Robust Adaptive Beamformer for Interference Suppression in a Multipath Environment

Adaptive beamforming is an effective spatial inter-ference suppression technology to improve expected signal quality in the receiving array system. However, it heavily relies on the uncorrelation between interferences from different directions. In a multipath environment, many adaptive beamformers will lose their ideal interference suppression capability. For this issue, a robust adaptive beamformer based on the minimum variance distortionless response (MVDR) criterion combined with a designed three-step spatial differencing smoothing operation (TSSD) is proposed in this paper. First, by applying the dif-ferencing calculation to the sampling covariance matrix (SCM), the obtained differencing matrix (DM) extracts the interference component from the SCM. Next, the enhanced matrix (EM) is formed by taking the absolute eigenvalues of DM to overcome the noise subspace perturbation introduced in the first step. Then, by performing the spatial smoothing on EM, spatial information of array received interferences blurred by the multipath propagation is recovered in the spatial smoothing matrix (SSM). Finally, SSM is used as a reliable substitute for the SCM to combine with the MVDR criteria to derive the proposed TSSD beamformer. Simulation results verify the effectiveness of the proposed TSSD beamformer for interference suppression in a multipath environment. Compared with four existing works, our proposal shows better interference suppression performance with low complexity, even in a spatially colored noise background.