Research On Robust Adaptive Beamforming Algorithm Under Non-ideal Condition

As a key technology in the field of signal processing,adaptive beamforming can flexibly process the received signal to ensure that the desired signal is undistorted while controlling the interference and noise signals.However,adaptive beamforming technology has high requirements for array manifold and desired signals,making the performance of beamforming algorithms drop sharply in many non-ideal situations.Therefore,researching the beamforming algorithm under non-ideal condition has important practical application value.Based on the basic spatial array signal processing model,several conventional beamforming algorithm have been simulated in this thesis.Aiming at the problem of desired signal steering vector mismatch,a method of estimating steering vector based on subspace is researched.By constructing desired signal subspace accurately,the presumed desired signal steering vector is modified.Furthermore,to overcome the error of the steering vector caused by angle mismatch and the shortcoming of the conventional method,a beamforming algorithm based on matrix reconstruction and steering vector estimation through the subspace reconstruction is proposed.By imposing a new constrains to the steering vector and reconstructing the covariance matrix through the estimated noise power,the robustness of the beamformmer in low signal-to-noise ratio and low snapshots is improved.In order to reduce the complexity of estimating steering vector through convex tools,a method based on eigen-decomposition is proposed which significantly reduces the complexity.In order to improve the performance of the beamforming algorithm in the non-ideal environment such array error,a beamforming algorithm based on reconstructed matrix which is based on estimating interference signal is proposed.Through the estimation of the interference signal,the reconstructed matrix of interference and noise signal is closer to the ideal matrix.Furthermore,to improve the performance of the beamforming algorithm in the array error environment,an estimation method of interference signal based on subspace projection is proposed.By constructing interference subspace,the more precise steering vector is estimated and the desired signal in the received signal is reduced.