Effect of power imbalance on multiuser detection of DS-CDMA systems

Abstract

This paper describes the effect of power imbalance on multiuser detection of Direct Sequence Code Division Multiple Access (DS-CDMA) systems. Unlike the conventional single-user detection technique which considers interference between users or multiple access interference (MAI) as noise, in multiuser detection scheemes of DS-CDMA systems MAI is eliminated successively. However in the present of near-far problems and fading channels, where recived power among different users are of diffetrent levels, the performance of multiuser detection methods degrade due to unreliable detections of users with low power levels. In this paper multiuser detection is described in a simple model and the performance for various number of users is evaluated using computer simulation. The effect of power imbalance among different users is presented to show the performance degradation.