Underdetermined DOA Estimation Algorithm Based on an Improved Nested Array

A nonuniform array group is proposed to solve the inflexibility problem of existing nested arrays. The array structure in the group is not required to be composed of two or more uniform linear sub-arrays on the premise of maintaining the same degree of freedom as that of nested arrays. Compared with nested arrays, a nonuniform array group is easier to arrange in airborne radar or limited physical space. For the nonuniform array group proposed in this study, an array is randomly selected for deployment, and the covariance matrix of the data received by the array is quantised. Accordingly, an algorithm for data de-redundancy and sorting is proposed, and the virtual array receiving data are obtained. Lastly, the target direction of arrival (DOA) is estimated using a sparse reconstruction method without losing array aperture. Simulation results show that the proposed method can achieve accurate DOA estimations at low signal-to-noise ratio and snapshot number.