Equalized parallel interference cancellation for uplink CDMA systems

An equalized parallel interference cancellation is proposed for uplink CDMA systems. The hard decisions of the RAKE receiver and 1-stage conventional parallel interference cancellation are combined and equalized by the proposed receiver for further performance improvements. By using digital two-bit-comparator, the hard decisions of the proposed detector at the current stage are compared with that of the previous stage, and then are separated into reliable and unreliable groups. The multiple access interference induced by reliable data estimates is regenerated and entirely subtracted from the soft outputs of the RAKE receiver. In contrast, the multiple access interference induced by unreliable data estimates is weighted and fractionally subtracted. The simulation results show that the proposed receiver significantly improves the system performance with negligible increase in complexity and memory