The performance of TDD/CDMA systems using pre-RAKE combining with different diversity techniques and imperfect channel estimation

The use of pre-RAKE combing technique decreases the complexity of the portable unit in time division duplex (TDD) applications while achieving the same multipath diversity effect of the RAKE receiver. Our analysis is focused on three main issues. First a comparison of the various diversity techniques and studying the effect of the diversity order of three different diversity combining techniques. Second, studying the effect of imperfect channel estimation on the system performance and comparing it with the ideal pre-RAKE system. The obtained conditional probability of error is evaluated through Monte-Carlo integration. Third, a comparison between pre-RAKE and RAKE systems under the same conditions. Both random codes and orthogonal codes are considered in investigating the performance of the two systems