A Bias-Free Adaptive Beamformer with GSC-APA

We propose a novel bias-free adaptive beamformer employing an affine projection algorithm with the optimal regularization parameter. The generalized sidelobe canceller affine projection algorithm suffers from a bias of a weight vectors under the condition of no reference signals for output of an array in the beamforming application. First, we analyze the bias in the algorithm and prove that the bias can be eliminated through a large regularization parameter. However, this causes slow convergence at the initial state, so the regularization parameter should be controlled. Through the optimization of the regularization parameter, the proposed method achieves fast convergence without the bias at the steadystate. Experimental results show that the proposed beamformer not only removes the bias but also achieves both fast convergence and high steadystate output signal-to-interference-plus-noise ratio. key words: adaptive beamformer, generalized sidelobe canceller, affine projection algorithm, bias-compensation