Non-orthogonal multiple access (NOMA) is considered to be a key technology for fifth-generation mobile communication networks due to its superior spectral efficiency. In this paper, the problem of energy efficient sub...
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ISBN:
(纸本)9781538647523
Non-orthogonal multiple access (NOMA) is considered to be a key technology for fifth-generation mobile communication networks due to its superior spectral efficiency. In this paper, the problem of energy efficient subchannel and power allocation is investigated for a downlink NOMA heterogeneous network. the energy efficient resource allocation problem is first formulated as a mixed integer nonconvex optimization problem. By exploiting convex relaxation and dual decomposition techniques, a closed-form expression is derived via a Lagrangian approach. Simulation results show that the proposed algorithm can converge within ten iterations and obtain high system energy efficiency.
the Dominant Mode Rejection (DMR) beamformer is designed to operate in non-stationary environments where few snapshots are available to estimate the sample covariance matrix (SCM). DMR assumes that the covariance can ...
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ISBN:
(纸本)9781538647523
the Dominant Mode Rejection (DMR) beamformer is designed to operate in non-stationary environments where few snapshots are available to estimate the sample covariance matrix (SCM). DMR assumes that the covariance can be split into orthogonal subspaces defined by the SCM eigenvectors: the first contains the loud interferers and the second contains the remaining signals and noise. the DMR approach requires an estimate of the rank of the interference subspace. Motivated by universal linear prediction, Buck and Singer propose a universal DMR beamformer that computes its weight vector as a linear combination of weight vectors for a set of fixed rank DMR beamformers. this universal DMR beamformer eliminates the need to explicitly estimate the rank of the interference subspace. Under reasonable mathematical assumptions, the universal DMR beamformer is guaranteed to converge to the performance of the best fixed rank beamformer in the set. this paper explores the performance of the universal DMR beamformer for a passive sonar data set acquired with a vertical line array deployed in the Philippine Sea.
High spatio-angular resolution diffusion MRI has been shown to provide accurate identification of complex fiber configurations. However, its application in clinics remains limited due to the long required acquisition ...
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ISBN:
(纸本)9781538647523
High spatio-angular resolution diffusion MRI has been shown to provide accurate identification of complex fiber configurations. However, its application in clinics remains limited due to the long required acquisition time. Recently, we have developed a method relying on an accelerated kq-space under-sampling scheme to recover the intra-voxel fiber configurations. In the current work, we generalize our method to consider a more realistic setting. We include into the kq-space measurement model the phase contamination induced by magnetic field inhomogeneities and motion during the signal acquisition. Simulations are performed on realistic synthetic data, considering boththe cases when the phase is perfectly known, and when it is pre-calibrated. Results show that, in boththe cases, the phase contamination does not penalize the recovery of the fiber configuration.
this paper is devoted to the problem of source detection with large sensor networks, in a context where the number of available samples N and the number of antennas M are of the same order of magnitude. We focus here ...
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ISBN:
(纸本)9781467310710
this paper is devoted to the problem of source detection with large sensor networks, in a context where the number of available samples N and the number of antennas M are of the same order of magnitude. We focus here on the popular likelihood penalization (LP) methods, such as Minimum Description Length (MDL) or Akaike Information Criterion (AIC). Such methods have been widely studied in the context where N >> M, and in particular the consistency of the MDL and the inconsistency of the AIC estimator were established in the asymptotic regime where N -> infinity while M remains constant. We propose here an analysis in the asymptotic regime where M, N both converge to infinity at the same rate, and using results from random matrix theory, we establish conditions on the penalty term to ensure consistency of LP methods in this latter regime. As a consequence, we deduce that the MDL method is always inconsistent while the AIC method can be consistent in certain situations.
Anti-jamming technique has become an increasing demand in radar systems due to the fast development of electronic countermeasures. To alleviate the extremely difficult deceptive jammer suppression problem, frequency d...
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ISBN:
(纸本)9781538647523
Anti-jamming technique has become an increasing demand in radar systems due to the fast development of electronic countermeasures. To alleviate the extremely difficult deceptive jammer suppression problem, frequency diverse array (FDA) based multiple-input multiple-output (MIMO) radar is devised and a sample selection based deceptive jammer suppression method is developed. the basic principle of the FDA-MIMO radar regarding its superiority in canceling the deceptive jammers is studied in detail. In order to handle the pseudo-random distribution issue of false targets within the secondary training samples, a subspace projection based sample selection method is proposed. When certain a priori knowledge of the true target is available, the time-delayed false targets can be adequately suppressed, even if the latter are in the mainlobe direction. Simulation examples demonstrate the effectiveness of our solution.
In recent years, the frequency diverse array (FDA) radar has attracted much attention due to its range-angle dependent beam-pattern. And multiple input multiple output (MIMO) radar has been widely investigated withth...
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ISBN:
(纸本)9781538647523
In recent years, the frequency diverse array (FDA) radar has attracted much attention due to its range-angle dependent beam-pattern. And multiple input multiple output (MIMO) radar has been widely investigated withthe advantage of transmit waveform diversity. In this paper, a FDA-MIMO Inverse Synthetic Aperture Radar (ISAR) is proposed to achieve anti-jamming of ISAR imaging. LFM (Linear Frequency Modulated) and SFCS (Stepped-Frequency Chirp signal) signals are transmitted to jammer and targets respectively, and the received signals are matched filtering by the signal transmitted to the targets. So the jamming signal can't matched withthe reference signal, the well anti-jamming effect can be obtained. the performance of the proposed method is evaluated by the simulation results.
Radio-interferometric imaging aims to estimate a sky intensity image from degraded undersampled Fourier measurements. At the dynamic range of interest to modern radio telescopes, the image reconstruction quality will ...
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ISBN:
(纸本)9781538647523
Radio-interferometric imaging aims to estimate a sky intensity image from degraded undersampled Fourier measurements. At the dynamic range of interest to modern radio telescopes, the image reconstruction quality will be limited by the unknown time-dependent calibration kernels. Hence the need of performing joint image reconstruction and calibration, and consequently of solving a non-convex blind deconvolution problem. Extending our recent work where the calibration kernels are assumed to be smooth in space, we further assume in this work that the calibration kernels are smooth in time. In addition, an average sparsity prior is used for the estimation of the image of interest. the resulting high dimensional non-convex non-smooth minimization problem is then solved by leveraging an alternating forward-backward algorithm which benefits from well-established convergence guarantees. Our results show that time-regularization is effective in enhancing imaging quality.
Each node or sensor in a network makes a local observation that is linearly related to a set of public and private parameters. the nodes send their observations to a fusion center to allow it to estimate a set of publ...
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ISBN:
(纸本)9781728119465
Each node or sensor in a network makes a local observation that is linearly related to a set of public and private parameters. the nodes send their observations to a fusion center to allow it to estimate a set of public parameters. However, the fusion center may also abuse this information to estimate other private parameters. To prevent leakage of the private parameters, each node first sanitizes its local observation using a local privacy mechanism before transmitting it to the fusion center. We consider the maximum privacy achievable under perfect utility in terms of the Cramer-Rao lower bounds. We propose a method to maximize the estimation error for inferring the private parameters while ensuring the estimation error for inferring the public parameters remains unchanged after sanitizing the sensors' measurements.
the unmanned aerial vehicles (UAVs) offer low-cost, flexible, and line-of-sight deployment for radar remote sensing as well as building temporary communications base stations in inaccessible or crowded areas. their li...
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ISBN:
(纸本)9781665406338
the unmanned aerial vehicles (UAVs) offer low-cost, flexible, and line-of-sight deployment for radar remote sensing as well as building temporary communications base stations in inaccessible or crowded areas. their limited battery power and small footprints is driving innovations to combine multiple functions in single hardware operating in the same spectrum. In particular, UAV-borne joint radarcommunications (JRC) systems are of significant interest. In this paper, we focus on a wide-bandwidth millimeter-wave JRC system for UAVs that employ ieee 802.11ad protocol for sensing. We model such a system for detecting dynamic users on the ground such as pedestrians and vehicles. Our method incorporates a realistic electromagnetic scattering center model of road targets and surface clutter in the pyBullet software to examine 802.11ad for UAV-borne sensing. Numerical experiments demonstrate that 802.11ad UAVborne sensing is able to capture several micro-Doppler characteristics.
We study the problem of sensor fusion in a simplified radar surveillance application. A potentially large number of narrowband radars with isotropic antennas monitor a two-dimensional area for an unknown number of tar...
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ISBN:
(纸本)9781467310710
We study the problem of sensor fusion in a simplified radar surveillance application. A potentially large number of narrowband radars with isotropic antennas monitor a two-dimensional area for an unknown number of targets. We use techniques from compressive sensing to distribute efficient projections of network observations, allowing for reconstruction of the target scene using a single snapshot of sensor data. We avoid the use of a fusion node, allowing all radars to individually estimate target locations after iterative communication with neighboring sensors. We study the robustness of the discretization of continuous target locations, comparing estimation performance of basis pursuit reconstruction methods to a sparse estimator based on a model-robust formulation. We test the approach on simulated scenarios, showing tradeoffs in the resolution of target localization as well as the communication bandwidths required for this inter-radar cooperation scheme.
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