A Novel Robust Wideband Beamformer with Frequency Invariance Constraints

A novel RB-WC-FI-FB (robust worst-case frequency invariance forward-backward) wideband beam former is proposed in this paper. It is developed to improve the robustness against estimation errors of direction of arrival (DOA) and limited sample number, as well as reduce the number of constraints. By incorporating forward-backward estimation and worst-case performance optimization method into the linearly constrained minimum variance (LCMV) beam former, the RB-WC-FB (robust worst-case forward-backward) beam former is developed. However, there still exists a problem of over-constrained in the RB-WC-FB beam former. To overcome this, a response variation (RV) element is introduced. Due to an increased number of degrees of freedom for interference suppression, a higher SINR can be obtained by the RB-WC-FI-FB beam former. The RB-WC-FI-FB beam former is formulated as a second-order cone (SOC) programming convex optimization problem that can be solved efficiently using interior point methods. Simulation results show that the proposed beam former has higher SINR compared with earlier robust beam forming techniques.