Analysis of an LMS linear equalizer for fading channels in decision directed mode

Kavitha, Veeraruna and Sharma, Vinod (2007) Analysis of an LMS linear equalizer for fading channels in decision directed mode. In: 13th European Wireless Conference, Paris, France, Apr.2007, Paris.

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Abstract

We consider a time varying wireless fading channel, equalized by an LMS linear equalizer in decision directed mode (DD-LMS-LE). We study how well this equalizer tracks the optimal Wiener equalizer. Initially we study a fixed channel.For a fixed channel, we obtain the existence of DD attractors near the Wiener filter at high SNRs using an ODE (Ordinary Differential Equation) approximating the DD-LMS-LE. We also show, via examples, that the DD attractors may not be close to the Wiener filters at low SNRs. Next we study a time varying fading channel modeled by an Auto-regressive (AR) process of order 2. The DD-LMS equalizer and the AR process are jointly approximated by the solution of a system of ODEs. We show via examples that the LMS equalizer ODE show tracks the ODE corresponding to the instantaneous Wiener filter when the SNR is high. This may not happen at low SNRs.

Item Type:	Conference Paper
Keywords:	Fading channels;LMS;Decision-Directed mode;tracking performance;ODE approximation.
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited:	14 Oct 2011 09:40
Last Modified:	14 Oct 2011 09:40
URI:	http://eprints.iisc.ac.in/id/eprint/41440

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