Open-loop power control error on a land mobile satellite link

In order to combat large scale shadowing and distance losses in a land mobile satellite system, an adaptive power control (APC) scheme is essential. Such a scheme, implemented on the uplink, ensures that all users´ signals arrive at the base station with equal average power as they move within the satellite spot beam. Because of the lengthy round-trip delay on a satellite link, closed-loop power control systems are only of marginal benefit. Therefore, an open-loop APC scheme is proposed to counteract the effects of shadowing. A fairly general channel model, consisting of log-normal shadowing; and Rician fading, is assumed. This can be applied to a specific two-state land mobile satellite channel model, involving shadowed intervals with Rayleigh fading and unshadowed intervals with Rician fading. It is found that the power control error can be approximated by a log-normally distributed random variable. To quantify the performance of the APC, the standard deviation of the power control error in decibels is derived