Home // International Journal On Advances in Networks and Services, volume 1, number 1, 2008 // View article

Fast Convergence Least-Mean-Square Algorithms for MMSE Receivers in DS-CDMA Systems

Authors:
Constantin Paleologu
Călin Vlădeanu
Safwan El Assad

Keywords: Code-division multiple-access (CDMA) system; gradient adaptive lattice (GAL) algorithm; least-mean-square (LMS) algorithm; minimum mean-squared error (MMSE) receiver.

Abstract:
This paper considers a minimum mean-squared error (MMSE) single user adaptive receiver for the asynchronous direct-sequence code-division multiple-access (DS-CDMA) system, based on the least-mean-square (LMS) algorithm. It is known that in this context the adaptive algorithm can be iterated several times during the same bit interval in order to achieve a faster convergence rate, which further reduces the length of the training sequence. The objective of this paper is twofold. First, instead of using such multiple iterations, we propose a single equivalent formula for updating the receiver coefficients, saving significant time processing. Secondly, in order to further increase the convergence rate, a division-free version of the gradient adaptive lattice (GAL) algorithm is proposed. Since the lattice predictor orthogonalizes the input signals, this algorithm achieves a faster convergence rate than the transversal LMS algorithm.

Pages: 30 to 39

Copyright: Copyright (c) to authors, 2008. Used with permission.

Publication date: February 24, 2009

Published in: journal

ISSN: 1942-2644