Soft-decision successive interference cancellation CDMA receiver with amplitude averaging and robust to timing errors

Abstract

Successive interference cancellation (SIC) is a low-complexity multiuser detection method for DS/CDMA systems. If the channel is AWGN or slowly varying, averaging the channel amplitude estimates over multiple bits can greatly improve performance. However, the error propagation associated with a hard-limiter decision rule prevents SIC from achieving the performance improvement from averaging. We propose a new soft-decision rule to be used with amplitude averaging, which combines linear and hard decision rules. A performance within 0.4 dB of the single-user bound is obtained. We also made the above soft-decision SIC robust to time delay errors.