Ntt Docomo, Inc.

Takayuki Ishiguro

Hiroyuki Ishii

Shinji Uebayashi

Osamu Nakamura

Sung Uk Moon

Toshiyuki Futakata

Mayu Yamada

Rie Nagato

Makoto Ito

Tomohiro Dohi

There is provided a control device enabling switching of communication of a mobile terminal with one system to communication with another system while reducing power consumption and workload of the mobile terminal. The control device is used in a communication system including a first mobile communication system, a second mobile communication system, and a mobile terminal being in communication with the first mobile communication system. The control device comprises a position measuring unit for measuring the position of the mobile terminal, a judgment unit for making a determination whether or not to switch the communication of the mobile terminal from the first mobile communication system to the second mobile communication system according to a position measurement result of the position measuring unit, and a switching unit for performing the above switching operation according to the determination of the judgment unit.

Control device of mobile communication system

A radio terminal () and a radio relay () perform radio communications therebetween by a radio communications system else than a TDMA system, an interference measurer () measures a degree of interference of each of radio slots constituting a radio channel employed in the radio communications system, a decision maker () makes a decision, depending on a measurement result of the degree of interference, whether or not the radio communications by the radio communications system is able to be continued, and a switcher () switches, as the decision is made of the radio communications by the radio communications system to be unable to be continued, the radio communications system to a radio communications system of the TDMA system.

Radio communications system, radio communications method, radio relay, and radio terminal

A control device for carrying out control of first and second radio base stations at a time of handover from a first radio base station to a second radio base station in radio communications between a radio terminal and a radio base station is provided to prevent the use of signals other than the control signals currently used in the areas before and after the moving, in the same channel as the control signals currently used in the moving target area, during the handover, such that it is possible to improve the receiving quality of the control signals at the radio terminal.

Communication method and system for improving control signal receiving quality during handover

A radio communication system comprises a radio terminal and a plurality of base stations. The base stations communicate with the radio terminal by connecting radio links with mutually different frequencies. The base stations comprise a control signal transmitter configured to transmit control signals in a plurality of control signal time slots included in one frame. The radio terminal comprises a reception time slot determining unit configured to determine reception time slots for receiving the control signals transmitted from the plurality of base stations, from among the plurality of control signal time slots, a control signal receiver configured to receive the control signals in the reception time slots determined by the reception time slot determining unit, and a communication signal transmitter configured to transmit communication signal to the base station in an uplink communication signal time slot other than the control signal time slots.

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

At a time of the handover, the communications with respect to the radio terminal related to the handover are carried out by using the same antenna as the antenna with respect to the other radio terminal that is already located in the moving target area, so that interferences due to the difference in the propagation paths can be suppressed to the minimum, and the receiving quality can be improved.

Method and system for determining antenna of radio base station at moving target area during handover

A communication channel allocation method allocates a communication channel to communications between a mobile terminal device and a second radio base station using a second frequency band which is close to a first frequency band used by a first radio base station, by detecting a first distance between the second radio base station and the first radio base station, detecting a second distance between the second radio base station and the mobile terminal device when the first distance is less than a first threshold, and allocating a communication channel of a frequency far from the first frequency band in the second frequency band to the communications between the second radio base station and the mobile terminal device when the second distance is less than a second threshold.

Radio communication system for reducing interferences with respect to other communication system using close frequency band

A receiver of a mobile station or a base station in radio communications is formed by a correlation unit for generating a delay profile for specifying paths by taking correlations by using replica signals for a received pilot signal, and a path selection unit for comparing a power level of each path in the delay profile with a threshold determined according to an index value regarding a communication state, selecting paths for which a comparison result satisfies a prescribed condition as valid paths, and outputting a selected delay profile formed by the valid paths as a channel estimation value.

Scheme for realizing path selection using optimum path selection threshold in radio communication

In radio communication, the throughput reduction of a whole radio communication system caused by discarding retransmission data at the time of handover is prevented. The system includes a radio terminal for conducting data transmission and reception with a radio base station by executing one or more processes, a process executer in the radio base station for executing processes depending upon a number of processes executed in the radio terminal, and transmitting/receiving data to/from the radio terminal, a handover monitor in the radio base station for monitoring for the occurrence of handover or for the possibility of occurrence of handover in the radio terminal, and a process number controller in the radio base station for controlling the number of processes executed by the process executer according to a result of monitoring conducted by the handover monitor.

Radio communication method, radio base station and radio terminal

A mobile phonereceives a home cell signal sent from a base station Band a foreign cell signal sent from a base station Bor from a mobile phonein a foreign cell A. The mobile phonereceives spreading codes C&#x2013;Csent from the base station B, as home cell codes. The mobile phonedetects the interference between the home cell signal and the foreign cell signal. When the interference is detected, the mobile phonereceives a spreading code Csent from the base station Bor from the mobile phone, as a foreign cell code. The mobile phonecancels an interference signal by joint detection, using the home cell codes and the foreign cell code.

Mobile communication terminal, interference cancellation system, interference cancellation method, and base station

A simplified interference elimination system is provided for eliminating from a first radio signal transmitted from a first radio terminal to a first radio base station, the effect of interference due to a second radio signal transmitted from a second radio terminal to a second radio base station. The second radio base station has an extractor for extracting the second radio signal from radio signals received in the second radio base station, and a transmitter for transmitting the extracted second radio signal to the first radio base station. The first radio base station has an interference eliminator for eliminating the second radio signal transmitted from the second radio base station from radio signals received in the first radio base station.

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Yokosuka, Japan

Takayuki Ishiguro