Conjugate Gradient based MMSE Decision Feedback equalization

Guido Dietl, Sabik Salam, Wolfgang Utschick, Josef A. Nossek

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

The performance of linear filters degrade drastically when applied to mitigate intersymbol interference caused by channels with frequent nulls in their spectral characteristics like, e.g., time-dispersive radio channels. In such cases, the well-known Decision Feedback Equalizer (DFE) is one possible nonlinear approach to improve the quality of the receiver. However, adapting the DFE filter coefficients to equalize timevarying channels is computationally intense, especially if the dimension of the observation vector is very high. In this paper, we apply the Conjugate Gradient (CG) algorithm to a conventional Minimum Mean Square Error (MMSE) DFE in order to reduce its computational complexity. Moreover, we compare its performance to the one of MMSE DFE versions which are based on the computationally efficient Least-Mean-Square (LMS) or Recursive Least-Squares (RLS) algorithm, respectively. The analysis additionally includes a detailed investigation of computational complexity with respect to the required number of FLoating point OPerations (FLOPs). Simulation results when applied to a digital communications system show the ability of the CG based MMSE DFE to outperform either the LMS and the RLS based MMSE DFE although its computational complexity is even smaller in most of the cases.

Original languageEnglish
Title of host publicationISWCS'08 - Proceedings of the 2008 IEEE International Symposium on Wireless Communication Systems
Pages523-527
Number of pages5
DOIs
StatePublished - 2008
Event2008 IEEE International Symposium on Wireless Communication Systems, ISWCS'08 - ReykjavIk, Iceland
Duration: 21 Oct 200824 Oct 2008

Publication series

NameISWCS'08 - Proceedings of the 2008 IEEE International Symposium on Wireless Communication Systems

Conference

Conference2008 IEEE International Symposium on Wireless Communication Systems, ISWCS'08
Country/TerritoryIceland
CityReykjavIk
Period21/10/0824/10/08

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