Made available in DSpace on 2016-04-04T18:25:00Z (GMT). No. of bitstreams: 1 Everton Dias de Oliveira.pdf: 3326034 bytes, checksum: 1cbd1cf1a33f81db24d9e630a5cddb94 (MD5) Previous issue date: 2015-12-14 / This paper presents the development of a system for monitoring surfasse temperature and air temperature in buildings in urban areas, using wireless data transmission with the IEEE 802.11 and IEEE 802.15.4 standards. This monitoring system includes the development of low sensors that can monitor the temperature of non-destructively, i.e. without the need to reform the building. Deals with the analysis of the use of wireless transmission networks with the IEEE 802.11 standard and the IEEE 802.15.4 standard, as a possible solution for temperature monitoring in buildings using wireless networks. Discusses the development of a technological application capable of performing the monitoring of the air temperature and surface buildings using standard wireless networks IEEE 802.15.4. It also presents a solution for temperature monitoring in intelligent buildings, using the IEEE 802.11 standard. / O presente trabalho apresenta, o desenvolvimento de um sistema para o monitoramento da temperatura de superf?cie e da temperatura do ar em edifica??es no meio urbano, utilizando transmiss?o de dados sem fio com os padr?es IEEE 802.11 e IEEE 802.15.4. Esse sistema de monitoramento compreende o desenvolvimento de sensores de baixo que possam monitorar a temperatura de forma n?o destrutiva, ou seja, sem a necessidade de reformas na edifica??o. Trata da an?lise da utiliza??o das redes de transmiss?o sem fio com o padr?o IEEE 802.11 e com o padr?o IEEE 802.15.4, como possibilidade de solu??o para o monitoramento da temperatura em edifica??es usando redes sem fio. Discorre sobre o desenvolvimento de uma aplica??o tecnol?gica capaz de realizar o monitoramento da temperatura do ar e de superf?cie em edifica??es usando redes sem fio padr?o IEEE 802.15.4. E tamb?m apresenta uma solu??o para o monitoramento da temperatura em edif?cios inteligentes, utilizando o padr?o IEEE 802.11.

Made available in DSpace on 2016-04-04T18:31:27Z (GMT). No. of bitstreams: 1 Manoel Peluso de Carvalho Filho.pdf: 1548469 bytes, checksum: 813f063c4ea17788aa795465c9e6e6f5 (MD5) Previous issue date: 2008-11-24 / Nowadays, the use of the wireless network technology has grown mainly motivated by the price of equipments, ease of installation, network maintenance and expansion of technical safety. The more you use the wireless network resource, the better should be the treatment related to its safety aspect. As the security level increases, the amount of information transmitted between the equipment decreases. This thesis aims to analyze the performance of WLAN network with the implementation of WEP and WPA / TKIP security protocols in an environment that uses applications whose characteristic is to generate small packets on the network. The LanTraffic TM software is used to generate traffic and also to capture the transmission rate in Kbps that flows through the stations. Three scenarios are simulated varying in the distance between the equipments. For each scenario, a comparative study was made and the WLAN behavior without the security resource analyzed, then it was analyzed with the WEP fitted and finally with the WPA/TKIP configured. To develop the experiments it was used a WLAN network in a controlled environment in the Laboratory Research on Radio System in PUC Campinas. Therefore, there is not external interference in the signal transmitted by equipments. / A utiliza??o da tecnologia de rede sem fio tem crescido ultimamente motivado principalmente pelo pre?o dos equipamentos, facilidade de instala??o, manuten??o da rede e amplia??o das t?cnicas de seguran?a. Quanto mais se utiliza o recurso de rede sem fio maior tem de ser o tratamento em rela??o ao aspecto de seguran?a. A medida que aumenta o n?vel de seguran?a, decresce a quantidade de informa??o transmitida entre os equipamentos. Esse trabalho visa analisar o desempenho de rede WLAN(Wireless Local ?rea Network) com a implementa??o dos protocolos de seguran?a WEP(Wired Equivalent Privacy) e WPA/TKIP(WI-FI Protected Access / Temporal Key Integrity Protocol). ? utilizado o software LanTrafficTM para gerar tr?fego na rede e tamb?m para capturar a taxa de transmiss?o em Kbps trafegados entre as STAs. S?o emulados tr?s cen?rios variando a dist?ncia entre os equipamentos. Para cada cen?rio foi confeccionado um comparativo e analisado o comportamento da WLAN configurado sem seguran?a, com o WEP habilitado e finalmente com o WPA/TKIP configurado. Para executar os experimentos utilizou-se uma rede WLAN no laborat?rio de pesquisa em sistema de r?dio (LP-SiRa) da PUC Campinas em um ambiente controlado. Com isso n?o h? interfer?ncias na transmiss?o dos sinais emitidos pelos equipamentos Ou seja, sem interfer?ncia externa no sinal transmitido entre os equipamentos.

Cette thèse a pour objectif l¤étude des mécanismes d¤interaction inter-couche et leurs applications pour des algorithmes adaptatifs pour contrôler les paramètres de transmission. Après une description rapide des protocoles des couches liaison et physiques du standard IEEE 802.11, nous présentons une analyse de performance des modes de transmission spécifiés par les normes 802.11a/b. La deuxième contribution de cette thèse porte sur la modélisation des réseaux 802.11. Nous proposons un modèle analytique qui prend en compte la position des terminaux radio par rapport au point d¤accès afin d¤évaluer les performances de la couche MAC. Nous proposons ensuite de nouveaux mécanismes de sélection du débit de transmission physique. Nous avons élaboré l¤algorithme AARF, basé sur l¤algorithme ARF, qui s'intéresse à la classe des terminaux dits à faible latence et offre des services d¤adaptation à court et à long terme. Un autre algorithme basé sur les mêmes idées que celles développées pour AARF, mais conçu pour fonctionner avec des systèmes à grande latence, a été implanté et expérimenté sur des terminaux à base du processeur Atheros. Enfin, nous avons élaboré un troisième algorithme de contrôle dynamique du mode de transmission en boucle fermée appelé CLARA qui est compatible avec les standards 802.11a/b/g. La dernière contribution de cette thèse porte sur l¤optimisation de la transmission de flots multimédias temps réel sur des réseaux 802.11. Nous présentons MORSA, un mécanisme d¤optimisation inter-couche efficace qui permet de sélectionner le mode de transmission à utiliser en fonction de l'état du canal de transmission et des caractéristiques de l'application.

Este trabalho estuda as potenciais melhorias na eficiência energética e vazão do método híbrido de requisição automática de retransmissão (Hybrid Automatic Retransmission Request, HARQ). A análise inclui as camadas física (PHY) e de acesso ao meio (MAC). É investigada a relação de compromisso gerada pelo HARQ, o qual demanda uma menor potência de transmissão para uma certa probabilidade de falha alvo ao custo de mais acessos ao canal. Uma vez que a competição para acesso ao canal na camada MAC é bastante custosa em termos de energia e atraso, os resultados mostram que a utilização do HARQ leva a uma grande melhoria de performance devido ao menor número de nós competidores – uma consequência da redução na potência de transmissão necessária. Contra-intuitivamente, esta análise leva à conclusão que retransmissões podem diminuir o atraso, melhorando a performance do sistema. Finalmente, são também investigados valores ótimos para o número de retransmissões permitidas, visando maximizar vazão ou/e eficiência energética. / This work studies the potential improvements in terms of energy efficiency and throughput of a hybrid automatic retransmission request (HARQ) mechanism. The analysis includes both the physical (PHY) and medium access (MAC) layers. We investigate the trade-off provided by HARQ, which demands reduced transmit power for a given target outage probability at the cost of more accesses to the channel. Since the competition for channel access at the MAC layer is very expensive in terms of energy and delay, our results show that HARQ leads to great performance improvements due to the decrease in the number of contending nodes – a consequence of the reduced required transmit power. Counter-intuitively, our analysis leads to the conclusion that retransmissions may decrease the delay, improving the system performance. Finally, we investigate the optimum values for the number of allowed retransmissions in order to maximize either the throughput or the energy efficiency.

Made available in DSpace on 2014-12-17T15:48:12Z (GMT). No. of bitstreams: 1 LeonardoDO_DISSERT.pdf: 3357434 bytes, checksum: 75c2c837997e2220e8de164c844c9b5d (MD5) Previous issue date: 2014-06-05 / Due to the constantly increasing use of wireless networks in domestic, business and industrial environments, new challenges have emerged. The prototyping of new protocols in these environments is typically restricted to simulation environments, where there is the need of double implementation, one in the simulation environment where an initial proof of concept is performed and the other one in a real environment. Also, if real environments are used, it is not trivial to create a testbed for high density wireless networks given the need to use various real equipment as well as attenuators and power reducers to try to reduce the physical space required to create these laboratories. In this context, LVWNet (Linux Virtual Wireless Network) project was originally designed to create completely virtual testbeds for IEEE 802.11 networks on the Linux operating system. This paper aims to extend the current project LVWNet, adding to it the features like the ability to interact with real wireless hardware, provides a initial mobility ability using the positioning of the nodes in a space coordinates environment based on meters, with loss calculations due to attenuation in free space, enables some scalability increase by creating an own protocol that allows the communication between nodes without an intermediate host and dynamic registration of nodes, allowing new nodes to be inserted into in already in operation network / Com o crescimento constante da utiliza??o de redes sem fio em ambientes dom?sticos, empresariais e at? industriais, aparecem novos desafios. A prototipa??o de novos protocolos nesses ambientes tipicamente ? restrita a ambientes de simula??o, onde existe a necessidade de uma dupla implementa??o, uma no ambiente de simula??o, onde se realiza uma prova de conceito inicial e outra em um ambiente real. Al?m disso, uma vez que se parta para ambientes reais, n?o ? trivial a cria??o de um testbed para redes sem fio de alta densidade, dada a necessidade de uso de v?rios equipamentos reais, e uso de atenuadores, redutores de pot?ncia, para tentar reduzir o espa?o f?sico necess?rio para cria??o desses laborat?rios. Nessa lacuna, o projeto LVWNet (Linux Virtual Wireless Network) foi inicialmente concebido para cria??o de testbeds completamente virtuais para redes IEEE 802.11 sobre o sistema operacional Linux. Este trabalho tem como objetivo extender o atual projeto LVWNet adicionando a ele os recursos de possibilitar a intera??o com hardwares wireless reais, dar um suporte inicial ? mobilidade atrav?s do posicionamento dos n?s em um ambiente de coordenadas no espa?o baseado em metros, j? com c?lculos de perda decorrente da atenua??o em espa?o livre, aumentar a escalabilidade com a cria??o de um mecanismo que permita a comunica??o direta entre os n?s sem necessidade de um host intermedi?rio al?m do registro din?mico de n?s, de modo que novos n?s podem ser inseridos na rede com a mesma j? em opera??o

Made available in DSpace on 2014-12-17T14:55:35Z (GMT). No. of bitstreams: 1 CarlosMDV.pdf: 1914852 bytes, checksum: a7e99d6b563c17f13d6bf2747cf54976 (MD5) Previous issue date: 2009-07-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This paper presents the performanee analysis of traffie retransmission algorithms pro?posed to the HCCA medium aeeess meehanism of IEEE 802.11 e standard applied to industrial environmen1. Due to the nature of this kind of environment, whieh has eleetro?magnetic interferenee, and the wireless medium of IEEE 802.11 standard, suseeptible to such interferenee, plus the lack of retransmission meehanisms, refers to an impraetieable situation to ensure quality of service for real-time traffic, to whieh the IEEE 802.11 e stan?dard is proposed and this environment requires. Thus, to solve this problem, this paper proposes a new approach that involves the ereation and evaluation of retransmission al-gorithms in order to ensure a levei of robustness, reliability and quality of serviee to the wireless communication in such environments. Thus, according to this approaeh, if there is a transmission error, the traffie scheduler is able to manage retransmissions to reeo?ver data 10s1. The evaluation of the proposed approaeh is performed through simulations, where the retransmission algorithms are applied to different seenarios, whieh are abstrae?tions of an industrial environment, and the results are obtained by using an own-developed network simulator and compared with eaeh other to assess whieh of the algorithms has better performanee in a pre-defined applieation / Este trabalho apresenta a an?lise de desempenho de algoritmos de retransmiss?o de tr?fego propostos para o mecanismo de acesso ao meio HCCA do padr?o IEEE 802.11 e aplicados ao ambiente industrial. Devido ? natureza deste tipo de ambiente, que pos?sui interfer?ncias eletromagn?ticas, e ? do meio de transmiss?o sem fio do padr?o IEEE 802.11, suscept?vel a tais interfer?ncias, em conjunto com a aus?ncia de mecanismos de retransmiss?o, remete a uma situa??o impratic?vel para garantias de qualidade de servi?o ao tr?fego de tempo real, ao qual o padr?o IEEE 802.11 e se prop?e e este tipo de ambiente requer. Desta forma, para resolver este problema, este trabalho prop?e uma nova abordagem que engloba a cria??o e avalia??o de algoritmos de retransmiss?o com o intuito de garantir um nivel de robustez, confiabilidade e qualidade de servi?o ? comunica???o sem fio presente em tais ambientes. Assim, de acordo com esta abordagem, em caso de erros na transmiss?o, o escalonador de tr?fego poder? gerenciar retransmiss?es para que os dados perdidos possam ser recuperados. A avalia??o da abordagem proposta ? realizada atrav?s de simula??es, onde os algoritmos de retransmiss?o s?o aplicados a diferentes cen?rios, que s?o abstra??es de um ambiente industrial, e os resultados dessa avalia??o s?o obtidos com o aux?lio de um simulador de redes desenvolvido e compa?rados entre si para avaliar qual dos algoritmos possui melhor efici?ncia em determinada aplica??o

Made available in DSpace on 2014-12-17T14:56:05Z (GMT). No. of bitstreams: 1 RicardoCOM_DISSERT.pdf: 2871437 bytes, checksum: ca804782bf10029c3e31983e4917ea6a (MD5) Previous issue date: 2012-04-18 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / This work presents a theoretical and experimental analysis about the properties of microstrip antennas with integrated frequency selective surfaces (Frequency Selective Surface - FSS). The integration occurs through the insertion of the FSS on ground plane of microstrip patch antenna. This integration aims to improve some characteristics of the antennas. The FSS using patch-type elements in square unit cells. Specifically, the simulated results are obtained using the commercial computer program CST Studio Suite? version 2011. From a standard antenna, designed to operate in wireless communication systems of IEEE 802.11 a / b / g / n the dimensions of the FSS are varied to obtain an optimization of some antenna parameters such as impedance matching and selectivity in the operating bands. After optimization of the investigated parameters are built two prototypes of microstrip patch antennas with and without the FSS ground plane. Comparisons are made of the results with the experimental results by 14 ZVB network analyzer from Rohde & Schwarz ?. The comparison aims to validate the simulations performed and show the improvements obtained with the FSS in integrated ground plane antenna. In the construction of prototypes, we used dielectric substrates of the type of Rogers Corporation RT-3060 with relative permittivity equal to 10.2 and low loss tangent. Suggestions for continued work are presented / Este trabalho apresenta uma investiga??o te?rica e experimental sobre as propriedades das antenas de microfita integradas com superf?cies seletivas em frequ?ncia (Frequency Selective Surface FSS). A integra??o se d? por meio da inser??o da FSS no plano de terra da antena patch de microfita. Essa integra??o visa a melhoria de algumas caracter?sticas das antenas como, por exemplo, ganho, largura de banda, dentre outras. As FSS utilizam elementos do tipo patch quadrado nas c?lulas unit?rias. Especificamente, os resultados simulados s?o obtidos utilizando-se o programa computacional comercial CST Studio Suite? vers?o 2011. A partir de uma antena padr?o, projetada para operar em sistemas de comunica??es sem fio dos padr?es IEEE 802.11 a/b/g/n, as dimens?es da FSS s?o variadas de forma a obter uma otimiza??o de alguns par?metros da antena, como casamento de imped?ncia e seletividade nas bandas de opera??o. Ap?s a otimiza??o dos par?metros investigados, s?o constru?dos dois prot?tipos de antenas patch de microfita com e sem a FSS no plano de terra. S?o feitas compara??es dos resultados simulados com os resultados experimentais obtidos pelo analisador de rede ZVB 14 da Rohde & Schwarz?. A compara??o visa validar as simula??es efetuadas e mostrar as melhorias obtidas com a FSS integrada no plano de terra da antena. Na constru??o dos prot?tipos, foram utilizados substratos diel?tricos da Rogers Corporation do tipo RT-3060 com permissividade relativa igual a 10,5 e baixa tangente de perdas. Sugest?es de continuidade do trabalho s?o apresentadas

Submitted by Rafael Santana (rafael.silvasantana@ufpe.br) on 2017-08-30T18:33:02Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Diego_Cananea_Dissertacao_Mestrado_CIn_UFPE.pdf: 981557 bytes, checksum: ea7555320bfcb0316c7f0fa816288cef (MD5) / Made available in DSpace on 2017-08-30T18:33:02Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Diego_Cananea_Dissertacao_Mestrado_CIn_UFPE.pdf: 981557 bytes, checksum: ea7555320bfcb0316c7f0fa816288cef (MD5) Previous issue date: 2016-09-08 / A estimação da capacidade e da banda disponível em redes têm sido objeto de diversas pesquisas nos últimos anos, principalmente por causa da evolução das tecnologias e crescimento do uso da Internet. Tais técnicas são de grande importância para que seja possível fazer um melhor aproveitamento da transmissão dos dados, evitando tanto a subutilização quanto o esgotamento de recursos. Existem inúmeros usos para as técnicas de estimação de banda, dentre as quais podemos citar streaming multimídia, aplicações peer-to-peer, protocolos de roteamento baseados na banda disponível, qualidade de serviço, protocolos de transporte fim a fim, entre outros. Com o interesse cada vez maior nestes tipos de aplicações, principalmente na transmissão de vídeo e áudio, a estimação de banda tem sido de bastante interesse para pesquisadores. A estimação de banda disponível em redes sem fio por si só já é um desafio para os pesquisadores e o novo padrão IEEE 802.11n trouxe novos mecanismos para otimizar a transmissão dos dados, alcançando assim maiores taxas. Porém, tais fatores contribuem para que as técnicas hoje existentes encontrem problemas ao tentarem estimar a banda disponível, causando assim resultados que deixam a desejar. Esta pesquisa demonstra experimentalmente a influência dos novos fatores adicionados pelo novo padrão, como a agregação de quadros e de canais, em técnicas ativas de estimação de banda disponível. É possível verificar, então, que todas tem sua acurácia diminuída, causando erros de estimações. Verificamos que mesmo no cenário mais simples, onde os novos fatores são desativados, boa parte dos métodos analisados obtiveram uma performance aquém do esperado, corroborando com a afirmação de que o ambiente de redes sem fio é um grande desafio para o desenvolvimento deste tipo de técnica. A técnica de estimação YAZ se mostrou mais robusta que as demais, aproximando-se dos valores de referência em quase todos os cenários propostos, com exceção para a agregação de quadros. Em uma análise mais específica de seu algoritmo, podemos demonstrar o porquê do erro no resultado da estimação de banda disponível neste contexto. / The estimation of capacity and available bandwidth in computer networks have been the subject of several studies in recent years, mainly because of changing technologies and increasing use of the Internet. Such techniques are of great importance to be able to make better use of data transmission, avoiding both underuse as resource depletion. There are numerous uses for bandwidth estimation techniques, among which we can mention textit stream multimedia applications textit peer-to-peer, routing protocols based on available bandwidth, quality of service, end to end transport protocols, among others. With the growing interest in these types of applications, especially in video and audio transmission, bandwidth estimation has been of great interest to researchers. The estimation of available bandwidth in wireless networks is itself a challenge for researchers and the new IEEE 802.11n standard has brought new mechanisms to optimize the transmission of data, thus achieving higher rates. However, these factors contribute to that existing techniques encounter problems when trying to estimate the available bandwidth, thus causing results that fall short. This research experimentally demonstrates the influence of new factors added by the new standard, such as frame aggregation and channels in active techniques for available bandwidth estimation. It’s possible see, then, that all has its diminished accuracy, causing estimation errors. We found that even in the simplest scenario, where new factors are disabled, most of the methods discussed perform so below expectations, supporting the claim that the wireless network environment is a major challenge for the development of this type of technique . The YAZ estimation technique was more robust than the others, approaching the reference values in almost all proposed scenarios, except for the frame aggregation. In a more specific analysis of their algorithm, we can demonstrate why the error in the result of the available bandwidth estimation occurs in this context.

Notre travail s'inscrit dans le cadre des recherches sur le Sleeping mode. Notre contribution est structurée principalement autour deux axes : l'étude et l'évaluation de la performance des processus de mise en veille/réveil des points d'accès et la sélection du nombre minimal des points d'accès dans un milieu urbain dense. Dans un premier temps, nous étudions les processus de mise en veille/réveil des points d'accès dans un scenario classique de réseau domestique. Ce scenario suppose que le point d'accès mis en veille doit détecter la présence d'un utilisateur potentiel dans sa zone de couverture et réagir par conséquence d'une façon autonome pour se mettre en état de fonctionnement normal. Nous avons choisi quatre processus de réveil du point d'accès, et nous avons ensuite étudié chacun de ces processus, et proposé un protocole de communication qui permette à un utilisateur d'envoyer l'ordre au point d'accès de s'éteindre. Lorsque cela était possible, nous avons utilisé le protocole COAP qui est prévu pour établir des sessions de commande pour l'Internet des Objets. Nous avons ensuite mesuré les performances du point de vue de l'économie d'énergie qu'il permet de réaliser et du délai entre le moment où un utilisateur potentiel est détecté et le moment où le point d'accès devient opérationnel. Nous avons aussi étudié un réseau dense dans un milieu urbain (le centre ville de Rennes) où la zone de couverture d'un point d'accès pouvait être partiellement ou totalement couverte par d'autres points d'accès. Pour évaluer la redondance dans le réseau, nous avons collecté des informations réelles sur les points d'accès en utilisant l'application Wi2Me. Le traitement de ces informations nous a permis d'identifier les points d'accès existants dans la zone étudiée et leurs zones de couverture respectives démontrant ainsi la superposition de ces zones de couverture et le potentiel d'élimination d'un certain nombre de points d'accès sans affecter la couverture globale. Nous avons alors proposé un système centralisé qui collecte les données de couverture des points d'accès observée par les utilisateur. Nous avons donc utilisé ce simple fait pour centraliser la vue du réseau de plusieurs utilisateurs, ce qui permet d'avoir une vue assez précise de la disponibilité des points d'accès dans une zone géographie. Nous avons alors proposé une représentation de ces données de couverture à travers des matrices qui traitent les différentes erreurs de capture (coordonnées GPS non précises, réutilisation des noms de réseaux, etc). Enfin, nous avons ensuite proposé deux algorithmes permettant de sélectionner l'ensemble minimal des points d'accès requis fournissant une couverture identique à celle d'origine. / The main goal of the thesis is to design an Energy Proportional Network by taking intelligent decisions into the network such as switching on and off network components in order to adapt the energy consumption to the user needs. Our work mainly focuses on reducing the energy consumption by adapting the number of APs that are operating to the actual user need. In fact, traffic load varies a lot during the day. Traffic is high in urban areas and low in the suburb during day work hours, while it is the opposite at night. Often, peak loads during rush hours are lower than capacities of the networks. Thus they remain lightly utilized for long periods of time. Thus keeping all APs active all the time even when the traffic is low causes a huge waste of energy. Our goal is to benefit from low traffic periods by automatically switch off redundant cells, taking into consideration the actual number of users, their traffic and the bandwidth requested to serve them. Ideally we wish to do so while maintaining reliable service coverage for existing and new coming users. First we consider a home networking scenario. In this case only one AP covers a given area. So when this AP is switched off (when no users are present), there will be no other AP to fill the gap of coverage. Moreover, upon the arrival of new users, no controller or other mechanism exists to wake up the AP. Consequently, new arriving users would not be served and would remain out of coverage. The study of the state of the art allowed us to have a clear overview of the existing approaches in this context. As a result, we designed a platform to investigate different methods to wake up an AP using different technologies. We measure two metrics to evaluate the Switching ON/OFF process for the different methods. The first is the energy consumed by the AP during the three phases it goes through. The second is the delay of time for the AP to wake up and be operational to serve the new users. In the second case we consider a dense network such as the ones found in urban cities, where the coverage area of an AP is also covered by several other APs. In other words, the gap resulting from switching off one or several APs can be covered by other neighbouring ones. Thus the first thing to do was to evaluate the potential of switching off APs using real measurements taken in a dense urban area. Based on this collected information, we evaluate how many APs can be switched off while maintaining the same coverage. To this end, we propose two algorithms that select the minimum set of APs needed to provide full coverage. We compute several performance parameters, and evaluate the proposed algorithms in terms of the number of selected APs, and the coverage they provide.

Le but principal des réseaux mesh sans fil (Wireless Mesh Networks-WMNs) est de fournir une dorsale de communication pour un grand nombre d'utilisateurs, car les WMNs doivent supporter un trafic énorme. Dans cette thèse, nous visons la maximisation d'utilisation et la répartition équitable de la bande passante dans les WMNs. Nous considérons deux environnements : WMN utilisant la norme IEEE 802.11 MAC, qui est caractérisée par son déploiement répandu et peu cher, et WMN utilisant les antennes directionnelles, qui représentent une technologie clé pour la réutilisation spatiale dans les réseaux sans fil. Pour les WMMs basés sur IEEE 802.11, nous concevons NICC, un protocole de contrôle de congestion qui reconnaît la congestion comme un problème lié au voisinage, et non pas au lien. NICC gère la congestion par une collaboration entre les nœuds d’un voisinage sans fil. En faisant usage de certains champs sous-exploités dans l'en-tête IEEE 802.11, NICC fournit un retour de congestion implicite et multi-bit. Ceci assure un contrôle précis du trafic sans affecter la bande passante. Pour les WMNs utilisant les antennes directionnelles, nous concevons FreeDMAC, un protocole MAC basé sur la technologie TDMA. FreeDMAC garantit que chaque nœud est conscient de toutes les transmissions dans son voisinage, ce qui évite les problèmes MAC causés par les antennes directionnelles, et ainsi, améliore l'utilisation de la bande passante. En outre, FreeDMAC est capable de fournir deux niveaux d’équité: équité entre les liens et équité entre les flux / The main purpose of Wireless Mesh Networks (WMNs) is to provide a communication backbone for a high number of end-users, thus WMNs have to support heavy traffic load. In this thesis, we intend to maximize utilization and achieve fair allocation of the bandwidth resources in WMNs. We consider two WMN environments: WMN using the IEEE 802.11 MAC standard, which is characterized by its cheap devices and widespread deployment, and WMN using directional antennas, which are emerged as an attractive technology to enhance the spatial reusability in wireless networks. For WMM based on IEEE 802.11, we design NICC, a congestion control scheme that recognizes congestion as neighborhood-related problem, and not a link-based one. Indeed, complex interference among neighboring nodes is the main starvation cause in WMNs. Therefore, NICC handles congestion using mutual cooperation within a wireless neighborhood. NICC makes use of some underexploited fields in the IEEE 802.11frame header in order to provide an implicit multi-bit congestion feedback, and thus ensure accurate rate control without generating overhead, making efficient use of bandwidth. For WMN with directional antennas, we design FreeDMAC, a TDMA-based MAC scheme with contention-free scheduling. FreeDMAC guarantees that each node is aware of all ongoing transmissions in its neighborhood, and thus avoids directional-related problems such as deafness, making efficient use of bandwidth. Moreover, FreeDMAC presents a link-slot assignment that provides two levels of fairness: Per-link and per-flow fairness