Kddi R&d Laboratories, Inc.

Kddi Corporation

Takayuki Warabino

Hajime Nakamura

Tadayuki Fukuhara

Masayoshi Ohashi

Daisuke Morikawa

Hideaki Iwashita

Shinji Ota

Hiroyasu Ishikawa

Hideyuki Shinonaga

Yoji Kishi

Naoki Fuke

Keizo Sugiyama

Kenji Saito

Shoichi Yamazaki

Takashi Matsunaka

Shouichi Yamazaki

In a case where another user's communication terminal (nTE) departs from a group, user's communication terminal (TE) updates encryption information, using the terminal individual information of only the communication terminals (nTEand nTE) which remain in the group (PN). User's communication terminal (TE) encrypts the PN-shared key (KPN), using the updated encryption information. User's communication terminal (TE) transmits the encrypted shared key information obtained from this encryption to a management device (PNSP), and updates the encrypted shared key information stored in the management device (PNSP).

Key sharing system, communication terminal, management device, key sharing method, and computer program

A wireless network system relays a broadcast signal in multiple stages and distributes data to terminals there around, and relay terminals determine whether to relay broadcast packets according to the direction vector and the position information, specified by the information transmission source terminal, referring to their own position information and direction, and relay and accept the packets or ignore them.

Wireless network system, relay terminal and program

A content display system is disclosed for offering, excellent multimedia content browsing/viewing environments to handheld device users, from a server of a communication network, by the use of a handheld device and a cooperating computer device cooperated to the handheld device. According to an aspect of the present invention, the content display system and method are adapted so that:

Content display system and method

A radio LAN master station system which provides long distance communication and suffers from small interference by another system located inside and/or outside of a service area comprises a transceiver, and a plurality of directional antennas each directed to a respective section with some angular spacing, through a power distributor which couples said transceiver with said antennas. Polarization plane of any antenna is orthogonal to polarization plane of an adjacent antenna.

Radio LAN master station system

A communication system capable of avoiding congestion in transmission of moving image data, includes (1) at least one receiving terminal, (2) a moving image delivery device for delivering moving image data to the at least one receiving terminal, (3) a moving image conversion device which has at least one moving image conversion unit for converting, in accordance with conversion parameters, the moving image data sent from the moving image delivery device, a conversion parameter setting unit for determining the conversion parameters, and a monitored result receiving unit, and (4) at least one packet switching node which has at least one data storage unit for preliminarily storing the moving image data from the moving image conversion device to be sent to the at least one receiving terminal, a data amount monitor unit for monitoring an amount of the moving image data stored in the at least one data storage unit to judge that the monitored data amount reaches a first threshold, and a monitored result sending unit for sending a congestion preview information to the moving image conversion device when the data amount monitor unit judges that the monitored data amount reaches the first threshold. The monitored result receiving unit receives the congestion preview information from the monitored result sending unit, and the conversion parameter setting unit determines the conversion parameters so that the moving image conversion unit converts the moving image data sent from the moving image delivery device into a moving image data with a smaller coding bit rate.

Communication system and method capable of avoiding congestion in moving image data transmission

Growing community of inventors

Kamifukuoka, Japan

Takayuki Warabino