基于非圆信号的高分辨率波达方向估计算法研究

发布时间：2018-04-11 17:32

本文选题：阵列信号处理 + 非圆信号　；参考：《中国科学技术大学》2017年硕士论文

【摘要】：近年来,利用信号的统计特性提升波达方向(DOA)估计算法的性能已经成为阵列信号处理的一个重要研究领域。其中,非圆信号因在阵列孔径拓展和估计精度提升等方面的优异性能,更是获得了越来越多的关注。非圆信号是指统计特性不具有旋转不变性的信号类型,其在现代通信领域十分常见,如AM、BPSK和UQPSK等信号。同时,随着现代雷达和通信等系统对DOA估计分辨率和估计精度的要求不断提高,对于高性能DOA估计算法的需求也日渐迫切。因此,基于非圆信号的高分辨DOA估计算法研究具有十分重要的理论意义和实用价值。目前对此问题的研究虽然取得了一定的成果,但是针对任意非圆率信号和相干非圆信号等方面的研究尚不充分。本论文在现有成果的基础上,针对这一问题进行了进一步的研究,主要工作可以简要概括如下:1.为提高任意非圆率信号的DOA估计性能,我们将信号的非圆特性和阵列的中心对称特性相结合,提出了基于中心对称阵列的高分辨DOA估计算法。实际应用中的多数阵列都属于中心对称阵列,如均匀线阵、对称线阵和均匀面阵等。由于中心对称阵列的阵元关于中心点对称,则对称阵元接收远场信号时,相对中心点的时延正好相反。因此,阵列导向矢量具有共轭对称特性。联合利用导向矢量的共轭对称性和信号的非圆特性,可以直接得到各个信号入射方向导向矢量的估计。再根据导向矢量和DOA的关系,就可以求解出所有的入射角度。我们不仅给出了一维DOA估计方法,而且以均匀面阵和均匀圆阵为例,给出了二维的DOA估计方法。并通过仿真实验验证了所提算法在分辨率、估计精度和对噪声的鲁棒性等方面的显著优势。2.对于多径传播条件下的非圆信号DOA估计,由于存在相干信号,信号协方差矩阵秩缺,导致传统高分辨算法失效。对此,我们提出一种分组处理相干非圆信号的DOA估计算法。首先,通过利用非圆特性估计各组的组导向矢量,并同时利用前向和后向的组导向矢量进行Toeplitz矩阵重构,得到各组对应的合成矩阵。对这些矩阵进行分解,就可以利用传统高分辨算法得到各组的初始DOA估计。为进一步提高估计精度,利用各组初始的估计结果重构对应的组导向矢量,再利用矩阵斜投影和前后向空间平滑得到更为精确的DOA估计。由于实现了分组估计,使得算法需要的阵元数减小,而估计精度却得到提高。仿真实验验证了所提算法的优越性能,尤其在低信噪比和小快拍的情况下,所提算法仍能准确地进行DOA估计。
[Abstract]:In recent years, improving the performance of DOA estimation by using the statistical characteristics of signals has become an important research field in array signal processing.Among them, non-circular signals have attracted more and more attention because of their excellent performance in array aperture expansion and estimation accuracy improvement.Non-circular signal is a kind of signal whose statistical characteristics are not rotation-invariant, and it is very common in modern communication fields, such as AM-BPSK and UQPSK signals.At the same time, with the increasing demand for the resolution and accuracy of DOA estimation in modern radar and communication systems, the demand for high-performance DOA estimation algorithm is becoming more and more urgent.Therefore, the research of high resolution DOA estimation algorithm based on non-circular signal has very important theoretical significance and practical value.Although some achievements have been made in the research of this problem, the research on arbitrary non-circular rate signal and coherent non-circular signal is not sufficient.On the basis of the existing achievements, this paper makes a further study on this problem, the main work can be summarized as follows: 1.In order to improve the performance of DOA estimation for arbitrary non-circular rate signals, a high-resolution DOA estimation algorithm based on center-symmetric arrays is proposed by combining the non-circular characteristics of the signals with the centrosymmetric characteristic of the array.Most arrays in practical applications belong to centrosymmetric arrays, such as uniform linear arrays, symmetrical linear arrays and uniform plane arrays.Because the elements of a centrosymmetric array are symmetric with respect to the center point, the delay relative to the center point is just the opposite when the symmetric array element receives the far-field signal.Therefore, the array guidance vector has conjugate symmetry.By combining the conjugate symmetry of the steering vector and the non-circular characteristic of the signal, the estimation of the steering vector in the incident direction of each signal can be obtained directly.According to the relationship between the steering vector and the DOA, all the angles of incidence can be solved.We not only give one-dimensional DOA estimation method, but also give two-dimensional DOA estimation method by taking uniform plane matrix and uniform circular array as examples.The simulation results show that the proposed algorithm has significant advantages in terms of resolution, estimation accuracy and robustness to noise.For the DOA estimation of non-circular signals under multipath propagation, because of the existence of coherent signals and the lack of rank of the signal covariance matrix, the traditional high-resolution algorithm is invalid.To solve this problem, we propose a DOA estimation algorithm for processing coherent noncircular signals.Firstly, the group guidance vectors of each group are estimated by using non-circular properties, and the Toeplitz matrix is reconstructed by both forward and backward group guidance vectors, and the corresponding composite matrices are obtained.By decomposing these matrices, the initial DOA estimation of each group can be obtained by using the traditional high resolution algorithm.In order to further improve the estimation accuracy, the corresponding group guidance vector is reconstructed by using the initial estimation results of each group, and the more accurate DOA estimation is obtained by matrix oblique projection and forward and backward spatial smoothing.Due to the realization of packet estimation, the number of matrix elements needed by the algorithm is reduced, but the estimation accuracy is improved.The simulation results show that the proposed algorithm has good performance, especially in the case of low signal-to-noise ratio (SNR) and small rapid-shot, the proposed algorithm can be used to estimate DOA accurately.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN911.7

【相似文献】