SINR , Power E ciency , and Theoretical System

| In this paper, we analytically derive an exact expression for the SINR of the two-stage parallel interference cancellation (PIC) multiuser detector in a synchronous , nonorthogonal, binary, CDMA communication system. In order to obtain an intuitive understanding, we consider an approximation to the SINR expression that is well justiied in scenarios where the error probability of the matched lter detector is reasonably low. Given a speciic SINR requirement for each user in the system, we derive an expression for the minimum transmit power necessary to meet this requirement when the two-stage PIC detector is used. We also derive an expression for a measure of the theoretical system capacity of PIC, deened as the maximum number of users possible in a system with nite available transmit power. Analytical results comparing PIC to the successive interference cancellation (SIC) detector and matched lter (MF) detector show that PIC requires less total transmit power and has greater theoretical system capacity than the SIC or MF detectors in the cases considered.