Ntt Docomo, Inc.

Toru Otsu

Hitoshi Yoshino

Shinji Takeda

Atsushi Fujiwara

Yuji Aburakawa

Yasushi Yamao

Shinzo Ohkubo

Koji Maeda

Koichiro Yamaguchi

Hiroyuki Kawai

Yuji Nakayama

Kozue Hamamoto

Shiro Kikuchi

Masaharu Hata

Hitochi Yoshino

Provided is a mobile communication system capable of determining a communication path to implement fast communication by multihop connection. A mobile communication system () comprises a mobile station (), at least one relay station (), and a base station () and implements packet transmission from the mobile station () to the base station () through a communication path with an intermediary of at least one relay station () or through a communication path without an intermediary of a relay station. The mobile communication system () is provided with a communication path determiner for determining a communication path with a largest communication speed or a communication path satisfying a required line quality, based on interference levels of respective signals received at a relay station () constituting a communication path between the transmitting station and the receiving station, and at the base station ().

Mobile communication system, transmitting station, receiving station, relay station, communication path determining method, and communication path determining program

A radio communication system for carrying out communications between radio stations by modulating a plurality of signal sequences to be transmitted and received into at least one frequency channel assigned to each of a plurality of cells is formed by a channel mapping means for rearranging for each cell a plurality of frequency channels assigned with respect to each cell, and newly assigning particular frequency channels as a transmission and reception band of said signal sequences, and a bandwidth control means for controlling a bandwidth of said assigned frequency channel according to a propagation state of said assigned frequency channel.

Radio communication system and radio communication method

A mobile communication system determines a communication path to implement fast communication by multihop connection. A mobile communication system includes a mobile station, at least one relay station, and a base station and implements packet transmission from the mobile station to the base station through a communication path with an intermediary of at least one relay station or through a communication path without an intermediary of a relay station. The mobile communication system is provided with a communication path determiner for determining a communication path with a largest communication speed or a communication path satisfying a required line quality, based on interference levels of respective signals received at a relay station constituting a communication path between the transmitting station and the receiving station, and at the base station.

A communication system includes a transmission unit configured to transmit control information relating to plural radio communication systems to a radio terminal through a dedicated control channel commonly used by the plural radio communication systems and for transmitting the control information relating to the plural radio communication systems.

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

A mobile communication system capable of determining a communication path to implement fast communication by multihop connection. The mobile communication system includes a mobile station, at least one relay station, and a base station and implements packet transmission from the mobile station to the base station through a communication path with an intermediary of at least one relay station or through a communication path without an intermediary of a relay station. The mobile communication system is provided with a communication path determiner for determining a communication path with a largest communication speed or a communication path satisfying a required line quality, based on interference levels of respective signals received at a relay station constituting a communication path between the transmitting station and the receiving station, and at the base station.

Mobile communication system, transmission station, reception station, relay station, communication path deciding method, and communication path deciding program

The multi-hop communication system according to the present invention is configured by a radio control stationconnected to a core network, and radio stations-. The radio control stationhas a control signal TX/RX unitwhich transmits/receives the control signal, an information signal TX/RX unitwhich transmits/receives the information signal, and a communication channel controllerwhich transmits a 'usage notification' indicating usage of communication channels managed by the radio control stationto the radio stations-using the control signal. The radio station has a control signal TX/RX unitwhich transmits/receives the control signal, and an information signal TX/RX unitwhich transmits/receives the information signal.

Multi-hop communication system, radio control station, radio station and multi-hop communication method

The object is to control interference in a permissible range by applying the CDMA system to signal collision in the conventional CSMA and TDMA base multihop systems and to relax the hidden terminal problem and others to enhance the throughput of the entire system by grouping of channel groups in multihop transmission and by control of transmission based on an interference level from another station. A multihop relay station calculates a desired signal level, for example, from an interference level at its own station of a packet sent from a mobile station, and notifies the mobile station of the desired signal level; and the mobile station calculates a transmission power amount of a packet from the desired signal level, determines whether the packet is transmissible to the station as a source of the desired signal level, and transmits the packet to the source station determined as a packet-transmissible station.

Radio communication system, base station, relay station, mobile station, and packet transmission control method

A method, device and system for arranging symbols to be sent in the frequency axis and for sending signals to a radio terminal inside an area using one or a plurality of carrier frequency bands, in a radio communication system with a hierarchical cell structure. The method includes detecting by a device at least one carrier frequency band signal pertaining to a transmission system other than that of its own station. A sending-symbol synchronization is detected based on at least one received signal upon detecting the carrier frequency band signal pertaining to the transmission system other than that of its own station. The signal is sent based on the derived symbol sending timing.

Sending radio station, receiving radio station, radio communication system, and radio communication method

A destination station in a wireless communication system for a multi-hop connection selects a transmission path having a minimum total of required transmission power values of respective stations on the transmission path among candidates of the transmission path from a source station to the destination station and transmits a pilot signal to the source station and a relay station, the pilot signal including identification information about the respective stations on the selected transmission path and required transmission power values thereof. Thus, the source station and the relay station, which have received this pilot signal, can determine the transmission path having the minimum total of the required transmission power values by use of the identification information included in the received pilot signal.

Wireless communication system for multi-hop connection, source station, radio station and pilot signal used therein

A reception side radio station has a notification signal generatorwhich transmits a notification signal for notifying information of a frequency of a radio link being used at the radio station, and a transmitterwhich transmits information indicating a reception power level and its frequency as radio signal data. On the other hand, a transmission side radio station has a notification signal measurerwhich measures a reception power level of the notification signal and detects the frequency notified by the signal, and a frequency band controllerwhich determines an assignable frequency band for a radio link between the transmission side radio station and the reception side radio station based on the radio signal data and the notification signal.

Communication control method and communication control system

A radio communication system comprises: a radio receiver including an interference canceller configured to generate a replica of a received signal and remove an interference signal from the received signal, and a frequency offset estimator configured to estimate a carrier frequency offset between a carrier frequency of the interference signal and a carrier frequency of a desired signal included in the received signal; and a radio transmitter including a frequency controller configured to adjust a carrier frequency of a transmitted desired signal to the carrier frequency of the interference signal based on the carrier frequency offset received from the radio receiver.

Radio communication system, radio station, and radio communication method

The present invention relates to a radio communication system comprising base stations and mobile stations and a method for controlling transmission power in the system where the base station is able to perform multi-point transmission for transmitting the same signal to a plurality of the mobile stations. In the present invention, the mobile station targeted for the multi-point transmission provides the base station of an increase request or a decrease request of the transmission power by respectively transmitting or not transmitting a predetermined signal to the base station.

Radio communication system, communication terminal apparatus, base station apparatus, and transmission power control method

In a burst signal transmitting/receiving method with transmission availability control, a method is provided for transmitting each burst signal with the transmission unit length appropriate for the transmission path condition at the time. Radio transmission path condition between a transmitting station and a receiving station is measured. A period during which the burst signal is to be transmitted is then determined on the basis of the measured radio transmission path condition. Before transmitted, the length of the burst signal is adjusted such that it is accommodated in such period.

Radio communication system, communication terminal, and method for transmitting burst signals

An information transmission system for transmitting information from a sending apparatus to a receiving apparatus is provided. The information transmission system includes: a sending apparatus for modulating an information signal, generating a plurality of signals including an optical signal from the information signal which is modulated, and transmitting the plurality of signals via a plurality of routes; and a receiving apparatus for receiving the plurality of signals from the sending apparatus, diversity-combining the plurality of signals, and outputting the information signal, in which the plurality of signals are a plurality of optical signals or signals including a radio signal.

Information transmission system and information transmission method, and, optical space transmission system and optical space transmission method

A communication control method used in a cellular mobile communication system in which each base station can radiate radio wave beams to a plurality of directions and each base station communicates with mobile stations by using the same frequency is provided in which the method includes the step of: controlling first timing at which a base station radiates a first radio wave beam such that the first timing is different from second timing at which another base station radiates a second radio wave beam which may cause interference with the first radio wave beam.

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Yokohama, Japan

Toru Otsu