DOA Estimation based on the Optimized Coprime Array Configuration

In this paper, a direction-of-arrival (DOA) estimation based on the optimized coprime array (OpCA) configuration is proposed. The proposed array, utilizing the two constituting subarrays N-array and M-array of the coprime array, where their sensors are N and 2M, respectively, shifts all the sensors of the M-array by a specific displacement amount L-s. Different displacement expressions for L-s are proposed for the purpose of being applicable for all the possible encountered coprime M and N values. Analytically, those displacements are optimized such that the number of the actual sensors for the proposed array is still the same as that for the coprime array (N + 2M - 1) and the number of central contiguous lags, which referred to as the uniform degrees of freedom (DOFs) capacity in the difference coarray, has been enhanced. This enhancement is shown by increasing the one-side uniform DOFs capacity of the coprime array from MN + M - 1 to MN +M - 1+ L-s + M, where L-s is the displacement value itself. The numerical simulation results using subspace-based DOA estimation methods are provided to demonstrate the effectiveness of the proposed geometry.