Advanced Telecommunications Research Institute International

Nec Communication Systems, Ltd.

Nec Communications Systems, Ltd.

Jun Hasegawa

Peter Davis

Sadao Obana

Naoto Kadowaki

Satoko Itaya

Akio Hasegawa

Tetsuya Ito

Akira Matsumoto

Kenichi Abe

Yoshihisa Kondo

Hiroyuki Iizuka

Yuichiro Ezure

When wireless communications are made between a first wireless device and a second wireless device along a route, two wireless devices which exist between the first and second wireless devices each determine the lowest maximum transmission rate (11 Mbps) in the wireless intervals on the route from themselves to the second wireless device to be their own transmission rate txRate (11 Mbps) and two other wireless devices which exist between the first and second wireless devices each determine the lowest maximum transmission rate (54 Mbps) in the wireless intervals on the route from themselves to the second wireless device to be their own transmission rate txRate (54 Mbps).

Wireless device which can improve stability in wireless communications and wireless network using the same

Radio apparatuses each has a plurality of channels and, when data is to be transmitted, selects a specific channel having relatively low signal interference from the plurality of channels. Each radio apparatus spreads transmission data with a prescribed spread code arbitrarily selected from a plurality of spread codes, and modulates the spread spectrum signal with the frequency of the specific channel to transmit. As a result, delay in an autonomously established wireless network can be reduced.

Radio apparatus

Radio devices (to) receive a prescribed number of Hello packets from each of n radio devices existing within one hop from each radio device, detects six pairs of maximum and minimum values MAX[] and MIN[] to MAX[] and MIN[] based on the plurality of reception signal strengths of the plurality of received Hello packets, detects two adjacent maximum values having the largest difference among six pairs of maximum and minimum values D_MAX[] and D_MIN[] to D_MAX[] and D_MIN[] when the six maximum values MAX[] to MAX[] are in descending order, and determines the average of two minimum values corresponding to the detected two maximum values as a threshold. The radio devices (to) each produce a routing table including routes having reception signal strengths equal to or more than the threshold.

Radio device

A radio device is located far from other radio devices in a radio network system. The radio device determines a threshold WIth for detecting a strength equal to or more than the minimum strength of radio waves transmitted/received in a stable radio wave environment based on a plurality of reception signal strengths of Hello packets received from radio devices adjacent to the radio device. Then, if the number of radio devices adjacent to the radio device when the threshold WIth is introduced is less than a standard value (such as five), the radio device stores the adjacent radio devices in the neighbor list without introducing the threshold WIth, and then, maintains in the routing table the routing information of routes passing through the adjacent radio devices based on the neighbor list.

Radio device for preventing isolated radio devices in network

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

Growing community of inventors

Kyoto, Japan

Jun Hasegawa