Iterative interference cancellation and decoding for DS-CDMA systems

Abstract

This paper discusses the integration of parallel interference cancellation (PIC) with forward error correction coding in a multiuser receiver for DS-CDMA systems. A soft-output PIC algorithm is followed by a log-MAP receiver for decoding of convolutional codes. An integrated receiver that implements multiple stages of interference cancellation and decoding is presented and evaluated through simulation. This integrated approach is compared with a partitioned approach, where the final stage output of PIC is followed by decoding using a soft-input Viterbi algorithm (VA). Results presented for BER and capacity of the two systems show that both techniques represent a substantial improvement over conventional detection, but the more complex integrated approach provides only a small improvement over the decoupled approach.