An Enhanced Expanding and Shift Scheme for Underdetermined DOA Estimation

An enhanced expanding and shift (EEAS) scheme, which is based on the original expanding and shift (EAS) scheme with coprime array (CPA), is proposed. By suitably exploiting the relationship among the sub-arrays in the fourth-order difference co-array (FODC) of the original EAS scheme and further enlarging the sensor spacing in the expanded sparse array, the proposed EEAS scheme can achieve increased consecutive sensors in its FODC. Compared with some representative FODC based sparse arrays, the proposed one can achieve much longer consecutive virtual array. Especially, when the sensor number approaches large, the number of consecutive virtual sensors will be significantly improved. Simulations experiments are carried out to verify the performance. Though the preliminary study is confined to some conditions, the proposed sparse array is effective and expected to be extended to a generalized condition.