Comparison between various diversity techniques of the pre-RAKE combining system in TDD/CDMA

This paper studies the performance of time division duplex (TDD) code division multiple access (CDMA) system with pre-RAKE transmission in a generalized Rayleigh fading multipath channel. We present a comparison between three various diversity combining techniques, namely, maximal ratio combining (MRC), equal gain combining (EGC) and zero-forcing equalization (ZFE), all supplemented by a selection diversity for the strongest paths in gain. We also consider the effect of imperfect channel estimation on the system performance.