Publications

2018

• Region-of-interest imaging with differentiated backprojection and angularly subsampled complementary sinograms
  
  • Reshef Aymeric
  • Nikoukhah Tina
  • Riddell Cyril
  • Tousset Yves
  • Ladjal Saïd
  • Bloch Isabelle
  , 2018. Recently, we introduced a two-pass analytical recon- struction that allows truncation to be accounted for in the image domain rather than the projection domain. In particular, we showed that backprojection of a vastly angularly undersampled sinogram of un-truncated data could be used to extrapolate the backprojection of a finely sampled, fully truncated sinogram of the same object to perform more accurate region-of-interest (ROI) imaging. The same extrapolation idea can be performed using differentiated backprojection (DBP). The goal of this study is to give a general DBP-based formula when reconstructing a finite set of projections in parallel geometry. We discuss the discretization of this formula, in particular when the image grid size is large with respect to the number of projections, and we show how it can be applied to our extrapolation problem.
• An Efficient SCA Leakage Model Construction Method Under Predictable Evaluation
  
  • Tang Ming
  • Wang Pengbo
  • Ma Xiaoqi
  • Chang Wenjie
  • Zhang Huanguo
  • Peng Guojun
  • Danger Jean-Luc
  IEEE-TIFS, 2018. (10.1109/TIFS.2018.2837644)
  DOI : 10.1109/TIFS.2018.2837644
• TCP Congestion Control in Datacenter Optical Packet Networks on Hybrid Switches
  
  • Minakhmetov Artur
  • Ware Cédric
  • Iannone Luigi
  J. Opt. Commun. Netw., 2018, 10 (7), pp.B71-B81. Optical packet switching (OPS) has long promised performance and energy consumption improvements by doing away with optical-to-electronic conversions required by electronic packet switching; however, not having practical optical buffers makes OPS highly vulnerable to contention. This study reports on the possible and plausible use of OPS technology on datacenter networks by coupling two concepts: optical switches with shared electronic buffers, also known as hybrid switches, and the introduction of TCP congestion control algorithms (CCAs) to control transport of optical packets. The stop-and-wait (SAW) and the modified additive increase multiple decrease (mAIMD) CCAs families are reviewed. For SAW, a basic version and a modified one -- stop-and-wait-longer, adapted for hybrid switches -- are analyzed. As for mAIMD, a TCP selective acknowledgment (SACK) implementation and its simplified modification TCP mSACK are studied. It is successfully shown that these algorithms paired with the use of shared electronic buffers in hybrid switches significantly outperform bufferless all-optical switches and reach the level of all-electronic switches in datacenters and local area networks in terms of network throughput. (10.1364/JOCN.10.000B71)
  DOI : 10.1364/JOCN.10.000B71
• Coverage Analysis and Load Balancing in HetNets With Millimeter Wave Multi-RAT Small Cells
  
  • Ghatak Gourab
  • de Domenico Antonio
  • Coupechoux Marceau
  IEEE Transactions on Wireless Communications, Institute of Electrical and Electronics Engineers, 2018, 17 (5), pp.3154-3169. We characterize a two tier heterogeneous network, consisting of classical sub-6 GHz macro cells, and multi radio access technology (RAT) small cells able to operate in sub-6 GHz and millimeter-wave (mm-wave) bands. For optimizing coverage and to balance loads, we propose a two-step mechanism based on two biases for tuning the tier and RAT selection, where the sub-6 GHz band is used to speed-up the initial access procedure in the mm-wave RAT. First, we investigate the effect of the biases in terms of signal-to-interference-plus-noise ratio (SINR) distribution, cell load, and user throughput. More specifically, we obtain the optimal biases that maximize either the SINR coverage or the user downlink throughput. Then, we characterize the cell load using the mean cell approach and derive upper bounds on the overloading probabilities. Finally, for a given traffic density, we provide the small cell density required to satisfy system constraints in terms of overloading and outage probabilities. Our analysis highlights the importance of deploying dual-band small cells, in particular, when small cells are sparsely deployed or in case of heavy traffic. (10.1109/TWC.2018.2807426)
  DOI : 10.1109/TWC.2018.2807426
• A Unified Framework of Clustering Approach in Vehicular Ad Hoc Networks
  
  • Ren Mengying
  • Zhang Jun J.
  • Khoukhi Lyes
  • Labiod Houda
  • Vèque Véronique
  IEEE Transactions on Intelligent Transportation Systems, IEEE, 2018, 19 (5), pp.1401-1414. Effective clustering algorithms are indispensable in order to solve the scalability problem in vehicular ad hoc networks. Although current existing clustering algorithms show increased cluster stability under some certain traffic scenarios, it is still hard to address which clustering metric performs the best. In this paper, we propose a unified framework of clustering approach (UFC), composed of three important parts: 1) neighbor sampling; 2) backoff-based cluster head selection; and 3) backup cluster head based cluster maintenance. Three mobility-based clustering metrics, including vehicle relative position, relative velocity, and link lifetime, are considered in our approach under different traffic scenarios. Furthermore, a detailed analysis of UFC with parameters optimization is presented. Extensive comparison results among UFC, lowest-ID, and VMaSC algorithms demonstrate that our clustering approach performs high cluster stability, especially under high dynamic traffic scenarios. (10.1109/TITS.2017.2727226)
  DOI : 10.1109/TITS.2017.2727226
• Impact of Aging on Template Attacks
  
  • Karimi Naghmeh
  • Guilley Sylvain
  • Danger Jean-Luc
  , 2018, pp.455-458. Template attack is the most powerful side-channel attack from an information theoretic point of view. This attack is launched in two phases. In the first phase (training) the attacker uses a training device to estimate leakage models for targeted intermediate computations, which are then exploited in the second phase (matching) to extract secret information from the target device. Process variation and discrepancy of operating conditions (e.g., temperature) between training and matching phases adversely affect the success probability of the attack. Attack-success degradation is exacerbated when device aging comes into account. Due to aging, electrical specifications of transistors change over time. Thereby, if the training and target devices have experienced different usage time, the attack will be more difficult. Aging alignment between training and target devices is difficult as aging degradation is highly affected by operating conditions and technological variations. This paper investigates the effect of aging on the success rate of template attacks. In particular, we focus on NBTI and HCI aging mechanisms. We mount several attacks on the PRESENT cipher at different temperatures and aging times. Our results show that the attack is more difficult if there is an aging-duration mismatch between the training and target devices. (10.1145/3194554.3194638)
  DOI : 10.1145/3194554.3194638
• Controlling software router resource sharing by fair packet dropping
  
  • Addanki Vamsi
  • Linguaglossa Leonardo
  • Roberts James
  • Rossi Dario
  , 2018.
• Color digital hologram compression based on matching pursuit
  
  • El Rhammad Anas
  • Gioia Patrick
  • Gilles Antonin
  • Cagnazzo Marco
  • Pesquet-Popescu Beatrice
  Applied optics, Optical Society of America, 2018, 57 (17), pp.4930-4942.
• On the Design of a side-looking Drone-borne GPR and its Physical Basis
  
  • Chandra Madhu
  • Tanzi Tullio
  , 2018.
• Mutual Coupling Modeling and Calibration in Antenna Arrays for AOA Estimation
  
  • Vo Tien Tu
  • Ouvry Laurent
  • Sibille Alain
  • Bories Serge
  , 2018. In antenna arrays, mutual coupling is an undesired effect which degrades the array pattern and the performance of array signal-processing algorithms like for Angle-Of-Arrival (AOA) estimation. Various approaches for mutual-coupling compensation that evaluate the coupling in receiving and transmitting modes have been studied. In this paper, a definition of the mutual coupling in receiving mode from the scattering parameters is introduced. A dissimilarity factor is added on the signals after the coupling calibration to simulate amplitude and phase variations at the termination of array elements. The coupling model shows the role of antenna characteristics and distance between the elements. When the antennas are all connected to a matched load and there is no dissimilarity between the antennas, the coupling in the receiving mode assimilates to that in the transmitting mode. To validate this statement, the coupling of an array of two patch antenna elements in these two modes is calculated, which shows an adequate agreement. A simplified technique calibrating the coupling and the dissimilarity is also proposed. The application of these couplingcalibration techniques together shows many possibilities to improve antenna arrays processing.
• Exploration of Planetary Hyperspectral Images with Unsupervised Spectral Unmixing: A Case Study of Planet Mars
  
  • Liu Jun
  • Luo Bin
  • Douté Sylvain
  • Chanussot Jocelyn
  Remote Sensing, MDPI, 2018, 10 (5), pp.737. We propose to replace traditional spectral index methods by unsupervised spectral unmixing methods for the exploration of large datasets of planetary hyperspectral images. The main goal of this article is to test the ability of these analysis techniques to automatically extract the spectral signatures of the species present on the surface and to map their abundances accurately and with an acceptable processing time. We consider observations of the surface of Mars acquired by the imaging spectrometer OMEGA aboard MEX as a case study. The moderate spatial resolution (≈300 m/pixel at best) of this instrument implies the systematic existence of geographical mixtures possibly conjugated with non-linear (e.g., intimate) mixtures. We examine the sensitivity of a series of state-of-the-art methods of unmixing to the intrinsic spectral variability of the species in the image and to intimate assemblages of compounds. This study is made possible thanks to the use of well-controlled synthetic data and a real OMEGA image, for which the present icy species (water and carbon dioxide ices) and their characteristic spectra are widely known by the planetary community. Furthermore, reference maps of component abundances are built by the inversion of a more realistic physical model (simulating the propagation of solar light through the atmosphere and reflected back to the sensor) in order to validate the methods with the real image by comparison with the maps extracted by unmixing. The results produced by the processing pipeline of the eigenvalue likelihood maximization (ELM), vertex component analysis (VCA) and non-negativity condition least squares error estimators (NNLS) are the most robust to non-linear effects, highly-mixed pixels and different types of mixtures. Despite this fact, the produced results are not always the best because the VCA method assumes the existence of pure pixels in the image, that is pixels completely occupied by a single species. However, this pipeline is very fast and provides endmember spectra that are always interpretable. Finally, it produces more accurate distribution maps than the spectral index methods. More generally, the potential benefits of unsupervised spectral unmixing methods in planetary exploration is emphasized (10.3390/rs10050737)
  DOI : 10.3390/rs10050737
• The effect of temperature on the dynamical states of a time delay mid-infrared quantum cascade oscillator
  
  • Spitz Olivier
  • Wu Jiagui
  • Khanal Sudeep
  • Carras Mathieu
  • Williams Ben
  • Wong Chee-Wei
  • Grillot Frédéric
  , 2018.
• Block Recursive MIMO Decoding
  
  • Askri Aymen
  • Rekaya-Ben Othman Ghaya
  • Khsiba Mohamed-Achraf
  , 2018.
• Algorithmes à base d'échantillonage pour l'entraînement de modèles de langue neuronaux
  
  • Labeau Matthieu
  • Allauzen Alexandre
  , 2018. L'estimation contrastive bruitée (NCE) et l'échantillonage par importance (IS) sont des procédures d'entraînement basées sur l'échantillonage, que l'on utilise habituellement à la place de l'estimation du maximum de vraisemblance (MLE) pour éviter le calcul du softmax lorsque l'on entraîne des modèles de langue neuronaux. Dans cet article, nous cherchons à résumer le fonctionnement de ces algorithmes, et leur utilisation dans la littérature du TAL. Nous les comparons expérimentalement, et présentons des manières de faciliter l'entraînement du NCE.
• An online sampling approachfor controlled experimentation and QoE modeling
  
  • Khokhar Mj
  • Spetebroot T.
  • da Hora Diego
  • Rossi Dario
  , 2018.
• Direct backprojection-filtration formula for region-of-interest imaging with few additional projections
  
  • Reshef Aymeric
  • Riddell Cyril
  • Tousset Yves
  • Ladjal Saïd
  • Bloch Isabelle
  , 2018. This paper provides a backprojection-filtration method for image reconstruction in divergent circular fan-beam and cone-beam geometries with flat detectors. It is based on a splitting of the acquisition angular range into angular sectors admitting filtering orientations in the image space where a simple, mono-directional Fourier-based filtering is possible. The new workflow is used for region-of-interest (ROI) reconstruction from dual-rotation acquisitions, consisting of a truncated, densely sampled acquisition and of a few additional non-truncated views. Results show that the reconstructed images using our new approach are similar to what FBP would achieve in the non- truncated case, and demonstrate the feasibility of an accurate direct reconstruction method for dual-rotation ROI imaging with very few non-truncated views.
• The Effect of Temperature on the Dynamical States of a Time Delayed Mid-infrared Quantum Cascade Oscillator
  
  • Spitz O
  • Wu J.
  • Khanal S
  • Carras M.
  • Williams B S
  • Wong C W
  • Grillot F.
  , 2018. Carrier-to-photon lifetime ratio is a key parameter in the non-linear dynamics study of quantum cascade lasers under external optical feedback. We experimentally investigate the influence of temperature on this parameter and hence on chaotic behaviors. (10.1364/CLEO_AT.2018.JTu2A.24)
  DOI : 10.1364/CLEO_AT.2018.JTu2A.24
• Optimized design and performance of a shared pump single clad 2 µm TDFA
  
  • Tench Robert E
  • Romano Clément
  • Delavaux Jean-Marc
  Optical Fiber Technology, Elsevier, 2018, 42, pp.18 - 23. We report the design, experimental performance, and simulation of a single stage, co-and counter-pumped Tm-doped fiber amplifier (TDFA) in the 2 μm signal wavelength band with an optimized 1567 nm shared pump source. We investigate the dependence of output power, gain, and efficiency on pump coupling ratio and signal wavelength. Small signal gains of >50 dB, an output power of 2 W, and small signal noise figures of <3.5 dB are demonstrated. Simulations of TDFA performance agree well with the experimental data. We also discuss performance tradeoffs with respect to amplifier topology for this simple and efficient TDFA. (10.1016/j.yofte.2018.02.012)
  DOI : 10.1016/j.yofte.2018.02.012
• Enabling Resilient Voltage-Controlled MeRAM Using Write Assist Techniques
  
  • Cai Hao
  • Wang You
  • Naviner Lirida
  • Yang Jun
  • Kang Wang
  • Zhao Weisheng
  , 2018.
• All-Polarization-Maintaining One- and Two-Stage Holmium-doped Fiber Amplifiers at 2051 nm
  
  • Tench Robert
  • Romano Clément
  • Delavaux Jean-Marc
  • Robin Thierry
  • Cadier Benoit
  • Laurent Arnaud
  , 2018, pp.Paper JTh2A.132.
• Full and Half Duplex-Switching Policy for Cellular Networks under Uplink Degradation Constraint
  
  • Arrano Hernan F
  • Kélif Jean-Marc
  • Coupechoux Marceau
  , 2018, pp.1-7. Full-duplex (FD) is a principle in which a transceiver can receive and transmit on the same time-frequency radio resource. Assuming perfect self-interference cancellation (self-IC), FD can potentially double the spectral efficiency (SE) of a given point-to-point communication. However in cellular networks, we may be far from this upper bound due to base stations (BSs) and users interference. In particular, even if the overall SE is improved, the uplink (UL) performance is degraded compared to a traditional half-duplex (HD) system. In this paper, we propose and evaluate a new duplex-switching (DS) policy in which BSs can adopt FD- or HD-mode according to the position of their scheduled users. This system is analyzed using stochastic geometry in terms of average SE (ASE) and signal-to-interference-plus-noise ratio (SINR). The proposed scheme allows to trade-off the downlink (DL) for the UL performance when comparing to a FD scenario. In terms of cell performance (UL+DL), our DS policy even outperform both HD and FD systems when the parameters are optimized.
• On minimum entropy and Gaussian transport
  
  • Rioul Olivier
  , 2018. A nontrivial linear mixture of independent random variables of fixed entropies has minimum entropy only for Gaussian distributions. This &quot;minimum entropy principle&quot; was first stated for two variables by Shannon in 1948 in the form of the entropy-power inequality which has long been proven useful for deriving converse multiuser coding theorems. It was also also applied to deconvolution problems by Donoho and generalized to linear transformations by Zamir and Feder, and more recently to Rényi entropies with different formulations by Bobkov and Chistyakov and by Ram and Sason. Available proofs involve either the integration over a path of Gaussian perturbation of Fisher information or minimum mean-squared errors, or a limiting case of Young's convolutional inequality with sharp constants. In this work, we show that a natural transportation argument from the Gaussian distribution yields simple derivations of the minimum entropy principle in all these cases. The basic ingredient is a change of variable in differential entropies which dates back to Shannon’s 1948 paper. We discuss possible generalizations and perspectives of this method.
• Hybrid Projective Nonnegative Matrix Factorization with Drum Dictionaries for Harmonic/Percussive Source Separation
  
  • Laroche Clément
  • Kowalski Matthieu
  • Papadopoulos Hélène
  • Richard Gael
  IEEE/ACM Transactions on Audio, Speech and Language Processing, Institute of Electrical and Electronics Engineers, 2018, 26 (9), pp.1499-1511. One of the most general models of music signals considers that such signals can be represented as a sum of two distinct components: a tonal part that is sparse in frequency and temporally stable, and a transient (or percussive) part composed of short term broadband sounds. In this paper, we propose a novel hybrid method built upon Nonnegative Matrix Factorisation (NMF) that decomposes the time frequency representation of an audio signal into such two components. The tonal part is estimated by a sparse and orthogonal nonnegative decomposition and the transient part is estimated by a straightforward NMF decomposition constrained by a pre-learned dictionary of smooth spectra. The optimization problem at the heart of our method remains simple with very few hyperparameters and can be solved thanks to simple multiplicative update rules. The extensive benchmark on a large and varied music database against four state of the art harmonic/percussive source separation algorithms demonstrate the merit of the proposed approach. (10.1109/taslp.2018.2830116)
  DOI : 10.1109/taslp.2018.2830116
• Future internet services based on LIPS technology
  
  • Li Yue
  , 2018. The Locator/Identifier Separation Protocol (LISP) was proposed in 2006 to initially address Internet scalability issues. It is based on a map-and-encap mechanism to split the who and the where of the current IP addresses. To retrieve the association between them, a new network entity called the Mapping Distribution System (MDS) is introduced. Although LISP is currently under standardization in Internet Engineering Task Force (IETF) and is deployed in the wild by two testbeds at the same time, it is still young. It lacks the thorough measurement work to show its real performance in large-scale networks. In this dissertation, we assess LISP from these different aspects: • The measurements on the MDS. • Proposing a comprehensive monitor to supervise the MDS. • The assessment of LISP interworking performance with legacy Internet. • The evaluation of LISP mobility.
• On Aggregation in Ranking Median Regression.
  
  • Clémençon Stéphan
  • Korba Anna
  , 2018.