Cellular channel modeling and the performance of DS-CDMA systems with antenna arrays

In this paper, a new channel modeling approach incorporating nonuniform propagation environments is introduced, and the bit error rate (BER) of a direct sequence code division multiple access cellular system incorporating antenna arrays for spatial filtering is derived analytically. Specifically, this paper introduces a channel model for, and analyzes the performance of, a system in an environment where the multipath signals on each of the diversity branches of a RAKE receiver have varying fading characteristics. This scenario would typically describe urban environments where a large number of multipath echoes are present, each with different fading statistics resulting from the nonhomogeneous propagation paths seen by each multipath echo. It is shown that nonuniform fading parameters for multipath signals can severely influence the system performance, especially at high E-b/N-0 levels. Furthermore, it is shown that the conventional assumption of identical fading statistics for all RAKE receiver branches provide a lower bound on the system performance.