources. The transmission power controller adjusts the second downlink transmission power in accordance with the number of user terminals capable of executing interference rejection combining, the downlink traffic amount for user terminals capable of executing interference rejection combining, or the number of downlink resource blocks allocated to user terminals capable of executing interference rejection combining.

Radio communication system and radio base station

A radio communication system includes multiple base stations including a first base station and a second base station, and a mobile station. A candidate base station selector selects multiple candidate base stations that are candidates for a radio access point for the mobile station on the basis of the reception powers reported by the mobile station. When the mobile station actually executes wireless communication with the base station, an access-point base station determiner determines, as an access-point base station that is the actual radio access point for the mobile station, a base station corresponding to a best reception quality among reception qualities measured in the protected resource and reception quality measured in the non-protected resource.

Radio communication system, mobile station, base station, and communication control method

A high-power radio base station includes a resource setter configured to determine a ratio of the number of second resources at which the radio communicator should stop radio transmission to the sum of the number of the second resources and the number of first resources at which the radio communicator should execute radio transmission. The resource setter determines the ratio on the basis of a first number and a second number, the first number being the number of mobile terminals that are assumed to be connected with the radio base station, rather than the low-power radio base station, when cell range expansion (CRE) is not applied, but are connected with the low-power radio base station by virtue of application of cell range expansion, the second number being the number of mobile terminals connected with the radio base station when cell range expansion is applied. The resource setter determines the ratio in such a manner that the greater the proportion of the second number to the first number, the smaller the ratio.

A mobile terminal apparatus, a radio base station apparatus and a radio communication method are provided which can perform optimum control during downlink CoMP transmission in an LTE-A system. The radio communication method according to the present invention includes steps of the mobile terminal apparatus receiving downlink signals including reference signals from a plurality of radio base station apparatuses associated with downlink CoMP, transmitting feedback information including the channel quality measurement results to the plurality of radio base station apparatuses, and steps of a radio base station apparatus receiving uplink signals including channel quality measurement results of a plurality of radio base station apparatuses associated with downlink CoMP and cell information on radio base station apparatuses whose average reception levels are within a first threshold range, and controlling, when there are radio base station apparatuses whose average reception level difference is within a second threshold range among radio base station apparatuses whose average reception levels are within the first threshold range, transmission power for both radio base station apparatuses.

Mobile terminal apparatus, radio base station apparatus and radio communication method

A radio communication system includes a first radio base station, second radio base stations, and mobile stations. Each of the mobile stations measures a first reception characteristic value and a second reception characteristic value for respective radio waves. The first radio base station determines the radio base station to which each of the mobile stations should connect, according to the first reception characteristic value, and classifies the mobile stations into a first mobile-station group and a second mobile-station group according to the second characteristic values. The first radio base station specifies a correction value according to the distribution of differences in the first reception characteristic value so as to reduce the sum of the number of mobile stations that belong to the second mobile-station group and that should connect to the first radio base station and the number of mobile stations that belong to the first mobile-station group and that should connect to second radio base stations.

A mobile station, where the mobile station includes a reception quality measurement unit, a channel quality information transmission unit, and a control signal transmission unit, where the reception quality measurement unit is configured to measure a reception quality of a pilot signal of each of a plurality of cells, when a radio link is established with the plurality of cells, where the channel quality information transmission unit is configured to transmit, to a first cell having the beset reception quality among the plurality of cells, channel quality information corresponding to the reception quality, and where the control signal transmission unit is configured to transmit, to a cell other than the first cell among the plurality of cells, a control signal requesting not to transmit a data signal by using the same resource as the first cell.

Mobile station, radio base station, and mobile communication method

In a mobile communication system including a first base station and a second base station, the first base station includes: a user information obtaining unit configured to obtain user information in the first base station, and the second base station includes: a user information obtaining unit configured to obtain user information in the second base station; a base station internal information collection unit configured to collect user information in the first and the second base stations; and a resource assignment determination unit configured to determine radio resources that can be used by the first base station and radio resources that can be used by the second base station based on the user information in the first and the second base stations.

Mobile communication system and radio resource assignment method

A radio communication system includes a first radio base station that forms a first cell; a plurality of second radio base stations each of which forms a second cell; and a mobile station provided with a radio communication unit that connects, by radio, to each radio base station. The first radio base station specifies a correction value according to the number of the second cells formed in the first cell of the first radio base station and signals the correction value to the mobile station. The mobile station corrects a characteristic value indicating the reception characteristic of radio waves from the second radio base station by using the correction value. Either the first radio base station or the mobile station selects the destination of the mobile station according to the characteristic value of the first radio base station and the corrected characteristic value of the second radio base station.

Radio communication system, radio base station, and communication control method

A mobile communications system includes a radio base station and a remote radio apparatus connected with a high-speed transmission medium to the radio base station. A user apparatus includes a unit which measures a received level of a signal transmitted from the radio base station and a received level of a signal transmitted from the remote radio apparatus and detects a change in relative magnitudes of measured values; a unit which measures a path loss between the user apparatus and the radio base station and a path loss between the user apparatus and the remote radio apparatus and detects a change in relative magnitudes of measured values; and a transmitter which transmits a report signal which shows that a predetermined event has occurred. The predetermined event occurs if the relative magnitudes of the received levels are reversed and/or if the relative magnitudes of the path losses are reversed.

User apparatus, radio base station, and method

A mobile station, a base station, a mobile communication system and a communication method enabling operations associated with simultaneous uplink reception in multiple stations to be simplified are provided. The base station includes a transmission timing determining unit determining a transmission timing based on scheduling conducted upon a data transmission request from a mobile station and notifying the mobile station of the transmission timing, and a receiving unit receiving data in accordance with the transmission timing.

Mobile station, base station, mobile communication system, and communication method

Provided is a base station comprising a multiplexer so constituted as to frequency-divide/multiplex a first channel for transmitting first data to be transmitted to a plurality of mobile stations, and a second channel for transmitting second data to be transmitted to one mobile station.

Base station, mobile station and frequency division multiplexing communication method

A base station apparatus includes a transmit diversity setting unit configured to set a transmit diversity mode to be applied to a user equipment terminal; a reception quality calculating unit configured to determine reception quality corresponding to the transmit diversity mode based on the transmit diversity mode set by the transmit diversity setting unit; a scheduling unit configured to determine a user equipment terminal to which a radio resource is to be allocated based on the reception quality determined by the reception quality calculating unit; and a notifying unit configured to notify the user equipment terminal to which the radio resource is allocated as determined by the scheduling unit of the transmit diversity mode to be applied.

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Yokohama, Japan

Akihito Morimoto