Multiuser detection with antenna arrays in the presence of multipath fading

Multiuser detection has been shown to be an attractive alternative to conventional matched filter detection of CDMA signals. Most of the detection schemes studied however assume perfect channel knowledge. In this paper we study two multiuser detection schemes which operate over diversity channels and have access to only noisy channel estimates. The first is an optimum approach and the second is based on decorrelation detection. These detectors must combat not only multiuser interference but also channel estimation noise. Performance measures which separately gauge a multiuser detectors' susceptibility to both of these impairments are introduced and evaluated for the proposed detectors. The decorrelation approach, while inferior in terms of rejecting multiuser interference, has the advantage of reduced sensitivity to channel estimation noise. This is illustrated in a simple two user, two diversity branch example.