A decision feedback decorrelator for a dual rate synchronous DS/CDMA system

A dual rate synchronous DS/CDMA system provides service to low bit rate and high bit rate users. In a fixed duration interval, a low rate user transmi ts one bit while a high rate user transmits M bits. The differences in the bit transmission rates result in different processing gains for each class of user. In this paper, we propose a decision feedback decorrelator for the dual rate synchronous DS/CDMA system which uses modified correlators and i nitiates the bit decision process at the end of the high rate bit interval. Each step of the decision process is executed by utilizing the decisions o f all previously decoded users. This dual rate decision feedback receiver ( evaluated by simulation) is found to outperform two types of decorrelators for dual rate CDMA systems. It is also observed that as the interferers gro w stronger relative to the desired user, the performance of the decision fe edback receiver for decoding the desired user approaches the single user bo und.