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International audience; Efficient modeling of Eddy Current Testing (ECT) signals is needed in many areas of industry. Probes design may be improved, and experimental signals interpretation may be better understood by using dedicated numerical simulation tools, provided that they are computationally effective and accurate, while remaining easy enough to be employed at end-user's level. A Boundary Element Method (BEM), dedicated to the numerical simulation of ECT signals due to complex narrow cracks affecting a Planar Multilayered Structure (PMS) and presenting arbitrary orientations is investigated herein. The theoretical formulation relies on the calculation of the dyadic Green operator, associated to the PMS, via appropriate vector wave functions expansions. Then, the use of the Discrete Complex Image Method followed by the application of the Generalized Pencil of Function (GPOF) method is proposed for the efficient computation of this operator. Validation results of the complete model, by comparison with experimental data in laboratory controlled condition and with data provided by a finite-element code, are presented and discussed.

Neighbor discovery, one of the most fundamental bootstrapping networking primitives, is particularly challenging in decentralized wireless networks where devices have directional antennas. In this paper, we study the following fundamental problem, which we term oblivious neighbor discovery: How can neighbor nodes with heterogeneous antenna configurations discover each other within a bounded delay in a fully decentralised manner without any prior coordination or synchronisation? We establish a theoretical framework on the oblivious neighbor discovery and the performance bound of any neighbor discovery algorithm achieving oblivious discovery. Guided by the theoretical results, we then devise an oblivious neighbor discovery algorithm, which achieves guaranteed oblivious discovery with order-minimal worst case discovery delay in the asynchronous and heterogeneous environment. We further demonstrate how our algorithm can be configured to achieve a desired tradeoff between average and worst case performance.

© 2019 IEEE. We target the minimum cost design of a 5G network exploiting Small Cells (SCs) carried by Unmanned Aerial Vehicles (UAVs). In our architecture, UAV-SCs can be recharged by a set of ground sites, which provide energy capabilities thanks to the exploitation of micro-generation (i.e., locally produced energy) and batteries. In addition, the ground sites are connected by means of a set of optical fibers forming a tree-based topology. We then define an optimization problem to minimize the total installation costs of the ground sites, the optical network, the batteries, and the sources of micro-generation, while ensuring the coverage of the territory through the UAV-SCs. Results demonstrate that it is possible to notably reduce the total costs compared to a legacy solution, which assumes the installation of fixed Base Stations (BSs) to provide full territory coverage.

Conference of 42nd Annual Review of Progress in Quantitative Nondestructive Evaluation, QNDE 2015, Incorporating the 6th European-American Workshop on Reliability of NDE ; Conference Date: 26 July 2015 Through 31 July 2015; Conference Code:119404; International audience; In this paper, a numerical solution of WFNDEC 2015 eddy current benchmark is presented. In particular, the Surface Integral Equation (SIE) method has been employed for numerically solving the benchmark problem. The SIE method represent an effective and efficient alternative to standard numerical solver like Finite Element Method (FEM) when electromagnetic fields need to be calculated in problems involving homogeneous media. The formulation of SIE method allows to properly solve the electromagnetic problem by meshing the surface of the media instead to the complete media volume as done in FEM. The surface meshing enables to describe the problem with a smaller number of unknowns with respect to FEM. This property is directly translated in an obvious gain in terms of CPU time efficiency.

International audience; In this paper, we study game dynamics and learning schemes for heterogeneous 4G networks. We introduce a novel learning scheme called cost-to-learn that incorporates the cost to switch, the switching delay, and the cost of changing to a new action and, captures the realistic behavior of the users that we have experimented on OPNET simulations. Considering a dynamic and uncertain environment where the users and operators have only a numerical value of their own payoffs as information, we construct various heterogeneous combined fully distributed payoff and strategy reinforcement learning (CODIPAS-RL): the users try to learn their own optimal payoff and their optimal strategy simultaneously. We establish the asymptotic pseudo-trajectories as solution of differential equations. Using evolutionary game dynamics, we prove the convergence and stability properties in specific classes of dynamic robust games. We provide various numerical examples and OPNET simulations in the context network selection in wireless local area networks (WLAN) and Long Term Evolution (LTE).

Molecular Communication (MC) is an emerging and promising communication paradigm for several multi-disciplinary domains like bio-medical, industry and military. Differently to the traditional communication paradigm, the information is encoded on the molecules, that are then used as carriers of information. Novel approaches related to this new communication paradigm have been proposed, mainly focusing on architectural aspects and categorization of potential applications. So far, security and privacy aspects related to the molecular communication systems have not been investigated at all and represent an open question that need to be addressed. The main motivation of this paper lies on providing some first insights about security and privacy aspects of MC systems, by highlighting the open issues and challenges and above all by outlining some specific directions of potential solutions. Existing cryptographicmethods and security approaches are not suitable for MC systems since do not consider the pecific issues and challenges, that need ad-hoc solutions.We will discuss directions in terms of potential solutions by trying to highlight the main advantages and potential drawbacks for each direction considered. We will try to answer to the main questions: 1) why this solution can be exploited in the MC field to safeguard the system and its reliability? 2) which are the main issues related to the specific approach?

41st Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE), Boise, ID, JUL 20-25, 2014; International audience; This work proposes a solution to the 2014 eddy current testing benchmark, published by the WFNDEC and proposed by the authors. The aim of this benchmark is to provide reference data for eddy current testing configurations involving magnetic sensors here Hall sensors as receivers, as they present some advantages in terms of resolution and sensitivity. After a presentation of the benchmark cases, the theoretical approach used to solve the equivalent electromagnetic problem is detailed and a alternative computation of eddy current signals is proposed. Then, simulations are quantitatively compared to experimental data in each case and the results are discussed.

The majority of work in cognitive radio networks have focused on single-hop networks with mainly challenges at the physical and MAC layers. Recently, multi-hop secondary networks have gained attention as a promising design to leverage the full potential of cognitive radio networks. One of the main features of routing protocols in multi-hop networks is the routing metric used to select the best route for forwarding packets. In this paper, we survey the state-of-the-art routing metrics for cognitive radio networks. We start by listing the challenges that have to be addressed in designing a good routing metric for cognitive radio networks. We then provide a taxonomy of the different metrics and a survey of the way they have been used in different routing protocols. Then we present a case study to compare different classes of metrics. After that, we discuss how to combine individual routing metrics to obtain a global one. We end the paper with a discussion of the open issues in the design of future metrics for cognitive radio networks.

This article belongs to the Special Issue Vehicular Communications and Networking; International audience; Recent vehicular networking activities include novel automotive applications, such as public vehicle to vehicle/infrastructure (V2X), large scale deployments, machine-to-machine (M2M) integration scenarios, and more. The platform described in this paper focuses on the integration of eHealth in a V2I setting. This is to allow the use of Internet from a vehicular setting to disseminate health-related information. From an eHealth viewpoint, the use of remote healthcare solutions to record and transmit a patient’s vital signs is a special telemedicine application that helps hospital resident health professionals to optimally prepare the patient’s admittance. From the automotive perspective, this is a typical vehicle-to-infrastructure (V2I) communication scenario. This proposal provides an IPv6 vehicular platform, which integrates eHealth devices and allows sending captured health-related data to a personal health record (PHR) application server in the IPv6 Internet. The collected data is viewed remotely by a doctor and supports his diagnostic decision. In particular, our work introduces the integration of vehicular and eHealth testbeds, describes related work and presents a lightweight auto-configuration method based on a DHCPv6 extension to provide IPv6 connectivity with a few numbers of messages

International audience; Eddy current testing (ECT) of narrow cracks is an important issue in several industrial areas. Efficient modeling tools are required in order to better interpret measurements, to design adapted probes, and to assess the reliability of testing procedures. A dedicated boundary element model (BEM) suitable for eddy current inspection of several narrow cracks affecting a planar-stratified conductive medium is proposed. The cracks' openings can be arbitrarily small, and their respective orientations be along parallel or orthogonal directions. The approach alleviates most of the computational difficulties of classical methods in such peculiar cases. Comparisons of the results with experimental and simulated data taken from the literature, completed with in-house experiments, illustrate its good accuracy and low computational burden.

In this paper, we tackle the problem of opportunistic spectrum access in cognitive radio networks. We consider a large number of unlicensed Secondary Users (SU) accessing a number of frequency channels partially occupied by licensed Primary Users (PU). Each channel is characterized by an unknown availability probability. We apply evolutionary game theory to model the spectrum access problem and propose imitation-based spectrum access policies based on the proportional imitation rule (PIR) and double imitation (DI) rule. We show that both policies converge exponentially in time to the Nash Equilibrium which is also the system optimum. The proposed spectrum access policies are evaluated by simulations which demonstrate their convergence to a stable equilibrium state which is also the system optimum.

International audience; The current state of the art of evolutionary coalitional game theory in wireless networking and communications is captured in this article, where solutions are discussed under their related applications. Fully distributed algorithms for global optima in network selection games are examined. Then the problem of dynamic network formation and evolutionary coalitional games in wireless networks are investigated. This article also points out the open research issues, new interests, and developments in this interdisciplinary field.

International audience; Security is becoming an increasingly important issue in the design of multimedia applications, which are widely used in the industry and academic organizations. However, existing scheduling schemes for real-time multimedia service in heterogeneous networks generally do not take into account security requirements when making allocation and control decisions. In this paper, we develop and evaluate a security-critical multimedia scheduling scheme in the framework of heterogeneous networks. At first, we construct a general media distortion model according to the observed parameters in each network, as well as each application's characteristic. After that, we exploit a scalable graph-based authentication method which achieves a good trade-off between flexibility and efficiency. Furthermore, a security-critical scheduling scheme is proposed by taking into account applications' timing and security requirements in addition to precedence constraints. The proposed scheme is applied to heuristically find resource allocations, which maximize the quality of security and the probability of meeting deadlines for all the multimedia applications running on heterogeneous networks. Extensive simulations are provided to demonstrate the effectiveness and feasibility of the proposed scheme. © 2010 Elsevier B.V. All rights reserved.

International audience; In recent years, wireless video transmission has emerged as one of the high growth applications of wireless communication technology. However, this error-prone network is packet based where many potential reasons may result in packet loss which has a devastating effect on the visual quality of images at the receiver. In this work, we study a coordinated application of Error-Resilient (ER) and Super-Resolution (SR) to enhance the resolution of image transmitted over wireless networks. Compressed video bitstreams require protection from channel errors in a wireless channel. The 3-D set partitioning in hierarchical trees (SPIHT) coder has proved its efficiency and its real-time capability in compression of video. A forward-error-correcting (FEC) channel (RCPC) code combined with a single automatic-repeat request (ARQ) proved to be an effective means for protecting the bitstream. Furthermore, a robust SR algorithm is proposed in the presence of different kinds of packet loss rate to enhance the image resolution. Experimental results indicate that the proposed robust resolution-enhancement scheme outperforms the competing methods from the aspects of PSNR (Peak-Signal-to-Noise Ratio) and visual quality under different packet loss rates. © 2010 Springer-Verlag Berlin Heidelberg.