Fujitsu Corporation

Tokyo Shibaura Electric Co., Ltd.

Namco Limited

Fujitsu Limied

Hiroshi Fujita

Makoto Yoshida

Yun Wen

Kazuyuki Ozaki

Yoshiharu Tajima

Masahiro Watanabe

Chenxi Zhu

Michiharu Nakamura

Michael John Beems Hart

Dorin Gheorghe Viorel

Taiji Kondo

Yuefeng Zhou

Kaoru Yokoo

Yoshifumi Toda

Osamu Abe

Katsuyuki Onozawa

Takayoshi Nakayama

Fujio Inagami

Kenichi Muramatsu

Masatoshi Takai

Tatsuhisa Yabushita

Osamu Kawano

Kenichi Nishikawa

Yasuhiro Wakatsuki

Atsuya Tanaka

Hiroo Urabe

Takeo Chida

A channel assignment apparatus includes an interfered amount processing unit that represents a value group by a symmetric matrix, the value group including, as an element, an amount of interference that occurs in each of wireless access points, performs a row exchange and a column exchange in the symmetric matrix based on magnitude of the amount of interference, and generates one of the upper triangular matrix and the lower triangular matrix from the symmetric matrix in which the row exchange and the column exchange are performed, an assigning unit that assigns a frequency channel to each of the wireless access points by using one of the upper triangular matrix and the lower triangular matrix in accordance with a predetermined algorithm for selecting an optimal assignment candidate corresponding to the magnitude of the amount of interference from among a plurality of assignment candidates for the frequency channel.

Channel assignment apparatus, wireless communication system, and channel assignment method

A wireless communication apparatus includes antenna elements, each receiving a first signal and a second signal, a first estimator that estimates first channel information of the first signal, a false signal generator that generates false signals that are equal in number to or greater in number than the number of the antenna elements, each of the false signals arriving from a unique direction that is different from a direction of arrival of the first signal, a weight generator that generates first weights, each being associated with a corresponding one of the false signals and forming a null in the direction of arrival of the first signal, a multiplier that multiplies a signals received by the respective antenna elements by the first weights to acquire weight-multiplied signals, and a second estimator that estimates second channel information of the second signal using the weight-multiplied signals.

Wireless communication apparatus, wireless communication system, and channel estimating method

A method for transmission of information about downlink and uplink parameters of a intermediate apparatus link in a multi-hop wireless communication system, the system comprising a first node apparatus, a second node apparatus and one or more intermediate apparatuses, each said apparatus being operable to transmit and receive information along a series of links forming a communication path for downlink and uplink communication, the communication path extending between the first node and second node apparatuses via the or each intermediate apparatus, each link comprising either a first node link between the first node apparatus and a said intermediate apparatus or an intermediate apparatus link between a said intermediate apparatus and a said apparatus which is not the first node apparatus, and the system having access to a minimum allocation unit for allocating time and transmission frequency bandwidth, the method comprising: obtaining values of downlink and uplink parameters for a particular intermediate apparatus link; mapping both values onto a single minimum allocation unit and transmitting them towards the first node apparatus.

System and method for downlink and uplink parameter information transmission in a multi-hop wireless communication system

A communication device includes: a packet receiving unit that receives, via a wireless ad hoc network, a packet transmitted from a node device; a congestion detection unit that detects, based on the packet received by the packet receiving unit, that congestion occurs in a communication path along which the packet reaches the packet receiving unit; a congestion control message generating unit that generates, when the congestion detection unit detects that the congestion occurs in the communication path, a congestion control message that instructs to take an action to avoid the congestion in the communication path; and a message transmitting unit that transmits the congestion control message generated by the congestion control message generating unit to the node device.

Device and system for preventing congestion in ad-hoc network

A wireless communication system includes a plurality of wireless terminals. Each of transmitting terminals executes direct communication or indirect communication. The wireless communication system includes a first obtainer that obtains a reception side terminal number which is the number of the wireless terminals with which the receiving terminal is able to communicate directly, a second obtainer that obtains a transmission side terminal number which is the number of the wireless terminals with which the transmitting terminal is able to communicate directly for each of a target transmitting terminal and a neighboring transmitting terminal, and a setter that selects one of the direct communication and the indirect communication based on the reception side terminal number, the transmission side terminal number for the target transmitting terminal, and the transmission side terminal number for the neighboring transmitting terminal, and executes the selected communication.

Wireless communication system, wireless communication method, and transmitting terminal

A wireless communication system constitutes a wireless ad hoc network. A plurality of wireless terminals include a receiving terminal and a plurality of the transmitting terminals. Each of the transmitting terminals executes direct communication or indirect communication. The wireless communication system includes a first obtainer that obtains a reception side terminal number which is the number of the wireless terminals with which the receiving terminal is able to communicate directly, a second obtainer that obtains a transmission side terminal number which is the number of the wireless terminals with which a target transmitting terminal, which is one of the plurality of transmitting terminals, is able to communicate directly, and a setter that selects one of the direct communication and the indirect communication based on the reception side terminal number and the transmission side terminal number, and sets the target transmitting terminal so as to execute the selected communication.

Wireless communication system, wireless communication method, transmitting terminal, and receiving terminal

A wireless station includes a receiver configured to receive a packet, a processor configured to set a retransmission start time of a packet transmitted to another wireless station based on the received packet, and a transmitter configured to control transmission of a packet that is the same as the transmitted packet in accordance with whether a response signal responsive to the transmitted packet is received before the set retransmission start time is reached.

Wireless station, communication system, and communication method

A radio station includes a weighting factor determining unit that outputs a value larger than one as a weighting factor when a traffic amount of an adjacent radio station positioned in a communicable range of the radio station exceeds a certain threshold, and a cost calculating unit that calculates a radio quality cost based on radio quality for each link between the radio station and each adjacent radio station, regards a multiplication result of the obtained radio quality cost and the weighting factor as a link cost when there is an input of the weighting factor from the weighting factor determining unit, and regards the obtained radio quality cost as a link cost when there is no input of a weighting factor from the weighting factor determining unit.

Radio station, routing method and radio communication system

A radio resource allocation method for use in a radio telecommunication system for a first radio telecommunication apparatus and a second telecommunication apparatus carrying out a radio telecommunication by using an allocated radio resource, comprising selecting a resource allocation pattern identifying a combination of radio resources allocatable within a resource management space from among a pre-prepared plurality of resource allocation patterns, and notifying the second radio telecommunication apparatus of pattern identifier information identifying the selected resource allocation pattern and of startup position information thereof within the resource management space.

Radio resource allocation method and telecommunication apparatus

A second wireless station includes a communicating unit that transmits a packet to a first wireless station and retransmits the packet when a response signal for the packet is not received by a predetermined response time limit; an acquiring unit that acquires from the first wireless station, transmission prohibition period information indicating a transmission prohibition period during which transmission of a signal by the first wireless station is prohibited; and a postponing unit that postpones the response time limit in the transmission prohibition period indicated by the acquired transmission prohibition period information to be after the transmission prohibition period ends.

An apparatus estimates an influence rate at which transmission of data to a first wireless communication device is influenced by a second wireless communication device that is undetectable by means of carrier sense. The apparatus determines transmission quantity based on the estimated influence rate, and detects a congestion state of the first wireless communication device. The apparatus transmits data to the first wireless communication device according to the determined transmission quantity when congestion for the first wireless communication device is detected.

Apparatus and method for transmitting data to a wireless communication device to minimize congestion and interference from undetectable devices through carrier sensing

In a gateway (GW), when interference is detected by an interference detection unit, a frame generation unit sends an interference broadcast signal. A terminal receives the interference broadcast signal sent at a maximum transmission power from the GW to which the terminal belongs. The interference broadcast signal includes information on a planned transmission power value that is a transmission power value of a data signal in the GW and is smaller than the maximum transmission power value. The interference broadcast signal is sent at the maximum transmission power value.

Multi-hop communication terminal, multi-hop communication system, and multi-hop communication method

A wireless terminal device includes: a processor connected to a memory, configured to: acquire an estimated reception sensitivity of the wireless terminal device based on reception powers from a plurality of other wireless terminal devices with which the wireless terminal device performs random access communication, notify the other wireless terminal devices of the estimated reception sensitivity of the wireless terminal device, and select a transmission destination from among the other wireless terminal devices based on requested reception powers of the other wireless terminal devices, the requested reception powers being calculated based on estimated reception sensitivities of the other wireless terminal devices notified from the other wireless terminal devices.

Wireless terminal device, wireless communication system and control method for wireless terminal device

A radio relay method for relaying signal transmitted and received between a base station apparatus and a mobile station apparatus, the radio relay method including: selecting a first relay method amplifying and transmitting reception signal, or a second relay method decoding, error correcting, re-encoding, and transmitting the reception signal, based on each reception quality between the relay station apparatus and the base station apparatus and between the relay station apparatus and the mobile station apparatus; and relaying the signal based on the selected first relay method or the selected second relay method.

Radio relay method, base station apparatus, and relay station apparatus

A radio communication system includes a gateway apparatus and a plurality of radio stations performing radio communication. The gateway apparatus includes, a generation unit that generates allocation information on one or more individual channels each allocated individually to one of a plurality of radio stations; and a transmission unit that transmits the generated allocation information, and the plurality of radio stations each of which comprising, a receiving unit that receives the allocation information; and a data transmission unit that performs data transmission through the one or more individual channels when information indicating an own station is included in the received allocation information, and performs data transmission by random access through a channel other than the one or more individual channels in a radio frame when information indicating the own station is not included in the received allocation information.

Growing community of inventors

Kawasaki, Japan

Hiroshi Fujita