Spatial Differencing Method for DOA Estimation Under the Coexistence of Both Uncorrelated and Coherent Signals

Direction-of-arrival (DOA) estimation is an important problem in array signal processing. An effective spatial differencing method is addressed, for the DOA estimation problem of a number of uncorrelated and coherent narrowband signals simultaneously impinging on the far field of a uniform linear array (ULA). In the proposed method, the uncorrelated sources are firstly estimated using conventional subspace methods, and then they are eliminated by exploiting the spatial differencing technique, that is, only coherent components remain in the spatial differencing matrix. Finally, the remaining coherent signals are estimated by utilizing the spatial differencing matrix. Compared with the previous works, the presented method can improve the DOA estimation accuracy, as well as increase the maximal number of detectable signals. The theoretical analysis and simulation results confirm the effectiveness of the method.