Nippon Telegraph and Telephone Corporation

Tomoyuki Kanekiyo

Haruhiko Kojima

Hiroyuki Nishi

A private communication system using bus type transmission path, in which a plurality of communication terminal devices for carrying out communications and a system main device for exchanging communications from the communication terminal devices are connected by upward and downward digital transmission paths for transmitting data in forms of upward and downward transmission frames formed by a plurality of cells in fixed length. The system main device determines an allocation of idle cells in each upward transmission frame to a communication from each communication terminal device according to a communication request made by each communication terminal device, and transmits a notification for the determined allocation to each communication terminal device by using an idle cell among the cells in each downward transmission frame, such that each communication terminal device recognizes allocated cells on the upward digital transmission path available for the communication from each communication terminal device according to the notification transmitted through the downward digital transmission path.

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Kanagawa-ken, Japan

Tomoyuki Kanekiyo