Objective function based group-wise successive interference cancellation receiver for dual-rate DS-CDMA system

An objective function based group-wise successive interference cancellation (GSIC) receiver is proposed for a dual-rate DS-CDMA system. In the receiver, user signals are divided into 2 groups for their data rates. Initial bit estimates for the users in group 1 are obtained by its matched filter (MF) bank. The initial bit estimates for the group 1 users are fed into the multiuser detection (MUD) algorithm that is based on iterative objective function optimization. The objective function is derived from the optimum multiuser detection. Then the estimates for the received signals of the group 1 users are regenerated and summed before being subtracted from the received signal. The initial bit estimates for the users in group 2 are obtained by its MF bank using the received signal with multiple access interference from the group 1 users subtracted. The initial bit estimates for the group 2 users are also fed into the MUD algorithm based on iterative objective function optimization. These procedures are done in multiple stages to achieve the desired performance. It is shown that the proposed receiver achieves significant performance improvement over the MF receiver, GSIC receiver, multi-stage PIC (parallel interference cancellation) receiver, and multi-stage partial PIC receiver for a Rayleigh fading channel.