Research On Adaptive Beamforming System Based On Array Error Analysis

Adaptive beamforming is one of the core technologies of array signal processing,which has the advantages of high resolution of signals and strong ability of multi-directional interference suppression.However,the capability of adaptive beamforming will be affected by errors in direction-of-arrival estimation,errors in antenna arrays,non-ideal characteristics of signals and other factors,which will seriously worsen the performance of the communication receiver if cannot be analyzed and compensated exactly.The paper focuses on the array steering vector mismatch and signal distortion caused by errors in antenna arrays and non-ideal characteristics of the receiver,on the premise of the linear constrained minimum variance adaptive beamforming algorithm.The compensation of non-ideal characteristics above,such as antenna array errors and the I/Q imbalance,contributes to the robustness of adaptive beamforming algorithm and the reception performance of wireless anti-jamming communication system.Firstly,the paper summarizes and analyzes the jamming signal model and the receiving antenna array signal model in anti-jamming communication system based on the theory of linearly constrained minimum variance beamfoming,and shows application scenarios and formulas of various jamming signals.Then expounds the principles of the antenna array with uniform arrays and uniform planar arrays as examples,and on the basis of this,establishes the linear constrained minimum variance adaptive beamforming model,and gives the iterative algorithm and the detailed derivation process.Later,the paper also introduces some fast algorithms of adaptive beamforming and their advantages and disadvantages.Next,the paper focus on the cause of the two non-ideal characteristics,antenna array errors and I/Q imbalance in transceivers,and their influence on the performance of communication system.The paper introduces the corresponding compensation algorithm:robust adaptive beamforming algorithm and I/Q imbalance compensation algorithm.After that,it studies a suitable robust adaptive beamforming algorithm and its iterative algorithm which could mitigate the effects of errors in antenna arrays,and propose the feedback-based I/Q imbalance compensation algorithm.Finally,the paper tests the performance of robust adaptive beamforming algorithm and I/Q imbalance compensation algorithm in simulation experiments.The robust algorithm can effectively protect the expected signal with different steering vectors compared with high power jamming signals,and steer a null accurately at the direction of the jamming to modify the influence of array error to a certain extent.Experiments show that the robust algorithm can effectively avoid the excessive offset of the main beam and the null.The paper establishes a communication model in the adaptive beamforming receiver which can compensate the I/Q imbalance of the transmitter.The amplitude and phase inconsistency of signal I and Q are compensated by the establishment of I/Q model,predistortion feedback and weight adjustment.The results show that the compensation of I/Q imbalance can effectively improve the output signal performance of the adaptive beamforming receiver,and the mitigation of mirror-frequency interference is obvious enough to improve the overall performance of anti-jamming receiver.