Variable loading level based on the exponential of the covariance matrix for robust adaptive beamforming

It is well-known that the standard capon beamformer (SCB) is sensitive to signal mismatch problem. To increase robustness of the SCB, diagonal loading (DL) of the covariance matrix has been widely used. However, a good choice of the DL level is still hard to make, although researchers have made great efforts to find the clear guidelines. In this paper, we propose to use the exponential of the covariance matrix (E-CM) method to provide a robust capon beamformer (RCB). The novel method could reduce the sensitivity of the DL level. Simulation results verify that the novel method could provide the RCB in a large range of the signal-to-noise ratio (SNR).