DOA estimation using subspacing tracking method for coherent waves

Recently, by development of mobile communications, radio wave environments are made more complicated. In this situation, high-resolution DOA (direction of arrival) estimation algorithms such as MUSIC and ESPRIT [1] were proposed and currently they are attracting much attention. These algorithms make use of eigenvalue-decomposition (EVD) of array covariance matrix, which brings about high computational load. Therefore, the development of the sequential or iterative computation of the eigenvalues and eigenvectors has been expected. As one of the sequential computation methods, PAST (Projection Approximation Subspace Tracking) method [2] is proposed in recent years and the low computational load of it is noteworthy. In this paper, we improve the PAST method by using the sub-array scheme (spacial smoothing processing) and the unitary transformation so that the PAST method can deal with the coherent waves and the case of less snapshots. Computer simulation is carried out to demonstrate the effectiveness of the improved PAST method in DOA estimation with MUSIC algorithm.