Advanced Telecommunications Research Institute International

Nec Communication Systems, Ltd.

Nec Communications Systems, Ltd.

Oki Electric Industry Co., Ltd.

National Institute of Information and Communications Technology, Incorporated

Nec Communications, Ltd.

Sadao Obana

Tetsuya Ito

Peter Davis

Akira Matsumoto

Naoto Kadowaki

Satoko Itaya

Yoshihisa Kondo

Jun Hasegawa

Akio Hasegawa

Hiroyuki Yomo

Koichi Yoshimura

Suhua Tang

Hiroyuki Iizuka

Kenichi Abe

Akira Yamaguchi

Youiti Kado

Masahito Iwai

Masanori Nozaki

Yuichiro Ezure

Bing Zhang

Toshiyasu Tanaka

Seiji Igi

Hisato Iwai

Ryutaro Suzuki

Oyunchimeg Shagdar

Mehdad Nori Shirazi

Yasuhisa Takizawa

Makoto Kawai

A wireless base station () includes a wakeup device () and a main device (). When the main device () is in a sleep mode, the wakeup device () is connected to the antenna (). Then, when the wakeup device () receives a wakeup signal for activating the wireless base station () from a terminal device assigned to the wireless base station () in a communication band used for wireless communication with the terminal device and when the information for identifying a wireless base station to be activated contained in the received wakeup signal is identical with the identification information of the wireless base station (), the wakeup device () outputs a driving signal to the main device (). The main device () transitions from the sleep mode to an operating mode in response to the driving signal from the wakeup device ().

Wireless base station and wireless communication systems using the same

Wireless base station and wireless communication system using the same

A terminal devicetransmits a wireless frame having a frame length or amplitude that represents the ID of a wireless base stationto be woken up to the wireless base station. The wireless base stationdetects the wakeup ID from the frame length or amplitude of the wireless frame from the terminal device, and, if the detected wakeup ID is identical with its own ID, transitions from a sleep mode to an operating mode. In this case, the wireless frame is the same wireless frame as that transmitted and received by the wireless communication module of the terminal deviceto and from the wireless base station

Terminal device, wireless base station wirelessly communicating with the same, and wireless communication system using terminal device and wireless base station

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

In wireless communication using links with neighbor wireless devices, a wireless device calculates ratios of throughput to maximum throughput for the links and calculates the costs of the links using the calculated ratios. Then the wireless device finds, for each destination, a route in which the sum of such calculated link costs is the minimum, and sends a packet to the destination using the route. As a consequence, routing can be done according to an isotonic, easy-to-implement routing protocol.

Wireless device which selects routes excluding loop routes and a mesh network including the same

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 source terminal measures characteristics of the path at the source terminal itself, produces a characteristics-measurement packet, and transmits the produced characteristics-measurement packet to a relay terminal. Upon receiving the characteristics-measurement packet, the relay terminal measures characteristics of the path at the relay terminal itself, renews the characteristics of the path included in the characteristics-measurement packet using the measured characteristics of the path, and transmits the characteristics of the wireless communication path to the destination terminal. The source terminal produces an admission-request packet and transmits the packet to the destination terminal. Upon receiving the admission-request packet, the destination terminal allows or rejects the traffic quality maintenance request according to the characteristics of the wireless communication path. The allowance or rejection of the quality maintenance request is transmitted to the source terminal with the admission-reply packet by the destination terminal.

Multi-hop wireless network system

A radio apparatus forming a radio network system calculates a calculated distance, based on a tentative self-position and tentative positions of a plurality of radio apparatuses existing in the vicinity. The radio apparatus successively and autonomously corrects the tentative self-position so that the calculated distance comes closer to the measured distance, relying more heavily on the calculated distance than the measured distance between itself and each of the plurality of radio apparatuses, and determines the position of itself. Other radio apparatuses also successively correct the tentative self-positions by the same method as the radio apparatus, and determine the positions of themselves.

Radio network system capable of autonomous estimation using position correction

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

Sadao Obana