Bi-directional multimedia satellite communication system employing superposed transmission

A bi-directional multimedia satellite communication system has been proposed to support high-speed Internet access. This system utilizes a low-cost user earth station with an ultra-small antenna for easy installation. Since this system utilizes ultra-small antennas, it employs the low-power spread spectrum (SS) scheme in the access link to keep the off-axis equivalent isotropic radiation power below the limit. For efficient use of transponders and frequency, SS signals are superposed on the high-speed TDM forward link signal. To demodulate access link signals under this condition, two novel technologies are introduced. They are the adaptive interference cancellation technique, and the parallel and staggered operation SS demodulation technique. This paper describes system configuration, the new technologies and the results of a system performance evaluation in an experiment. The results of the evaluation demonstrate that superposed transmission over the forward link and low-power access link signals is feasible