Dissertations / Theses on the topic 'IEEE 802.11'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 18 dissertations / theses for your research on the topic 'IEEE 802.11.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Manshaei, Mohammad Hossein. "Cross layer interactions for adaptive communications in IEEE 802. 11 wireless LANs." Nice, 2005. http://www.theses.fr/2005NICE4105.
Full textThe main goal of this thesis is to propose efficient adaptive communication mechanisms using cross layer interactions in IEEE 802. 11 WLANs. First, we present a detailed performance evaluation of 802. 11a/b PHY layer transmission modes. The second contribution of the thesis concerns 802. 11 MAC/PHY layers modelling. An analytical model that accounts for the positions of stations with respect to the access point while evaluating the performance of 802. 11 MAC layer, has been proposed. The third contribution of the thesis concerns rate adaptation mechanisms and especially cross layer algorithms between MAC and PHY layers. An adaptive rate selection algorithm, called AARF for low latency systems that improves upon ARF to provide both short-term and long-term adaptation has been proposed. In this field, we also present a new rate adaptation algorithm designed for high latency systems named AMRR that has been implemented and evaluated on an AR5212-based device. We then propose a closed-loop, dynamic rate selection algorithm that can be implemented in all 802. 11a/b/g compliant wireless local area networks. This algorithm called CLARA is a culmination of the best attributes of the transmitter-based ARF and the RBAR control mechanisms with additional practical features to facilitate multipath fading channel sensing and feedback control signalling. The last contribution of the thesis is on the optimization of real time multimedia transmission over 802. 11 based networks. In particular, we propose a simple and efficient cross layer mechanism, called MORSA, for dynamically selecting the transmission mode considering both the channel conditions and characteristics of the media
Ramirez, Rojas Octavio. "Architectures pour la gestion de la mobilité dans les réseaux IEEE 802. 11." Versailles-St Quentin en Yvelines, 2005. http://www.theses.fr/2005VERS0016.
Full textLe but de cette thèse a été l'étude et la proposition de solutions pour gérer la mobilité de l'utilisateur dans des réseaux utilisant le standard IEEE 802. 11. Dans cette thèse, nous avons développé deux architectures. Dans la première, nous avons introduit une architecture sécurisée pour gérer le roaming des nœuds mobiles dans les réseaux sans fil. Le but de cette architecture SMMArc (Service Mobility Management Architecture) a consisté à offrir des services à l'utilisateur d'après son profil. La deuxième architecture a été développée de manière à gérer des connexions TCP lorsque les nœuds mobiles changent de domaine en cours de communication. Cette architecture ATHOMIC (Architecture managing Tcp Handoff Over Mobile Ip Connections) a permis de réduire la probabilité de perte des segments lorsque les nœuds mobiles changent de domaines IP
Dhoutaut, Dominique. "Etude du standard IEEE 802. 11 dans le cadre des réseaux ad hoc." Lyon, INSA, 2003. http://theses.insa-lyon.fr/publication/2003ISAL0094/these.pdf.
Full textStudy of the IEEE 802. 11 standard un ad hoc networks context: from simulation to experimentation. The mobiles composing ad hoc networks do not rely on any fixed infrastructure and organise themselves depending on nodes movements. This research area is quite recent, and most of the work concerns routing. Because of its commercial availability and its ease of use, IEEE 802. 11 standard (Wi-Fi) is generally chosen to develop and test ad hoc routing protocols. But 802. 11 has not been originally designed for multi-hops networks and has limitations in this context that we intend to highlight. Using simulations then real world experimentations, we bring up many problems ranging from medium access equity to transmission range and environment impact. With its detailed study of these phenomena, this PhD has an impact in particular over ad hoc routing protocols and the way they are designed, but also over upper layers protocols, TCP being the first of them
Meraihi, Naimi Amina. "Délai et routage dans les réseaux ad hoc 802. 11." Versailles-St Quentin en Yvelines, 2005. http://www.theses.fr/2005VERS0027.
Full textAvec l'émergence des applications multimédia dans les réseaux ad hoc, des garanties de la qualité de service QoS sont de plus en plus exigées. Le premier obstacle à franchir consiste en la connaissance de l'état du réseau en terme de délai ou de bande passante ou tout autre critère, que ce soit par modélisation ou par le biais de mesures. Dans le cadre de cette thèse, nous nous sommes intéressés à l'étude du délai et du routage avec délai dans des réseaux sans fil ad hoc particuliers que sont les réseaux 802. 11. Nous avons tout d'abord modélisé le mode d'accès DCF du protocole 802. 11. Nous avons ensuite déduis les délais moyens et les distributions de délai à un saut et multi sauts. Grâce au simulateur ns-2, nous avons pu étudié et validé notre modèle analytique. Par ailleurs, nous avons montré que les délais dans les réseaux 802. 11 suivent une loi puissance. Nous avons proposé une extension du protocole de routage proactif OLSR, que nous avons appelé DOLSR, pour le support du délai. DOLSR calcule les routes qui minimisent le délai moyen de bout en bout en se basant sur l'évaluation périodique locale du délai à un saut effectuée grâce à la modélisation et la diffusion de ce dernier via des paquets particuliers. Nous avons implémenté DOLSR sous ns-2 et étudié ses performances en terme de délai et de perte de paquets. Finalement, nous avons proposé, comme alternative au routage avec délai moyen, un routage avec distribution de délai. Ce problème étant NP complet, nous avons utilisé les résultats de l'analyse asymptotique du délai pour proposer une solution
Karbaschi, Golnaz. "Routage basé sur la qualité des liens dans des réseaux multi-sauts IEEE 802. 11." Paris 6, 2008. http://www.theses.fr/2008PA066055.
Full textMundangepfupfu, Tinotenda Leslie. "Simulation modelling of QoS enhancements in IEEE, 802. 11 networks and the effects of channel modelling." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/11682.
Full textRomdhani, Lamia. "Conception inter-couche de réseaux adhoc IEEE 802. 11 pour le provisionnement de la qualité de service." Paris, ENST, 2006. http://www.theses.fr/2006ENST0024.
Full textThis dissertation focuses on the design, implementation, and evaluation of 802. 11-based cross-layer mechanisms for the enhancement of the support of the QoS feature. Before the cross-layer study, we have also explored the idea of enhancing separately a communications layer; namely the existing 802. 11e MAC protocol which is designed for the QoS support. Although the improvements achieved, this study shows the limitations of the layered architecture that demonstrated its good performance in wired networks. Due to the large number of cross-layer cooperation possibilities, we emphasize, in this work, on the cooperation between the MAC and the network layers. We believe that the cooperation between these two layers provides better performance improvement than the cooperation between other layers. In particular, we focus on the problem of routing data packets in a way that takes into account channel contention level, network characteristics, and higher-layer protocol requirements. We address the optimal routing with regard to links stability, average end-to-end delay, and energy conservation with and without assistance/initiation from the network. We design several cross-layer mechanisms that aim to overcome the issue of routing in MANETs while enhancing important QoS metrics (path stability, energy consumption, end-to-end delay, etc. ). To this end, we extract the adequate parameters from both MAC and network layers and adapt them to provide QoS enhancement based on new inter-layer cooperation algorithms. Furthermore, we identify the challenges that face the cross-layer architectures comparing to the traditional layered architecture for enhancing communication protocols
Ksentini, Adlen. "Qualité de service (QoS) dans les réseaux locaux sans fil basés sur la technologie IEEE 802. 11." Cergy-Pontoise, 2005. http://biblioweb.u-cergy.fr/theses/05CERG0254.pdf.
Full textNext-generation Wireless Local Area Networks (WLAN) are involved to support a variety of services and traffic types. Among these services real-time applications, unlike Web and data transfert, requiere a strict Quality of Service (QoS) support such as: (i) low end-to-end delays; (ii) bandwidth guarantee and low drop rate. Since the IEEE 802. 11 standard fails to introduce differentiation between traffic classes, providing QoS in 802. 11-based network is very challenging. Indeed, both MAC layer and Physical layer designed by the IEEE 802. 11 standard support only best-effort transmission. Usually, the IEEE 802. 11 standard features the specifications for the two OSI's lower layers (MAC and Physical). The Medium Access Control (MAC) introduces two medium access protocols that are conceptly different: (i) Distributed Coordination Function (DCF) is a contention-based access mechanim executed independatly at each wireless station; (ii) Point Coordination Function (PCF) is a pooling-based mechanism that needs a central station to regulate the wireless traffic. The popularity of IEEE 802. 11 is mainly due to DCF, whereas PCF is barely implemented in today's products due to its complexity and inneficiently for the data transmission. Further, unlike DCF that can be deployed in every network configuration (ad-hoc and infrastructure), PCF is designed only for infrastructure-based configuration. By considering that MAC layer is the key element that provides QoS support in 802. 11-based wireless networks, our work through this thesis is to study and improve the legacy MAC layer and more especially the DCF access mechanism. Accordingly, we leverage the MAC's capability to support real-time's QoS requirements. The contributions of this thesis are organized onto two axes: •Improve the Backoff Binary Backoff (BEB) algorithm employed by DCF in two hostils environements: (i) when the newtwork operates with high collisions (high network load); (ii) when the network operates in noisy environements (high Bit Error Rate). •Study the concepts and the fesability of QoS in the 802. 11 MAC layer through the introduction of: (i) a new MAC protocol featuring QoS supports; (ii) a cross-layer architecture involoving the H. 264 encoder and the 802. 11e MAC layer aiming at ensure a robust video transport over WLAN
Taifour, Mahmoud. "Améliorations de la couche MAC IEEE 802. 11 pour la qualité de service dans les réseaux ad hoc." Lille 1, 2006. http://www.theses.fr/2006LIL10136.
Full textSarr, Cheikh. "De l'apport d'une évaluation précise des ressources pour la Qualité de Service des réseaux ad hoc basés sur IEEE 802. 11." Lyon, INSA, 2007. http://theses.insa-lyon.fr/publication/2007ISAL0046/these.pdf.
Full textMobile Ad hoc Network (MANET) is an autonomous system of mobile nodes connected by wireless links. They require no fixed infrastructure such as base station to operate; therefore, it is an attractive networking option for connecting mobile devices quickly and spontaneously. The nodes themselves address topology changes due to the mobility, the arrival or the departure of nodes. Today, several applications general multimedia data or rely on the proper transmission of sensitive control traffic. These applications may benefit from a quality of service (QoS) support. Therefore, this field has been extensive/y studied and more and more QoS solutions are proposed for ad hoc networks. During my thesis, I focus on one of the fundamental resources, the bandwidth. Estimating the remaining bandwidth at a given time an in a given part of the network is tricky, as the medium is shared between close nodes in a wireless network. This implies that computation of the available bandwidth between two neighbor nodes requires identification of all the emitter's potential contenders and of all the receiver's potential jammers. I propose therefore a new technique to estimate residual bandwidth in ad hoc networks which present good performances. From this estimation, i have also developed a management scheme for QoS and Best Effort flows in order to increase the acceptance rate of QoS flows. Finally, we also compute an evaluation of end-to-end delay in these ad hoc networks
Lundgren, Klara. "Kvalitativ Riskanalys: trådlös kommunikation i en butiksmiljö." Thesis, Linköping University, Department of Computer and Information Science, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6023.
Full textExamensarbetet är utfört på Axfood AB som vill se om det finns behov av att införa olika skyddsåtgärder beroende på vilken information som kommuniceras i ett trådlöst nätverk i butik. För att komma fram till ett förslag på vilka skyddsåtgärder som är lämpliga att införa vid trådlös kommunikation i en butiksmiljö har jag genomfört en kvalitativ riskanalys. Ett antal väl definierade scenarion har fungerat som en konkret utgångspunkt för riskanalysen.
I den kvalitativa riskanalysen har hot som är speciellt intressanta vid trådlös kommunikation identifierats och en riskbedömning gjordes genom att bedöma sannolikhet och konsekvens av dessa hot. Även skyddsåtgärder identifierades för att tillsammans med resultatet från riskbedömningen avgöra vilken nivå av skyddsåtgärder som är lämpliga i de olika scenarierna. Med utgångspunkt i scenarierna har sedan konkreta rekommendationer för olika skyddsåtgärder gjorts. Det har visat sig att det i de flesta fall är samma grundläggande rekommendationer som har getts för de olika scenarierna.
Detta examensarbete ska kunna användas av företaget som underlag för att besluta vilka skyddsåtgärder som är nödvändiga att investera i beroende på vilka tjänster som deras trådlösa nätverk ska tillhandahålla. Examensarbetet kan även vara intressant för andra företag som överväger att införa trådlösa nätverk.
Meraihi, Rabah. "Gestion de la qualité de service et controle de topologie dans les réseaux ad hoc." Paris, ENST, 2005. http://www.theses.fr/2005ENST0003.
Full textWith the widespread development of multimedia services in mobiles networks, numerous researches on quality of service support in ad hoc networks have been proposed. Existent studies are often based on restricted hypotheses and limited constraints. In this thesis, we first propose a new routing protocol which performs terminal differentiation and uses a reliable network core that maximizes high quality wireless hops. We address then the need of a cross-layer QoS management in MANET using IEEE 802. 11 MAC protocol. The interaction between layers improves network performance, since it takes into account the different constraints in the variable ad hoc environment. An other aspect of the thesis treats of the topology control in mobiles ad hoc networks. Our contribution proposes to control the ad hoc network topology through the deployment of dedicated mobile routers depending on the mobile nodes’ locations. Thus, the network topology is hierarchical and based on a stable high quality mobile backbone formed by mobile routers having a long autonomy. This thesis was done as part of the ITEA Ambience project in which I contributed to the development of a platform, where mechanisms represented before are studied
Makhlouf, Abderrahim. "Étude des mécanismes de l'équite de la qualité de service dans les réseaux Ad-Hoc." Paris 6, 2009. http://www.theses.fr/2009PA066744.
Full textKhalifé, Hicham. "Techniques de contrôle pour réseaux sans fils multi-sauts." Paris 6, 2008. http://www.theses.fr/2008PA066458.
Full textSawma, Gilbert. "Un système de pilotage autonomique pour la distribution de charge dans les réseaux sans fil Wi-Fi." Paris 6, 2009. http://www.theses.fr/2009PA066755.
Full textCoupechoux, Marceau. "Protocoles distribués de contôle d'accès au médium pour réseaux ad hoc fortements chargés." Paris, ENST, 2004. http://www.theses.fr/2004ENST0021.
Full textThis thesis contributes to the domain of medium access control for wireless ad hoc networks. These networks are by definition created for the occasion and usually have to operate without any existing fixed infrastructure. Chapter 1 gives a synthesis of contention-based and conflict-free MAC protocols. IEEE 802. 11 DCF, heir of the first family, is able to address single and multi-hop communications. The foremost objective of this dissertation is to find alternative schemes for improved MAC performance in highly loaded networks. Chapter 2 studies the capacity of IEEE 802. 11b in case of access point (AP) centric networks with TCP, UDP, and Voice over IP traffic. The performance degradation due to the near-far effect is highlighted and some solutions are proposed. A real world deployment is presented for outdoor proviosining of high speed Internet to low density areas. Advantage of using the multi-hop concept to extend the coverage range of an AP and the corresponding issues of degradation in throughput and fairness at high input loads have been analysed in detail. In chapter 3, we propose a new slotted protocol, called CROMA, to overcome the weaknesses of IEEE 802. 11 in highly loaded multi-hop ad hoc networks. An analytical study and extensive simulations show that CROMA clearly outperforms IEEE 802. 11 in the targeted environments. Chapter 4 explores three examples of cross-layer mechanisms. Capacity improvments have been demonstrated in three cases: (i) A scheduling policy can take advantage of node mobility. (ii) Multi-user diversity improves CROMA reservation scheme based on slotted ALOHA. (iii) Multi-user detection can offer additional improvment for reservation too
Vannier, Rémi. "Profiterole : un protocole de partage équitable de la bande passante dans les réseaux ad hoc." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2009. http://tel.archives-ouvertes.fr/tel-00965326.
Full textCorreia, Bruno Filipe Ferreira. "Towards Energy Efficient Multimedia Streaming in Mobile Devices." Master's thesis, 2014. http://hdl.handle.net/10316/35745.
Full textIn the last few years the mobile devices have been increasingly used as part of the people daily routines. The Android smartphones and tablets are responsible for a large part of this increase and are used around the clock, causing the energy consumption in these devices to be a concern. Since these devices are most of the time connected to the Internet, the energy consumed by the IEEE 802.11 interface is responsible for a fast drain in the battery lifetime, leading to the need of finding solutions to reduce the wireless interface energy consumption. Therefore, this work presents the state of the art concerning the IEEE 802.11 technology and a discussion of the most important energy consumption optimizations presented in the literature. To allow the study of the energy consumption in Android devices, a testbed setup is described and was used to perform a characterization of the IEEE 802.11 interface energy consumption in Android devices. The results showed that the implemented power saving techniques do not provide a proper trade-o↵ between the energy consumption and the end-user expectations in the presence of Continuous Media Applications. Since the Continuous Media Applications are expected to be responsible for the most part of the mobile traffic in a few years, proposing mechanisms that keep the end-user expectations while reducing the energy consumption becomes a challenge. With this challenge in mind, this work presents the EXPoSE framework which aims to extend the control of the IEEE 802.11 interface to the endusers, in Android devices. The validation of this framework in a real testbed showed energy savings between 5% and 54% while taking into account the end-user configurations. Furthermore, this work also proposes the enhanced Power save Algorithm for continuous Media Applications (OPAMA) lite mechanism for Android devices. The experimental evaluation in a real testbed showed a clear benefit of employing this mechanism in the presence of Continuous Media Applications, since, it is possible to reduce more than 55% of the energy consumption while keeping the end-user expectations, namely the maximum allowed delay. Keywords: IEEE 802.11, Continuous Media Applications, Android, Energy, End-Users.