Adaptive beamforming as an inverse problem

In previous work, the authors developed a minimum-mean-square-error beamformer (MMSE-BF). When they compared it to the minimum-variance distortionless-response beamformer (MVDR-BF), they concluded that it is especially suited for correlated returns. This improvement is at the cost of some frequency distortion in wideband applications. To circumvent this problem, the minimum-mean-square-error distortionless-response beamformer (MMSEDR-BF) is introduced. Its behavior is compared with the MVDR-BF and the MMSE-BF. Adaptive beamforming is discussed as an inverse problem. Within this framework, the authors suggest the use of alternative norms, e.g. the L/sub 1/ norm. Preliminary results for L/sub 1/ adaptive beamforming are presented.>