Sparse Array Design And Underdetermined DOA Estimation Based On MIMO Radar

Coprime arrays have become a research hotspot in recent years with advantages of low coupling and high degree of freedom for underdetermined direction of arrival.Due to the holes and redundant data in virtual array,a waste of space and computing resources arises.In recent years,MIMO technology has been widely utilized in field of DOA estimation for the advantages of large virtue array.In this thesis,array designs and low-complexity pre-processing method based on MIMO radar are studied to solve the problem of holes in virtual array and redundant data from covariance matrix,respectively.The main work is as follows.Firstly,prototypek₁-k₂ order extended coprime array is inductive by the characteristics of the existing coprime array.On this basis,k₁-k₂ order extended coprime is derived by reducing number of elements.By selecting a pair of specific coprime number as element spacing of the subarray,basic coprime array with hole-free coarray is studied.Then,Combined basic coprime array with symmetric coprime array,MIMO successive coprime array structure with hole-free and large aperture is advanced,whose expression of DOF is demonstrated by mathematical derivation.Secondly,to solve the problem of redundant data in the virtual array of coprime array,a novel coprime array configuration with increased DOF is proposed.Combined with nested configuration,shifted coprime array and improved shifted coprime array are proposed,which can fully expand aperture.Furthermore,MIMO shifted successive coprime array is advanced combined with basic array,whose hole-free coarray with large virtual aperture is proved by mathematical derivation.Finally,we generalize a novel virtual data processing method with low complexity exploiting the mapping between physical array and virtual array.This method calculate the single snapshot data in virtual array by received data directly,which avoids the calculation of complete covariance matrix.The usefulness of these results is demonstrated using examples applied for DOA estimations.