Enhanced Nested Array Configuration With Hole-Free Co-Array and Increasing Degrees of Freedom for DOA Estimation

In this letter, we propose an enhanced nested array (ENA) configuration consisting of two uniform linear arrays (ULAs) with different separations and an additional sensor, whose resulting difference co-array (DCA) is hole-free. As compared with most of the existing sparse array configurations, the proposed ENA has simple closed-form expressions for array geometry and degrees of freedom (DOF), and also can provide more consecutive DOF and larger array aperture. Based on the above good properties of the ENA, compressive sensing (CS) approach is employed for direction-of-arrival (DOA) estimation by solving an l1-norm minimization problem. The theoretical propositions are proved and numerical simulations are performed to demonstrate the superior performance of the proposed ENA.