Robust Adaptive Beamforming With Noncircularity Restoral

With the wide application of adaptive beamforming technology in the field of practical application, robust beamforming has been a hot research topic in the field of array signal processing. In recent years, with the advantage of which has been concerned, the noncircular signals have been widely used in the real communication and information processing systems. So the study of the steering vector mismatch and other non-ideal factors is the focus of the research on the robust adaptive beamforming algorithm for noncircular signals. The paper focused on a robust beamforming method based on the noncircularity restoral. The main content is:(1) Based on diagonal loading(DL) technique, a method of constructing a cost function for determining the diagonal loading capacity of a cost function based on the noncircular feature restoral criterion is introduced, which is called a Noncircularity Restoral for Diagonal Loading(NRDL). Compared with the existing method, the method can achieve the automatic calculation of the optimal load quantity, and it also has better robustness for direction error.(2)Based on the Eigenspace Projection(EP) method, a new method of eigenspace projection robust beamforming based on non circular feature restoral is proposed, which is called the Noncircularity Restoral Eigenspace Projection(NREP) method. On the basis of EP method, the new method modifies the pointing direction of the main beam via maximizing the noncircularity coefficient of the beamformer output, and the eigenspace projection is adopted to avoid effect of the finite sample size. The new method improves the output performance of the beam forming at the same time to ensure the robustness.(3)Explore the potential for applicating high-order noncircular signal characteristics in robust beamforming method, then propose High-order Noncircularity Restoral for Diagonal Loading(NHRDL) method and High-order Noncircularity Restoral Eigenspace Projection(HNREP) method. The two method does not need to set user parameters, and can be applied to arbitrary order noncircular signals, and has a wider application. In addition, the HNREP method not only has more significant advantages in performance, but also is not sensitive to the noncircular characteristics of the sidelobe interference signal, even in the case of high noncircular rate of the interference signal can also show good performance. Therefore, it has a wide range of applications.