Direction finding using spatial smoothing with interpolated arrays

The problem of estimating the directions of arrival (DOAs) of signals, some of which may be perfectly correlated, is considered. A computationally efficient estimation algorithm which combines the ideas of spatial smoothing and array interpolation is derived. In one of its forms the proposed algorithm uses the root-MUSIC (root multiple signal classification) technique to compute the DOA estimates, thus avoiding the search procedure associated with the conventional MUSIC algorithm. The proposed technique can be applied to arbitrary array geometries and a general signal covariance matrix. The performance of the algorithm was evaluated by extensive simulations, and compared with the Cramer-Rao lower bound for the DOA estimates