Robust Adaptive Beamforming Algorithm Baesd On Variable Diagonal Loading

Adaptive beamforming is considered a common task in array signal processing relying on its superior spatial resolution, anti-jamming capability and other advantages. It is widely applied to fields of radar, wireless communications, sonar, acoustics, geography, astronomy, medicine and so on. Beamforming can achieve perfect performance theoretically, but in practical applications, a variety of complex environments and error factors could cause performance degradation or even failure, so it is very necessary for research robust adaptive beamforming algorithm.In recent decades, a lot of robust adaptive beamforming algorithms have been proposed, diagonal loading is a very important technique among them. On this basis, this paper makes two innovations:Firstly, given many current domestic and foreign papers did not take the steering vector uncertainty array response into account, so this paper puts forward the method of calculating the value of uncertainty array fluctuations combining geometric interpretation and mathematical derivation and proves that the response fluctuations are equal to weight vector norm constraint. This is the theoretical basis of the proposed algorithm. Secondly, this paper proposes a new robust adaptive beamforming algorithm named weight vector norm constraint variable diagonal loading algorithm, which changes the traditional diagonal white noise into colored noise to achieve calculating the load factor and variable diagonal loading. Simulation experiments show that the algorithm is more effective than other comparison algorithms. The main contents of this paper are as follows:(1)The basic theory of adaptive beamforming background and foundation is introduced,building theoretical research model, describing some algorithms which is belong to diagonal loading technology and its better computational derivation process, analyze their advantages and disadvantages of computational complexity and performance.(2)A new variable diagonal loading algorithm based on weight vector norm constraint is proposed, the whole idea has been described above. Solving the question of calculating load factor by deducing a monotonically decreasing function which prove the existence of closed form solution. Its specific value can be obtained by dichotomy. The load factor in this paper is joint decision by loading uncertain set value, the number of array elements and uncertainties set array response to fluctuations.(3) The simulation results get by comparing with other robust algorithms show that performance of the proposed algorithm are close to the ideal optimum in the number of snapshots and SNR. However, there is still room for improvement in regard of steering vector error.