On Optimal Chip Equalization for Equal-Power Synchronous CDMA Systems

Extensive work has been done on linear chip equalization of CDMA signals. In this paper we show how to apply the optimal chip equalization, which is shown to be part of the symbol Bayesian minimum mean square error estimator, and it is applicable for the downlink of a CDMA system with equal user powers. Although the optimal chip equalizer’s complexity is high, we believe it is worthy to study as a new equalization method for CDMA, which may give a new dimension in the CDMA equalization research, and as a reference to the linear chip equalization. We implemented a suboptimal receiver based on the optimal chip equalization idea which outperforms, as expected, the linear chip equalizer, and also the partial parallel interference canceller at high signal-to-noise ratios, without the explicit knowledge of the users’ spreading codes.