PERFORMANCE OF DS-CDMA WITH IMPERFECT POWER-CONTROL OPERATING OVER A LOW EARTH ORBITING SATELLITE LINK

The analysis of both performance and capacity of direct sequence CDMA in terrestrial cellular systems has been addressed in the technical li terature. It has been suggested that CDMA be used as a multiple access method for satellite systems as well, in particular for multispot bea m Low Earth Orbit Satellites (LEOS). One is tempted to argue that sinc e CDMA works well on terrestrial links, it will nominally work as well on satellite links. However, because there are fundamental difference s in the characteristics of the two channels, such as larger time dela ys from the mobile to the base station and smaller multipath delay spr eads on the satellite channels, the performance of CDMA on satellite l inks cannot always be accurately predicted from its performance on ter restrial channels. In this paper, we analytically derive the performan ce of a CDMA system which operates over a low earth orbiting satellite channel. We incorporate such effects as imperfect power control and d ual-order diversity to obtain the average probability of error of a si ngle user.