A Novel $k$-times Extended Coprime Array for DOA Estimation With Increased Degrees of Freedom

This work proposes a novel k-times extended coprime array for direction-of-arrival (DOA) estimation that achieves more consecutive degrees-of-freedom (DOF) than the existing k-times extended coprime array with the same number of sensors. If M and N are the parameters of the coprime array, it will be proved that the increase in consecutive DOF of the proposed k-times extended coprime array is O(MN) over the existing k-times extended coprime array. We carry out the analysis of the proposed array considering N even and N odd. The closed-form expressions of the number of consecutive DOF are provided for both cases. Spatial smoothing MUltiple SIgnal Classification (MUSIC) is used to estimate the directions of the sources. All the required simulations are carried out to prove the superiority of the proposed coprime array over the existing coprime arrays.