EURASIP Journal on Advances in Signal Processing
Volume 2007 (2007), Article ID 68291, 9 pages
doi:10.1155/2007/68291
Research Article
Generalized Broadband Beamforming Using a Modal Subspace Decomposition
Department of Information Engineering, Research School of Information Sciences and Engineering, Canberra 0200, ACT, Australia
Received 29 September 2005; Revised 29 March 2006; Accepted 1 April 2006
Academic Editor: Vincent Poor
Copyright © 2007 Michael I. Y. Williams et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
We propose a new broadband beamformer design technique which
produces an optimal receiver beam pattern for any set of field
measurements in space and time. The modal subspace decomposition
(MSD) technique is based on projecting a desired pattern into the
subspace of patterns achievable by a particular set of space-time
sampling positions. This projection is the optimal achievable
pattern in the sense that it minimizes the mean-squared error
(MSE) between the desired and actual patterns. The main advantage
of the technique is versatility as it can be applied to both
sparse and dense arrays, nonuniform and asynchronous time
sampling, and dynamic arrays where sensors can move throughout
space. It can also be applied to any beam pattern type, including
frequency-invariant and spot pattern designs. A simple extension
to the technique is presented for oversampled arrays, which allows
high-resolution beamforming whilst carefully controlling input
energy and error sensitivity.