A high performance robust beamforming scheme is proposed to combat model mismatch. Our method lies in the novel\nconstruction of interference-plus-noise (IPN) covariance matrix. The IPN covariance matrix consists of two parts. The first part\nis obtained by utilizing the Capon spectrum estimator integrated over a region separated from the direction of the desired signal\nand the second part is acquired by removing the desired signal component from the sample covariance matrix. Then a weighted\nsummation of these two parts is utilized to reconstruct the IPN matrix. Moreover, a steering vector estimation method based on\northogonal constraint is also proposed. In this method, the presumed steering vector is corrected via orthogonal constraint under\nthe condition where the estimation does not converge to any of the interference steering vectors. To further improve the proposed\nmethod in low signal-to-noise ratio (SNR), a hybrid method is proposed by incorporating the diagonal loading method into the\nIPN matrix reconstruction. Finally, various simulations are performed to demonstrate that the proposed beamformer provides\nstrong robustness against a variety of array mismatches. The output signal-to-interference-plus-noise ratio (SINR) improvement of\nthe beamformer due to the proposed method is significant.
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