A New Nested Array Configuration With Increased Degrees of Freedom

In this paper, a new linear array configuration based on the concept of two-level nested array is proposed. Specifically, the proposed array configuration consists of two uniform linear arrays (ULAs) plus a separate sensor with appropriate spacing apart. Compared with the original two-level nested array, the degrees of freedom of our proposed array configuration can be increased by 2L - 6 for an array with L physical sensors. Moreover, the virtual array aperture can be enlarged by nearly (L
²
/2 - L - 2)d
₁
, where d
₁
is the inter-element spacing of the first ULA. Owing to these advantages, our proposed array configuration has enhanced resolution and achieves better performance in parameter estimation, such as direction-ofarrival (DOA) estimation. Numerical simulations of DOA estimation exhibit the effectiveness and superiority of this array configuration.