On spatial filtering for angle-of-arrival estimation in a scattering environment by eigendecomposition-based methods

A method of spatial filtering is proposed as a preprocessor to restore the high resolution performance of eigendecomposition-based methods when used with a linear array for angle-of-arrival (AOA) estimation in the presence of spatially distributed coherent interference (SDCI). Applying the conventional bandpass filters used in the spatial frequency domain, the spatial filtering method effectively suppresses the unwanted coherence interference outside a specified frequency region. Therefore, the success of the method hinges on the assumption that direct arrival and its coherent interference are well separated in spatial frequency (in angle). Under this assumption, the eigendecomposition methods with a spatial filtering preprocessor can give accurate AOA estimates of direct arrivals in spite of the presence of SDCI. Simulation results are shown for the case of scattering from an infinite circular cylinder, using discrete prolate spheroidal sequences as the optimum band-pass preprocessing filters, and a uniformly spaced linear array, in a conjunction with the MUSIC algorithm.