Fujitsu Corporation

Takahiro Koharagi

Katsumi Kobayashi

Hiroaki Kawasumi

Taiji Kondo

Takao Ito

Takuji Furusawa

Masaharu Nozawa

Shinichi Hirata

Yoshihiko Shirokura

Shigemasa Matsubara

Masashi Kuwahara

Kobun Nakajima

Satoshi Kurosawa

Yosuke Nishikata

Mitsuaki Yasuoka

Jun Hasegawa

Satoshi Ikeda

Manabu Kai

Teruhisa Ninomiya

Koichi Ishibashi

Yukio Hayashi

Yasuaki Kamimura

Joji Maruyama

Naoto Miyauchi

Katsunori Hayashi

A node includes a time difference measurement unit and a time setting unit. The time difference measurement unit measures a time difference between a first time based on latest received time information and a second time based on second-latest received time information. The time setting unit calculates an adjustment time difference when the time difference exceeds an allowable range of error that is smaller than an allowable range of maintainable communication, sets a time obtained by adding the adjustment time difference and the second time to the time of the node when the adjustment time difference is within the allowable range of maintainable communication, and sets a time obtained by adding a time difference corresponding to the allowable range of maintainable communication and the second time to the time of the node when the adjustment time difference exceeds the allowable range of maintainable communication.

Node and method for communication control

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 node apparatus for forming a wireless ad-hoc network, including: a recognition possibility determination unit that determines whether or not a gateway apparatus connecting the wireless ad-hoc network to other network can be recognized; an adjoining node detection unit that detects other node apparatus which is the source of a received packet as an adjoining node; a channel switching unit that switches, when the recognition possibility determination unit determines that the gateway apparatus cannot be recognized, the channel used for reception of packets transmitted in the wireless ad-hoc network successively to each of a plurality of channels; and a channel selection unit that selects a channel to be used for communication in the wireless ad-hoc network based on the number of adjoining nodes detected by the adjoining node detection unit in each of the plurality of channels.

Node apparatus, communication system, and channel selection method

In a planar inverted F antenna, a second radiation element is provided parallel to the GND surface and extending partially with respect to a first radiation element in a longitudinal direction, so as to substantially increase a width of the first radiation element in the vicinity of a power supply section.

Planar inverted F antenna

A gateway apparatus including: a route control packet generating unit that generates a route control packet for constructing routes between node apparatuses forming an ad hoc network and the gateway apparatus; a channel designation signal generating unit that generates channel designation signal for designating a second channel different from a first channel on which the ad hoc network transmits and receives packets; a time designation signal generating unit that generates time designation signal for designating switching time to the node apparatus for switching the channel used for transmission and reception of packets to the second channel; a radio communication unit that transmits the route control packet, the channel designation signal and the time designation signal on the first channel; and a channel switching unit that switches, when it is time to switch, the channel on which the radio communication unit transmits and receives a signal to the second channel.

Gateway apparatus, node apparatus, communication system, and channel switching method

A distribution method is performed in a distribution system including a distribution source device for distributing data and a plurality of distribution destination devices. The distribution method includes searching, by the distribution source device, for the distribution destination devices by expanding a search range by plural stages; executing in each stage, by the distribution source device, an allowance process of allowing distribution of the data to the distribution destination devices found by searching in each stage; detecting in a predetermined range, by the distribution destination device, another distribution destination device that has acquired the data before the distribution destination device performing the detecting; and executing, by the distribution destination device, an acquiring process of acquiring the data from the other distribution destination device, according to allowance of distribution.

Distribution method and distribution system

Growing community of inventors

Tokyo, Japan

Takahiro Koharagi