Adaptive dual-channel demodulation in CDMA mobile satellite systems

In the following analysis, assuming a satellite DS-CDMA system for mobile communications, the performance degradation due to imperfect phase reference is investigated. It is assumed that a low percentage of the users of a satellite mobile system may have to front a more severe multipath environment. In a mobile radio system, the phase synchronisation can be a critical issue if the channel is affected by multipath. The use of dual channel demodulation is a viable and efficient strategy on the forward link, since only one common pilot channel is needed in this case. If the same dual channel demodulation is considered for the return link, an unacceptable capacity reduction may result. In this paper an efficient dual channel demodulation scheme is proposed for the return link, and the impact on the overall system performance or capacity is analysed