Set-Membership Adaptive Algorithms based on Time-Varying Error Bounds for Interference Suppression

TL;DR

This paper introduces set-membership adaptive algorithms with time-varying error bounds for interference suppression in CDMA systems, improving performance with fewer updates and better error bound management.

Contribution

It proposes a new framework for error bound specification considering parameter dependency and interference, along with algorithms for interference power tracking.

Findings

Outperforms previous techniques in simulations

Requires fewer parameter updates

Reduces overbounding and underbounding risks

Abstract

This work presents set-membership adaptive algorithms based on time-varying error bounds for CDMA interference suppression. We introduce a modified family of set-membership adaptive algorithms for parameter estimation with time-varying error bounds. The algorithms considered include modified versions of the set-membership normalized least mean squares (SM-NLMS), the affine projection (SM-AP) and the bounding ellipsoidal adaptive constrained (BEACON) recursive least-squares technique. The important issue of error bound specification is addressed in a new framework that takes into account parameter estimation dependency, multi-access and inter-symbol interference for DS-CDMA communications. An algorithm for tracking and estimating the interference power is proposed and analyzed. This algorithm is then incorporated into the proposed time-varying error bound mechanisms. Computer simulations show that the proposed algorithms are capable of outperforming previously reported techniques with a significantly lower number of parameter updates and a reduced risk of overbounding or underbounding.