Generalised augmentation approach for arbitrary linear antenna arrays

We investigate DOA (direction-of-arrival) estimation for arbitrary linear arrays, where the antenna, positions may be non-integer values in half-wavelength units. We introduce an approach based on arbitrary virtual linear arrays to resolve manifold ambiguity and estimate DOA's in the superior case. These virtual arrays adopt the set of covariance lags specified by the original array and so themselves have an incomplete set of covariance lags. A maximum entropy completion algorithm for the partially-specified Hermitian covariance matrix is proposed. This is followed by an algorithm which searches for a fixed number of plane wavefronts (''generalised Pisarenko completion''). The variety of possible virtual array geometries also permits a ''randomised'' approach, whereby the DOA estimates are determined as the stable point of partial solutions calculated over the set of particular virtual geometries. Numerical simulations demonstrate the high efficiency of manifold ambiguity resolution, and a remarkable proximity to the Cramer-Rao bound for DOA estimation.