By exploiting the sparsity of radar target image, it is hopeful to obtain a high-resolution target image in multiple-input-multiple-output (MIMO) radar via a sparse representation (SR) method. However, for the three-d...
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By exploiting the sparsity of radar target image, it is hopeful to obtain a high-resolution target image in multiple-input-multiple-output (MIMO) radar via a sparse representation (SR) method. However, for the three-dimensional (3-D) imaging, the conventional SR method has to convert the 3-D problem into the one-dimensional (1-D) problem. Thus, it will inevitably impose a heavy burden on the storage and computation. A multidimensional smoothed L0 (MD-SL0) algorithm is proposed based on the conventional smoothed L0 algorithm. The proposed MD-SL0 can directly apply to the multidimensional SR problem without transforming to the 1-D case. As a result, a MIMO radar 3-D imaging method via MD-SL0 is achieved with high computation efficiency and low storage burden. Finally, the effectiveness of the method is validated by the results of comparative experiments. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
In this study, a robust adaptive beamformer against large direction-of-arrival (DOA) mismatch for multiple-input-multiple-output radar is proposed with linear phase and magnitude constraints on main lobe. First, the f...
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In this study, a robust adaptive beamformer against large direction-of-arrival (DOA) mismatch for multiple-input-multiple-output radar is proposed with linear phase and magnitude constraints on main lobe. First, the full-dimensional weight vector (WV) is expressed as the Kronecker product of the transmit and receive array WVs based on the WV separable principle. For the transmit array WV, the authors find an interesting property that the Fourier spectrum of its conjugate inverse arrangement is equal to its array response function within a phase factor. This property also exists in the receive array WV. Using this property, the phase response of the transmit and receive array, respectively, is set to be linear based on designing a finite impulse response filter. Then, a bi-quadratic cost function with respect to the transmit and receive WVs is established by only constraining the real magnitude response and it is effectively solved by the bi-iterative algorithm. The proposed beamformer has lower computational complexity and faster sample convergence rate, compared with the traditional magnitude response constraints beamformers with full degrees of freedom. Moreover, it can provide good robustness against large DOA mismatch. Numerical experiments are provided to demonstrate the effectiveness of the proposal.
The authors deal with the robust design of multiple-input-multiple-output (MIMO) space-time transmit code (STTC) and space-time receive filter (STRF) for a point-like target embedded in signal-dependent interference. ...
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The authors deal with the robust design of multiple-input-multiple-output (MIMO) space-time transmit code (STTC) and space-time receive filter (STRF) for a point-like target embedded in signal-dependent interference. Specifically, they assume that the radar exploits knowledge provided by dynamic environmental database, to roughly predict the actual scattering scenario. Then, they devise an iterative method to optimise the (constrained) STTC and the (constrained) STRF which sequentially improves the worst-case (over interfering scatterers statistics) signal-to-interference-plus-noise ratio (SINR). Each iteration of the algorithm is handled via solving two (hidden) convex optimisation problems. The resulting computational complexity is linear with the number of iterations and polynomial with the sizes of the STTC and the STRF. At the analysis stage, they assess the performance of the proposed algorithm in terms of the achieved SINR. They show that properly exploiting the spatial degrees of freedom offered by the MIMO system, it is possible to obtain considerable SINR gains with respect to the conventional single-input-single-output system. Moreover, their results highlight the capability of the proposed method to robustify the performance of the designed system against possible knowledge inaccuracies.
This study presents an improved joint estimation method of signal parameters via rotational invariance technique (ESPRIT) algorithm for low-complexity simultaneous estimation of direction of departure (DOD) and direct...
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This study presents an improved joint estimation method of signal parameters via rotational invariance technique (ESPRIT) algorithm for low-complexity simultaneous estimation of direction of departure (DOD) and direction of arrival (DOA) in a multiple-input-multiple-output radar system. The proposed algorithm is based on a data matrix and estimates DOD and DOA without a pairing operation. The computational complexity of the proposed joint ESPRIT algorithm is derived to be less than that of conventional two dimension multiple signal classification (2D-MUSIC) and reduced dimension multiple signal classification. The authors' simulation results demonstrate that the proposed algorithm achieves performance very close to that of 2D-MUSIC and better performance than that of the ESPRIT algorithm.
Owing to covariance matrix estimation error, desired signal steering vector mismatch, and the existence of target signal in training samples, most of adaptive beamforming algorithms suffer from a great performance deg...
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Owing to covariance matrix estimation error, desired signal steering vector mismatch, and the existence of target signal in training samples, most of adaptive beamforming algorithms suffer from a great performance degradation. Aim at this, this study proposes a robust adaptive beamforming algorithm for multiple-input-multiple-output radar. To be specific, the sample covariance matrix is replaced by the reconstructed covariance matrix, to narrow the difference between the maximum and minimum noise eigenvalues. In addition, the diagonal loading technique is applied to correct the mismatched desired signal steering vector by maximising the output signal-to-interference-plus-noise ratio of adaptive beamformer, and a simple closed-form solution to loading factor can be further obtained. Computer simulation results demonstrate that the proposed algorithm can efficiently improve the robustness of adaptive beamformer against both covariance matrix estimation error and desired signal steering vector mismatch.
Both waveforms of the frequency diverse array radar and the orthogonal frequency division multiplexing multiple-input-multiple-output radar are range coupled, so they provide an inherent advantage of angle-range joint...
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Both waveforms of the frequency diverse array radar and the orthogonal frequency division multiplexing multiple-input-multiple-output radar are range coupled, so they provide an inherent advantage of angle-range joint imaging. The derivation of the signal models shows that the ranging principles are the same and the main differences lie in the spectrum structures and the demodulation schemes. Space-range adaptive processing (SRAP) is proposed for the two kinds of radar systems. Numerical simulations show that super-resolution angle-range images with extra-low sidelobes can be obtained via SRAP. The super-resolution performances of the range-coupled radars are evaluated and analysed.
Since the spectrum of the ground clutter in the ground-based pulse radar is spatially-temporally decoupled, a simple pulse-to-pulse canceller is often used as a moving target indication filter for suppressing the grou...
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Since the spectrum of the ground clutter in the ground-based pulse radar is spatially-temporally decoupled, a simple pulse-to-pulse canceller is often used as a moving target indication filter for suppressing the ground clutter near the zero-Doppler frequency. In contrast, in the airborne phased-array radar, which is a typical single-input-multiple-outputradar, the spectrum of the ground clutter is spatially-temporally coupled each other, and the two-dimensional pulse-to-pulse canceller (TDPC) for ground clutter cancellation has been developed by using the ground clutter model in the spatial-temporal domain. Based on the ground clutter model of multiple-input-multiple-output (MIMO) radar, the authors can extend the existing TDPC to more general form that can suppress the ground clutter in the MIMO radar. As the MIMO TDPC can be calculated offline by utilising the geometry knowledge of the ground clutter of MIMO radar, it can be used as an efficient and convenient ground clutter pre-filtering tool.
This study gives explicit closed-form expressions of the stochastic Cramer-Rao bounds (STO-CRBs) on direction-of-departure and direction-of-arrival estimation accuracies for collocated multiple-input-multiple-output (...
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This study gives explicit closed-form expressions of the stochastic Cramer-Rao bounds (STO-CRBs) on direction-of-departure and direction-of-arrival estimation accuracies for collocated multiple-input-multiple-output (MIMO) radar with unknown spatially coloured noise. In some special cases, i.e. the CRB of direction estimation accuracy for monostatic MIMO radar, the white noise scenario is discussed. Theoretical comparisons between the STO-CRBs and the deterministic ones are presented. Finally, these bounds are numerically compared.
The presence of fault antennas in bistatic multiple-input-multiple-output (MIMO) radar causes a significant degradation of angle estimation performance. In this study, the authors present a signal-processing scheme fo...
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The presence of fault antennas in bistatic multiple-input-multiple-output (MIMO) radar causes a significant degradation of angle estimation performance. In this study, the authors present a signal-processing scheme for bistatic MIMO radar with impaired receive array including array diagnosis as well as angle estimation. The damaged antenna in the receiver, which is incapable of receiving the target signals and leaves only the thermal noise generated within the receiver itself, leads to a decrease in the entropy of its received data. The dissimilarity of the entropy values between the damaged and normal receive antennas is used for array diagnosis. Thereafter, the useless noise data of the detected fault antennas is removed in the receive signal matrix, so that the successive data missing occurs along the row directions of the signal subspace matrix. A low-rank block-Hankel structured matrix is constructed from the incomplete signal subspace matrix, which can facilitate the exploitation of the matrix completion technique to recover that successive missing data. On the basis of the restored rotational invariance structure of the complete signal subspace, the estimation of signal parameters via rotational invariance technique can then be applied for angle estimation. Simulation results confirm the validity of the proposed methods.
The frequency diverse array (FDA), which exploits a small frequency increment across the transmitting antenna elements, has been recently introduced to multiple-input-multiple-output (MIMO) radar to offer the capabili...
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ISBN:
(纸本)9781479981311
The frequency diverse array (FDA), which exploits a small frequency increment across the transmitting antenna elements, has been recently introduced to multiple-input-multiple-output (MIMO) radar to offer the capability of range-angle-dependent beampattern and target localization. Traditionally, the two-dimensional (2D) subspace-based methods and grid-based sparse reconstruction algorithms are used to obtain angle and range in FDA-MIMO radar. In this paper, with a single measurement, we propose a gridless angle and range estimation approach for FDA-MIMO radar based on decoupled atomic norm minimization (DANM). First, we convert the 2D-ANM based angle and range estimation into a decoupled semi-definite programming problem with two one-dimensional (1D) Toeplitz Hermitian matrices. Then we apply the matrix enhancement and matrix pencil method and construct a permutation matrix to obtain joint angle and range estimation and parameter pairing. Numerical results verify that the proposed approach overcomes the grid-mismatch effect of the sparse reconstruction-based OMP algorithm and outperforms the subspace-based MUSIC method.
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