Robust adaptive array beamforming under steering vector errors

This paper considers adaptive array beamforming in the presence of random steering vector errors. We first formulate the problem of finding an optimal steering vector as an optimization problem. The cost function to be minimized consists of two terms which utilize a posteriori information due to the received signal data and a priori information due to the probabilistic distribution of steering errors, respectively. Two methods are then presented to find the optimal steering constraint vector. It is shown that each method yields a closed-form optimal solution if the steering error vector is an additive Gaussian random vector. We also investigate the performance for each method. Modification of the proposed methods and an implementation algorithm for dealing with the case of steering vector errors due to phase perturbation are also presented. Finally, several computer simulation examples are presented for illustration.