Study On Direction Of Arrival Estimation For Coherent Signals Based On Antenna Array

Direction of arrival(DOA)estimation is a hot research area of antenna array signal processing,which is widely used in communication,target detection,and passive positioning.The advantage of this technique is that it does not require other auxiliary equipment,and only relies on the antenna array to achieve DOA estimation;the technique has the characteristics of low cost,high accuracy,and high efficiency.However,the presence of multipath effects leads to the generation of coherent signals during transmission,which leads to increased errors and decreased estimation accuracy of existing estimation algorithms.Therefore,the study of DOA estimation techniques for coherent signals is of practical significance.In this paper,we first establish the mathematical models of regular and coherent signals according to the signal characteristics,and then introduce and analyze the characteristics of classical estimation,maximum likelihood,spatial smoothing class algorithms and so on.In addition,the algorithm performance evaluation index the Cramér–Rao(CRB)is introduced.The above work provides theoretical support for the subsequent research.This paper subsequently investigates DOA estimation techniques for coherent signals,including:(1)In order to solve the problem that the number of linear equations and the number of principal singular vectors decreases when enhanced principal-singular-vector utilization for modal analysis(EPUMA)algorithm deals with coherent signals,this paper investigates the use of space translation method to increase the number of linear equations.By dividing the antenna array into two sub-arrays and modeling the two sub-arrays mathematically,the equivalent signal subspace is obtained.Then through a series of mathematical operations,the relationship between the Toeplitz matrix containing polynomial coefficients and the equivalent signal subspace is established,thus effectively increasing the number of linear equations.The simulation results show that the proposed algorithm outperforms the original algorithm in all parameters under different signal-to-noise ratios(SNR)and different snapshot numbers.(2)In order to solve the problem that EPUMA algorithm does not make full use of data covariance matrix information when processing coherent signals,this paper introduces a reconstruction method of Toeplitz matrix.In this method,the array model and the corresponding target signal model are built on the premise of an odd number of antenna array elements.Then,an equivalent data covariance matrix is constructed by using the reconstruction method of Toeplitz matrix.Finally,the equivalent data covariance matrix is substituted into EPUMA algorithm.The advantage of this method is to achieve decoherence without introducing auxiliary matrix and noise preprocessing.Simulation results show that the proposed algorithm can effectively improve the resolution and reduce the error.(3)In order to solve the problem that the performance of existing algorithms degrades due to the similarity of incident angles and the number of target signals when processing coherent signals,this paper proposes a multiple-Toeplitz matrix based spatially translational DOA estimation algorithm.This method solves the above problems by combining the advantages of spatial translation method,Toeplitz matrix reconstruction method and smoothing technique.The simulation is developed from many aspects,such as signal-to-noise ratio,resolution,and computing speed.Compared with the reference method,this method can process coherent signals with higher resolution and lower error,and is not affected by the number of signals and incident angle.It has the characteristics of strong anti-interference ability and a small amount of computation.