The effect of correlated shadowing on power control error in satellite CDMA systems

Power control process tries to counter balance the power fluctuations in the channel and keep the received power within the prescribed limits. This process has to be accurate in CDMA systems, where all mobile user signals must be received at the same power level in order to maximize the system capacity. In a land mobile satellite channel, if the shadowing autocorrelation changes very rapidly, the length of the round trip propagation delay inherent in the satellite channel would make it difficult for the power control algorithm to track the power variations in the received signal, resulting in an unacceptable performance. In the literature, it is well known that the magnitude of variability (i.e. sigma) of the shadowing process has a crucial effect on the performance of adaptive power control. In this paper, it is demonstrated that in addition to the magnitude of variability, shadowing autocorrelation property also significantly affects the power control performance and it should be taken into account in the mobile satellite system performance evaluations