Generalized Sidelobe Canceller for Time-Domain Region-of-Interest Beamforming

One of the key challenges in array signal processing is the lack of precise source location information, which can arise from estimation errors or the presence of a moving source. Conventional beamformers, which rely on accurate spatial information, perform suboptimally under such conditions. Region-of-interest (ROI) beamformers address this limitation by focusing on a spatial region rather than a single direction. In this work, we introduce a new ROI beamformer based on the generalized sidelobe canceller (GSC) framework with time-domain convolutive filters. The proposed beamformer can concentrate on a specified ROI while suppressing noise and interference from other directions. To evaluate the efficacy of the proposed beamformer, we derive several performance metrics. Then we analyze various blocking matrix designs, focusing on signal leakage as a key factor in interference suppression without distorting the desired signal. Furthermore, an adaptive implementation based on the recursive least-squares (RLS) algorithm is developed, along with a low-complexity variant using the nearest Kronecker product (NKP) approximation. Simulation results demonstrate the effectiveness of the proposed ROI-GSC beamformer.