Improved Nested Array DOA Estimation Based on Sum Difference Virtual Array

The continuous range of the nested array sum co-array (SCA) is deduced by analyzing the continuous range of the difference co-array (DCA) of the nested array (NA). After comparison, it is found that there are many redundant virtual elements between DCA and SCA. For the purpose of reducing the redundancy and enhance the freedom of the virtual array, we propose an improved nested array structure, namely sum difference translation nested array (SDTNA). SDTNA changes the continuous range of SCA and reduces the redundancy, while the continuous range of DCA remains unchanged. SDTNA has longer contiguous virtual arrays and higher degrees of freedom than NA and coprime array (CA). Compared with Diff-sum NA (DsNA), SDTNA outperforms DsNA when the total number of arrays is less than 10. When the total number of arrays is greater than or equal to 10, the performance of SDTNA is close to that of DsNA. Simulation experiments verify the superiority of SDTNA in terms of degrees of freedom and estimation accuracy when the total number of arrays is less than 10.