WorldCat Identities

Laboratoire d'électronique, antennes et télécommunications (Sophia Antipolis, Alpes-Maritimes)

Overview
Works: 55 works in 55 publications in 2 languages and 55 library holdings
Roles: Other, Degree grantor
Publication Timeline
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Most widely held works by antennes et télécommunications (Sophia Antipolis, Alpes-Maritimes) Laboratoire d'électronique
Caractérisation numérique d'antennes VLF-LF en environnement réel by David Saintier( )

1 edition published in 2018 in French and held by 1 WorldCat member library worldwide

Submarine communications are the main usage of the very low frequency (VLF). This frequency band allows to radiate up to a few tens meter of depth and to a very long distance. Antennas for such telecommunications are necessarily small in regard to the wavelength. However, these structures are composed of hundred meters of thin metallic cables and their locations are often chosen for their dielectric characteristics or the structural advantage provided by the relief. To evaluate such antennas, we propose to use a home-made software, based on the TLM method. Such technique can be efficient for studying wide band electromagnetic problems in complex dielectric environment. Then we have improved the TLM Thin Wire model and we have evaluated its performances in realistic environment. In this document, we present our work and its validation by comparing our results to those obtained with the commercial software FEKO, based on the MoM, considered as the most suitable technique for this kind of problem. A solution assuring a good accuracy of the model for an arbitrary orientation of the Thine Wire in the 3D cartesian grid was proposed. We have also specified the limitations of the bent wire and the wires junction. In addition, we have studied the interaction between the wire and inhomogeneous media. This is an ambitious problem for which we brought some elements of answer but which remains a challenge. Finally, we have tested our software on some realistic antenna systems. The simulations of a valley span T antennas system allow to understand the functioning of such radiating structure and to show the interest of our method. The computation times are significantly lower with the TLM method than with FEKO to deal with antennas above such complex ground. However, the simulations of a Trideco antenna with aerial or buried radial ground plane showed the actual limitations of the TLM software which remains handicapped by an insufficient accuracy of the wires junction model and the inhomogeneous media interactions
Nouveau modèle TLM thermique pour la dosimétrie numérique de structures fortement hétérogènes by Oualid Makhlouf( )

1 edition published in 2016 in French and held by 1 WorldCat member library worldwide

For several years, the development of the wireless technologies using the electromagnetic waves in various applications (telecommunications, medical, military ...) does not stop increasing. Thus, it becomes necessary to evaluate the effects of the environment on antennas upstream to their conception to optimize the transmission between diverse connected objects. Furthermore, studies on the systems using the electromagnetic waves lead to ask a number of questions about waves/living interaction, obliging us to consider highly heterogeneous models such as human body.In front of difficulties of measures, the simulation allows to quantify numerically the power absorbed by tissues and the corresponding temperature rise. In this domain, the TLM method (Transmission Line Matrix) has proved to be particularly adapted to the simulation of the SAR in highly heterogeneous structures thanks to the co-localisation of the fields at the centre of mesh.In this thesis, a tool based on the TLM method to make dosimetrics studies by calculating the SAR and the temperature in highly heterogeneous media has been developed. The first step was dedicated to the development of a “module” to calculate the SAR and the implementation of an interface to read the voxelized models. Then, a thermal solver based on the TLM was developed in order to simulate the temperature in biological media exposed to the EM waves. Finally, the comparison with the commercial software CST allowed to validate our tool and to apply it afterward to study the exposure of a human head to the radiation of a Smartphone modelled by a PIFA antenna operating at 900MHz
Conception d'antennes et de circuits d'adaptation associés pour des objets communicants 4G by Aykut Cihangir( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

With the introduction of the fourth generation (4G) of cellular mobile communications, there has been an increase in the frequency bands that a generic mobile phone should be able to operate. This requirement poses some challenges in the design of the transceiver modules of the device as well as the RF front-end and the antenna. From the antenna design point of view, the newly added frequency bands especially LTE bands 12-13-17 which goes down to 700MHz creates the main design challenge: covering 700-960MHz (30% bandwidth) in the low-band, considering also backward compatibility with the former technologies like GSM850/900. Since the space reserved for the antenna is electrically small in this frequency range, special design techniques are necessary to obtain the required bandwidth for a generic mobile terminal antenna. It should also be taken into account in the design phase, that the antenna needs to be appropriate for operation in the data-rate enhancement techniques like MIMO (multiple input multiple output) and carrier aggregation in LTE-Advanced. Furthermore, considering the real use cases of the mobile terminal, the effect of the user (hand, head and both) on the antenna performance should also be investigated. In this thesis, several antenna designs for 4G coverage in mobile terminals are proposed. Different antenna topologies are evaluated consisting of tunable/passive antennas as well as single/multi-feed structures
Étude et conception d'antennes miniatures et directives à polarisation circulaire pour lecteurs RFID UHF by Sylvain Pflaum( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

RFID technology is now a part of our daily lives. The corresponding applications are more and more numerous and widespread. This work having been done in the framework of the PACID textile project, this thesis has the ambition to research innovative solutions for RFID readers in order to enhance the management, the traceability and the security of the industrial and commercial textiles.Towards this end, the antenna reader has to be miniature while being low-cost, directive and in circular polarization in the RFID UHF band (0.865-0.868 GHz). The two main technological challenges that we have faced for the reader antenna is managing its main direction of propagation to restrict and control the reading zone as well as the miniaturization of its size in order to easily integrate it into any environment. To respond to this problem, the research areas discussed in this manuscript were: The obtaining of the circular polarization using short-circuited resonators. The study and design of microstrip antennas based on EBG (Electromagnetic Band Gap). Type metamaterials to improve their directivity by using the original properties of these structures. The research of new miniaturization techniques for printed antennas by introducing a new EBG ground plane
Étude d'un système d'imagerie microonde multistatique-multifréquence pour la reconstruction d'objets enfouis by Erwan Guillanton( Book )

1 edition published in 2000 in French and held by 1 WorldCat member library worldwide

Ce travail de thèse porte sur l'utilisation du rayonnement électromagnétique pour la détection et la reconstruction d'objets ou de structures hétérogènes enfouis ou enterrés dans des milieux optiquement opaques. Un processus d'imagerie microonde se décompose en deux phases : l'acquisition des champs diffractés et l'inversion numérique de ces mesures par des algorithmes de reconstruction. Ce travail porte principalement sur le premier aspect, à savoir la mise au point d'un prototype d'imageur microonde ultra large bande (ULB) et multistatique pour éviter un déplacement mécanique ou manuel des antennes et ainsi permettre une acquisition rapide du champ diffracté sur la ligne de mesure. Les antennes ULB du système d'imagerie ont été optimisées pour des applications militaires et humanitaires (détection des mines antipersonnel), génie civil (épaisseur des chaussées, auscultation des ouvrages d'art en maçonnerie), géophysiques et archéologiques. Des résultats expérimentaux sur sites test sont présentés. Toutefois, le deuxième aspect est également abordé par l'intermédiaire du développement d'un code de modélisation 3D du problème d'interaction ondes électromagnétiques-matières résolu par une méthode de différences finies harmoniques qui permettra d'étendre au cas tridimensionnel les algorithmes d'imagerie existant au laboratoire afin de prendre en compte la polarisation de l'onde émise et de traiter des modèles plus réalistes
Conception d'antennes à base de métal liquide pour applications multiples by Mathieu Cosker( )

1 edition published in 2017 in French and held by 1 WorldCat member library worldwide

Aujourd'hui l'électronique fait partie intégrante de nos vies. En effet, de plus en plus d'objets intègrent de l'électronique permettant de les connecter, on appelle cela l'internet des objets (IoT). Tous ces dispositifs disposent d'une connectivité sans fil, rendant ainsi indispensable l'intégration d'une ou plusieurs antennes. De plus, l'électronique devant s'adapter à des objets de plus en plus petits et flexibles embarquant de plus en plus de capteurs tout en consommant de moins en moins d'énergie, il est intéressant de se pencher sur l'étude de nouveaux matériaux pour la réalisation d'antennes devant s'adapter à ces nouvelles contraintes. Dans ce cadre, nous nous sommes attachés dans ce travail de recherche, à la conception de structures antennaires à base de métaux liquides à température ambiante dans le but de réaliser des antennes conformables de formes complexes associant l'impression 3D, des antennes reconfigurables et des structures rayonnantes ayant la capacité de capteur. Dans ce manuscrit des prototypes d'antenne comportant ces caractéristiques ont été simulés, réalisés et mesurés
Une approche de modélisation au niveau système pour la conception et la vérification de systèmes sur puce à faible consommation by Ons Mbarek( )

1 edition published in 2013 in English and held by 1 WorldCat member library worldwide

Une solution de gestion de puissance d'un système sur puce peut être définie par une architecture de faible puissance composée de multiples domaines d'alimentation et de leur stratégie de gestion. Si ces deux éléments sont économes en énergie, une solution efficace en énergie peut être obtenue. Cette approche nécessite l'ajout d'éléments structurels de puissance et de leurs comportements. Une stratégie de gestion doit respecter les dépendances structurelles et fonctionnelles dues au placement physique des domaines d'alimentation. Cette relation forte entre l'architecture et sa stratégie de gestion doit être analysée tôt dans le flot de conception pour trouver la solution de gestion de puissance la plus efficace. De récentes normes de conception basse consommation définissent des sémantiques pour la spécification, simulation et vérification d'architecture de faible puissance au niveau transfert de registres (RTL). Mais elles manquent une sémantique d'interface de gestion des domaines d'alimentation réutilisable ce qui alourdit l'exploration. Leurs sémantiques RTL ne sont pas aussi utilisables au niveau transactionnel pour une exploration plus rapide et facile. Pour combler ces lacunes, cette thèse étend ces normes et fournit une étude complète des possibilités d'optimisation de puissance basées sur la composition et la gestion des domaines d'alimentation pour des modèles fonctionnels transactionnels utilisant un environnement commun USLPAF. USLPAF comprend une méthodologie alliant conception et vérification des modèles transactionnels de faible consommation, ainsi qu'une bibliothèque de techniques de modélisation et fonctions prédéfinies pour appliquer cette méthodologie
Modélisation au niveau transactionnel de l'architecture et du contrôle relatifs à la gestion d'énergie de systèmes sur puce by Hend Affes( )

1 edition published in 2015 in French and held by 1 WorldCat member library worldwide

Les systèmes embarqués sur puce (SoC) envahissent notre vie quotidienne. Avec les progrès technologiques, ils intègrent de plus en plus de fonctionnalités complexes impliquant des charges de calcul et des tailles de mémoire importantes. Alors que leur complexité est une tendance clé, la consommation d'énergie est aussi devenue un facteur critique pour la conception de SoC. Dans ce contexte, nous avons étudié une approche de modélisation au niveau transactionnel qui associe à un modèle fonctionnel SystemC-TLM une description d'une structure de gestion d'un arbre d'horloge décrit au même niveau d'abstraction. Cette structure développée dans une approche de séparation des préoccupations fournit à la fois l'interface pour la gestion de puissance des composants matériels et pour le logiciel applicatif. L'ensemble des modèles développés est rassemblé dans une librairie ClkARCH. Pour appliquer à un modèle fonctionnel un modèle d'un arbre d'horloge, nous proposons une méthodologie en trois étapes : spécification, modélisation et simulation. Une étape de vérification en simulation est aussi considérée basée sur des contrats de type assertion. De plus, nos travaux visent à être compatibles avec des outils de conception actuels. Nous avons proposé une représentation d'une structure de gestion d'horloge et de puissance dans le standard IP-XACT permettant de produire les descriptions C++ des structures de gestion de puissance du SoC. Enfin, nous avons proposé une approche de gestion de puissance basée sur l'observation globale des états fonctionnels du système dans le but d'éviter ainsi des prises de décisions locales peu efficaces à une optimisation de l'énergie
Réseaux d'antennes miniatures super-directifs reconfigurables basses fréquences pour l'IoT by Sana Souai( )

1 edition published in 2021 in French and held by 1 WorldCat member library worldwide

The Internet of Things (IoT) refers to any system where objects are connected to the Internet; it incorporates network connectivity architecture, advanced sensors and devices. According to recent research, about 30 billion objects are now collecting data and performing all sorts of tasks.The aim of this thesis is the development in a small space of a low frequency miniature and super-directive antenna array. Coupling will be taken into account in this work and the optimal weightings necessary to maximize directivity will be determined. Prototypes will also be produced to validate the simulation results. The study and 3D electromagnetic simulation of the antennas will be carried out mainly with commercial software (HFSS, CST, ...).In our first study, a switchable beam and super-directive Electrically Small Antenna (ESA) dipole deployed at an IoT network gateway at 868 MHz was presented. Reconfigurability is achieved using PIN diodes to reduce the back radiation and to steer the beam to the desired direction. The proposed structure generates a high directivity of 6.8 dBi in simulation and 6.7 dBi in measurement at 868 MHz for each beam in the azimuth plane.In the second study, we thought about improving the antenna gain previously presented. Getting inspired by the Yagi antenna structure, we added four directors to each element to enhance the directivity and to steer the main bean in two different directions. A simulated directivity of 8.5 dBi in simulation and 8.4 dBi in measurement at 868 MHz for both directions.To maintain low-side lobes, we propose the use of a Non-Foster circuit to convert positive impedance into negative impedance, as a load for the parasitic element to take into account the resistive part of the load and thus maximize the gain of the array. The other advantage with this kind of circuit is that it facilitates reconfigurability in several directions by just varying the load impedance to be converted
Étude de circuits d'alimentation actifs d'antennes imprimées by Yassine Turki( Book )

1 edition published in 2001 in French and held by 1 WorldCat member library worldwide

This work of thesis can bit spit into four main aspects. A first study has been made concerning discrete and continuous microwave phase shifters used in phased arrays antennas. The second part concerning tunable antennas exposes two antennas integrating their feeding circuit (phase shifter-amplifier) by using a multilayer structure technology, and also a parametric study concerning feeding of a shorted patch with coplanar waveguide. His work is completed by the insertion of a varator diode to control the radiating element resonance frequency and validate this type of feeding. To enhance the matching and polarization characteristics of patch antennas, two self-adjusting antennas have been developed. The first one is able to change its resonance frequency if the radiating element is inclined to be mismatched due to a perturbation in its close environment. The second antenna has the particularity to change its polarization direction depending on the received electromagnetic field. These antennas and their feedback circuits are exposed and constitute the third part of this thesis. In the last aspect study has been done concerning the possibility to control the printed reflect arrays radiation patterns by using active devices
Optimisation d'antennes et de réseaux d'antennes planaires par gradient de forme et ensembles de niveaux (Level Sets) by Zhidong Zhao( )

1 edition published in 2015 in English and held by 1 WorldCat member library worldwide

The objective of this thesis work is to find the optimal shape of planar antenna elements and arrays from imposed constraints (e.g. desired or imposed radiation patterns, gain or directivity) or to reconstruct the shape from experimental measurements. The optimization algorithm is based on the gradient-type method and an active contour reconstruction by means of the Level Set method. The forward problem is solved using an integral formulation of the EM problem with finite element discretization. The shape gradient is computed using two different methods: one is finite differential method based on nodal point mesh derivation with an infinitesimal modification of the triangular elements on the contour along the outward normal direction, another the topological shape gradient, which is computed based on a topological deformation on a contour. A narrow band level set method has been developed to evolve the contour of antennas and arrays using the deformation velocity computed from the shape gradient. Different configurations of antennas and antenna arrays are studied for investigating the performance of the optimization algorithm. Frequency hopping and multi-frequency techniques have been used for optimizing the shape within a frequency band. Shape optimization for planar antenna miniaturization has a large number of applications, particularly, for reflectarrays
Gestion des ressources et de l'énergie orientée qualité de service pour les systèmes robotiques mobiles autonomes by Dinh Khanh Ho( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

Mobile robotic systems are becoming more and more complex with the integration of advanced sensing and acting components and functionalities to perform the real required missions. For these technical systems, the requirements are divided into two categories: functional and non-functional requirements. While functional requirements represent what the robot must do to accomplish the mission, non-functional requirements represent how the robot performs the mission. Thus, the quality of service and energy efficiency of a robotic mission are classified in this category. The autonomy of these systems is fully achieved when both functional and non-functional requirements are guaranteed without any human intervention or any external control. However, these mobile systems are naturally confronted with resource availability and energy capacity constraints, particularly in the context of long-term missions, these constraints become more critical. In addition, the performance of these systems is also influenced by unexpected and unstructured environmental conditions in which they interact. The management of resources and energy during operation is therefore a challenge for autonomous mobile robots in order to guarantee the desired performance objectives while respecting constraints. In this context, the ability of the robotic system to become aware of its own internal behaviors and physical environment and to adapt to these dynamic circumstances becomes important.This thesis focuses on the quality of service and energy efficiency of mobile robotic systems and proposes a hierarchical run-time management in order to guarantee these non-functional objectives of each robotic mission. At the local management level of each robotic mission, a Mission Manager employs a reinforcement learning-based decision-making mechanism to automatically reconfigure certain key mission-specific parameters to minimize the level of violation of required performance and energy objectives. At the global management level of the whole system, a Multi-Mission Manager leveraged rule-based decision-making and case-based reasoning techniques monitors the system's resources and the responses of Mission Managers in order to decide to reallocate the energy budget, regulate the quality of service and trigger the online learning for each robotic mission.The proposed methodology has been successfully prototyped and validated in a simulation environment and the run-time management framework is also integrated into our real mobile robotic system based on a Pioneer-3DX mobile base equipped with an embedded NVIDIA Jetson Xavier platform
Étude et conception d'un nouveau système intégré à une plateforme de monitoring pour la détection des décharges partielles en UHF pour les équipements électriques by Alexandre Marchal( )

1 edition published in 2019 in French and held by 1 WorldCat member library worldwide

La société SENSeOR a développé un système dédié à la surveillance de la température pour les équipements moyenne/haute tension afin d'éviter certaines pannes pouvant avoir des conséquences majeures sur le réseau d'énergie électrique. Cependant, des phénomènes autres que l'augmentation de la température sont aussi présents dans ces équipements à l'instar des décharges partielles (DP) dont la détection permettrait d'établir un diagnostic fiable et efficace de l'état de santé de l'appareil. C'est ce que propose le travail de recherche présenté. Pour cela, nous présenterons les caractéristiques définissant l'isolation d'un système électrique et les différentes propriétés régissant le phénomène de décharge partielle. Nous exposons également les problématiques et objectifs ainsi que l'intérêt d'opter pour la méthode UHF comme méthode de détection et pourquoi cibler des topologies d'antennes de type Ultra Large Bande (ULB) en tant que capteurs de DP, et en quoi ce type d'antenne, constitue un allié fort dans la détection des DP. La conception d'une nouvelle antenne ULB imprimée et miniature adaptée au contexte de détection des DP, à savoir un environnement restreint de type cavité métallique telle qu'une cellule moyenne tension AIS (Air Insulated Switchgear) est ensuite présentée ainsi que la technique utilisée pour élargir sa bande passante. La dernière partie de ce travail est consacré à l'élaboration du système complet de détection UHF des DP avec la description des développements hardware et logiciel. Enfin, les différents tests mis en place en laboratoire et in-situ afin de valider et caractériser le système conçu sont présentés
Caractérisation de la performance temporelle et de la consommation électrique de systèmes embarqués basés sur des plates-formes multiprocesseurs/coeurs et mettant en oeuvre du logiciel temps réel : FORECAST : perFORmance and Energy Consumption AnalysiS Tool by Joffrey Kriegel( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

The number of available commercial platforms is constantly increasing. The choice of an architecture that fit as much as possible the requirements is therefore more and more complex. This is even more real with the availability of recent multiprocessors architectures. As a consequence, methodologies with their associated tools are required in order to quickly evaluate future platforms, so that choices can be made early in the design flow. So far, evaluating either the performance or the power consumption of a dedicated platform was performed through executing benchmarks and applications on this platform. In this thesis, a new methodology with its associated tools, called FORECAST, is proposed to model both the hardware and software of a system, and then to estimate its performance and its power consumption. Our methodology is based on efficient models, easy to characterize using only information provided by constructor datasheets. Moreover, our approach is able to automatically generate an executable code of the system that can be simulated on the host machine. This simulation allows a rapid execution of multiple test cases. Our approach is therefore well adapted for performing architecture exploration. A lot of experimentations have been performed using our tool FORECAST for different applications (H.264 video decoder, radio application, benchmarks. . .) and different hardware platforms. Results obtained both in performance and in power consumption have then been compared with existing platforms (OMAP3, OMAP4, i.MX6, QorIQ. . .), but also with two collaborative projects, OpenPeple (ANR) and COMCAS (Catrene), dealing also with performance and power estimations. The comparison demonstrates the accuracy of our approach as the estimation is always below a 20% error margin. These experimentations have also shown that our methodology provides a very efficient ratio between the modeling effort and the accuracy of the estimations
Conception de systèmes antennaires MIMO multi-standards LTE pour les nœuds relais by Lamia Sadaoui( )

1 edition published in 2018 in French and held by 1 WorldCat member library worldwide

To deploy the fourth generation called 4G/LTE or "LTE advanced", mobile operators face strong constraints: they must ensure a good geographic coverage but also an excellent quality of service. This requires new methods that go far beyond what has been implemented for GSM or 3G networks. The telecom industry has created the concept of "small cells" that reinforce the "macrocells" deployed by the operators. This thesis tries to provide a solution to this problem and more particularly through the development of antennas for a product called "smart cell". This study, supported by the FUI project NETCOM, should enable mobile operators to extend the coverage and capacity of their networks at a lower cost while maintaining a good quality of service. To do that, the aim of this thesis more particularly is the design of a multi-band multi-antennas MIMO system (Multiple-Input Multiple-Output) dedicated to relay nodes for the deployment of the fourth generation 4G/LTE or "LTE advanced". The antenna design considers the coverage of the three LTE operating frequency bands and must be compatible with them. The (700-900 MHz) frequency band is used for the LTE 700 and LTE 800 bands, (1710-1880 MHz) for the GSM 1800/LTE 1800 bands and the last (2500-2690 MHz) for the LTE 2600 bands. In our first study, a reference system with 4 access was studied in simulation and measured, for only the low band 700-900 MHz. In a second study, we tried to cover the other two higher bands to have a tri-band system using the parasitic elements to get a three-band MIMO system with 4 access. We studied then, the influence of the environment close to the antenna system, with the presence of a metallic radiator. As we often encounter a frequent problem in multi-antenna systems which is the coupling problem between the different access of a multi antenna system, so we have studied and realized a decoupling technique. This technique was used to enhance the isolation between the different access
Antennes implantées et système de localisation pour petits animaux utilisant la technologie RFID by Van Hieu Nguyen( )

1 edition published in 2018 in French and held by 1 WorldCat member library worldwide

The monitoring of small animals in laboratory tests and the remote analysis of their behavior, with low cost and in real time interest researchers for a long time. This can be done by implanting miniature wireless sensors requiring vital components among which the most challenging is the antenna. Indeed, the main difficulty in designing antennas for bio-implantable communication devices is to provide an effective radiating structure, despite the volume constraints and the high impact of the surrounding biological tissues. Although many studies have focused on the use of implanted antennas dedicated to the MICS band (402405 MHz), it should be noted that at these frequencies, the size of the antennas can be a real disadvantage in the case of small animals, requiring miniaturization structures. Another solution consists in the using RFID (Radio-Frequency Identification) technology in the UHF band at 868 MHz. Indeed, it has two major advantages: it facilitates the implementation of the tag and does not require the addition of a battery to power the implanted device. This thesis funded by the ANR (French National Research Agency) within the framework of the Labex UCN@Sophia aims at designing a wireless system, including implantable RFID tags, reader's antennas and the reader connected to a computer that is responsible for the centralized management of information on a server for monitoring and collecting the data of laboratory mice. This thesis presents the design of implanted antennas for RFID tags in a homogeneous model representing the body of a mouse. After an analysis of a link budget allowing to determine the minimum performance of the implanted antenna to be designed for a reliable and an efficient communication, two RFID passive tag antenna designs have been optimized to obtain final structures able to be implanted or injected in the back of a mouse. A characterization of the proposed solutions in terms of impedance, E and H fields and SAR (Specific Absorption Rate) was then performed in a homogeneous phantom. Finally, an interrogation system capable to estimate the position of several animals placed in a cage thanks to the RSSI (Received Signal Strength Indicator) levels is presented
Evaluation of power management strategies on actual multiprocessor platforms by Jabran Khan Jadoon( )

1 edition published in 2013 in English and held by 1 WorldCat member library worldwide

L'objectif de cette thèse est d'étudier l'efficacité énergétique des stratégies basse consommation pour des plateformes représentatives. Principalement, nous nous intéresserons aux stratégies énergétiques pour des systèmes embarqués multicœur en étudiant le comportement de politiques logicielles qui permettent la réduction effective de l'énergie tout en répondant aux exigences applicatives. Le travail présenté dans ce mémoire vise à étudier des stratégies de gestion de la consommation pour des plateformes monoprocesseur puis multiprocesseur concrètes. L'approche utilisée pour cette étude fut basée sur des plateformes représentatives afin d'identifier les paramètres significatifs, aussi bien au niveau matériel qu'au niveau applicatif, à l'inverse de nombreux travaux dans lesquels ces paramètres sont assez peu pris en compte voir ignorés. Ce travail analyse et compare diverses expérimentations menées sur des politiques énergétiques basées sur des techniques DVFS (Dynamic Voltage and Frequency Scaling) et DPS (Dynamic Power Switching) et définit les conditions sous lesquelles ces stratégies sont efficaces. Ces expérimentations ont permis d'établir des conclusions remarquables qui peuvent servir de pré-requis lors de la définition de stratégies efficaces de gestion de la consommation. Ces résultats montrent également que pour obtenir des stratégies efficientes il est nécessaire de tenir compte du domaine applicatif. Enfin, il faut noter que les modèles de haut de niveau de consommation ont été définis sur la base des mesures effectuées et afin d'estimer les gains énergétiques dès les premières étapes d'un flot de conception
Antennes quasi-auto-complémentaires pour terminaux mobiles multi-standards by Cédric Requin( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

Une antenne auto-complémentaire possède des caractéristiques radioélectriques très intéressantes en ce qui concerne l'élargissement de sa bande passante. Basée sur le principe de Babinet, l'auto-complémentarité permet en effet de maximiser la largeur de bande de par la complémentarité air-métal dans la structure de l'antenne. L'objectif de cette thèse est d'étudier quels pouvaient être les apports de l'auto-complémentarité dans le cas d'antennes à fortes contraintes d'intégration telles que celles utilisées pour les terminaux mobiles. Pour tester les limites de notre étude, nous avons choisi d'appliquer nos résultats à l'intégration d'antennes auto-complémentaires dans un objet communicant de type Smartphone multi-standards. Les antennes dites AC doivent par conséquent satisfaire de nombreux critères de performances tout en montrant leur capacité d'intégration. Celle-ci est rendue d'autant plus délicate, que la miniaturisation implique à son tour des phénomènes physiques limitant certaines performances, notamment en basse fréquence avec la nouvelle bande LTE. Dans une première étude, nous avons considéré différentes antennes et opté pour les antennes IFA-AC sur un plan de masse fini afin de couvrir initialement les bandes hautes DCS/PCS/UMTS et WLAN/LTE2600. Dans une seconde étude, nous avons amélioré leurs performances à l'aide d'éléments structurels nouveaux et interdépendants (éléments rayonnants de type double IFA), qui nous ont permis d'obtenir des résultats probants relatifs notamment à la couverture des bandes LTE800 et GSM. Enfin, nous avons complété notre projet en optimisant le lien radio par l'intégration de plusieurs éléments rayonnants AC sur un même PCB
Conception de systèmes multi-antennaires pour techniques de diversité et MIMO : application aux petits objets nomades communicants by Ibra Dioum( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

The transmission demand for increasing data rate becomes more and more important with the development of new services in radio communication networks. To answer to this demand, one solution consists in increasing the transmission capacity of the radio channel between the base station and the handset terminal. This can be realized by increasing the number of radiating elements involved in the transmission and the reception of this radio link: we talk about MIMO (Multiple Input Multiple Output) technique. The work realized in this thesis concerns mainly design, optimization and characterization of multi-antenna systems for MIMO and diversity techniques in LTE (Long Term Evolution) bands. Three multi bands prototypes are proposed whose two planar systems and one compact IFAs antennas system. News multiband solution and antenna position influence on the PCB were studied to realize spatial, polarization and pattern diversity with low correlation between received signals on each antenna and a good efficiency. The neutralization line was used for antennas isolation and its application in multiband was realized. The antenna load impedance has been studied with Youla & Carlin method in order to improve the frequency bandwidth of the compact IFA structure. Diversity and MIMO performances of these systems were evaluated in different propagation environments. They show that these systems can be effectively used for diversity and MIMO application
Étude et minimisation du facteur de qualité des antennes pour de petits objets communicants by Oumy Diop( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

Currently, wireless devices play an important role in everyday life. For ease-of-use, these devices are becoming smaller and require very small antennas. However, the size reduction of these antennas necessarily implies a degradation of their performance. Consequently, the design of electrically small antennas (ESA) requires a very good theoretical understanding of the electromagnetic phenomenon that takes place, especially in terms of accurate performance that can be expected for an ESA with given dimensions. An important parameter of an ESA is its intrinsic quality factor since it is inversely proportional to its impedance bandwidth. Indeed, maximizing the matching bandwidth of an antenna consists in minimizing its quality factor. Facing this problem, many researches have been developed to determine the possible limits of the quality factor of ESA. The first research axis of this thesis is to study the quality factor of ESA to determine whether optimal dimensions exist to approach the fundamental quality factor limits. The second part of the thesis studies miniature antennas for biomedical implants operating at 2.45 GHz. These antennas are printed on a specific microelectronic substrate to ensure a better resolution in terms of metallic traces in order to reduce the size and allow easier integration to facilitate interconnections with RF front-end. The challenge consists in maximizing the performance of these antennas. The presented results are supported by means of electromagnetic models and simulations on one hand. Also, several prototypes are fabricated to validate these simulations
 
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Alternative Names
Centre national de la recherche scientifique (France). Unité de recherche associée (D 1400)

Centre national de la recherche scientifique (France). Unité mixte de recherche (6071)

Centre national de la recherche scientifique (France). Unité mixte de recherche (7248)

LEAT

Université Côte d'Azur. Laboratoire d'électronique, antennes et télécommunications

Université de Nice-Sophia Antipolis. Laboratoire d'électronique

Université de Nice-Sophia Antipolis. Laboratoire d'électronique, antennes et télécommunications

Languages
French (15)

English (5)