Direction of Arrival Estimation of Quasi-Stationary Signals Using Unfolded Coprime Array

Direction of arrival (DOA) estimation of quasi-stationary signals (QSS) is discussed in this paper, and an algorithm using unfolded coprime array is proposed. Coprime array consists of two uniform linear subarrays with coprime relationship, and the two subarrays of the unfolded coprime array in this paper are arranged along the positive axis and negative axis, respectively. Through the vectorization of the low dimensional cross-covariance matrix and the further exploiture of the non-circularity within the second-order statistics of QSS, 2MN-1 degrees of freedom can be achieved with M+N physical elements. The uniqueness of the DOA estimation based on the non-continuous virtual elements generated from the unfolded coprime array is proved, and unitary polynomial root finding technique is employed to estimate the DOA. The proposed algorithm has low complexity, and it can obtain better DOA estimation performance and handle more sources than Khatri-rao subspace approach and original coprime array-based method. Simulation results verify the effectiveness of the proposed approach.