Performance comparison of decorrelator designs for multiuser detection in asynchronous CDMA channel

In this paper, a reduced rank extended window decorrelator (RREWD) for asynchronous CDMA detection is derived. The reduction in the rank of the extended window signal space is obtained through interference cancellation. It is shown that the reduction in rank of the decorrelation matrix improves the performance and user capacity of the extended window decorrelator. Further, it is demonstrated that the edge assisted decorrelator, which also work on the similar principle of interference cancellation, exhibit the identical architectures as that of the RREWD. The results have become more demonstrative by introducing a classification for the decorrelators. The type of signature sequences used in processing the received signal at the receiver decides the class to which the decorrelator may belong. Full signature sequences based decorrelators are considered as the members of class-I while those that used partial/full signature sequences form class-II. A comparison of these two classes of decorrelators is presented to highlight the relative merits.