| CPC G01S 3/143 (2013.01) | 4 Claims |
|
1. A two-dimensional direction-of-arrival estimation method for a coprime surface array based on virtual domain tensor filling, wherein the method comprises the following steps:
(1) configuring a receiving end with a coprime surface array by using 4MxMy+NxNy−1 physical antenna array elements, wherein Mx, Nx and My, Ny are a pair of coprime integers respectively; decomposing the coprime surface array into two sparse uniform sub-surface arrays
 and  , wherein contains 2Mx×2My antenna array elements, array element spacings in an x axial direction and a y axial direction are respectively Nxd and Nyd, includes Nx×Ny antenna array elements, array element spacings in the x axial direction and the y axial direction are respectively Mxd and Myd, and an unit interval d is taken as half of wavelength λ of an incident narrowband signal;(2) if there are K far-field narrowband uncorrelated signal sources from {(θ1, φ1), (θ2, φ2), . . . , θK, φK)} directions, θk and φk are respectively an azimuth angle and an elevation angle of a kth incident signal source, k=1, 2, . . . , K, utilizing a three-dimensional tensor
 to express T sampling snapshot signals of a sparse uniform sub-surface array
as follows: wherein sk=[sk,1, sk,2, . . . , sk,T]T is a multi-snapshot sampling signal waveform corresponding to the kth incident signal source, [⋅]T represents a transpose operation, ∘ represents an outer product of a vector,
 is a noise tensor independent of each signal source, are respectively steering vectors of
in the x axial direction and the y axial direction, correspond to a signal source with an incoming wave direction of (θk, φk), and are expressed as follows: and wherein
 represent respectively actual positions of physical antenna elements of the sparse uniform sub-surface array
in the x axial direction and the y axial direction, and expressing the T sampled snapshot signals of the sparse uniform sub-surface array
by another three-dimensional tensor as follows:
 wherein
 is a noise tensor independent of each signal source, are respectively steering vectors of
in the x axial direction and the y axial direction, correspond to a signal source with an incoming wave direction of (θk, φk), and are expressed as follows: and wherein
 represent respectively actual positions of physical antenna elements of the sparse uniform sub-surface array
in the x axial direction and the y axial direction, and obtaining a second-order cross-correlation tensor
 by solving cross-correlation statistic of the three-dimensional tensors
 and  : wherein σk2=E[sksk*] represents power of a kth incident signal source,
 represents a cross-correlation noise tensor, <⋅,⋅>r represents a tensor contraction operation of two tensors along a rth dimension, E[⋅] represents a mathematical expectation operation, and (⋅)* represents a conjugation operation; the cross-correlation noise tensor
 only has an element with a value σn2 in the (1, 1, 1, 1)th position, wherein σn2 represents a noise power, and elements in other positions have the same value 0;(3) defining dimension sets J1={1,3}, J2={2,4}, and obtaining a virtual domain signal
 by performing a tensor transformation of dimension merging on the cross-correlation tensor
 : wherein by respectively forming a difference set array on an exponential term,
 configure a two-dimensional augmented virtual surface array along the x axial direction and the y axial direction, ⊗ represents a Kronecker product; therefore, UW corresponds to a non-continuous virtual surface array W of size JWx×JWy, JWx=3MxNx−Mx−Nx+1, JWy=3MyNy−My−Ny+1, and the non-continuous virtual surface array W contains holes in an entire row and an entire column;
(4) configuring a virtual surface array W that mirrors the non-continuous virtual surface array W about a coordinate axis, and superimposing the W and W on a third dimension into a three-dimensional non-continuous virtual cubic array
 correspondingly, rearranging elements in a conjugate transposed signal UW* of the virtual domain signal UW to correspond to positions of virtual array elements in W, so as to obtain a virtual domain signal UW corresponding to the virtual surface array W; superimposing UW and UW in the third dimension to obtain a virtual domain tensor
 corresponding to the non-continuous virtual cubic array  , which is represented as: wherein bx(k) and by(k) are respectively steering vectors of the non-continuous virtual cubic array
on the x axial direction and the y axial direction, and correspond to the signal source with the incoming wave direction (θk, φk); due to existence of the holes in , bx(k) and by(k) respectively correspond to elements in hole positions in in the x axial direction and the y axial direction which are set to be zero, represents a mirror transformation factor vector corresponding to W and W; since the non-continuous virtual surface array W contains the holes in the entire row and the entire column, the non-continuous virtual cubic array
obtained by superimposing W with a mirror image part thereof W contains contiguous holes, corresponds to virtual field tensor of the non-continuous virtual cubic array , and thus contains contiguous missing elements;(5) designing a translation window of size Px×Py×2 to select a sub-tensor
 of the virtual domain tensor , wherein contains elements of which indices are (1: Px−1), (1: Py−1) and (1:2) respectively in three dimensions of ; then, translating the translation window by one element in turn along the x axial direction and the y axial direction, dividing into Lx×Ly sub-tensors, expressed as  , sx=1, 2, . . . , Lx, sy=1, 2, . . . , Ly, wherein a value range of a size of the translation window is as follows: and Lx, Ly, Px, Py satisfy the following relationship:
 superimposing the sub-tensors
 with the same index subscript sy in a fourth dimension to obtain Ly four-dimensional tensors with Px×Py×2×Lx dimensions; further, superimposing the Ly four-dimensional tensors in a fifth dimension to obtain a five-dimensional virtual domain tensor wherein the five-dimensional virtual domain tensor
 contains spatial angle information in the x axial direction and the y axial direction, spatial mirror transformation information, and spatial translation information in the x axial direction and the y axial direction; defining dimension sets K1={1, 2}, K2={3}, K3={4, 5}, and merging through the dimensions of to obtain a three-dimensional reconfigured virtual domain tensor  wherein the three dimensions of
 respectively represent the spatial angle information, the spatial translation information and the spatial mirror transformation information, thus, the contiguous missing elements in the original virtual domain tensor  are randomly distributed to the three spatial dimensions contained in  ;(6) designing a virtual domain tensor filling optimization problem based on tensor kernel norm minimization:
 wherein optimization variable
 is a filled virtual domain tensor corresponding to the virtual uniform cubic array
 , ∥⋅|* represents a tensor kernel norm, Ω represents a position index set of non-missing elements in , PΩ(⋅) represents a mapping of a tensor on Ω, wherein the virtual domain tensor filling optimization problem is solved to obtain  ;(7) expressing the filled virtual domain tensor
as follows: wherein pk=dy(k)⊗dx(k), qk=gy(k)⊗gx(k) are the space factors of
, respectively represent steering vectors of the virtual uniform cubic array
 along the x axial direction and the y axial directions, are respectively spatial translation factor vectors corresponding to the x axial direction and the y axial direction in a process of intercepting the sub-tensor by the translation window; performing canonical polyadic decomposition on the filled virtual domain tensor
to obtain an estimated values of three factor vectors pk, qk and ck, which are expressed as pk, qk and ĉk; and extracting angle parameters contained in exponential terms of pk and qk to obtain a two-dimensional direction-of-arrival estimation result (θk, φk), whereinthe receiving end with the coprime surface array steers, based on the two-dimensional direction-of-arrival estimation result (θk, φk), vectors corresponding to the signal source with the incoming wave direction (θk, φk).
|