Focused Widely Linear Beamforming

The problem addressed in this paper concerns the extension of widely linear beamforming to the wideband case, developing a wide-focused linear beamformer for the extraction of a wideband second-order (SO) noncircular signal-of-interest (SOI) contaminated by uncorrelated interferences and noise. In the proposed beamformer, the beamforming array observation is first focused to adopt a standard linear minimum variance distortionless response (MVDR) framework. The augmented SOI steering vector then is obtained by estimating the SOI noncircularity parameter with the newly proposed oblique projection with an augmented sparse representation scheme. The covariance matrix of the virtual interference, true interference and noise is further reconstructed using the newly presented complementary spatial spectrum technique. The wideband widely linear spatial filtering is finally realized via MVDR like beamforming. The performance of the proposed beamformer is verified by simulation.