Hitachi, Ltd.

Susumu Matsui

Naoko Iwami

Keiko Takahara

Yasuhiro Takahashi

Takeshi Kondou

Masashi Yano

Mika Mizutani

Tetsuhiko Hirata

Shoji Fukuzawa

Atsushi Shimizu

Kazuma Yumoto

Masato Hayashi

Matsuaki Terada

Keishi Takebe

Takahiro Fujishiro

Eriko Ando

Yasuko Fukuzawa

Tohru Hoshi

Norihisa Matsumoto

Yasuhiko Nagai

Tatsuya Yokoyama

Mototsugu Nishioka

Kazuya Monden

Hisashi Umeki

Shuichi Ishida

Mitsuhiro Noda

Akinori Honda

Taro Saito

Shiro Baba

Yasushi Akao

Yoshiyuki Nakayama

Naomichi Nonaka

Toshio Okochi

Tatsuaki Osafune

Tomoichi Ebata

Kenji Kawakita

Jiro Kashio

Yukio Nakata

Keiko Tanigawa

Toru Saito

Toshiaki Koyama

Koji Tsukada

Yoshinobu Yamamoto

Haruo Shibata

Keisuke Shirai

Koji Hirayama

Noriyuki Tanaka

Yutaka Otsu

Hisao Sasaki

Tetsuo Manchu

Sinichi Kouyama

Atsushi Teshima

Toshiya Ouchi

Kazuhisa Tanaka

Shouji Fukuzawa

One objective of the present invention is to determine a location for a relay terminal in a radio network, without preparatory surveying a radio status, and to arrange the relay terminal at the location. Another objective is to provide a method for retrieving the arranged relay terminal. When a relay terminal is to be arranged, the relay terminal transmits a survey packet to examine the quality of communication with a communication terminal or other relay terminal. Where a location is appropriate, the relay terminal gives a notice. The arranged terminal relays communication. Further, when the relay terminal is to be retrieved, the relay terminal carried by a user transmits a retrieval packet to the arranged relay terminal, which notifies the user of its presence by light, sounds, or returning a packet. In this manner, a single relay terminal provides functions of arrangement, relay and retrieval.

Radio network expansion method

A voice communication system, which is connected to a LAN to which communication terminals are connected and to a public network to which telephones are connected, is provided with a communication server between the LAN and public network having different protocols from each other. The communication server enables a voice communication between a telephone on the public network and a communication terminal connected to the LAN by performing processing similar to that for a voice communication between two communication terminals connected to the LAN. The communication server determines whether an address of the other party inputted by a user is a communication terminal address or a telephone number, and transmits a voice communication request to a communication terminal of the other party when the address is a communication terminal address. When the address is a telephone number, the user acquires the communication terminal address of the communication server, and transmits a voice communication request to the communication server. Thereafter, the voice communication processing is performed through the communication server.

Voice communication system and voice communication method

To make is possible to perform communication adapted to changes in a communication environment, a wireless communication device comprises a wireless communication unit for performing communication with another communication device through a wireless communication network, a communication quality evaluation unit for generating an evaluation value with regards to a communication quality of the communication, a communication mode switch unit for switching communication modes for use in the communication according to the evaluation value.

Wireless communication device, controlling method and program therefor

On ad hoc networks in which connection relationships among communication terminals constantly change, the processing load increases when authentication is performed each time a connection relationship changes. According to this invention, when communication terminals possess the same common key, mutual authentication is conducted with that common key, and when communication terminals do not possess the same common key, mutual authentication is conducted with a public key. Communication terminals that conducted mutual authentication exchange and retain a common key that they selected and common keys received from other communication terminals. When neither communication terminal possesses a common key at authentication, one terminal creates a common key and distributes it to the other terminal, and when one terminal has a common key it creates that common key and distributes it to the other terminal. Further, a common key possessed by a communication terminal corresponding to a relay node is broadcast periodically.

Authentication method of ad hoc network and wireless communication terminal thereof

In a network system including a first relay connected to a wire network and a radio network, a second relay for relaying data in the radio network, a first terminal connected by wireless to the first relay, and a second terminal connected by wireless to the second relay, the first relay keeps first information indicating a correspondence between an address of the second terminal, an identifier of a group to which the second terminal belongs, and an identifier of the second relay and second information indicating a correspondence between identifiers of groups formed by virtually subdividing the wire network and an identifier of a group to which the second terminal belongs, and the first relay transmits a packet according to the first or second information.

Network system

A first and a second terminal carry out radio communications, the first terminal selects, based on an expectation saved in the concerned first terminal, a relay terminal relaying data to be transmitted to the second terminal and transmits the data, with a first information item indicating the address of the first terminal and a second information item indicating the address of the second terminal, to the relay terminal; and the relay terminal transmits the received first and second information items, and the data, to the second terminal; and if the second terminal receives the first and second information items, and the data, it transmits a completion report to the first terminal, based on expectation values saved by the second terminal concerned, making it capable of checking whether it has been possible to surely send and deliver the data.

Data communication between networks using relay devices

The present invention relates to a common key sharing method in an ad hoc network constituted by wireless communication terminals implemented with relay functions thereon, comprising a common key generating step in which a first wireless communication terminal responsible for relaying generates a common key, a common key distributing step in which the first wireless communication terminal responsible for relaying distributes the common key to a second wireless communication terminal within a wireless communication area, and a transferring step in which the second wireless communication terminal which received the common key holds the common key, and the second wireless communication terminal transfers the common key to a third wireless communication terminal within a wireless communication area, when the second wireless communication terminal is responsible for relaying. Accordingly, it is possible to share a common encryption key within the ad hoc network.

Common key sharing method and wireless communication terminal in ad hoc network

A voice communication system, which is connected to LAN to which communication terminals are connected and to a public network to which telephones are connected, is provided with a communication server between the LAN and public network having different protocols from each other. The communication server enables a voice communication between a telephone on the public network and a communication terminal connected to the LAN by performing processing similar to that for a voice communication between two communication terminals connected to the LAN. The communication server determines whether an address of the other party inputted by a user is a communication terminal address or a telephone number, and transmits a voice communication request to a communication terminal of the other party when the address is a communication terminal address. When the address is a telephone number, the user acquires the communication terminal address of the communication server, and transmits a voice communication request to the communication server. Thereafter, the voice communication processing is performed through the communication server.

In order to efficiently use each of storage physical devices fast in access rate for each data block even where a deviation in access frequency exists within a file, in a storage system comprising a plurality of the storage physical devices, a policy is stored within the storage system in advance with respect to the placement of file's data blocks, and data of each file is evaluated with respect to the policy upon storage of the file's data blocks. A decision as to in which storage physical device the corresponding data blocks should be located, is made based on the evaluation result of the policy.

Storage system

Growing community of inventors

Machida, Japan

Susumu Matsui