An adaptive multiuser interference rejection algorithm for direct-sequence code division multiple access

In this paper we consider a direct sequence code division multiple access (DS-CDMA) system from the framework of a discrete event dynamic system (DEDS) and develop infinitesimal perturbation analysis (IPA) for estimating the sensitivity of the average probability of bit-error in such systems. The above estimates are shown to be unbiased, and this technique is then further incorporated into a stochastic gradient algorithm for achieving adaptive multiuser interference rejection. Specifically, we develop an algorithm for an adaptive linear detector with the average probability of error being the minimization criterion. This algorithm is shown to converge, and the resulting detector performs better than both the matched filter detector as well as the minimum mean squared error (MMSE) detector