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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.
31

EnergyBox: Tool improvement and GUI

Polis, Rihards January 2014 (has links)
EnergyBox is a parametrised estimation tool that uses packet traces as input to simulate the energy consumption of communication in mobile devices. This tool models the transmission behaviour of a smart phone by analysing a recorded packet trace from the device. The purpose of the thesis is to reimplement the original EnergyBox energy consumption modelling tool. The project aims to develop support for a graphical user interface (GUI) and a code base that is easier to modify and maintain. The motivation for the reimplementation of the tool is to simplify its usage and to structure the code so that new features can be added. The existing features such as the calculation of total power consumed by the packet trace and the modelling of a device's energy states are reimplemented and new features are developed. Among the new features, a GUI is added to simplify the usage of the application features such as the detection of the recording device's IP address and the ability to alter the configuration parameters used as input to the energy model. The application is written with a GUI and modularity in mind. This is achieved using Java's proprietary new GUI framework - JavaFX, which supports built-in chart and graph GUI elements, that can be easily integrated and supported. The energy modelling engines follow the semantics of the original implementation and the evaluation shows that the new implementation's results are identical to the original tool in 94.94% of the tested cases.
32

USB dongles for mobile broadband : Data communications for laptop computers

Liu, Enfei January 2015 (has links)
Today a growing number of people need to work on laptops with wireless Internet connection. There are two common wireless Internet access solutions: wireless local area network (WLAN) via hotspot, and high speed wide area cellular network via mobile broadband device such as 3G/4G Universal Serial Bus (USB) dongle. USB dongle was the pioneer product in 3G/4G market, and it is still a popular device in many countries. Mobile broadband can offer both high speed access and mobility. Technically mobile broadband allows Internet connection as long as your mobile transceiver can access your cellular network operator’s network. However, in practice the data rates experienced by a user via mobile broadband are not comparable to the data rates that are available via WLAN. Moreover, mobile broadband has been implemented according to multiple different standards. Hence, in order to provide a user with locally optimal service requires that user must make use of heterogeneous networks. Furthermore, the variety of networks gets increasing due to the emergence of various 4G networks. The aim of this thesis is to explore how heterogeneous networks could be exploited to provide a user of a laptop computer with locally optimal service, while hiding the complexity of this heterogeneous service. The research focuses on the implications of integrating multiple network interfaces into a single USB dongle. Our research shows that multi-mode USB dongle is still needed in market, though there are competitions from smartphones and mobile WiFi devices. We point out that the PPP (Point to Point Protocol) based USB dongle should update to Ethernet USB protocols such as RNDIS (Remote Network Driver Interface Specification) or USB CDC (Communications Device Class) protocols. Furthermore, we suggest a USB dongle should be able to work as a WLAN access point to share Internet with other mobile devices, and it should also work as a WLAN client which can join other hotspots. If hotspot operators can authenticate USB dongles by SIM cards, then users can easily access a great number of hotspots belong to these operators. / Mer än någonsin behöver människan arbeta med bärbara datorer med anslutning till trådlöst Internet. Det finns två vanliga trådlösa Internet-anslutningar: trådlöst lokalt nätverk (WLAN på engelska) via en hotspot, eller höghastighets mobilnät via mobilt bredband som 3G/4G Universal Serial Bus (USB) dongel. USB dongeln var pionjär produkten inom 3G/4G marknaden, och den är fortfarande en populär enhet i många länder. Mobilt bredband kan erbjuda både tillgång till höga hastighet och bra mobilitet. Mobilt bredband tillåter, rent tekniskt, användaren hålla en Internet-anslutning så länge mobilen har tillgång till mobilnätets operatörsnät. Men i praktiken är datahastigheterna, som användaren upplever ha via det mobila bredbandet, inte jämförbar med de datahastigheter som är tillgängliga via WLAN. Dessutom har mobilt bredband implementerats enligt flera olika standarder. Således, för att förutse en användare med en optimal lokal tjänst, krävs det att användaren måste använda heterogena nätverk. Dessutom blir olika nätverk allt större på grund av uppkomsten av olika 4G-nät. Syftet med denna avhandling är att undersöka hur heterogena nätverk skulle kunna utnyttjas för att förutse en laptop användare med optimal lokal nätverksservice, samtidigt dölja komplexiteten för användaren om den heterogena tjänsten. Forskningen fokuserar på konsekvenserna av att integrera flera nätverksgränssnitt till en enda USB-dongel. Vår forskning visar att det fortfarande behövs en multi-mode USB dongel på marknaden, dock existerar det konkurrens från smartphones och mobila WiFi-enheter. Vi påpekar även i avhandlingen att PPP (Point-to-Point Protocol) baserade USB dongeln bör uppdateras till Ethernet USB-protokoll, såsom RNDIS (Remote Network Driver Interface Specification) eller USB CDC (Communications Device Class) protokoll. Vidare föreslår vi att en USB-dongel bör kunna fungera som en kopplingspunkt för att dela Internet med andra mobila enheter, och att den också bör fungera som en WLAN-klient som kan ansluta sig till andra hotspots. Om hotspot operatörer kan autentisera USB-donglar genom SIM-kort, så kan användarna enkelt få tillgång till ett stort antal hotspots som tillhör dessa operatörer.
33

Energy consumption reduction mechanisms in mobile networks / Mécanismes de réduction de la consommation d'énergie dans les réseaux mobiles

Saker, Louai 02 December 2011 (has links)
La consommation en énergie des réseaux de télécommunications a suscité un intérêt grandissant au cours des dernières années et les opérateurs mobiles cherchent des solutions innovantes pour optimiser l’efficacité énergétique. Dans cette thèse, nous nous focaliserons sur les schémas d’optimisation de la consommation d’énergie des réseaux d’accès mobiles. Nous commençons par étudier la stratégie de partage de charge qui minimise la consommation d’énergie dans la cellule tout en limitant l’impact sur la Qualité de Service. Le gain obtenu par ces algorithmes de gestion des ressources radio reste cependant limité; ceci est dû au fait que la consommation d’énergie ne dépend pas que de la charge, mais comporte une importante partie constante. Pour obtenir un gain plus important, nous proposons la mise en veille de certaines ressources du réseaux aux heures creuses où le trafic est faible, ce qui mène à des gains substantiels. Nous proposons ensuite un contrôleur de gestion de la mise en veille qui choisit l’action optimale en fonction de l’état du réseau. En effet, l’activation d’une nouvelle ressource n’est pas instantanée et un effet ping-pong peut apparaitre suite aux commandes simultanées d’activation/désactivation des ressources. Nous adaptons nos contrôleurs afin de prendre en compte ces imperfections, et nous montrons comment déduire la politique optimale. Nous étudions ensuite le cas de déploiement de petites cellules dans des réseaux hétérogènes et montrons que leur efficacité énergétique est améliorée par rapport au réseau purement macro-cellulaire, pourvu que la consommation d’énergie de petites cellules reste faible. Nous proposons ensuite un contrôleur optimal qui active/désactive les petites cellules en se basant sur des informations de trafic et de localisation des usagers. Nous considérons différents cas de figure avec une information complète, partielle ou retardée et montrons que ces schémas de mise en veille permettent d’atteindre d’importants gains de consommation d’énergie / In the recent years, more importance has been given to the energy consumption issue in telecommunication networks and mobile operators are rethinking their network design for optimizing its energy efficiency. In this thesis, we propose schemes for optimizing the energy consumption of mobile access networks. We begin by proposing energy-aware Radio Resource Management (RRM) schemes and show that a load balancing between available resources gives some energy savings. However, these gains remain small as a large part of the energy consumption is load-independent. We thus propose sleep mode schemes of resources in the network (cells or carriers) and show that they give a large gain when traffic is low. We then propose optimal sleep mode controllers that give, for each traffic scenario, the best actions to take in each state of the network. We make two observations: the first is that activating a new resource is not instantaneous, leading to QoS degradation if a conservative policy is not considered, and the second is that a ping-pong effect may appear at the frontier between two capacity regions. We adapt our controllers to take into account these imperfections, and show how to derive the optimal policy using Markov decision theory. We then extend our works to the case of small cell deployment in heterogeneous networks, composed of macro and small cells base stations. We study the capacity and power consumption of these networks and show that the energy efficiency is increased for some deployment strategies when the power consumption of small cells is low. We then propose sleep mode for small cells and develop optimal sleep/wakeup schemes based on the information on traffic load and user localization in the cell, in the cases where this information is complete, partial or delayed. We show that these sleep mode schemes achieve large energy consumption gains
34

Architecture and remote interaction techniques for digital media exchange across 3G mobile devices

Yousef, Kharsim January 2009 (has links)
For users away from the office or home, there is an increasing demand for mobile solutions that offer effective collaborative facilities on the move. The mobile cellular device, or “smart phone”, can offer a ubiquitous platform to deliver such services, provided that its many physical and technological constraints can be overcome. In an effort to better support mobile collaboration, this thesis presents a contributing Mobile Exchange Architecture (MEA) designed to improve upon the capabilities provided by mobile devices to enable synchronous exchange of digital media during a phone conversation using wireless networks and cellular devices. This research includes the design and development of one such MEA in the form of a fully functional Photo-conferencing service, supporting shared remote interaction techniques, simultaneous voice communication and seamless digital media exchange between remote and collocated mobile users. Furthermore, through systematic design, experimental evaluations and field studies we evaluate the effects of different shared remote interaction techniques – 'pointing', 'scaling', 'mixed' and 'hybrid' – assessing the task effort required by users when interacting around shared images across resource constrained mobile devices. This thesis presents a direction for the future development of technologies and methods to enable a new era of scalable always-to-hand mobile collaborative environments.
35

Proměny konkurence na českém telekomunikačním trhu / Competition transformation on the Czech telecommunication market

Ryba, Jakub January 2007 (has links)
Diplomová práce ?Proměny konkurence na českém telekomunikačním trhu? je zaměřena především na analýzu nedávného turbulentního vývoje telekomunikací v České republice. Se zaměřením na společnost Telefónica O2 Czech Republic,a.s. práce popisuje hlavní faktory, které telekomunikační trh utvářely v uplynulých letech ? zabývá se významnými tržními aliancemi i otázkou regulace odvětví. Závěr práce je věnován hlavním trendům v telekomunikacích, kterými jsou především fixní a mobilní konvergence, VoIP, sítě třetí generace (3G), mobilní virtuální operátoři (MVNO) a televize přes IP (IPTV).
36

Redes e serviços VoIP/3G e WEB 2.0

Ferreira, Décio de Jesus January 2008 (has links)
Estágio realizado na PT Inovação / Tese de mestrado integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 2008
37

Approche multicouches pour la reconfigurabilité de systèmes de communications de 3ème génération

Krikidis, Ioannis 11 1900 (has links) (PDF)
Un circuit de télécommunication est reconfigurable s'il est capable de changer de fonction en temps réel, comme par exemple le passage d'un standard de communication à un autre, ou l'optimisation des performances suite à une modification contextuelle. La reconfigurabilité nécessite de mener conjointement une étude au niveau algorithmique et au niveau architectural de façon à respecter les contraintes de flexibilité, rapidité et consommation. Dans cette thèse la reconfigurabilité a été étudiée dans le cadre du standard WCDMA de façon à optimiser conjointement la performance et la consommation de puissance lors d'un changement du canal de propagation ou des paramètres de communication. Une des contributions de cette thèse est une nouvelle méthode de reconfigurabilité appelée "Approche itérative". Cette approche essaye de tirer parti des algorithmes ayant des opérateurs similaires et se prêtant à la sérialisation des calculs. Les systèmes de communications et de traitement du signal utilisent de nombreux algorithmes itératifs propices à l'utilisation de cette méthode. L'approche itérative permet de disposer de grain de calcul fin qui joue en faveur de la diminution de la complexité et de la facilité à mettre en commun des ressources entre différents algorithmes. Un autre atout est d'autoriser l'ajustement de la qualité de l'algorithme en jouant sur le nombre d'itérations. La consommation dynamique d'une structure sérielle de ce type est généralement supérieure à la structure factorisation. En revanche la consommation statique qui devient non négligeable dans les technologies CMOS <0.1m est nettement inférieure du fait de la taille réduite du grain de calcul. Pour certaines fonctions, tous les opérateurs peuvent ne pas être utilisés, mais la faible granularité des opérateurs minimise l'utilisation sous optimale du matériel. Le nombre d'itérations peut aussi être limité par le temps imparti pour le traitement. Mais en considérant qu'un itération ne peut durer qu'un cycle d'horloge avec une architecture pipeline, le rapport entre la fréquence d'horloge (>>200Mmots/s) et les débits binaires (quelque Mbits/s à quelques 10Mb/s) offre un nombre d'itération suffisant pour de nombreuses fonctions. Les exemples décrits dans cette thèse illustrent l'intérêt de cette méthode. Plus précisément, nous nous sommes intéressés aux algorithmes de réception d'un système DS-CDMA et à leur implémentation matérielle. La similarité de calcul entre trois fonctions de base qui sont: la démodulation en râteau (RAKE), l'estimation du canal, et l'annulation d'interférence (IC); ainsi que leur nature itérative, a débouché sur quelques algorithmes de réception chargés d'adapter le comportement aux conditions environnementales. Ces algorithmes optimisent la performance du système et minimisent la surface de matériel. Cette approche est donc particulièrement efficace pour l'implémentation de terminaux qui ont des contraintes de puissance et de surface très critiques.
38

Uplink Interference Management of High Bit Rate Users in Evolved WCDMA

Axelsson, Samuel January 2005 (has links)
<p>The WCDMA air interface, used in the third generation mobile communication systems, is currently being evolved to improve the uplink, i.e. the radio links carrying traffic from the mobile user to the fixed network. An enhanced uplink concept is being developed to meet the expected needs from future applications like multimedia and video-streaming. This thesis studies interference management when high bit rates are introduced in the enhanced uplink. The study is performed through theoretical assessments and simulations using WCDMA system simulators.</p><p>An optimization scheme using a basic system throughput based scheduling is derived to attain a theoretical assessment of bit rate limits. The throughput optimization is achieved at the expense of user-experienced fairness. Users located on cell coverage area overlap show to be most complicated to manage.</p><p>The need for interference management is primary when the network deployment consists of small cells while coverage requirements are most essential when the cell size increases. By exploiting the benefits of directional antennas the antenna tilt can be tuned to increase performance resulting in increased bit rates, increased system throughput and increased resource efficiency. The improvements are attained without trade-offs and the different components of the study concur unanimously.</p>
39

Packet Data Flow Control in Evolved WCDMA Networks / Flödeskontroll av Paketdata i Vidareutvecklade WCDMA Nätverk

Bergström, Andreas January 2005 (has links)
<p>The key idea of the new, shared high-capacity channel HSDPA, is to adapt the transmission rate to fast variations in the current radio conditions, thus enabling download peak data rates much higher than what WCDMA can offer today. This has induced a need for data that traverses the mobile network to be intermediately buffered in the Radio Base Station, RBS. A scheduling algorithm then basically selects the user with the most beneficial instantaneous radio conditions for access to the high-speed channel and transmission of its data over the air interface.</p><p>The purpose of this thesis is to design a flow control algorithm for the transmission of data packets between the network node directly above the RBS, the RNC, and the RBS. This flow control algorithm should keep the level of the buffers in the RBS on such a level that the air interface may be fully utilized. Yet it is not desirable with large buffers since e.g., this induces longer round-trip times as well as loss of all data in the buffers whenever the user moves to another cell and a handover is performed. Theoretical argumentations and simulations show that both of these requirements may be met, even though it is a balancing act.</p><p>Suggested is a control-theoretic framework in which the level in the RBS buffers are kept sufficiently large by taking into account predictions of future outflow over air and by using methods to compensate for outstanding data on the transport network. This makes it possible to keep the buffer levels stable and high enough to fully utilize the air interface. By using a more flexible adaptive control algorithm, it is shown possible to reach an even higher utilization of the air interface with the same or even lower buffering, which reduces the amount of data lost upon handovers. This loss is shown to be even more reduced by actively taking system messages about upcoming handover events into account as well.</p>
40

A study of security in wireless and mobile payments

Ali, Ahmed January 2010 (has links)
<p>Mobile payments are increasing in popularity in recent years. New mobile solutions are being developed in the form of new Internet capable mobile devices such as the IPhone and new wireless networks such as the LTE and WiMAX networks.</p><p>This report will present, explain and compare some of the most popular wireless networks that enable mobile payments, from a security point of view. The chosen networks are 3G with connection to GSM, and WLAN networks. The main security mechanisms involved in each network, and how they work will be studied. Security requirements and some of the most important threats each network faces will be presented and discussed. The main purpose of the report is to examine if mobile payments offer an acceptable level of security to the average user.</p>

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