Broad-Band DOA Estimation and Beamforming in Multipath Environment

Indukumar, KC and Reddy, VU (1990) Broad-Band DOA Estimation and Beamforming in Multipath Environment. In: Record of the IEEE 1990 International Radar Conference, 1990, 7-10 May, Arlington,VA, pp. 532-535.

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Abstract

Recently, Buckley [1] has developed orthogonal low-dimension models for broad-band sources and used them in DOA (direction of arrival) estimation and beamforming. The dimensionality of this low-dimension model is the number of significant eigenvectors of the source sample covariance matrix. When two or more sources impinge on the array, the dimensionality of the composite signal subspace is taken to be the sum of the dimensions of individual source representation spaces. This is the case when the sources are uncorrelated. In this paper, considering a two-source model, we first show thatthe dimensionality of the composite signal subspace collapses when the signals from these sources are correlated, as it happens in the case of multipath, and the extent by which it collapses depends on the degree of correlation. Using the F-norm ( Robenius norm ) of the cross-correlation matrix of the direct and multipath signals as a measure of correlation between them, we illustrate how the norm decreases as the delay increases, indicating that the degree of correlation falls with delay. We propose spatial smoothing for reducing the norm and show that the norm decreases to zero asymptotically with the number of subarrays. We then derive an analytical expression for an upper bound on the F-norm and using this, we study the effect of spacing and directions of the sources on the rate of decorrelation with progressive smoothing. Simulations are provided to illustrate the impact of progressive smoothing on DOA estimation and beamforming performance.

Item Type:	Conference Paper
Publisher:	IEEE
Additional Information:	Copyright 1990 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited:	30 May 2006
Last Modified:	19 Sep 2010 04:27
URI:	http://eprints.iisc.ac.in/id/eprint/7036

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