Pseudo-decorrelating multiuser receivers for asynchronous code division multiple access (CDMA) systems in a Rayleigh fading environment

A new type of a linear decorrelating receiver, named Pseudo-Decorrelator, f or asynchronous code division multiple access systems over a Rayleigh fadin g multipath channel is presented in this paper. Starting with the analyis o f the multiple access components of the decision statistics, the outputs of a bank of matched filters, the (K x 3K) cross-correlation matrix for each bit is obtained. The non-square cross-correlation matrix is then inverted u sing the concept of Penrose's generalized inverse of a matrix. In this rece iver, the detection process can be started before the whole sequence is rec eived at the receiver, and computing the inverse of a (KN x KN) cross-corre lation matrix, generally required for linear decorrelating receivers, can b e avoided because it is enough to compute only the generalized inverse of a (K x 3K) cross-correlation matrix for each data bit. Here, K is the number of users and N is the length of input data sequence. Simulation results ar e also presented for K-user systems over a Rayleigh fading multipath channe l.