An Improved co-Prime Parallel Array With Conjugate Augmentation for 2-D DOA Estimation

This paper proposes an improved co-prime parallel array (CPPA) configuration for two-dimensional direction of arrival (2-D DOA) estimation. Specifically, the proposed array consists of a CPPA and two extra sensors along the vertical axis. The array aperture is extended through two steps. Firstly, a virtual parallel symmetric co-prime array (ViP-SCPA), consisting of two symmetric co-prime arrays(SCPAs), is constructed by using the conjugate augmented processing(CAP). Secondly, a one-dimensional (1-D) virtual co-array of ViP-SCPA is derived by exploiting the difference and sum co-array of the CPPA. Based on the obtained 1-D virtual co-array of ViP-SCPA, the 2-D DOA estimation is cast as a 1-D DOA estimation problem, for which both subspace-based methods and sparse representation algorithms can be adopted. To evaluate the array apertures of the proposed array, analytical expressions are derived to quantify the achievable number of unique lags, and the maximum number of consecutive lags of the resultant 1-D virtual co-array of ViP-SCPA. Simulation results verify the effectiveness of the proposed configuration by using the classical multiple signal classification (MUSIC) and sparse representation(SR) algorithm respectively.