Performance of multibeam CDMA-based LEO satellite systems with imperfect power control

Bit error probability of a DS-CDMA multispot beam LEO system with imperfect power control is analysed in this paper. The power control error is assumed to be a lognormal random variable. The channel is a combination of Rician and Suzuki distributions. For more realistic applications the multiple-access interference due to all users seen by the serving satellite for the user of interest is taken into account. This differs from other reported work in which only part of all possible interference was considered. The numerical results with different numbers of interferers show that the interference coming from the users located outside the footprint but seen by the reference satellite has a non-trivial effect on the system capacity. However, the multiple-access interference can be reduced by increasing the elevation restraint of each satellite footprint. Estimates on this reduction are given. It is also shown that the performance of shadowed users is highly sensitive to the power control error. (C) 1998 John Wiley & Sons, Ltd.