Performance Investigation of Robust Linearly Constrained Minimum Variance Beamforming for Direction of Arrival Mismatch

A robust linearly constrained minimum variance (LCMV) beamforming using directional and null constraints with a diagonal loading technique is discussed in this paper. The diagonal loading adds robustness against the direction of arrival mismatch and provides satisfactory output power and signal to interference plus noise ratio (SINR) in the mismatch region without broadening the beam. This paper first compares the proposed robust LCMV method with the conventional LCMV method in the presence of direction of arrival mismatch. Then its performance is compared with the LCMV using existed fixed diagonal loading method. The proposed robust method raises the output power by 1.88 dB and output SINR by 0.58 dB at 3 degree disparity angle compared to the LCMV with fixed diagonal loading technique. Simulations are performed in MATLAB to analyze the performance of the proposed method.