Fast Convergence Least-Mean-Square Algorithms for MMSE Receivers in DS-CDMA Systems
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, the authors 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.