Structured sparse array design exploiting two uniform subarrays for DOA estimation on moving platform

Array motion can efficiently enhance the achievable number of degrees-of-freedom (DOFs) by the virtue of filling the neighboring holes of each lag in the difference co-array of a linear sparse array. In this paper, a new structured sparse array design exploiting two uniform subarrays on a moving platform is proposed for direction-of arrival (DOA) estimation problems. The proposed array design yields a fully filled co-array. It compresses sensor spacing of one subarray to three times the unit sensor spacing while dilating that of the other subarray. The numbers of sensors in the two subarrays are chosen as arbitrary integers without the limitation of coprimality. The conditions on the array parameters to achieve full augmentability under array motion are provided. Closed-form expressions of maximum DOFs in the difference co-array of the synthetic array, which comprises the sensor positions before and after motion, are delineated. The non-coprimality of the sensor numbers is analyzed when the two subarrays are aligned at the reference sensor, and shown to offer higher DOFs than the coprimality. Numerical results of DOA estimation using the proposed array design are provided for performance comparison and validations of analysis. (C) 2020 Elsevier B.V. All rights reserved.