Two-dimensional direction of arrival estimation method for a mixture of noncoherent and coherent narrowband signals

In this paper, we investigate the two-dimensional (2D) direction-of-arrivals (DOAs) estimation of a mixture of noncoherent (including uncorrelated and correlated) and coherent narrowband signals impinging on a simple structured planar array consist of two parallel uniform linear arrays (ULAs), and a new oblique projection based method is proposed for estimating the DOAs of these mixed incident signals, where the computationally intensive eigendecomposition is avoided. In the proposed method, the 2-D DOAs of noncoherent and coherent signals are estimated separately, while the difficulties such as the separation of the noncoherent and coherent signals and the automatic pairing of the azimuth and elevation angles of same signal are overcame. Furthermore for overcoming the “saturation” problem encountered in estimation of coherent signals, an iterative alternate scheme is presented. The theoretical analysis and simulation results confirm the effectiveness of proposed method.