Predictive action power control scheme for a mobile satellite system

The mobile satellite propagation channel exhibits severe signal shadowing and multipath fading resulting in attenuation of the transmit signal. To mitigate these adverse channel effects a predictive control scheme is presented here to regulate the transmit signal strength and hence provide an efficient usage of satellite and mobile station (MS) power source. The proposed scheme aims to forward predict channel gain variations at the receiver and issue appropriate control signal to the transmitter. A TDMA based mobile satellite system is used to simulate the power control scheme on the reverse link (mobile to earth station) with an assumption of availability of ideal measure of received signal strength. A Rician model with single ray specular component is used to generate different propagation channels to evaluate the performance of the proposed power control scheme for different scenarios ranging from rural to urban. The control scheme delivers a desired mean received signal strength with an average standard deviation of /spl plusmn/1.5 dB. Simulation results show that the controller is capable of combating the cyclic specular multipath effects together with other slowly varying fading components, but fails to control the short term fast Rayleigh fading.