Coherent interference suppression method with virtual array and multi-stage spatial smoothing

In the presence of coherent interference, adaptive beamforming algorithm fails to form nulls in the direction of interference, leading to cancellation of expect signal. To address this issue, this paper proposes a coherent interference suppression method with virtual array and multi-stage spatial smoothing (MSS). In the proposed method, the adaptive weight acquired by the spatial smoothing (SS) algorithm is applied to all subarrays to generate a virtual array. Another adaptive weight is then acquired from the virtual array using the SS algorithm and applied to all subarrays of the virtual array to generate another virtual array. The process is iterated until there are insufficient array elements for SS. The proposed method can deeply break the correlation between expect signal and coherent interference and form deep nulls in the direction of coherent interference.