2-D DOA Estimation Based On Sparse Array

Direction-of-arrival(DOA)estimation based on sparse array has received much attention and research for its advantages in array aperture and promising commercial and military applications in recent years.In this thesis,first the existing DOA estimation method that based on the sparse and conventional full array has been analyzed and summarized.In order to alleviate the problem that the estimation precision and system cost existing in 2-D DOA estimation,the sparse linear array(SLA)has been introduced into the L shaped and double parallel linear array,putting forward four kinds of simplified sparse planar array of different configuration and the corresponding high accuracy 2-D DOA estimation algorithm.The specific research contents of this thesis are as follows:1.A high-precision estimation method of 2-D DOA employing a partial sparse Lshaped array structured by one traditional ULA,one auxiliary sensor and one sparse uniform linear array(SULA)with the inter sensor spacing is wavelength has been proposed.The proposed method exploit the noise-free property of the cross-correlation matrix(CCM)of the received data of different sensors and the linear transform to obtain the almost noise-free signal subspace.Then the elevation angle estimates can be obtained by exploiting the rotation invariance of the SULA and the proposed disambiguity algorithm.With the help of estimated elevation angles,the shift invariance of the ULA and the spatial smoothing technique,the corresponding azimuth angles can be obtained.The proposed method can not only improve the estimation accuracy of direction finding,realize automatic matching of the estimated angles,but also its disambiguation algorithm is simple and well to understand.2.A high accuracy estimation method of 2-D DOA based on a sparse L-shaped array structured by one SLA with the minimum inter sensor spacing is half the wavelength,one auxiliary sensor and one SULA with the inter sensor spacing is wavelength has been proposed.In the proposed method,the high accuracy elevation angles are estimated by the SLA and an improved MUSIC method which utilize the recursive grid to improve the search efficiency.Then the estimated elevation angles are used to estimate the array manifold matrix of the x-axis.Further,by adopting the method of the second estimation the azimuth anglescan be obtained.The proposed method can not only realize unambiguous and high accuracy estimation for the azimuth and elevation angles,but also achieve automatic pairing of the 2-D DOA estimates.3.A sparse two parallel array structured by an auxiliary sensor,two SULAs that of different number of sensors and the corresponding computational efficient 2-D DOA estimation method is proposed.The proposed method utilize the thinking of the propagator method(PM),by using the disambiguation algorithm to obtain the high accuracy 2-D DOA.In addition,the corresponding Cramer-Rao Lower Bounds(CRLB)has been analyzed and derived.The proposed algorithm take good use of the geometric advantages of the sparse two parallel array and don't need any extra pairing and peak searching operation.4.A sparse two parallel array structured by two identical SULAs,an auxiliary sensor and the corresponding high accuracy 2-D DOA estimation method is proposed.The proposed method exploit the CCM and the shift invariance of the subarray to obtain the electric angle that between the x and y axis,respectively.Then the corresponding matching algorithm is used to make the angle paired.