Open-loop power control error on a frequency selective CDMA channel

In order to combat 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 on a frequency-selective multipath fading channel. The power control scheme has been simulated. It has been 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 presented as a function of the measurement time and vehicle velocity