Coarray MUSIC-group delay: high resolution source localization using non uniform arrays

Abstract

Non-uniform linear arrays (NULA) operate in the difference coarray domain to localize more sources than the number of physical sensors. Usually, the spectral magnitude of the subspace-based coarray MUSIC algorithm is used for this task of underdetermined source localization. However, the phase spectrum of coarray MUSIC, which has not yet been utilized, exhibits sharp transitions at the direction of arrival (DOA) of the respective sources. As a result, the negative differential of this phase called the coarray group delay shows peaks at the DOAs. In this correspondence, a new source localization technique called the coarray MUSIC-Group delay (coarray MGD) described as the product of the coarray-MUSIC magnitude and the coarray group delay function is introduced. It is shown that as long as the difference coarray of the NULA is a uniform linear array (ULA), the group delay function displays an additive property in the coarray spatial domain. Owing to this property, the proposed coarray MGD technique is able to localize and resolve more closely-spaced sources than the coarray MUSIC magnitude method. Numerical simulations are performed to validate the high resolution property of the proposed method.