Implementation of the Decorrelating Receiver for Asynchronous DS-CDMA Systems over Multipath Fading Channels

Abstract

This paper presents a decorrelating detector for DS-CDMA asynchronous systems over multipath fading channels. The decorrelating receiver applies the inverse correlation matrix of signature waveforms to detect the received signal. A procedure for finding such an inverse matrix is developed. This procedure employs the reciprocal basis, derived from the basis of normalized user signatures, to cancel simultaneously both the multiuser and the intersymbol interference. The proposed multiuser detector operates over a finite detection window, and the only restriction imposed on the set of signatures is that the signatures must be independent at the receiver end. If the channel is slowly variant, the detector can be very efficient for high bit rate transmissions. Theoretical bounds for the multiuser interference are obtained. Simulation results, in which both binary and non-binary sequences are used, reveal that the behaviour of the detector approaches the single user bound when an adequate set of signatures is employed. The reduced complexity of this detector indicates that it could be a good candidate for practical implementation.