L’arrivée de la prochaine technologie 5G va permettre la connectivité des billions de terminaux mobiles et donc une énorme augmentation du trafic de données. A cet égard, les fournisseurs des services Cloud doivent posséder les infrastructures physiques capables de supporter cette explosion de trafic. Malheureusement, les architectures filaires conventionnelles des centres de données deviennent staturées et la congestion des équipements d’interconnexion est souvent atteinte. Dans cette thèse, nous explorons une approche récente qui consiste à augmenter le réseau filaire du centre de données avec l’infrastructure sans fil. En effet, nous exploitons une nouvelle technologie émergente, la technologie 60 GHz, qui assure un débit de l’ordre de 7 Gbits/s afin d’améliorer la QoS. Nous concevons une architecture hybride (filaire/sans fil) du réseau de centre de données basée sur : i) le modèle "Cisco’s Massively Scalable Data Center" (MSDC), et ii) le standard IEEE 802.11ad. Dans une telle architecture, les serveurs sont regroupés dans des racks, et sont interconnectés à travers un switch Ethernet, appelé top-of-rack (ToR) switch. Chaque ToR switch possède plusieurs antennes utilisées en parallèle sur différents canaux sans fil. L’objectif final consiste à minimiser la congestion du réseau filaire, en acheminant le maximum du trafic sur les canaux sans fil. Pour ce faire, cette thèse se focalise sur l’optimisation du routage et de l’allocation des canaux sans fil pour les communications inter-rack, au sein d’un centre de données hybride (HDCN). Ce problème étant NP-difficile, nous allons procéder en trois étapes. En premier lieu, on considère le cas des communications à un saut, où les racks sont placés dans le même rayon de transmission. Nous proposons un nouvel algorithme d’allocation des canaux sans fil dans les HDCN, qui permet d’acheminer le maximum des communications en sans-fil, tout en améliorant les performances réseau en termes de débit et délai. En second lieu, nous nous adressons au cas des communications à plusieurs sauts, où les racks ne sont pas dans le même rayon de transmission. Nous allons proposer une nouvelle approche optimale traitant conjointement le problème du routage et de l’allocation de canaux sans fils dans le HDCN, pour chaque communication, dans un mode online. En troisième étape, nous proposons un nouvel algorithme qui calcule conjointement le routage et l’allocation des canaux pour un ensemble des communications arrivant en mode batch (i.e., par lot). En utilisant le simulateur réseau QualNet, considérant toute la pile TCP/IP, les résultats obtenus montrent que nos propositions améliorent les performances comparées aux méthodes de l’état de l’art / The high proliferation of smart devices and online services allows billions of users to connect with network while deploying a vast range of applications. Particularly, with the advent of the future 5G technology, it is expected that a tremendous mobile and data traffic will be crossing Internet network. In this regard, Cloud service providers are urged to rethink their data center architectures in order to cope with this unprecedented traffic explosion. Unfortunately, the conventional wired infrastructures struggle to resist to such a traffic growth and become prone to serious congestion problems. Therefore, new innovative techniques are required. In this thesis, we investigate a recent promising approach that augments the wired Data Center Network (DCN) with wireless communications. Indeed, motivated by the feasibility of the new emerging 60 GHz technology, offering an impressive data rate (≈ 7 Gbps), we envision, a Hybrid (wireless/wired) DCN (HDCN) architecture. Our HDCN is based on i) Cisco’s Massively Scalable Data Center (MSDC) model and ii) IEEE 802.11ad standard. Servers in the HDCN are regrouped into racks, where each rack is equipped with a: i) Ethernet top-of-rack (ToR) switch and ii) set of wireless antennas. Our research aims to optimize the routing and the allocation of wireless resources for inter-rack communications in HDCN while enhancing network performance and minimizing congestion. The problem of routing and resource allocation in HDCN is NP-hard. To deal with this difficulty, we will tackle the problem into three stages. In the first stage, we consider only one-hop inter-rack communications in HDCN, where all communicating racks are in the same transmission range. We will propound a new wireless channel allocation approach in HDCN to hardness both wireless and wired interfaces for incoming flows while enhancing network throughput. In the second stage, we deal with the multi-hop communications in HDCN where communicating racks can not communicate in one single-hop wireless path. We propose a new approach to jointly route and allocate channels for each single communication flow, in an online way. Finally, in the third stage, we address the batched arrival of inter-rack communications to the HDCN so as to further optimize the usage of wireless and wired resources. For that end, we propose: i) a heuristic-based and ii) an approximate, solutions, to solve the joint batch routing and channel assignment. Based on extensive simulations conducted in QualNet simulator while considering the full protocol stack, the obtained results for both real workload and uniform traces, show that our proposals outperform the prominent related strategies

A evolução dos sistemas de comunicação sem fio ou wireless apresentam até agora três gerações em menos de duas décadas. Fazendo parte desta evolução estão os sistemas de telefonia celular e os emergentes Sistemas de Comunicação Pessoal ou PCS (Personal Communications Systems). Este trabalho visa apresentar duas questões importantes na evolução destes sistemas, primeiro a questão da segurança e segundo a questão da interconexão com redes heterogêneas. No trabalho, abordando a questão de segurança, são estudados, analisados e comparados os mecanismos de autenticação e privacidade implementados nos atuais padrões de telefonia celular digital e analógico, como sistemas AMPS (celular analógico americano), USCD (celular digital americano) e GSM (celular digital europeu). São identificadas a vulnerabilidade e os fraudes mais comuns nestes sistemas. Também são analisados as propostas das recentes pesquisas e o state of art em termos de segurança, para os sistemas PCS emergentes. Como conclusão apresentado um quadro comparativo resumindo as principais características de segurança adotados pelos sistemas abordados neste estudo. Uma vez apresentado os aspectos de segurança em forma isolada para cada um dos sistemas acima mencionados, é apresentado a questão segurança no contexto da interconexão com redes heterogêneas. A interconexão com redes heterogêneas é outro problema a ser resolvido na implementação da terceira geração de sistemas wireless, para fornecer o roaming automático e a mobilidade pessoal e de terminal. Neste trabalho são revisados os protocolos de sinalização SS7 (Signaling System Number 7) e MAP (Mobile Application Part), como requisitos importantes na solução da interconexão e interoperabilidade entre as redes fixas atuais com as futuras redes móveis. Como conclusão deste estudo é apresentado a proposta de uma arquitetura de protocolos de sinalização, representando a interconexão de um sistema PCS baseado no padrão J-STD-007, com a rede de telefonia celular IS-95. Esta interconexão é realizada através de uma interface de rede denominada IIF (Interworking and Interoperability Function) usando protocolos de sinalização por canal comum SS7 e MAP. Finalmente são apresentados as conclusões quanto aos objetivos alcançados, e é proposto um trabalho futuro, tomando como base o desenvolvido neste trabalho. / The evolution of wireless communications systems has developed into the third generation which is mainly represented by the Telephone Cellular Systems and PCS (Personal Communication systems). This work presents an overview about two importante issues in the evolution of the Wireless Communication Systems: Security and Interworking. Initially we carry out our study on the wireless communication security issue by analyzing and comparing some major authentication features and privacy characteristics implemented in the currently standardized cellular phone systems such as AMPS (American Analog Cellular), USCD (American Digital Cellular) and GSM (Euroupean Digital Cellular). For this end. we tentatively determine how vulnerable to the fraudulent attacks these systems are and what are those frauds commonly occurring in these systems. Also we analyze the state of art and some proposals for security problems in PCS systems found in the literature. We conclude our preliminary study with a table summarizing some principal systems' characteristics in the security issue. Next, we extend our discussion to the case of heterogeneous networks. In fact, the interconnection of heterogeneous networks is another important issue that needs to be deeply investigated in order to develop a rebust third generation of wireless communication systems, special those capable of providing automatic "roaming" and personal as well as terminal mobility. In this work we particularly discuss the protocols employed in the signaling system SS7 ( Signaling Systems Number 7) and MAP ( Mobile Application Part) which are important issues in terms of the interworking and interoperability of wireless and wireline networks. As a conclusion of this discussion, we propose a protocol architecture based on the RM-OSI model relating to the interconnection of a PCS system, J-STD-007, with the IS-95 cellular phone networks. Note that the proposed model uses the signaling systems SS7 and MAP. Finally we present some importante conclusion with respect to the objetives achieved in this work, and propose some future research activities based on this work.

Orientadores: João Marcos Travassos Romano, Hisham Abou-Kandil, Mohamed Abbas-Turki / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação e ENS-Cachan (École Normale Supérieure de Cachan) / Made available in DSpace on 2018-08-18T08:26:12Z (GMT). No. of bitstreams: 1 Chaves_FabianodeSousa_D.pdf: 2605316 bytes, checksum: 88049a9675c3cd7f4955cc1925e8bd01 (MD5) Previous issue date: 2010 / Resumo: A interferência é um dos fatores limitantes do desempenho individual e global em redes de comunicação sem fio. Neste trabalho, duas técnicas clássicas de gerenciamento de interferência são estudadas: o controle de potência de transmissão e a equalização de canal. Três abordagens são consideradas para o controle de potência distribuído e oportunista. A primeira tem por base a teoria dos jogos estáticos não-cooperativos e teorias de funções iterativas, resultando em uma classe de algoritmos. Na segunda abordagem, propomos diferentes algoritmos derivados de formulações e soluções tradicionais dos controles H2 e misto H2/Hoo.Por fim, aplicamos a teoria dos jogos dinâmicos ao problema para a obtenção de dois novos algoritmos de controle de potência. A segunda parte da tese, que trata do problema da equalização, é dividida em dois tópicos. No primeiro, fazemos uma análise de "pior caso" do atraso de equalização por meio de conceitos da teoria dos jogos não-cooperativos. No segundo tópico, apresentamos duas propostas para a reunião das características desejáveis dos equalizadores H2 e Hoo: uma combinação convexa dos dois filtros e um esquema de adaptação do nível de robustez do filtro Hoo. / Abstract: Interference is a limiting factor of individual and global performance in wireless communication networks. In this work, two classical interference management techniques are studied: the transmission power control and the channel equalization. Three approaches are considered for distributed and opportunistic power control. The first one is based on static non-cooperative game theory and theories of iterative functions, providing a class of algorithms. In the second approach, we propose different algorithms derived from formulations and traditional solutions of H2 control and mixed H2/Hoo control. Finally, we apply dynamic game theory to the problem for obtaining two new power control algorithms. The second part of the thesis, devoted to channel equalization, is divided into two topics. In the first one, we provide a "worst case" analysis for equalization delay by using concepts of noncooperative game theory. In the second topic, we present two proposals for the combination of the desirable characteristics of H2 and Hoo equalizers: a convex combination of the two filters and a scheme for adapting the robustness level of the Hoo filter. / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

Orientador: Yuzo Iano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-12T15:19:02Z (GMT). No. of bitstreams: 1 Ribeiro_ThatianeCristinadosSantosdeCarvalho_M.pdf: 2904973 bytes, checksum: e3c67793847764cf8eac05c50f45b48f (MD5) Previous issue date: 2008 / Resumo: A transmissão de vídeo em redes Wireless é abordada pela pesquisa, devido o grande aumento na utilização dessas redes na ultima década. O acesso à banda larga por essas redes é feito de forma eficiente, rápida e com baixo custo de implementação e manutenção da rede. A motivação para o desenvolvimento é utilizar essas redes e a rede IPTV para promover a interatividade e uma forma do canal de retorno para Sistemas de Televisão Digital, que estão sendo implementadas atualmente no Brasil. O canal de Retorno da TV Digital é importante para o sistema, pois um dos objetivos é prover a interatividade entre os usuários. Isso deve ser feito de forma simples com baixo custo e com tecnologia compatível a região do usuário. A simulação trata de um sistema de transmissão unicast que seria semelhante a uma interatividade local e dedicada. O usuário transmite o conteúdo de uma só vez. Os dados que são transmitidos pela provedora de serviços, são armazenados no set-top-box, e só são modificados em caso de novo fluxo de dados, quando há atualização ou acesso a nova área de serviços. Os testes feitos durante a pesquisa, transmitem conteúdo em tempo real e avaliam de forma quantitativa o desempenho das redes IEEE 802.11b e IEEE 802.11g. / Abstract: The streaming video transmission on Wireless networks is concerned in the research due to the large increase in the use of such networks in the last decade. Broadband access for these networks is made efficiently, quickly and with low implementation and maintenance costs of the network. The motivation for developing this research is to use these networks and IPTV network to promote interactivity and a return channel for digital television system, currently being implemented in Brazil. The return channel is important for the Digital TV system, because one of the goals is to provide interactivity for the users. This should be done in a simple, low cost way and with technology compatible in the region of the user. The simulation deals with a unicast transmission system which is similar to a local and dedicated interactivity. The user transmits all the contents at once. The data transmitted by a service provider are stored on set-top box and are modified only in case of new data flow, when there are updates or access to new area of services. The tests performed during the research, it was broadcasted contents in real time and evaluated quantitative the performance of IEEE 802.11b and IEEE 802.11g networks. / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Syftet med examensarbetet är att analysera, implementera och utvärdera metoder för nätverksövervakning av trådlös kommunikationsutrustning i företaget Fibras nätverk. I dag sköts driften av cirka 2300 accesspunkter i Västerås stads trådlösa nätverk av Fibra. I nätverket ingår ett antal Wireless LAN Controller (WLC), vars uppgift är att hantera och konfigurera alla accesspunkter. Varje WLC kan hantera upp till 400 accesspunkter och sköter exempelvis autentiseringen av användarna. Dessutom finns det en Whats Up Gold server, vars uppgift är att samla in information om det trådlösa nätverket. Själva nätverksövervakningen presenteras i ett webbgränssnitt för drift personalen på Fibra. Examensarbetet utvärderar vilka delar av nätverket som bör övervakas, vilken information som ska samlas in och hur resultatet av övervakningen ska presenteras för drift personalen på Fibra. Dessutom görs en utvärdering av hur kommunikationen mellan Whats Up Gold servern och WLC sker bäst. Det nätverksövervakningsprogram som Fibra valt använda är Whats Up Gold. Examensarbetet inkluderar dock samtliga aspekter av nätverksövervakningsproblemet, inte bara de som ingår i programmet Whats Up Gold. Resultatet av implementationen innebär att driftpersonalen på Fibra får en särskild vy i Whats Up Gold webbgränssnitt. Den används för att felsöka och för att få en översikt av det trådlösa nätverket. Personalen får också tillgång till en larmvy, där WLC och berörda accesspunkter visas vid eventuella driftstörningar. Larmfunktionen i WLC skickar automatiskt SMS och e-mail till personal som har beredskap. Lösningen för att göra kommunikationen möjlig mellan server och WLC görs med en PBR (Policy Based Routing). En PBR är en teknik för att göra routing beslut baserat på diverse kriterier som är konfigurerade av en administratör. Genom att Fibra inför bra nätverksövervakning kommer antalet oplanerade driftstopp minska och tillgängligheten öka. Det innebär också att eventuella nätverksfel upptäcks snabbare och felsökningen i nätverket blir betydligt lättare. Nätverksövervakning sparar följaktligen både pengar och tid för ett företag som Fibra. / The purpose of this study is to analyse, implement and evaluate methods for network monitoring of wireless communication in the company Fibra. Today, Fibra managed the operation of around 2,300 access points in Västerås. The network includes a number of Wireless LAN Controller (WLC), whose task is to manage and configure all access points. Each WLC can have up to 400 access points and manage, for example, authentication of users. A servers job is to collect information from the wireless network and monitoring the result and present it in a web interface for the administrators. The thesis evaluates which parts of the network that should be monitored and what information should be gathered and how the results of the monitoring will be presented to the user. There should also be an evaluation of how the communication between the server and the WLC should be done. The network monitoring tools Fibra select to use is Whats Up Gold. The work, however, includes all aspects of the network management problem, not just those included in the program Whats Up Gold. The result of implementation means that the operating staff at Fibra received a special view of Whats Up Gold's web interface, used to troubleshoot and get an overview of the wireless network. The staff will also have access to an alarm view, where the WLC and the access points displayed on any incident. The alarm function of the WLC automatically sends SMS and e-mail to personal on duty. The solution to make communication possible between the server and the WLC is made with a PBR (Policy Based Routing). A PBR is a technology to make routing decisions based on various criteria that are configured by an administrator. By implementing network monitoring, the number of unplanned downtime is reduced and availability increased. It also means that any network failure is detected faster and troubleshooting the network becomes much easier. Network Monitoring consequently saves both money and time to a company such as Fibra.

Abstract In visible light communication (VLC), light emitting diodes (LEDs) are used as transmitters; the air is the transmission medium and the photodiodes are used for receivers. This is often referred to as light fidelity (Li-Fi). In this thesis, we provide the methodology to evaluate the performance of VLC hotspot networks in the context of data downloading on the move scenarios by using throughput-distance relationship models. In this context, first we study the different properties of optical transceiver elements, noise sources, characterization and modelling of artificial light interference, different link topologies and then we introduce the throughput-distance relationship model. Secondly, the analytically based throughput-distance relationship has been developed for evaluating the performance of VLC hotspot networks in indoor environment in both day and night conditions. Simulation results reveal that background noise has a significant impact on the performance of VLC hotspots. As expected, in both indoor and outdoor environments the VLC hotspot performs better at night than during day. The performance of VLC hotspot networks is also quantified in terms of received file size at different bit error rate requirements and velocities of the mobile user. Thirdly, we study the performance of hybrid (Radio-Optical) WLAN-VLC hotspot and compare its performance with stand-alone VLC-only or WLAN-only hotspot cases. In this case, we also consider the data download on the move scenarios in an indoor environment for a single-user as well as for multi-user cases. In this hybrid WLAN-VLC hotspot, both the WLAN and the VLC are characterized by their throughput and communication range. Simulations have been performed to evaluate the performance of such network for data downloading on the move scenario by taking into account performance metrics such as filesize, average connectivity and system throughput. Simulation results reveal that the considered hybrid WLAN-VLC performs always better than stand-alone VLC-only or WLAN-only hotspot both for a single and multi-user cases. Finally, this thesis analyses the feasibility and potential benefits of using hybrid radio-optical wireless systems. In this respect, cooperative communication using optical relays are also introduced in order to increase the coverage and energy efficiency of the battery operated device. Potential benefits are identified as service connectivity and energy efficiency of battery operated device in an indoor environment. Simulation results reveal that user connectivity and energy efficiency depend on user density, coverage range ratio between single-hop and multi-hop, relay probabilities and mobility of the user. / Tiivistelmä Näkyvään valoon pohjautuvassa tiedonsiirrossa (VLC) valodiodeja (LED) käytetään lähettiminä, ilma on siirtokanava ja valoilmaisimia käytetään vastaanottimina. Tätä kutsutaan usein nimellä light fidelity (Li-Fi). Tässä työssä tarjoamme menetelmiä VLC ”hotspot” verkkojen suorituskyvyn arviointiin tiedonsiirtonopeus-etäisyysmalleilla skenaarioissa, jossa tietoa ladataan liikkeessä. Tässä kontekstissa tutkimme ensin optisen lähettimen komponenttien eri ominaisuuksia, kohinan lähteitä, keinovalon häiriömalleja ja tiedonsiirtolinkkien topologioita, jonka jälkeen esittelemme tiedonsiirtonopeuden ja etäisyyden välisen mallin. Toiseksi kehitetyn analyyttisen tiedonsiirto-etäisyys mallia käytetään arvioitaessa VLC hotspot verkkojen suorituskykyä sisäympäristössä sekä päivä että yö olosuhteissa. Simulointien tulokset osoittavat, että taustakohinalla on suuri vaikutus VLC verkkojen suorituskykyyn. Kuten odotettua, sisä- ja ulkotiloissa VLC hotspot toimii paremmin yöllä kuin päivällä. VLC hotspot verkkojen suorituskyky arvioidaan myös vastaanotetun tiedoston koon, eri bittivirhesuhteen vaatimuksilla ja liikkuvan käyttäjän nopeuden suhteen. Kolmanneksi tutkimme hybridi WLAN-VLC hotspot verkon suorituskykyä ja vertaamme sen suorituskykyä pelkän VLC- tai WLAN hotspot tapauksessa. Käsittelemme myös skenaarioita jossa tiedoston lataus tapahtuu liikkeessä sisätilassa yhden käyttäjän sekä monen käyttäjän tapauksissa. Tässä hybridi WLAN-VLC hotspot, sekä erilliset WLAN- ja VLC verkot ovat määritelty niiden tiedonsiirtonopeuden ja kantaman perusteella. Näiden verkkojen suorituskykyä arvioitaessa on tehty joukko tietokonesimulointeja verkossa tapahtuvasta tietojen lataamisesta liikkeessä ottamalla huomioon suorituskyvyn mittarit kuten tiedoston koko, keskimääräinen yhteyden kesto ja saavutettu läpäisy. Simuloinnin tulokset paljastavat, että hybridi WLAN-VLC toimii aina paremmin kuin pelkkä VLC tai WLAN hotspot sekä yhden että monen käyttäjän tapauksessa. Lopuksi työssä analysoidaan ehdotetun järjestelmän toteutettavuus ja mahdolliset edut käytettäessä hybridejä radio-optisia langattomia järjestelmiä. Tältä osin esitellään myös kooperatiiviseen viestintään perustuvat optiset releet parantamaan verkon kattavuutta ja energiatehokkuutta akkukäyttöisissä laitteissa. Mahdolliset hyödyt tunnistetaan palvelun konnektiivisuudessa ja energiatehokkuudessa akkukäyttöisissä laitteissa sisätiloissa. Simulointien tulokset osoittavat, että käyttäjien konnektiivisuus ja energiatehokkuus riippuvat käyttäjätiheydestä, kantaman ja etäisyyden välisestä suhteesta yhden hypyn ja monen hypyn välillä, releointi todennäköisyydestä ja käyttäjien mobiliteetista.

L'interférence est un facteur de limitation de performance individuelle et globale dans les réseaux de communication sans fil. Dans ce travail, deux techniques classiques de gestion de l'interférence sont étudiées : le contrôle de puissance d'émission et l'égalisation du canal. Trois approches sont considérées pour Le contrôle de puissance décentralisé et opportuniste. La première est basée sur la théorie des jeux non-coopératifs statiques et les théories de fonctions itératives, d'où résulte la proposition d'une classe d'algorithmes. Dans la deuxième approche, nous proposons quelques algorithmes dérivés de formulations et de solutions traditionnelles de la commande H2 et de la commande mixte H2/H-infini. Finalement, nous appliquons la théorie des jeux dynamiques sur le problème, ce qui produit deux nouveaux algorithmes de contrôle de puissance. La deuxième partie de la thèse, où le problème d'intérêt est l'égalisation du canal, est divisée en deux thèmes. Dans le premier, nous développons une analyse de «pire cas» pour le retard d'égalisation par des concepts de la théorie des jeux non-coopératifs. Dans le deuxième thème, nous présentons deux approches pour la conjugaison des caractéristiques désirables des égaliseurs H2 et H-infini : une combinaison convexe des deux filtres et un schéma d'adaptation du niveau de robustesse du filtre H-infini. / Interference is a limiting factor of individual and global performance in wireless communication networks. In this work, two classical interference management techniques are studied: the transmission power control and the channel equalization. Three approaches are considered for distributed and opportunistic power control. The first one is based on static non-cooperative game theory and theories of iterative functions, providing a class of algorithms. In the second approach, we propose different algorithms derived from formulations and traditional solutions of H2 control and mixed H2/H-infinity control. Finally, we apply dynamic game theory to the problem for obtaining two new power control algorithms. The second part of the thesis, devoted to channel equalization, is divided into two topics. In the first one, we provide a "worst case" analysis for equalization delay by using concepts of non-cooperative game theory. In the second topic, we present two proposals for the combination of the desirable characteristics of H2 and H-infinity equalizers: a convex combination of the two filters and a scheme for adapting the robustness level of the H-infinity filter.

Le repérage (localisation topologique) des capteurs dans un réseau sans fil ouvre la porte à de nombreuses applications. Les techniques actuelles basées sur la puissance du signal reçu restent peu fiable compte-tenu de la stabilité des mesures dans le circuit. Des techniques plus précises inspirées des radars ont été proposées mais cela nécessite un type de radio adaptée qui s'avère trop couteuse, autant en termes d'implémentation qu'en termes de consommation électrique. Cependant, une des difficultés majeure de l'adaptation de ces techniques de localisation aux réseaux de capteurs sans fil reste leur inadéquation avec leur faible coût de réalisation et la faible consommation électrique requise pour ces dispositifs autonomes. En particulier, les étages radio et de génération d'horloge des modems ZigBee introduisent une grande incertitude sur la fiabilité des mesures. Les algorithmes digitaux très complexes demandent à être tout particulièrement étudiés et améliorés afin de ne pas dépasser un budget de consommation extrêmement réduit tout en tentant d'atteindre une complexité d'implémentation aussi faible que possible.Les travaux de cette thèse se concentrent sur 2 principaux objectifs: l'élaboration d'un circuit digital étant capable de calculer de temps d'arrivée en temps réel, et l'élaboration de prototypes permettant le positionnement d'un noeud. La principale contrainte, est l'utilisation d'un seul canal ZigBee de la norme 802.15.4. Ce travail a permi d'appréhender les problèmes liés à la mesure de distance et envisager l'adaptation de ces techniques aux contraintes spécifiques des réseaux de capteurs sans fil et du type de radio utilisée. / Tracking sensors in a wireless network leads to many applications. However, current techniques based on the received signal strength are unreliable given the stability of measurements. More accurate techniques inspired from radars have been proposed but they require an expensive radio. However, one of the most difficult aspects regarding the localization in a wireless sensor network remains their inadequacy with their low-cost and low-power characteristics. For example, clock generation of ZigBee modems introduce strong uncertainties regarding the reliability of measurements. Demanding digital algorithms must be carefully studied and improved in order not to exceed requirements defined by industrials. In other words, the purpose is to design an implementation as cheap as possible while keeping a minimum accuracy. The work of this thesis focuses on two main objectives: the development of a digital circuit capable of calculating time of arrivals, and the development of prototypes for a future positioning feature. The main constraint is the use of a single channel from the ZigBee 802.15.4 standard. This work enabled to understand issues regarding the distance measurements and adapt them given wireless sensor network constraints.

<p>A wireless revolution has occurred resulting in the formation of a proverbial backbone of wireless devices that our everyday functionality, productivity, and general way of life have become dependent. Consequently, victimizing an already constrained and finite wireless spectrum with further demands for increased bandwidths, greater channel capacities, and an insatiable plea for faster access rates. In-band full-duplexing (IBFD) is an innovative and encouraging technology that aims to answer this tacit mitigation call by bolstering spectral efficiency through simultaneous same frequency band transmission and reception. Conventionally, transceiver-based systems have their respective transmission and reception dictated by occurring in either disparate time slots (half-duplex) or distinct frequencies (out-of-band full-duplex). By achieving simultaneous same band communication, a theoretical doubling in spectral efficiency is rendered feasible. However, transmitter to receiver leakage, or self-interference (SI), remains the most barring frustration to IBFD realization. Being locally generated, SI is considerably stronger (often 50-100dB) than the desired signal-of-interest (SOI). Left unresolved, this unwanted energy saturates the receiver’s amplifiers and desensitizes its analog-to-digital converters. Thus, rendering the SOI unintelligible. Therefore, a means of self-interference cancellation (SIC) is necessitated to suppress any polluting SI to levels that of or below the receiver’s noise floor.</p><p></p>In this thesis an in-depth history of in-band full duplex technology is first presented, followed by a condensed examination of the SIC domains. Pertinent theory is presented pertaining to noise analysis and estimation relevant to a proposed IBFD transceiver architecture. Finally, a modelled simulation of this transceiver, developed in MATLAB, is presented. Subsequent results detailing an investigative study done on a fully adaptive tapped-branch analog self-interference canceller are shown. Said canceller’s variable phase and amplitude weights are set via real-time training using gradient descent algorithms. Evaluation of the results reveal marginal effect on the SIC efficacy due to transmission path nonlinearity and noise distortions alone. However, expansion of model consideration for conceivable cancellation hardware nonlinearities reveals an indirectly proportional degradation of SIC performance by up to 35dB as distortion levels vary from -80 dBm to -10 dBm. These results indicate consideration of such non-idealities should be an integral part of cancellation hardware design for the preclusion of any intrinsic cancellation impediments.

<div>With the constant advancement of modern radio technology, the safety of radio communication has become a growing concern for us. Communication has become an essential component, particularly in the application of modern technology such as unmanned aerial vehicle (UAV). As a result, it is critical to ensure that a drone can fly safely and reliably while completing duties. Simultaneously, machine learning (ML) is rapidly developing in the twenty-first century. For example, ML is currently being used in social media and digital marking for predicting and addressing users' varies interests. This also serves as the impetus for this thesis. The goal of this thesis is to combine ML and radio communication to identify and classify UAV interference with high accuracy.</div><div>In this work, a ML approach is explored for detecting and classifying jamming attacks against orthogonal frequency division multiplexing (OFDM) receivers, with applicability to UAVs. Four types of jamming attacks, including barrage, protocol-aware, single-tone, and successive-pulse jamming, are launched and analyzed using software-defined radio (SDR). The jamming range, launch complexity, and attack severity are all considered qualitatively when evaluating each type. Then, a systematic testing procedure is established, where a SDR is placed in the vicinity of a drone to extract radiometric features before and after a jamming attack is launched. Traditional ML methods are used to create classification models with numerical features such as signal-to-noise ratio (SNR), energy threshold, and important OFDM parameters. Furthermore, deep learning method (i.e., convolutional neural networks) are used to develop classification models trained with spectrogram images filling in it. Quantitative indicators such as detection and false alarm rates are used to evaluate the performance of both methods. The spectrogram-based model correctly classifies jamming with a precision of 99.79% and a false-alarm rate of 0.03%, compared to 92.20% and 1.35% for the feature-based counterpart.</div>