A shared resource TDMA approach to increase the rain margin of 12/14-GHz satellite systems

A method to increase the rain margin of a satellite system by as much as 10 dB is presented. The technique does not require site diversity, large antennas, or greater satellite radiated power, all of which are quite inefficient because they represent additional system resources which are only infrequently called upon during rain attenuation events. Rather, the technique creates a small pool of time division multiple access (TDMA) time slots, shared among all earth terminals in the network, to be used only when needed by the sites experiencing rain attenuation above the power margin. Coding techniques are employed during rain events to extract additional margin from these pooled resources with little bandwidth penalty. The hard-ware complexity to enable TDMA operation with coding during rain events is assessed and found to be quite modest. Although the transponder data rate may be in the neighborhood of 600 Mbits/s, the decoder operates at a much lower speed by virtue of the low TDMA duty cycle associated with a given ground station.