Multipath parameter estimation for DS-CDMA with aperiodic spreading codes

For high performance CDMA communications, multiuser detection is often required to suppress the multiple access interference (MAI). Existing multiuser detectors rely on channel information to recover multiuser digital signals. This paper studies the channel estimation and carrier recovery problem for DS-CDMA systems using aperiodic spreading codes. The maximum likelihood channel estimator is derived. The resulting multiuser optimization problem is solved iteratively via alternating optimization technique. It is shown by computer simulation that the proposed algorithm can reach global maxima almost always under medium SNR.