Bidirectional MMSE Algorithms for Interference Mitigation in CDMA Systems over Fast Fading Channels

TL;DR

This paper introduces adaptive bidirectional MMSE algorithms that leverage channel correlation in fast-fading CDMA channels to enhance interference mitigation and tracking performance.

Contribution

It proposes novel bidirectional NLMS and CG algorithms with adaptive mixing, exploiting channel time correlation for improved robustness in fast-fading environments.

Findings

Enhanced interference suppression in DS-CDMA systems.

Improved tracking of fast-fading channels.

Demonstrated performance advantages through simulations.

Abstract

This paper presents adaptive bidirectional minimum mean-square error (MMSE) parameter estimation algorithms for fast-fading channels. The time correlation between successive channel gains is exploited to improve the estimation and tracking capabilities of adaptive algorithms and provide robustness against time-varying channels. Bidirectional normalized least mean-square (NLMS) and conjugate gradient (CG) algorithms are devised along with adaptive mixing parameters that adjust to the time-varying channel correlation properties. An analysis of the proposed algorithms is provided along with a discussion of their performance advantages. Simulations for an application to interference suppression in DS-CDMA systems show the advantages of the proposed algorithms.