Direction-of-arrival estimation for uncorrelated and coherent signals with fewer sensors

A novel direction-of-arrival (DOA) estimation method with fewer sensors is proposed when uncorrelated and coherent signals coexist, and two effective criteria to estimate the number of uncorrelated and coherent signals are also developed. First, the DOA matrix is constructed. Then, the DOAs of uncorrelated signals can be estimated by these proposed criteria and the related eigenvalues of the DOA matrix. Secondly, with the eigenvectors of the DOA matrix, which are related to coherent signals, the coherent signals that belong to the multipath of different far-field sources can be resolved separately using a spatial smoothing technique. Moreover, the DOA estimation accuracy of coherent signals can be further improved by an orthogonal projection technique. Simulation results demonstrate the effectiveness and efficiency of the proposed method.