DOA Estimation of Noncircular Signals for Unfolded Coprime Linear Array: Identifiability, DOF and Algorithm (May 2018)

An ambiguity-free direction of arrival (DOA) estimation method is presented for unfolded coprime linear array (UCLA) in this paper to resolve noncircular signals. Unlike the existing methods which process the two subarrays of coprime linear array separately, we stack the received signals of the two subarrays and derive the total subspace to produce the MUSIC spectrum. Specifically, we demonstrate that the ambiguity problem can be suppressed owing to the coprime property and the true DOA estimates can be obtained immediately. As the self-information and mutual information are jointly employed, the proposed method can achieve the full degrees of freedom (DOFs) and improved DOA estimation performance. Meanwhile, the extended aperture of UCLA can be feasibly exploited, which endows the proposed method with an enhanced identifiability. In addition, the non-circularity is utilized to double the available DOF and further improve the estimation accuracy of the proposed method. Simulation results verify the effectiveness and superiority of the proposed method.