SATELLITE-COMMUNICATIONS IN THE MULTIMEDIA ERA

In Japan, the first step towards a public switched network for multime dia communications was realized with the establishment of a network kn own as N-ISDN. In this network, a satellite communications system was introduced as a means to enhance the flexibility and reliability of th e terrestrial network. In recent years, many connectionless type compu ter communications networks have been planned all over the world, and satellite communications systems can be expected to play an important role in these networks. In this paper, multimedia communications netwo rks are categorized into two types, i.e., a connection-oriented (GO) t ype of network and a connectionless (CL) type of network. Examples of satellite communications systems applied to these two network types ar e introduced. One example, the 'DYANET-II system', which was introduce d for the connection-oriented type of multimedia networks in Japan, wi ll be described. NTT's next multimedia satellite communications system , which is suitable for the connectionless type of communications, wil l also be introduced. Finally, the role of satellite communications in multimedia telecommunications will be discussed.