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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

An Economic Model of Subscriber Offloading Between Mobile Network Operators and a WLAN Operator

Patterson, Cameron Webster 03 November 2014 (has links)
With increasing mobile data demand there is a push towards heterogeneous networks. Small-scale operators (SSOs) of WLANs are becoming more prevalent, while Mobile Network Operators (MNOs) seek an outlet for their customers' data usage. These conditions prompt the need for an effective relationship between the two parties for the purpose of offloading cellular data traffic to WLANs in a way that is economically beneficial to all involved. This thesis presents a model of such a relationship, in which the SSO sets a strategic offloading price per subscriber and several MNOs can choose how many subscribers they want to offload in order to minimize their costs. We determine the optimal offloading price, identify how the SSO incorporates its own network's quality of service (QoS) into its price decision, and examine the way in which the MNOs' cost structures affect their ability to offload. This model can be applied by both MNOs and SSOs to make informed network deployment decisions, even before engaging in an offloading relationship. / Master of Science
232

Network-assisted positioning in confined spaces : A comparative study using Wi-Fi and BLE

Leifsdotter, Emelie, Jelica, Franjo January 2024 (has links)
This thesis compares and evaluates the accuracy of two RSSI-based tri-lateration methods in an indoor setting, implementing either Wi-Fi andBluetooth Low Energy (BLE) while using commercially available hardware.The purpose of evaluation is part of the long-term vision of improving thesafety of workers in adverse environments such as factories, by providing awearable Indoor Positioning System where other systems like GPS are notsuitable due to signal obstruction. Within a confined space replicating in-tended real-world conditions in terms of signal attenuation and adversity,30 consecutive measurements of signal strength readings (RSSI) to threereference nodes were collected at 10 randomized sample positions, andwas repeated across 5 tests. The accuracy of trilateration was evaluatedusing an averaged Root Mean Square Error (RMSE) over the five tests. Itwas observed that RSSI using Wi-Fi achieved better accuracy of predictingthe actual position within the testing environment than signal-strength us-ing BLE, with Wi-Fi and BLE achieving an accuracy of 0.88 and 1.85 metersrespectively. However, because of the power efficiency of BLE it is a viablecandidate for a future low-cost and device-based Indoor Localization Sys-tem to potentially be used and worn by workers. The results while alignedwith similar existing literature, infer what a low-cost indoor positioningsystem might achieve. Future research with the goal of developing suchsolutions could benefit from implementing both Wi-Fi and BLE as the basisof signal strength trilateration.
233

Passive antenna systems printable on conformable supports / Système passif antennaire imprimable sur support conformable

Nguyen, Hong Duc 23 May 2018 (has links)
Au cours des dernières années, en raison de la demande croissante de produits de plus enplus légers, plus petits et moins chers à l'intérieur des appareils portables, l'électronique flexible émerge sur le marché commercial comme une nouvelle génération d'électroniques. Les substrats rigides conventionnels sont remplacés par des matériaux plus minces, flexibles et à faible coût tels que papier, polymère, plastique pour la fabrication des composants et circuits. En même temps, les futurs boîtiers électroniques demandent de plus en plus de nombreux systèmes sans fil afin d'offrir de multiples services et applications (ZigBee/Z-Wave, WLAN, DECT, Bluetooth, RF4CE, 3G/4G, etc.). À cause de l'intégration d'un très grand nombre d'antennes pour satisfaire l'opération de toutes ces applications, les connectivités deviennent donc un grand défi pour les exigences de coût. C'est pourquoi on voudrait remplacer l'ensemble du système d'alimentation/d'interconnexion à la carte mère PCB par une technologie homogène, collective. Ce travail de thèse vise à développer une nouvelle technologie "verte" et faible coût dédiée à la conception et réalisation de systèmes antennaires et d'interconnexions sur les matériaux flexibles (tels que papier) à base d'encres conductrices et de procédés de fabrication additifs comme impression. Le défi scientifique est de concevoir des systèmes antennaires répartis spatialement sur les faces internes en plastique du boîtier électronique sous forme des stickers RF 3D et connectés directement à la carte PCB par une solution innovante, à faible coût pour des applications multimédia sans fil dans la gamme de fréquences de 1.8-6 GHz. / In recent years, due to the growing demand for lighter, smaller and cheaper electronic products Inside portable devices, clothing and packaging materials, flexible electronics is emerging on the commercial market as a new generation of electronics. Conventional rigid substrates will be replaced by thin, flexible, low-cost materials such as paper, polymer, and plastic for the manufacturing of components and circuits. Concurrently with the powerful development of flexible electronics, the future electronic devices have drastically demanded more wireless systems in order to offer multiple services and applications (ZigBee/Z-Wave, WLAN, DECT, Bluetooth, RF4CE, 3G/4G, etc.). Because of the integration of a great number of antennas to satisfy the operation of all these applications, the connectivities thus become a big challenge for cost constraints. This is the reason why we would like to replace the entire interconnection system with the PCB mainboard by a homogeneous, collective technology.This thesis work aims at developing "green", low-cost and innovative technology devoted to the design and realization of antenna systems and interconnections on flexible materials (such as paper) based on conductive inks and additive manufacturing processes like printing. The scientific challenge lies on the design of spatially distributed antenna systems on the internal plastic sidewall of the electronics box in the form of 3D RF stickers and directly connected to the PCB mainboard by an innovative, low-cost solution for wireless multimedia applications in the frequency range of 1.8-6 GHz.
234

Biochemical composition of protists

Boëchat, Iola Gonçalves 08 March 2005 (has links)
Trotz der Schlüsselstellung heterotropher Protisten als Bindeglied zwischen dem mikrobiellen und dem klassischen Nahrungsnetz ist noch wenig über ihre biochemische Zusammensetzung und ihren Nährwert bekannt. In der vorliegenden Doktorarbeit wurde untersucht ob die biochemische Zusammensetzung von Protisten (1) von deren Nahrungsgrundlage (Alge oder Bakterien) und Ernährungsweise (Autotrophie, Mixotrophie oder Heterotrophie) abhängt und (2) ihre Nahrungsqualität für räuberisches Rotatorien (Keratella quadrata) bedingt. Die Fettsäure-, Sterol- und Aminosäurezusammensetzung vier heterotropher Protisten spiegelte generell die ihrer Nahrung wider. Es trat jedoch eine Akkumulation dieser biochemischen Substanzen in den Protisten auf. Auch die Ernährungsweise eines Flagellaten (Ochromonas sp.) beeinflusste stark dessen biochemische Zusammensetzung, insbesondere die Konzentrationen an mehrfach ungesättigten Fettsäuren (PUFAs). Bei der Untersuchung des Nährwertes vier heterotropher Protisten für K. quadrata wurden signifikante Korrelationen zwischen verschiedenen PUFAs, drei Sterolen und einer Aminosäure (Leucin) der Protisten und der Eiproduktion der Rotatorien festgestellt. Auch die experimentelle Supplementierung eines Flagellaten mit einer PUFA (Docosahexaensäure, DHA) erhöhte seinen Nährwert für die Rotatorien signifikant. Die Ergebnisse verdeutlichen die Fähigkeit heterotropher Protisten, die biochemische Zusammensetzung organischer Materie schon auf einer unteren Ebene des aquatischen Nahrungsnetzes zu verändern, nämlich beim Übergang zwischen Algen/Bakterien und dem Mesozooplankton. Hier können biochemische Änderungen weitreichende Folgen für den Stoff- und Energiefluß des gesamten Nahrungsnetzes nach sich ziehen. / Heterotrophic protists are an important link between the microbial and the classical food web. However, little is known about their biochemical composition and nutritional quality as prey. In this thesis, I analysed (1) whether the biochemical composition of the protists depends on their dietary resources (bacterial or algal food) or trophic mode (autotrophy, mixotrophy or heterotrophy), and (2) whether the biochemical composition of protists determines their nutritional quality as prey for a rotifer species (Keratella quadrata). The fatty acid, sterol, and amino acid composition of four heterotrophic protists generally resembled the dietary composition, but the protists accumulated these compounds. Moreover, the trophic mode strongly affected the composition of a flagellate (Ochromonas sp.), especially that of polyunsaturated fatty acids (PUFAs). When investigating the nutritional quality of four protist species for K. quadrata, several PUFAs, three sterols (desmosterol, ergosterol, stigmastanol), and one amino acid (leucine) of the protists were significantly correlated with the rotifer’s egg production. Moreover, the nutritional quality of a heterotrophic flagellate for the rotifer was significantly enhanced by artificially supplementing the flagellate with a PUFA (docosahexaenoic acid, DHA). The thesis highlights the ability of heterotrophic protists to modify the biochemical composition of organic matter at an early stage in aquatic food webs, i.e. at the interface between algae/bacteria and mesozooplankton. Biochemical modifications at this stage may profoundly affect matter and energy transfer through the entire food web.
235

Human impacts on the structure and ecological function of littoral macroinvertebrate communities in lakes

Brauns, Mario 15 July 2009 (has links)
Das litorale Makrozoobenthos ist eine bedeutende biotische Komponente in Seen und trägt substantiell zur Biodiversität und Funktion von Seeökosystemen bei. Allerdings unterliegt das Litoral zunehmenden anthropogenen Nutzungen, deren ökologische Auswirkungen jedoch kaum quantifiziert wurden. In dieser Doktorarbeit wurde untersucht, welche Bedeutung maßgebliche Umweltfaktoren auf die Zusammensetzung des litoralen Makrozoobenthos haben, und wie sich anthropogene Nutzungen auf die Zusammensetzung und Funktion des Makrozoobenthos auswirken. Die Zusammensetzung des Makrozoobenthos wurde durch die Uferstruktur, Trophie und das hydrodynamische Regime bestimmt. Die faunistische Ähnlichkeit zwischen Habitaten war jedoch signifikant geringer als zwischen Trophiestufen, so dass die Uferstruktur, und nicht die Trophie, einen größeren Einfluss auf das Makrozoobenthos hat. Strukturelle Degradation führte zu einer Reduktion der Habitatheterogenität, was eine signifikante Verringerung der Diversität und eine signifikant veränderte Artenzusammensetzung verursachte. Infolgedessen war die Komplexität der Makrozoobenthos-Nahrungsnetze an degradierten Ufern signifikant geringer als an natürlichen Ufern. Erhöhte Wasserstandsschwankungen führten zum Ausfall von Wurzelhabitaten und der damit assoziierten Makrozoobenthos-Gemeinschaft. Schiffsinduzierter Wellenschlag führte zur Verdriftung des Makrozoobenthos von ihren Habitaten bereits bei geringen Sohlschubspannungen. Die Effekte von Wasserstandsschwankungen und schiffsinduziertem Wellenschlag wurden jedoch durch Habitate mit hoher struktureller Komplexität verringert. Mit dieser Doktorarbeit konnte ich ein mechanistisches Verständnis darüber erarbeiten, wie anthropogene Nutzungen die Wirkungsbeziehungen zwischen Umweltfaktoren und Artengemeinschaften verändern und welche ökologischen Auswirkungen dies hat. Diese Kenntnisse können als wissenschaftliche Basis zur Bewertung von anthropogenen Beeinträchtigungen des Litorals dienen. / Littoral macroinvertebrates are an important biotic component of lakes by contributing substantially to the biodiversity and functioning of lake ecosystems. Humans alter the littoral and riparian areas for various purposes, but the resulting ecological impacts on littoral macroinvertebrates have not been quantified. In this thesis, I investigated the significance of key environmental factors for littoral macroinvertebrate communities and how human alterations of these environmental factors impact the structure and function of macroinvertebrate communities. Macroinvertebrate community composition was significantly related to littoral structure, trophic state and the hydrodynamic regime. The significantly higher compositional dissimilarities among habitats than among trophic state suggested that littoral structure was the more important driver of community composition. Structural degradation caused a significant reduction of habitat heterogeneity and resulted in a significant reduction of species diversity and a significant altered community composition. This caused a significant reduction of macroinvertebrate food web complexity and substantial alterations of the trophic base of the food webs. Climate-change induced water level fluctuations resulted in the loss of root habitats and the specific community associated with this habitat. Ship-induced waves had substantial direct effects, since macroinvertebrates were detached from their habitats by waves even at moderate shear stress levels. However, the impacts of water level fluctuations and ship-induced waves were mitigated by the presence of habitats with high structural complexities. This thesis provided a mechanistic understanding of how human activities alter relationships between environmental factors and biotic communities. This knowledge can be used to develop scientifically sound approaches to assess the persistent human impacts on lake ecosystems.
236

Influence of turbidity on social structure in guppies, Poecilia reticulata

Borner, Karoline 17 October 2016 (has links)
Umweltveränderungen kommen natürlicherweise vor und viele Spezies waren im Laufe ihrer Evolutionsgeschichte davon betroffen. Durch die Aktivitäten des Menschen jedoch finden diese in höherer Geschwindigkeit und größerem Umfang statt und stellen so für viele Spezies eine neue Herausforderung dar. Einen großen Einfluss auf die Umwelt nimmt der Mensch durch Verschmutzung, welche zu Veränderungen der Physiologie der Organismen und deren Verhalten führen und damit Einfluss auf die Populationsdynamik und letztendlich auf die Biodiversität haben kann. In meiner Dissertation untersuchte ich den Einfluss durch Bergbau ausgelöster Trübung auf das Verhalten und die soziale Struktur des Guppys. Er nutzt soziale Interaktionen für eine höhere Effizienz bei der Nahrungssuche und Räubervermeidung. Die Nutzung sei-nes dafür eingesetzten Sehsinns ist bei Trübung stark eingeschränkt. Ich untersuchte die Reaktion Trübung unerfahrener Fische aus Labor und Feld auf Trübung. Es zeigte sich, dass beide ihre sozialen Interaktionen in trübem Wasser verringerten. Eine zusätzliche Markow-Ketten-Analyse ergab aber auch, dass Laborfische Kontakte zu bestimmten In-dividuen der Gruppe verstärkten und Feldfische ihre initiierten Kontakte behielten. An-schließend studierte ich den Unterschied der sozialen Struktur Trübung erfahrener und - unerfahrener Fische. Trübung erfahrene Fische erhöhten die Gesamtzahl der Interaktio-nen, reduzierten jedoch die Anzahl der initiierten Kontakte im Gegensatz zu unerfahre-nen Fischen. Diese Strukturänderung, vermute ich, erhöht den Zusammenhalt und damit den In-formationsfluss im Schwarm. Die Ergebnisse von Folgeversuchen, nämlich der Erhalt der Paarungsanzahl und die effektivere Vermeidung einer Räuberattrappe bei Trübung er-fahrenen Fischen, unterstützen diese Vermutung. Die Arbeit zeigt, dass Guppys in der Lage sind, sich durch Änderung Ihrer sozialen Struktur an trübe Verhältnisse anzupas-sen. Dies könnte auch Einfluss auf ihre Populationsstruktur haben. / Most species have been subjected to environmental changes during their evolutionary history. However, due to human activity, environmental changes are currently occurring at higher speeds and on a greater scale, presenting new challenges for many species. Pollution, as a major type of human-induced environmental change, may not only affect physiology but also behaviour, thereby affecting population dynamics and consequently biodiversity. The topic of my dissertation is the effect of turbidity from quarrying on the behaviour and social association pattern of the guppy (Poecilia reticulata). Turbidity impairs the fish’s ability to use visual cues during social interactions, which in turn helps increases efficiency of foraging and avoiding predators. I investigated the initial re-sponse of guppies to turbidity and subsequently tested whether turbidity-experienced vs turbidity-inexperienced populations differ in their social association patterns and how they cope with ecological challenges. Both lab-reared and wild-caught guppies that were inexperienced with turbidity reduced social associations in turbid water in con-trast to turbidity-experienced fish. A Markov chain analysis revealed that lab-reared guppies increased associations with particular neighbours. Similarly, wild-caught gup-pies maintained the number of initiated associations under turbid conditions. The in-crease in non-initiated associations suggests a stronger connectivity within the shoal, leading to higher information transmission in a poor visual environment. Additional results showed that this altered social structure enabled turbidity-experienced fish to maintain the frequency of mating attempts in turbidity and to avoid predation risk. This suggests that guppies have the ability to adjust to turbidity, but with major changes in their social structure, which might have an impact on population dynamics.
237

應用Wi-Fi與GPS技術於室外定位之研究 / Study on Outdoor Positioning With Wi-Fi/GPS

郭清智 Unknown Date (has links)
由於可攜式行動裝置近年來快速成長,隨著行動裝置與地理資訊的結合發展出的適地性服務 (Location-Based Service, LBS),也呈現越來越多的應用方式。LBS最基本的功能為定位,定位精度好壞也影響著LBS的應用面,越高的定位精度應用面越廣。常見的定位方式便是用GPS導航定位,但是在都會地區越是繁榮的地方往往過多的建物使衛星訊號被阻擋,導致GPS的定位會受到影響,造成平面誤差量會在15公尺以上,或是無法定位。利用都市區域有Wi-Fi訊號分布的特性,藉由區分不同的Wi-Fi訊號來源與接收強度,做出定位判斷,可以使原本GPS無法定位的區域,也可以利用Wi-Fi訊號來做定位。本研究嘗試使用高感度GPS接收器,在建物周邊定位,及在GPS無法運作時使用Wi-Fi訊號來做定位依據,提高整體的定位成功率,並嘗試利用Wi-Fi定位與GPS協同運作來提高整體精度。Wi-Fi定位採用訊號紋辨識法,欲使用訊號紋辨識法必先建立Wi-Fi訊號資料庫,包含地理坐標與對應的訊號來源與強度分布。實驗區為政治大學山下校區綜合院館四周面積約1.76公頃區域,模擬被遮蔽狀況下的GPS導航定位精度,配合Wi-Fi定位來輔助GPS定位結果。結果顯示利用兩種定位系統,可使平面平均定位誤差小於10公尺,高程平均定位誤差小於1.5公尺。 / The positioning accuracy is an important issue for Location-Based Service (LBS). LBS has many products, and its applications are usually based on Global Positioning System (GPS), because GPS navigation has been very mature. GPS has a typical outdoor positioning error of up to 15 meters for civilian users. Hence it has become a viable method for civilian to carry out coarse positioning. However, it has its shortcomings. GPS is available only in outdoors with a clear view of the sky. Since Wi-Fi (Wireless Fidelity) has become another positioning technology which is capable of performing positioning in indoor environments and urban canyons. Wi-Fi positioning is using fingerprinting in this study. This study is desirable to integrate GPS and Wi-Fi positioning technologies for ubiquitous positioning. The related issues of Wi-Fi/GPS technologies, such as database quality, analysis of algorithms, and database processing procedures were studied. Test data sets from National Chengchi University (NCCU) campus will be used to test the proposed algorithms. By using those two positioning system , it is revealed that the positioning accuracy made at the test sites resulted that the 2D coordinate average error is less than 10 meters, elevation positioning average error is less than 1.5 meters.
238

Internet of Things & Kommunikationsprotokoll / Internet of Things & Communication Protocol

Sabel, Ida January 2015 (has links)
Genom att studera olika kommunikationsprotokoll kunna svara på vad det är som gör att ett visst protokoll är bäst anpassat för att användas mellan mobila enheter och IoT-enheter. I arbetet användes en kvalitativ litteraturstudie för att ge en grundlig teoretisk bakgrund samt en experimentell studie där ett par teorier undersökts ifall de stämmer med resultaten ifrån verkligheten. De fem faktorerna kompatibilitet, batteritid, frekvens, räckvidd och tillförlitlighet undersöktes hos kommunikationsprotokollen Bluetooth Low Energy (BLE), Närfältskommunikation (NFC) och Wi-Fi. Dessa tre valdes eftersom de stöds av nyare mobila plattformar idag. Kommunikations-protokollen analyserades sedan gentemot olika användningsområden inom IoT, eftersom påståendet vad som är bäst anpassat beror på vad situationen kräver för egenskaper. En systemutvecklare som ska välja kommunikationsprotokoll till en IoT-tillämpning och läser denna rapport bör själv jämföra de olika protokollen mot varandra inom de fem faktorerna för att kunna avgöra vilket protokoll som passar bäst inom dennes situation. I arbetet utfördes endast experimentella studier på BLE på grund av begränsningar inom utrustningen. Ytterligare experiment inom NFC och Wi-Fi skulle ge ett bredare perspektiv med fler infallsvinklar. / By studying different communication protocols respond to what it is that makes a certain protocol best suited for use between mobile devices and IoT devices. This study used a qualitative literature study to create a proper theoretical background and an experimental study where two theories were investigated in whether they matched wih the results from the reality. The five factors compatibility, battery loss, frequency, range and reliability were investigated in the communication protocols Bluetooth Low Energy (BLE), Near field communication (NFC) and Wi-Fi, these three because they are supported by newer mobile platforms today. The communication protocols were then analysed against various uses in the IoT, since the claim what it is that makes it best suited depends on what the situation requires. A system developer that is about to select the communication protocol to use in an IoT application and reads this study should compare the different protocols to each other within the five factors to determine which protocol is best suited for his situation. This study only performed experimental studies on BLE because of limitations in the equipment. Additional experiments on NFC and Wi-Fi would provide a wider perspective.
239

Etude par simulation et mesure d'un système d'exposition d'animaux aux ondes radioélectriques induites par les systèmes wi-fi / Study by simulation and measure of a system of exhibition of animals in the radio waves led by the Wi-Fi systems

Wu, Tongning 20 February 2009 (has links)
Ce travail de thèse consiste en la conception et l'analyse d’un système d'exposition des animaux in vivo avec les signaux Wi-Fi dans une chambre réverbérante. La nouvelle méthode d'excitation est appliquée avec 6 antennes qui fonctionnent aléatoirement pour avoir un champ plus homogène et des ondes venant de toutes les directions. Cette configuration permet d'éviter une grande taille du brasseur de la chambre réalisée. La répartition de puissance chez les rats est étudiée par la méthode hybride de simulation-mesure. La puissance incidente est enregistrée de même que le champ au centre de la chambre. Le rapport de la puissance incidente sur E carré moyenné est déterminé. La méthode FDTD est choisie pour la simulation et permet d’analyser la répartition de la puissance absorbée par les rats. La distribution du champ dans la chambre suit une statistique de Rayleigh comme il a été prouvé par les études et les mesures. Donc, la boîte de Huygens est utilisée pour émettre des ondes planes aléatoires (avec les paramètres suivant distribution Rayleigh) et exposer les rats. On peut alors obtenir le rapport de DAS pour le corps entier chez les rats sur E carré moyenné dans la chambre. Donc il est possible de relier le DAS corps entier chez les rats et la puissance d’entrée dans la chambre à E carré moyenné. Une autre méthode de simulation est aussi appliquée pour vérifier ce résultat. L’évaluation de la variabilité des résultats pour plusieurs paramètres à différents âges des rats est effectuée. En générale, les sources de variabilité sont classifiées selon trois parties : simulation, mesure, et interface entre les deux. Le DAS corps entier chez les rats pendant toute la période d’exposition avec le domaine de variabilité sont présentés dans ce travail. Cette étude pourra être utilisée afin d'évaluer des résultats d’une exposition à long terme des animaux. Elle pourra aussi servir à caractériser le champ dans des environnements domestiques et urbains / This thesis dedicates to design and analysis for the animal in vivo Wi-Fi exposure system by reverberation chamber. 6 random functioned antennas are deployed in the reverberation chamber to radiate the rats with homogenous field and Omni-direction waves. So, there is no significant size stirrer in the system. Power absorption by rats is studied by the simulation-measurement hybrid method. In this method, by measurement, incident power and the mean squared E in the system are recorded. The ratio these factors are obtained. For simulation, FDTD is chosen to analyse the power absorption by the rats. E distribution in reverberation chamber is proved as Rayleigh statistics by studies and measurements. One Huygens box is constructed to radiate the rats. There is no need to realise the wall, the antennas and the accessories of the system. So the whole body averaged SAR can be obtained with the mean squared E in the chamber. Then whole body averaged SAR is linked with the incident power. One other method has also been applied to verify the results. Evaluation of the result variability depending on different parameters of rats with different ages is performed. The variability comes from simulation, measurement and interface between these two parts. Whole body averaged SAR with the variability domain on function of the rat's age is presented in this thesis. This work can be used to evaluate the long term animal exposition. It can also serve to characterise the field in modern domestic and urban environments
240

Modélisation et optimisation de la consommation énergétique d'un système de communication Wi-Fi / Modeling and optimization of the energy consumption of a Wi-Fi communication system

Benali, Wissem 17 October 2017 (has links)
La forte augmentation du nombre de terminaux connectés ces dernières années et l'utilisation croissante des technologies de communication impacte de manière non négligeable la facture énergétique. Pour enrayer cette augmentation de la consommation énergétique, il devient primordial de pouvoir comparer en termes de consommation les algorithmes de communications numériques, afin de développer l'architecture de transmission la moins énergivore. Dans cette thèse, la couche physique des standards Wi-Fi IEEE 802.11ac est analysée sous un angle énergétique. La puissance dissipée dans les circuits pour faire fonctionner les algorithmes de traitement de signal est prise en compte en plus de la puissance d'émission d'antenne classique. La méthodologie mise en œuvre inclut à la fois des simulations et des développements sur plateforme matérielle (FPGA), permettant d'obtenir des évaluations de la consommation plus réalistes. Nous avons dans un premier temps analysé de façon isolée les éléments composant les chaines de communications numériques. Puis nous avons intégré les périodes d'activité et d'inactivité de chaque élément dans le calcul de la consommation énergétique globale des chaines. Nous proposons une méthode pratique et efficace d'estimation de la consommation, incluant une base de données issue de simulations, et une analyse théorique des taux d'activité de chaque élément de la chaine. Ces résultats permettent d'analyser la répartition de la consommation en puissance des éléments composant les émetteurs et les récepteurs, et de comparer diverses architectures et jeux de paramètres. En particulier, nous avons évalué l'impact de deux architectures de Transformées de Fourier Rapides sur la consommation globale du système. / The strong increase of the number of connected devices in recent years and the increasing use of communication technologies has a significant impact on the energy bill. To stop the increase in energy consumption, it is essential to be able to compare the digital communication algorithms in terms of consumption, in order to develop the most energy-efficient transmission architecture.In this thesis, the IEEE 802.11ac Wi-Fi standard of physical layer is analyzed at an energy point of view. The power dissipated in the circuits for operating the signal processing algorithms is taken into account in addition to the antenna transmission power. The implemented methodology includes both simulations and developments on a hardware platform (FPGAs), resulting in more realistic consumption assessments.First, we analyzed separately the components of the digital communications chains. Then we integrated the periods of activity and inactivity of each element in the calculation of the global energy consumption of the chains. We propose a practical and efficient method of estimating consumption, including a database derived from simulations, and a theoretical analysis of the activity rates of each element of the chain.These results make it possible to analyze the distribution of the power consumption of the elements composing transmitters and receivers, and to compare various architectures and sets of parameters. In particular, we evaluated the impact of two Fast Fourier Transform architectures on overall system consumption.

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