Joint interference cancellation and Viterbi decoding in DS-CDMA

Abstract

Direct-sequence code-division multiple access (DS-CDMA) is a popular wireless technology. In DS-CDMA communications, all of the users' signals overlap in time and frequency and cause mutual interference. In this paper a novel multi-user decoding scheme for coded synchronous DS-CDMA is proposed. The decoder performs joint successive interference cancellation (SIC) and Viterbi decoding (VD) in each step of the interference cancellation. In a conventional SIC scheme, SIC is performed first, followed by VD that uses the outputs of the last stage of the SIC scheme for metric calculation. Simulated bit error probability for the proposed scheme is presented and compared with bit error probability of a conventional scheme. A capacity increase of at least 4 compared to SIC followed by VD is reported in one example.