Adaptive Control of Satellite EIRP to Reduce Outage Caused by Fading

The output EIRP or the available bandwidth of a satellite in general limits the amount of traffic which can be handled by SATCOM systems. As the frequency congestion drives future SATCOM systems to higher frequencies, the former constraint will be the more important one because of the severe fades caused by precipitation. Rather than using fixed fade margins, the link power can be dynamically allocated from a common pool of satellite EIRP. By judicious, adaptive allocation of the satellite EIRP among the various users, the traffic supported can be maximized while maintaining the link availability. This paper reports techniques and statistical results of four different ways of allocating the EIRP. By using adaptive centralized control of the terminals transmit power and a variable satellite transmit antenna adaptively controlled by ground commands to compensate for link fades, most efficient use of the satellite EIRP is made. The performance of this technique is derived and compared with others of less complexity and that of a system with fixed satellite antenna and transmit power levels.