Complexity Reduction of Direct - Sequence Code Division Multiple

In this paper we consider an asynchronous direct-sequence code division multiple access (DS-CDMA) communication system over an AWGN channel. We are interested in reducing the computational complexity of a receiver by lowering the dimensionality of the received vector. Dimension reduction has previously been done in an ad hoc manner by several researchers. In this paper we derive an optimum form of dimension reduction. The optimality criteria is that the Cram er-Rao bound on estimators of propagation delay, received phase and power are invariant to the reduction transform .