Robust Adaptive Beamforming Against Significant Angle Mismatch

Array signal processing has been widely used in radar,sonar,wireless communications,microphone array speech processing,medical imaging,radio astronomy,and other areas.Adaptive beamforming algorithm,as an important branch of array signal processing,has been one of the research focuses in recent years.The conventional adaptive beamforming has high resolution and good interference suppression ability if the steering vector of the desired signal is known accurately.However,Antenna arrays in real systems may suffer from various types of uncertainties or mismatches,such as look direction mismatch,mutual coupling effect of the antenna array,local scattering,the amplitude and phase errors of antenna array and so on,which degrades the performance of conventional adaptive beamforming dramatically.Therefore,it is necessary to improve the robustness of the adaptive beamforming.In this paper,on the basis of previous results,the main content and results are as follows:1.Introduce the research background of adaptive beamforming,and elaborate the detailed technologic advances about robust beamforming.2.Based on the introduction of the basic mathematical model of beamforming and the common types of errors,the influence of different array errors on the performance of conventional adaptive beamforming algorithm is analyzed theoretically.The simulation results further validate the theoretical analysis3.Introduce several classic robust beamforming algorithm,and the advantages and disadvantages of each algorithm are analyzed by simulation results.4.A new approach to robust adaptive beamforming in the presence of significant direction-of-arrival(DOA)mismatch is presented.The steering vector of desired signal is estimated.Then,the beamformer weight vector is obtained by applying the general-rank signal model-based robust beamforming approach to achiever robustness against arbitrary steering vector errors.The effectiveness of the proposed algorithm has been shown by simulation results.The proposed algorithm in this paper is compared with some existing robust algorithms.The simulation results show that the proposed algorithm has strong robustness in the presence of significant DOA mismatch.The main beam is aligned with the desired signal incident direction.The proposed approach has a higher ouput signal to interference and noise ratio.