A directionaly constrained distortionless multistage LCMV beamformer
Daniel Wolff, Yaakov Buchris, Israel Cohen · 2016
In this paper, we generalize the recently proposed multi-stage minimum variance distortionless response beamformer to all distortionless linearly constrained minimum variance (LCMV) beamformers with directional constraints. Given Ncconstraints and an M-element microphone array, we propose to divide this array into K-element microphone sub-arrays (Nc≤ k ≤ M) on which LCMV beamforming is performed. The K-element outputs are then used as new sensor inputs, and the operation is performed recursively until there is only one output at the last stage. The multistage LCMV beamformer satisfies all the imposed directional constraints but with reduced complexity compared to the conventional one. Simulation results show that in the presence of diffuse noise, the multistage LCMV beamformer achieves higher white noise gain than that of the classic LCMV beamformer, although the directivity factor is slightly decreased.