Design and Performance Analysis of a DS/CDMA Multiuser Detection Algorithm in a Hybrid Form

The conventional code division multiple access (CDMA) detector based on IS-95 standard shows severe degradation in communication quality as the number of users increases due to multiple access interferences(MAI). This problem thus restricts the user capacity Various multiuser detection algorithms have been proposed to overcome the MAI problem. The existing detectors can be generally classified into one of the two categories: linear multiuser detection and subtractive interference cancellation detectors. In the linear multiuser detection, a linear transform is applied to the soft outputs of the conventional detector. In the subtractive interference cancellation detection, estimates of the interference are generated and subtracted out from the received signal. There has been great interest in the family of the subtractive interference cancellation detection because the linear multiuser detection exhibits the disadvantage of taking matrix inversion operations. The successive interference cancellation (SIC) and the parallel interference cancellation (PIC) are the two most popular structures in the subtractive interference cancellation detector. The SIC structure is very simple in hardware complexity, but has the disadvantage of increased processing delay time, while the PIC structure is good in performance, but shows the disadvantage of increased hardware complexity. In this paper, we propose a hybrid form of SIC and PIC in order to achieve good performance as well as simple hardware complexity A performance analysis of the proposed hybrid scheme has been made, and the superior characteristics of the hybrid structure are demonstrated by extensive computer simulations.