Tracking performance of an LMS-Linear Equalizer for fading channels

Kavitha, Veeraruna and Sharma, Vinod (2006) Tracking performance of an LMS-Linear Equalizer for fading channels. In: Forty-Fourth Annual Allerton Conference Allerton House, UIUC, Illinois, USA, Sept 27-29, 2006, UIUC, Illinois, USA.

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Abstract

We consider a time varying wireless fading channel, equalized by an LMS linear equalizer. We study how well this equalizer tracks the optimal Wiener equalizer. We model the channel by an Auto-regressive (AR) process. Then the LMS equalizer and the AR process are jointly approximated by the solution of a system of ODEs (ordinary differential equations). Using these ODEs, the error between the LMS equalizer and the instantaneous Wiener filter is shown to decay exponentially/polynomially to zero unless the channel is marginally stable in which case the convergence may not hold.Using the same ODEs, we also show that the corresponding Mean Square Error (MSE) converges towards minimum MSE(MMSE) at the same rate for a stable channel. We further show that the difference between the MSE and the MMSE does not explode with time even when the channel is unstable. Finally we obtain an optimum step size for the linear equalizer in terms of the AR parameters, whenever the error decay is exponential.

Item Type:	Conference Paper
Keywords:	Fading channels;LMS Linear equalizer;tracking performance;ODE approximation.
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited:	10 Nov 2011 04:57
Last Modified:	10 Nov 2011 04:57
URI:	http://eprints.iisc.ac.in/id/eprint/42009

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