Nec Communication Systems, Ltd.

Nec Corporation

Advanced Telecommunications Research Institute International

Nec Communications Systems, Ltd.

Yuichiro Ezure

Tetsuya Ito

Hiroyuki Iizuka

Akira Matsumoto

Kenichi Abe

Toru Yamamoto

Satoko Itaya

Peter Davis

Sadao Obana

Masahito Iwai

Akio Hasegawa

Naoto Kadowaki

Jun Hasegawa

Takahiro Hasegawa

Hidehiro Endou

Atsushi Fujimura

Yoshiaki Takakura

Article position estimation system comprises: article movement recognition part; reference point recognition part; position information generation part; and article position estimation part. Article movement recognition part generates article movement information including time point when article is taken out by mobile body or time point when article placement is completed by mobile body. Reference point recognition part recognizes reference point and generates reference point recognition information including identification information according to recognized reference point, reference point recognition time point, and information related to recognized reference point. Position information generation part generates information related to position of mobile body at reference point recognition time point based on reference point recognition information. Article position estimation part estimates position of mobile body at the time when article is moved by using at least position of mobile body at reference point recognition time point.

Article position estimation system and article position estimation method

A sensor network systemis provided with a plurality of sensor nodes, . . . and configured to decide a parent node for each of the plurality of sensor nodes so as to form a network topology having a tree structure using each of the plurality of sensor nodes as a node. The sensor network system forms the network topology so that, with respect to each of the plurality of sensor nodes, the number of child nodes owned by the sensor node is close to a value obtained by multiplying a maximum containing number, which is a maximum number of sensor data that can be contained by one packet, by a natural number ().

Sensor network system, sensor network control method, sensor node, sensor node control method, and sensor node control program

A multihop wireless network includes a plurality of wireless nodes. Each wireless node calculates a metric value indicating a quantity of providing a guideline for selecting a superordinate destination node with each candidate for the superordinate destination node when carrying out a multihop wireless communication with a specific wireless node based on peripheral node information about node information received from the peripheral wireless nodes and determines the superordinate destination node based on the calculated metric value. The network system selects a superordinate wireless node as a target wireless node expected to change the number of the wireless nodes existing in a subordinate hierarchy, and intentionally changes a value of the node information sent from the target wireless node to the peripheral wireless nodes.

Path control method for multihop wireless network

The present invention is to allow prompt and reliable synchronization of belonging information management table even in environments where there is a possibility of receiving update notification information from a plurality of wireless base stations, without needing unnecessarily large traffic for synchronization of belonging information management table. Wireless base station stores belonging information management table, to which belonging information of a terminal belonging to the base station is associated with, to new/old judgment information for judgment of new/old of update. Belonging information update unit performs update of belonging information including the new/old judgment information thereof. Further, upon receiving update notification information from other wireless base station, the belonging information update unit updates the belonging information management table based on the update notification information. The update notification information includes at least updated portion in the belonging information and new/old judgment information.

Wireless base station, communication system, belonging information management method and storage medium for storing program

A wireless communication system allocates resource information used in performing wireless communication to wireless base stations in order not to generate interference between access-side wireless interfaces and backbone-side wireless interfaces. Each of the wireless base stations includes an access-side wireless interface for covering wireless terminal devices and a backbone-side wireless interface for connecting the wireless base stations with each other. The wireless base station allocates resource information that is common to the wireless base stations to the backbone-side wireless interface that performs the wireless communication between the wireless base stations, and allocates resource information that does not generate interference with the backbone-side wireless interface to the access-side wireless interface.

Resource allocation apparatus, central control apparatus, wireless base station, wireless communication system, resource allocation method and resource allocation program in computer-readable medium

The use of a wireless interface is dynamically changeable according to connection states of stations belonging to access points. Therefore, limited wireless interfaces are efficiently utilized without requiring operation in which the user conducts a complex setting operation. First, connection states of stations belonging to access points are measured. Based on information of the connection states, the connection destination of a wireless connection unit of an access point under consideration is changed over between an access point and a station.

Wireless communication system, system controller, access point, station, communication control method and computer-readable medium storing communication control program

The route maintenance unit outputs a period setting request to the period setting unit when the communication unit normally receives a Hello packet for the first time. The period setting unit sets a link connection confirmation period in response to the period setting request and outputs the set period to the route maintenance unit. The route maintenance unit maintains a radio link between the radio device in which the route maintenance unit is provided and an adjacent device upon receiving a data packet other than a Hello packet from the adjacent radio device even if a Hello packet is not received in the link connection confirmation period. Consequently, route disconnection or switching occurs less often.

Radio device having fewer route disconnections and switchings by using control packets to maintain radio links

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Tokyo, Japan

Yuichiro Ezure