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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.
1

BitTorrent Traffic Measurements and Models / Mätningar av och modeller för BitTorrenttrafik

Erman, David January 2005 (has links)
The Internet has experienced two major revolutions. The first was the emergence of the World Wide Web, which catapulted the Internet from being a scientific and academic network to becoming part of the societal infrastructure. The second revolution was the appearance of the Peer-to-Peer (P2P) applications, spear-headed by Napster. The popularity of P2P networking has lead to a dramatic increase of the volume and complexity of the traffic generated by P2P applications. P2P traffic has recently been shown to amount to almost 80% of the total traffic in a high speed IP backbone link. One of the major contributors to this massive volume of traffic is BitTorrent, a P2P replication system. Studies have shown that BitTorrent traffic more than doubled during the first quarter of 2004, and still amounts to 60% of all P2P traffic in 2005. This thesis reports on measurement, modelling and analysis of BitTorrent traffic collected at Blekinge Institute of Technology (BTH) as well as at a local ISP. An application layer measurement infrastructure for P2P measurements developed at BTH is presented. Furthermore, a dedicated fitness assessment method to avoid issues with large sample spaces is described. New results regarding BitTorrent session and message characteristics are reported and models for several important characteristics are provided. Results show that several BitTorrent metrics such as session durations and sizes exhibit heavy-tail behaviour. Additionally, previously reported results on peer reactivity to new content are corroborated. / Nya resultat angående trafikkarakteristik och modeller för BitTorrenttrafik presenteras.
2

Measurements and Models of One-Way Transit Time in IP Routers / Mätningar av en-vägskorsningstid i IP routrar

Constantinescu, Doru January 2005 (has links)
The main goals of this thesis are towards an understanding of the delay process in best-effort Internet for both non-congested and congested networks. A novel measurement system is reported for delay measurements in IP routers, which follows specifications of the IETF RFC 2679. The system employs both passive measurements and active probing and offers the possibility to measure and analyze different delay components of a router, e.g., packet processing delay, packet transmission time and queueing delay at the output link. Dedicated application-layer software is used to generate UDP traffic with TCP-like characteristics. Pareto traffic models are used to generate self-similar traffic in the link. The reported results are in form of several important statistics regarding processing and queueing delays of a router, router delay for a single data flow, router delay for multiple data flows as well as end-to-end delay for a chain of routers. They confirm results reported earlier about the fact that the delay in IP routers is generally influenced by traffic characteristics, link conditions and, to some extent, details in hardware implementation and different IOS releases. The delay in IP routers may also occasionally show extreme values, which are due to improper functioning of the routers. Furthermore, new results have been obtained that indicate that the delay in IP routers shows heavy-tailed characteristics, which can be well modeled with the help of several distributions, either in the form of a single distribution or as a mixture of distributions. There are several components contributing to the OWTT in routers, i.e., processing delay, queueing delay and service time. The obtained results have shown that, e.g., the processing delay in a router can be well modeled with the Normal distribution, and the queueing delay is well modeled with a mixture of Normal distribution for the body probability mass and Weibull distribution for the tail probability mass. Furthermore, OWTT has several component delays and it has been observed that the component delay distribution that is most dominant and heavy-tailed has a decisive influence on OWTT. / Mätningar och modeller för en-vägskorsningstid presenteras.
3

Dynamic network adaptation for energy saving / Adaptation dynamique des réseaux sans fil pour économiser de l'énergie

Shehadeh, Dareen 04 December 2017 (has links)
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.

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