Research On Robusrt Beamforming Algorithms In The Complex Electromagnetic Environment

Adaptive beamforming in complex electromagnetic environment, its robustness is a key problem in signal processing. So robust beam-forming has been a hot research direction in the past twenty years, scholars have proposed a lot of algorithms. This paper mainly studies the robust beam-forming algorithms in complex electromagnetic environment. Firstly this paper analyses some classic robust adaptive beam-forming algorithms, such as the diagonal loading, feature space algorithm, we verify them and propose the improvement. At the same time, studies the robust beamforming algorithms based on noncircular signals.The main work of this paper is as follow.1、Several beamforming optimization criterions were listed, the same points and the different points were analyzed,the advantages and disadvantages of the criterions were illustrated.2、Some classic robust beamforming algorithms were studied, such as the diagonal loading algorithm, feature space algorithm. We focuses on the diagonal loading algorithms, such as the NCCB algorithm, USCCB algorithm, WCPO algorithm and so on, and analysis their principles, show their performances.3、A variety of robust algorithms in particular small sampling and a large number of array element conditions were studied, such as the CC, GLC algorithms. The linear combination method of telescopic sharpening of matrix algorithm based on small sampling and a large number of array element was proposed. The algorithm still has good robustness especially in the condition of the number of array element is larger than the snapshots.4、The robust beamforming algorithms based on spatial filtering thought were studied, such as the covariance reconstructed and the two layers beamforming algorithm. Based on the study of these two algorithms, a new way of thinking was obtained. The sampling signal contains the desired signal which leads to robustness problem, the problem can be solved by removing the desired signal. Simulation proves that it has a good performance.5、Adaptive beamforming algorithms for noncircular signals were studied. Firstly, we put forward the definition and its difference from circular signals, and then analyze the MVDR method in noncircular domain extended WLMVDR. Secondly, using the character of high order statistics is not zero of noncircular signals, propose the WLMDDR method. Simulation shows that WLMDDR is much better than WLMVDR method. Finally, propose the method of the noncircular coefficient based on two layers robust beamforming algorithm.