Abstract
In this paper, two noniterative direction-of-arrival (DOA) estimation algorithms of noncircular signals in nonuniform noise environment are proposed. Different from the mainstream nonuniform iterative algorithm, the algorithms we proposed in this paper could attain DOA estimation effectively in nonuniform noise environment without iterative and convex optimization processing. In the direct removal of nonuniform noise (DRONN) method, the noise subspace is estimated by using special processing of the array output covariance matrix, moreover, it does not require to estimate the noise covariance matrix. On the other hand, the piecewise estimation of nonuniform noise (PEONN) method first estimates the noise covariance matrix, and the noise subspace used in this process is estimated by using the DRONN method, then the generalized eigendecomposition (GED) is used to estimate the noise covariance matrix. The above two proposed methods are able to suppress the interference of nonuniform noise effectively, and accurately estimate DOA without iterative processing. In addition, the two proposed methods use the reduced-dimensional noncircular multiple signal classification (RD-NC-MUSIC) algorithm to estimate DOA without complex two-dimensional spatial search, and they can effectively reduce the computational complexity. The effectiveness of the two proposed methods are proved via the simulation results.
Highlights
Direction-of-arrival (DOA) estimation has become an essential and indispensable branch of array signal processing [1]–[13], which is extensively applied in detections, underwater acoustics, wireless communications, locations, tracking [5] and assistant vehicle localizations [6]
The proposed methods are compared with the NC-multiple signal classification (MUSIC) method [17], the unitary matrix completion (UMC) method [27], and the method in [28], and referring to [28], we re-derived the Cramer-Rao bound (CRB) of noncircular sources in nonuniform noise
The proposed methods improve the accuracy of angle estimation by taking advantage of the noncircularity of signal, and solve the problem of subspace estimation in nonuniform noise environment
Summary
Direction-of-arrival (DOA) estimation has become an essential and indispensable branch of array signal processing [1]–[13], which is extensively applied in detections, underwater acoustics, wireless communications, locations, tracking [5] and assistant vehicle localizations [6]. In order to further reduce the computational complexity, a noniterative subspace-based DOA estimation method has been proposed in [28]. In the DRONN method, according to the noncircularity of the signal, we use the received data matrix and its conjugation to extend the received data matrix, and the noise subspace is estimated by removing the diagonal elements of the covariance matrix. It can remove the effect of nonuniform noise on covariance, and lose some signal data.
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