Research On DOA Estimation Technology Of Non-Uniform Array

As a very important research direction in signal processing,direction of arrival estimation(DOA)can be widely used in radar,communication and other practical fields.When using uniform linear array(ULA)to receive signals,the number of incident signals shall not exceed the number of array elements corresponding to the antenna receiving array.Therefore,the antenna array can only process more signals at the same time by increasing the number of array elements.When the number of array elements increases,we need to spend more hardware resources and energy to maintain the array antenna equipment in practical engineering applications.Because the array layout of non-uniform array is more sparse,the freedom of the array can be increased through virtual array,and the angle that can be estimated can be greater than the actual number of physical elements of the array.Classical non-uniform array models such as nested array coprime array can increase the degree of freedom of the array through the virtual array,and the estimated angle can be greater than the actual number of physical elements of the array,so as to realize underdetermined DOA estimation.However,there are still many problems to be studied and solved in the field of DOA estimation of non-uniform array.Therefore,this thesis studies the algorithms related to DOA estimation based on basically non-uniform array.The main work and innovations are as follows:(1)This thesis first introduces the array signal model related to DOA estimation of non-uniform array,and then introduces the correlation algorithm of DOA estimation of non-uniform array.Firstly,the principle of differential common array of non-uniform array is introduced,then the principle and implementation process of decoherence using spatial smoothing algorithm are introduced,and another matrix reconstruction algorithm that can realize decoherence is introduced,Finally,the sparse reconstruction algorithm based on compressed sensing is introduced.(2)The signal models of non-uniform arrays such as nested array,coprime array and enhanced nested array and the related DOA estimation algorithms are introduced,and the experimental simulation is carried out.Finally,an algorithm based on sum,difference and matrix filling is proposed by using enhanced nested array.The experimental results show that the proposed algorithm has the improvement of degree of freedom and estimation accuracy compared with the traditional algorithm.(3)The concept of coherent signal is introduced,and then the principle and steps of DOA estimation of coherent signal using spatial smoothing algorithm for uniform linear array are introduced.Then the existing algorithms of estimating coherent signal using non-uniform arrays such as nested array and coprime array are introduced.Finally,an algorithm based on Toeplitz matrix reconstruction and matrix filling is proposed by using coprime array,The experimental simulation shows that the algorithm proposed in this thesis has certain advantages compared with other existing algorithms.(4)Using the non-uniform array model,the related DOA estimation algorithm is applied to practical engineering,and the application scenario is short wave direction finding.Firstly,the appropriate parameters of non-uniform array are selected according to the required parameters,and then the related DOA estimation algorithms are simulated to verify the feasibility of various algorithms in the actual scene.