Experiments on satellite TDMA system for multimedia communications

As a new form of communications, computer networks represented by the Internet have become widespread. In these networks, multimedia information such as static and dynamic images, audio, data file, and so on are handled. In such multimedia communications, the access circuits of the users are low-speed ones while the return links to the users are large-capacity, high-speed circuits and, therefore, the configuration has an asymmetric bidirectional form. In this paper, as a highly efficient method of transmission of asymmetric bidirectional multimedia communications with different speeds, which can be adopted only to satellite systems, the TDMA signals of variable transmission speeds are used in the return links of multiple connected transmitting stations. The multiplexed SSMA signals are superposed on TDMA signals of the low-speed forward links. Such a multimedia satellite TDMA communication system is proposed and a fabricated prototype is used in the satellite connections of the NTT Yokosuka and Musashino Research Centers. In this prototype, the actual TDMA capacity is 42.24 Mbits/s while 20 circuits of 32 kbits/s are accommodated in the SSMA signal. (C) 2001 Scripta Technica.