A demand-assigned mixed TDMA and FDMA/TDMA system

The concept of an effective demand-assigned satellite communications system is presented. High- and low-data rate TDMA terminals and large and small G/T earth stations can be employed at network nodes having a wide range of traffic requirements. With proper time-sharing of the satellite transponder, a mixed TDMA and FDMA/TDMA transmission mode can minimize terminal costs at nodes with low traffic requirements and maximizes the transponder throughput. Burst-rate reduction, centralized control for each subnetwork, and simple open-loop synchronization methods are employed at nodes with low traffic requirements to achieve cost reduction. It is shown that networks with nonhomogeneous traffic requirements can be cost-effectively served with such a system.