Efficient Joint Estimation of DOA, Range and Reflectivity in Near-Field by Using Mixed-Order Statistics and a Symmetric MIMO Array

Abstract

Most works in the literature on parameter estimation with multiple-input multiple-output (MIMO) systems are limited to estimating only the direction of arrival (DOA), and/or based on the far-field assumption. However, the joint estimation of DOA and range is an important challenge for near-field (NF) applications. In addition, backscatter coefficient estimation, as one of the most important parameters of radar systems, has been neglected in existing works. In this paper, the joint estimation of the DOA, range and reflectivity is presented for a MIMO array in the NF. By employing the symmetry property in the array, first, two special spatial expressions based on fourth-order and second-order statistics from the received data are defined so that the output of the first expression lacks targets' range information. By collecting the information of all the sensors and calculating all the interactions between the transmit and receive sensors based on the first expression, a spatial cumulant matrix is constructed. In two different approaches, with/without the use of eigendecomposition, the virtual steering vectors are extracted. Next, DOAs are estimated by a one-dimensional (1D) spectral search. The second expression, which contains both angle and range information, is used to construct several covariance submatrices and then to construct a covariance matrix with a size corresponding to the array's dimensions. Then, corresponding ranges are estimated by employing estimated DOAs, eigendecomposition and 1D spectral searches. Finally, the equations required to estimate the reflectivity are derived. The simulation results show the remarkable performance of the proposed method in terms of computational time and estimation accuracy.

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“…2 is approximately equal to 2 0.71 0.71m × . Therefore, due to the size of the aperture and the operating frequency, targets with a range of less than approximately 66m are located in the NF region [38]. Also, the theoretical cross-range and range resolutions [14,17] are approximately equal to 1.07cm and 3.33cm, respectively.…”

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“…1) is considered. Due to the size of the aperture (0.71 × 0.71 m 2 ) and the operating frequency, targets with a range of less than approximately 66m are located in the near-field (NF) region [31].…”

A multi-resolution analysis-based approach to accelerate data acquisition for near-field MIMO millimeter-wave imaging

“…The values of the simulation parameters are given in Table 1, where λ is the wavelength at the center frequency of 79GHz. According to the aperture size and operating frequency presented in Table 1, targets in the range of approximately less than 39m are considered to be located in the NF region [22].…”