Oki Electric Industry Co., Ltd.

Kentarou Yanagihara

Yuki Kubo

Masanori Nozaki

Hiroshi Nishimura

Daisuke Anzai

Provided is a wireless communication device that mutually exchanges at least a notification signal including its own identification code and an identification code of a surrounding wireless communication device with the surrounding wireless communication device, the wireless communication device including: a transmission unit for periodically transmitting the notification signal; a reception unit for receiving the notification signal; a recording/updating unit for recording/updating surrounding-wireless-communication-device information of each of surrounding wireless communication devices when the reception unit has received the notification signal, the surrounding-wireless-communication-device information including an identification code of a wireless communication device at a transmission side and an identification code of a surrounding wireless communication device around the wireless communication device at the transmission side that are included in the notification signal; and an abnormality detecting unit for detecting abnormality of the surrounding wireless communication device from the surrounding-wireless-communication-device information recorded in the recording/updating unit.

Wireless communication device, method, and system

A packet relay system in which each node calculates a link cost of each adjacent node based on an arrival rate of a packet from each adjacent node, acquires an accumulated value of a link cost calculated by each node in a range of nodes from a sink node for each adjacent node, calculates, for each adjacent node, a path cost of the one adjacent node by adding the link cost calculated to the accumulated value, and relays a data packet to one adjacent node selected from among nodes adjacent to the node based on a path cost of each adjacent node. This enables establishment of an upstream path to a sink node without increasing the amount of communication in a network.

Packet relay system and wireless node

A wireless device operates in a first mode, in which it relays communications between neighboring wireless devices, and a second mode, in which it does not relay communications. The wireless device periodically transmits information indicating its operating mode to the neighboring wireless devices. In the first mode, when not transmitting mode information or communication data, the wireless device stands by with its receiver powered, ready to receive mode information or communication data from neighboring wireless devices. In the second mode, the wireless device is normally in a sleep state and wakes up only at scheduled intervals to transmit and receive mode information and communication data. The wireless device stores the received mode information and selects its operating mode according to the stored mode information, selecting the second mode when this does not prevent the prevent communication with or among the neighboring wireless devices.

Wireless device and wireless system

In a communications apparatus, a communication controller transmits and receives signals on any of plural channels. A channel switching controller is responsive to channel switching information selectively defining plural reception-waiting periods using the channels to alter a channel to be used by the communication controller. A neighboring node channel controller exchanges channel switching information with other nodes to manage the channel switching information received from the other nodes. When transmitting transmission signals, a transmission controller refers to the channel switching information of the other nodes, and controls repetitive transmission of the transmission signals on the channel thus searched for.

Communications apparatus transmitting data on channels adaptively switchable

A tree topology in a multi-hop wireless network is configured by having each node other than the root node select a parent node within direct communication range, thereby becoming a child node of the selected parent node. Neighboring nodes provide selection values such as routing costs and local structural information indicating the existing topology in their vicinities, including parent-child relationships. The selection of the parent node is based on the received selection values, but the local structural information is used to bias the selection in favor of neighboring nodes with at least one other child node. This selection strategy reduces the number of parent nodes in the network and enables more nodes to operate as end nodes, which can then conserve power by carrying out sleep control.

Wireless network and terminal, and network configuration method and device

A wireless communication system includes a first node, multiple second nodes, and multiple third nodes that communicate with the first node through the second nodes. The second and third nodes transmit control information to their neighboring third nodes, which calculate link costs from the reception status of the control information. The control information transmitted by each node includes a path cost indicating the cost of a path between the transmitting node and the first node. From the path costs in received control information, each third node selects a second node through which to communicate with the first node, and selects a parent node as the destination of the first hop on the path through the selected second node to the first node. Routing is thereby accomplished autonomously without having the second nodes flood the system with routing requests.

Wireless communication system and nodes

A packet is transmitted from a source node to a destination node via a relay path in a multi-hop network. The packet is transmitted by cache routing or source routing, depending on the presence or absence of information identifying the destination node in a history table maintained at the source node. In source routing, relay path information is included in the packet. In cache routing, relay nodes obtain routing information from entries in their own cache routing tables. Each entry indicates only the destination node and the next relay node, and each cache routing table has a limited size. When a series of packets are transmitted to the second node, cache routing can be used for all but the first packet, thereby reducing packet overhead.

Wireless communication apparatus

A handover control method carried out at a mobile station for switching a destination base station in a multi-hop network includes a reception step of receiving a communication signal and information of neighboring base stations used to identify a base station existing in the surrounding area of the base station transmitted from the base station, and a control step of controlling handover on the basis of the signal and information thus received. The control step includes a present destination decision step of deciding the base station currently connected, a switching decision step of using the information of neighboring base stations to decide whether or not the base station to be connected is to be switched over, and a switching step of switching over the base station to be connected on the basis of the decision result of the switching decision step. Thus unnecessary handover operations can be reduced.

Handover control between base stations in a multi-hop mobile communication network

A wireless communication apparatus prepared in each of wireless terminals configuring a wireless network adapted to transmit and receive a data signal and terminal information to and from peripheral wireless terminals of a subject wireless terminal; to manage the terminal information received from the peripheral wireless terminals; to determine a relay network to which the subject terminal belongs on the basis of the terminal information of the peripheral wireless terminals when the subject terminal can be connected to at least one of the relay networks provided within the wireless network; to transmit terminal information including information indicating the relay network of the subject terminal to the peripheral wireless terminal; and to use the relay network of the subject terminal as a data signal transfer route to perform forward processing. Thus, the apparatus can prepare plural transfer routes to avoid wireless signal interference and collision and balance the power consumption among the terminals.

Wireless communication apparatus for selecting suitable transfer route on wireless network

In a system for location estimation, information necessary for location estimation is acquired from a wireless signal. The first estimated location of each of target terminals is found out on the basis of the acquired information necessary for location estimation, and the locations of reference terminals. The second estimated location of each target terminal is found out on the basis of the information necessary for location estimation, the first estimated locations of the target terminals other than that target terminal of which the location estimation is being carried out, and on the locations of the reference terminals. Thus, the system for location estimation avoids the problem associated with an increased sphere of location estimation and with an increased communication traffic attendant on an increased number of target terminals, and achieves location estimation of high accuracy.

Method and a system for location estimation using location estimated

A location estimation system in which the location of a target device is estimated from the known locations of a set of anchor devices and information obtained from wireless signals transmitted between the target device and the anchor devices. The estimation process makes use of parameters indicating propagation characteristics of the wireless signals. When the location of the target device has been estimated, new values are estimated for the parameters, based on the estimated location of the target device. The new parameter values are then used to estimate the location of the target device again. The location estimation and parameter estimation process is iterated until a predetermined condition is satisfied.

Location estimation method and system, and wireless device

A first estimated location of a target terminal to be estimated in its location is obtained based on information derived from radio signals for location estimation and also locations of anchor terminals. Then, on the basis of the first estimated location thus obtained, estimated distances are calculated while expected values are calculated based on information required for location estimation to compare the estimated distances with the expected-values. Depending on the comparison result, one or more anchor terminals are selected as nonuse terminals. On the basis of information required for location estimation derived from radio signals sent by the anchor terminals other than the selected nonuse terminals and also on the locations of the anchor terminals except the nonuse terminals, a second estimated location of the target terminal is obtained.

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Hyogo, Japan

Kentarou Yanagihara