Unitary Matrix Completion-Based DOA Estimation of Noncircular Signals in Nonuniform Noise

Abstract

In this paper, a novel direction-of-arrival (DOA) estimation algorithm is proposed for noncircular signals with nonuniform noise by using the unitary matrix completion (UMC) technique. First, the proposed method utilizes the noncircular property of signals to design a virtual array for approximately doubling the array aperture. Then, the virtual complex-valued covariance matrix with the unknown nonuniform noise is transformed into the real-valued one by utilizing the unitary transformation to improve the computational efficiency. Next, a novel UMC method is formulated for the DOA estimation to remove the influence of nonuniform noise. Finally, the DOA without the influence of the unknown noncircularity phase is obtained by using the modified estimation of signal parameters via rotational invariance technique (ESPRIT). Especially, for handling the coherent sources, the forward-backward spatial smoothing technique is utilized to reconstruct a full-rank covariance matrix so that the signal subspace and the noise subspace can be correctly separated. Due to utilizing the extended array aperture and the unitary transformation, the proposed method can identify more sources than the number of physical sensors and provides higher angular resolution and better estimation performance. Compared with the existing DOA estimation algorithms for noncircular signals, the proposed one can effectively suppress the influence of the nonuniform noise. The simulation results are provided to verify the effectiveness and superiority of the proposed method.INDEX TERMS Direction-of-arrival estimation, noncircular, nonuniform noise, unitary matrix completion.

High‐resolution angle estimation method in partly calibrated subarray‐based bistatic multiple‐input multiple‐output radar with unknown non‐uniform noise

“…The search range and search interval of the spectrum is set at and , respectively, for the spectral peak searching methods. The proper form of the orthogonal waveform is overlooked in the simulation similar to [31].…”

“…As a result, the non‐uniform noise condition, lately, has received massive attention. This has, hence, lead to the development of a wide variety of appropriate non‐uniform noise subdual techniques to achieve satisfactory performance [31–33]. For instance, while Wang et al.…”

Noniterative DOA Estimation Algorithms of Noncircular Signals in Nonuniform Noise Environment

“…In this section, we have carried out all sorts of simulation trails to evaluate the performance of the proposed methods in this paper. The proposed methods are compared with the NC-MUSIC method [17], the UMC method [27], and the method in [29], and referring to [29], we re-derived the Cramer-Rao bound (CRB) of noncircular sources in nonuniform noise. We assume that sensors number of ULA is M =8, and the desired DOAs are 1  =−3 and 2  =6.…”

“…Nonidentical sensor noise powers will lead to nonuniform noise, and the noise covariance matrix is with different diagonal elements [23,24]. In recent years, in order to address the problem of DOA estimation in nonuniform noise environment, a variety of methods have been proposed [23][24][25][26][27][28][29]. A deterministic ML estimator has been proposed in [23], and its implementation is based on iterative process.…”

“…However, the high computational complexity generated by the iterative process has not been fundamentally solved. Then a unitary matrix completion (UMC) method has been proposed in [27], this method uses convex optimization to estimate DOA. Its computational complexity is better than that of iterative algorithm [28], but it is still on the high side.…”