Fujitsu Corporation

Mitsubishi Denki Kabushiki Kaisha

Yoshihiko Shirokura

Taiji Kondo

Takao Ito

Katsumi Kobayashi

Hiroaki Kawasumi

Takahiro Koharagi

Yukio Hayashi

Yosuke Nishikata

Satoshi Kurosawa

Koichi Ishibashi

Wataru Fushimi

Shigemasa Matsubara

Yasuaki Kamimura

Kobun Nakajima

Satoshi Ikeda

Yushi Naito

Shuji Ito

Yukimasa Sugino

Hiroaki Tamai

Toshiaki Tomisawa

Shinichi Hirata

Hideaki Ebisawa

Mitsuaki Yasuoka

Naoto Miyauchi

Masahiro Machida

Takafumi Kawakami

Kazuya Takeuchi

Syuuji Itou

Tetsuhiro Murata

A communication device is provided in a wireless multi-hop network. The communication device receives a sequence number, a divided time acquired by dividing a time width allocated for transmitting detected usage data by a division number, and the division number. The communication device calculates a remainder by dividing the received sequence number by the division number and calculates a transmission offset time based on the remainder and the divided time. The communication device transmits the usage data based on the calculated transmission offset time.

Communication device and communication method

A data communication apparatus forms a mesh network together with at least one gateway includes a frame generating unit and a frame transferring unit. The frame generating unit generates a meter data frame to transmit to a gateway. The meter data frame is a frame including meter data. The frame transferring unit transfers the meter data frame received from another data communication apparatus. The meter data frame is addressed to the gateway. The frame generating unit transmits the meter data frame to which number of alternate routing that indicates number of allowable transmission attempts from a data communication apparatus adjacent to a destination gateway of the meter data frame to the gateway is added. The frame transferring unit changes the number of alternate routing added thereto to a value smaller by 1 than a value that has been set and transits the meter data frame to another data communication apparatus.

Data communication apparatus, data communication system, and data communication method

An ad hoc network system includes a plurality of nodes that communicate with a specific node. Each of the nodes includes a calculator and a selector. The calculator calculates a cumulative value of the number of communication nodes connected through the node by adding the numbers of communication nodes from an upstream side, which is a side closer to the specific node than the node, to the node. The selector selects a node serving as a connection destination out of the nodes located on the upstream side on the basis of the cumulative value of the number of communication nodes calculated by the calculator.

Ad hoc network system and route selection method

A communication system includes: a specific node; and a plurality of nodes that are installed at fixed positions and perform ad hoc wireless communication with the specific node. The nodes each include a link quality evaluating unit, an upstream route constructing unit, a communicating unit, and a downstream route constructing unit. The link quality evaluating unit performs route evaluation using a hello frame based only on a track record of reception of the hello frame in order to perform upstream communication toward the specific node to form a network. The upstream route constructing unit constructs an upstream route based on the route evaluation. The communicating unit performs upstream communication toward the specific node on a regular basis with a predetermined frequency. The downstream route constructing unit constructs a downstream route from the specific node based on a route in the upstream communication toward the specific node.

Communication system and communication method

A communication device is included in an ad hoc network in a reactive routing scheme. The communication device includes a receiving unit, a selecting unit, and a transfer control unit. The receiving unit receives a route request frame including overall quality information on routes through which the route request frame has passed. The selecting unit selects a route request frame to be transferred to another communication device based on the quality information, from the route request frames received by the receiving unit through a plurality of routes. The transfer control unit transfers the route request frame selected by the selecting unit to the another communication device, and discards the route request frame when a quality value indicated by the quality information of the route request frame is smaller than a predetermined reference value.

Communication device and communication control method

A wireless LAN system includes at least one LAN terminal wirelessly connected to a plurality of base stations, at least one IP terminal connected to an IP network, and a diversity device connected to the IP network and that relays packet transmission between the LAN terminal and the IP terminal via the IP network. The LAN terminal sequentially establishes association with a predetermined number of the base stations, and a plurality of data is transmitted parallelly via the predetermined number of the base stations, between the LAN terminal and the diversity device. At the receiving end, one of the plurality of data is selected and output.

Radio LAN system, diversity apparatus, and radio LAN terminal

A control unit ( ) sets up a path in a protocol conversion apparatus ( ) based on call setting information from the calling side terminal. A signal monitor unit ( ) monitors main data transmitted in the path and sent/received between the terminals. When a specific connectivity confirmation sequence is detected by the signal monitor unit ( ), the result is forwarded to the control unit ( ). Based on the forwarded result, the control unit ( ) specifies a protocol of the calling side terminal and a protocol of the called side terminal. A protocol conversion unit ( ) performs the most suitable protocol conversion based on the specified protocols.

Protocol conversion apparatus and protocol conversion method

In establishing an audio one link connection wherein an audio signal is not encoded/decoded in a relay station, loud noises may be produced if the states of two audio tandem relay devices which make a pair during relay are changed from a normal connection state to a relay connection state at different times. In order to solve this problem, comfort noise generators are provided. In detail, when a first pattern signal is detected while a relay call is connected via a relay exchange, switches are switched to be connected at a contact point,, and a switch is at a contact point,. Upon detection of a second pattern signal, the switches are connected at the contact points,, while the switches are connected at the contact points,. With this arrangement, outputs from the comfort noise generators are selected and outputted during a period from first pattern signal detection to second pattern signal detection, during which the states of the two devices of a pair are different. As a result, occurrence of loud noises is prevented.

Tandem relay device

When a signal is transmitted from an STM line to an ATM relay channel, the signal is compressed to be cell assembled into a cell. To the contrary, a signal from the ATM relay channel is cell disassembled into separate data and then expanded. In cases where signals are exchanged between ATM relay channels, a multistage relay device does not repeatedly execute signal compression/expansion to the signal. Switching for the above operations is achieved, utilizing a signal pattern inserted into audio data. With this arrangement, an audio one-link operation is established in the environment where an STM and an ATM coexist. Because compression/expansion processes are not repeatedly conducted, delay in relaying is avoided.

Multistage relay device

Growing community of inventors

Tokyo, Japan

Yoshihiko Shirokura