Differentially coherent blind multiuser receiver for Rayleigh fading CDMA channels

Abstract

This paper studies the performance of a blind adaptive multiuser receiver in slow and fast fading channels. The receiver consists of fractionally spaced equalizer, adaptive weight mechanism, matched filter, and differential decoder. Thus, the complexity of the receiver is slightly higher than the conventional receiver. The main problem of an adaptive multiuser receiver is the requirement of training sequences for the adaptation process. Due to time-varying interference and fading effect in time-correlated channels, the training sequence is difficult to obtain or becomes defective. The blind multiuser receiver considered in this paper does not require any training sequences, but retains all the advantages that adaptive receivers have. Simulation results show that the receiver is effective in fading channels with perfect power control and with near-far effect. The blind adaptive multiuser receiver is an attractive alternative to the conventional receiver in Rayleigh fading CDMA channels.