Research in the field of telecommunications has achieved real time economical communication between distant locations. It is more important to research the technologies required to realize a human-oriented intelligent communication system. One of high grade communication system is that provides a very realistic sensation for the receiver of different multipoints. The system will enable people at different locations to perform cooperative tasks while experiencing the sensation of being gathered in one virtual place. This Paper describes the virtual space teleconferencing system which is one of communications with realistic sensations.

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International videoconferencing service in Japan was commenced in 1986 by KDD linking 1.5Mbps digital path via INTELSAT satellite. The network is steadily expanding and has now connectivity with eleven countries. The traffic volume is rather low yet. Appreciation for utilities of the service is, however, gradually increasing and application of the service is expanding to a variety of business areas. Ad-hoc videoconferencing in large events is also increasing. Recent progress and future prospect of international videoconferencing are presented in this paper.

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This paper describes design concepts, functions and architecture of a developed personal multimedia teleconferencing terminal which realize face-to-face like communications over a narrowband ISDN by Integrating voice, portrait video, high resolution bilevel graphics, full color still pictures, handwritten images and handwritten pointers.

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A system design principle called group communication architecture which has been developed for supporting group cooperative work is proposed. This architecture serves as a basis for assisting geographically separate group members to work together efficiently and effectively with interchange and sharing of multimedia information. It consists of two models: a function model which defines hierarchically structured service functions, and a system model which provides service interfaces and communication protocols. Distributed conference systems in which desktop (workstation) conferencing and teleconferencing can be conducted in a unified manner have been designed using this architecture.

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Described here is a distributed multiparty desktop conferencing system called MERMAID (Multimedia Environment for Remote Multiple Attendee lnteractive Decision-making). The system is based on Group Communication Architecture (GCA). MERMAID system provides participants flexible floor passing control, convening control, dynamic joining and leaving control, efficient conference preparation support, user-friendly interfaces, and the means for sharing such multimedia information as video, vdi.ce, text, graphics, images, and handdrawn figures. This paper describes MERMAID system's configuration, providing functions, server configuration and their functions. Features of MERMAID are: 1) wide area multiparty realtime communication, 2) flexible conference support, 3) multi-media communication and presentation, 4) user-friendly interface, and 5) cost-effectiveness. Application systems of MERMAID are also described.

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Recently studies on Audio Graphic Conference (AGO and Computer Supported Cooperative Work (CSCW) are being actively done. This paper introduces a concept of "Desk Top Conference (DTC)" application which might be situated in between AGC and CSCW. Based on DTC, we designs PC Document Conference System as one of the possible set of DTC. Realtime remote editing facility is a main purpose of this system. In detail, the document structure and document processing model based on ODA (Open Document Architecture), remote editing and document management protocol which use DTAM (Document Transfer and Manipulation) and man-machine interface based on Multi-windows have been proposed.

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This paper describes the basic requirements for MCU (Multipoint Control Unit) which provides multipoint Teleconference services. Those requirements, such as CONFERENCE GROUP MANAGEMENT. DOCUMENTS MANAGEMENT. MULTIPOINT COMMUNICATION CONTROL. SUB-GROUP COMMUNICATION FLOOR MANAGEMENT ERROR MANAGEMENT are considered from the "Group communication" view point. Based on those requirements, we have developed the prototype of MCU and evaluated on the environment of using 64Kbps data channel in consideration of ISDN applications.

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Tokyo Electric Power Company, together with several Japanese and the U. S. industries, has jointly developed:two types of color motion videophones for personal use in office. They are expected to be new communication equipments which have potential to replace conventional audio telephones. They will be quite useful for efficient/prompt procedure of routine business works as well as effective contact in case of emergency/disaster. Prototypes glade are designed to be connected with existing private digital telephone network. The role of them is to Provide early evaluation of necessary functionarity and handiness as business tools while careful observation is kept going on international standardization activities of compression algolithm and frame format with regard to video-phone.

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