Edge decision assisted decorrelators for asynchronous CDMA channels

Asynchronous decorrelating detector is a linear multiuser detector in code-division multiple-access (CDMA) environment. It has relatively good performance and low-computational complexity. However, the ideal asynchronous decorrelating detector requires the observation of the entire input bit sequence. Implementation of this ideal detector based on a long bit sequence results in long delays and high computational complexity. In fact, if the observed window does not cover the entire data sequence, the classical asynchronous decorrelating detector is no longer near-far resistant. In this paper, we propose a method using initial decisions on bits for both edges of the finite observed window. These initial decisions are used to assist subsequent decisions of the whole sequence inside the observed window based on the decorrelating method. This new edge decision assisted decorrelator (EDAD) method is shown to be near-far resistant.