ROBUST MVDR BEAMFORMER FOR NULLING LEVEL CONTROL VIA MULTI-PARAMETRIC QUADRATIC PROGRAMMING

Abstract

MVDR beamformer is one of the well-known adaptive beamforming techniques that offers the ability to resolve signals that are separated by a fraction of an antenna beamwidth. In an ideal scenario, the MVDR beamformer can not only minimize the array output power but also maintain a distortionless mainlobe response toward the desired signal. Unfortunately, the MVDR beamformer may have unacceptably low nulling level, which may lead to significant performance degradation in the case of unexpected interfering signals. A new robust MVDR beamforming is presented to control the nulling level of adaptive antenna array. In this proposed approach, the beamforming optimization problem is formulated as a multi-parametric quadratic programming (mp-QP) problem such that the optimal weight vector can be easily obtained by real-valued computation. The presented method can guarantee that the nulling level are strictly below the prescribed threshold. Simulation results are presented to verify the efficiency of the proposed method. Received 25 February 2011, Accepted 21 March 2011, Scheduled 25 March 2011 Corresponding author: Fu Lai Liu (fulailiu@126.com). † F. L. Liu is also with School of Automation, Southeast University, Nanjing, China.