Made available in DSpace on 2016-04-29T14:23:53Z (GMT). No. of bitstreams: 1 Ana Carolina Rocha Vaz.pdf: 691245 bytes, checksum: 0fd6901a116520cf58e82d6d007d39d3 (MD5) Previous issue date: 2010-03-19 / The aim of this project is to identify and analyze the impacts of mobile telephone use in society. It was observed that use of this device can strengthen relationships through the exchange of information between users by means of photos, videos, text messages and phone calls. The mobile phone has proven to be a key element in ubiquitous computing and what differentiates it from other mobile devices is the fact that it can combine a number of features in one super-portable piece of equipment. Mobile phones are an efficient tool for coordinating activities. The possibility of rescheduling commitments in real-time, during breaks between one activity and another, can transform the experience of time according to researchers. The addition of localization systems to this device allowed new methods of appropriating physical space, especially in urban centers. The consequences of being available any time, any place, were also discussed. There are two movements going in opposite direction: although we have our entire social network available, at the same time, we become more vulnerable to those who wish to find us. This study is the result of reading the work of authors who analyzed the social changes occurring due to the advances in the development of smart technologies such as Pierre Levy and Manuel Castells. The issue of the impact caused by the use of mobile phones was discussed based on the research by Lucia Santaella, André Lemos, Adriana Souza e Silva, Richard Ling and Howard Rheingold / Este trabalho tem por objetivo apontar e analisar os impactos do uso do telefone celular na vida em sociedade. Observou-se que o uso desse aparelho pode fortalecer relacionamentos através da troca de informações entre os usuários por meio de fotos, vídeos, mensagens de texto e chamadas de voz. O celular mostrou ser o elemento central da computação ubíqua e o que o diferencia dos outros dispositivos móveis é o fato de poder reunir uma série de recursos dentro de um equipamento superportátil. O telefone móvel é uma ferramenta eficiente para a coordenação de atividades e a possibilidade de reagendamento de compromissos em tempo real, nos intervalos entre uma atividade e outra, pode transformar a experiência do tempo, segundo estudiosos da área. A inserção de sistemas de localização nesse dispositivo permitiu novas formas de apropriação do espaço físico, sobretudo nos centros urbanos. As conseqüências de se estar acessível o tempo todo, de qualquer lugar, também foram discutidas. Há dois movimentos ocorrendo em sentidos opostos: ao mesmo tempo em que temos ao nosso alcance nossa rede de contatos, também ficamos vulneráveis para quem quiser nos encontrar. Essa pesquisa é resultado da leitura do trabalho de autores que analisam as mudanças sociais que ocorreram com o avanço no desenvolvimento das tecnologias da inteligência, como Pierre Levy e Manuel Castells. A questão do impacto do uso do telefone celular foi discutida a partir de pesquisas de Lucia Santaella, André Lemos, Adriana Souza e Silva, Richard Ling e Howard Rheingold

Current network architectures, as well as mobility management protocols, are generally deployed in a centralized manner. Moreover, these protocols are designed to be always activated, even when not needed. As the number of mobile users and the volume of their traffic increase, such centralized architectures are expected to encounter scalability issues as well as performance issues. Recently, mobile network operators are experiencing a rapid increase in mobile data traffic. In order to cope with this, a new trend is to flatten networks architectures and hence IP mobility management protocols need to be adapted for such evolution. Therefore, there is a need to define novel mobility management mechanisms that are both distributed and offered dynamically. In order to cope with this context, the thesis concerns designing, analyzing, and evaluating novel IPv6 network architectures and mobility protocols that are distributed and dynamic, and in particular Distributed Mobility Management (DMM). Before proposing any extension, we categorize the existing mobility schemes and carry out a comparative analysis on each category. Then, we propose a new distributed dynamic mobility management scheme based on the Mobile IPv6 (MIPv6) protocol, with an optional extension for the joint use with the Session Initiation Protocol (SIP). After, we carry out a performance analysis in terms of mobility costs, handover, and quality-of-service. Finally, we study the impacts on other aspects such as security considerations and location management.

The aim of this thesis is to investigate the traffic patterns in the mobile data networks. In this work, a simple Cellular Digital Packet Data (CDPD) network was modeled in order to be used in simulations. For the purpose of using in the CDPD model, a synthetic bursty traffic model was produced and using different traffic patterns some performance investigations were made in CDPD network. During the whole work, OPNET simulation tool was used. The CDPD network modeled by OPNET simulation tool was compared with a CDPD model described in the literature and the differences were shown. The new model has some new features: 1) Burst transmission of MAC blocks. 2) Exponential backoff. 3) New packet structures. 4) Frame segmentation and encapsulation into MAC layer frames. Using OPNET, a traffic having higher level of burstiness was produced and applied to the CDPD network model. Under the bursty traffic, some CDPD performance parameters were collected and according to the collected results some suggestions were given.

The telecommunications industry faces difficult challenges as more and more devices communicate over the internet. A telecommunications network is a complex system with many parts and some are candidates for further automation. We have focused on interfrequency measurements that are used during inter-frequency handovers, among other procedures. A handover is the procedure when for instance a phone changes the base station it communicates with and the inter-frequency measurements are rather expensive to perform. More specifically, we have investigated the possibility of using deep learning—an ever expanding field in machine learning—for predicting inter-frequency measurements in a Long Term Evolution (LTE) network. We have focused on the multi-layer perceptron and extended it with (variational) autoencoders or modified it through dropout such that it approximate the predictive distribution of a Gaussian process. The telecommunications network consist of many cells and each cell gather its own data. One of the strengths of deep learning models is that they usually increase their performance as more and more data is used. We have investigated whether we do see an increase in performance if we combine data from multiple cells and the results show that this is not necessarily the case. The performances are comparable between models trained on combined data from multiple cells and models trained on data from individual cells. We can expect the multi-layer perceptron to perform better than a linear regression model. The best performing multi-layer perceptron architectures have been rather shallow, 1-2 hidden layers, and the extensions/modifications we have used/done have not shown any significant improvements to warrant their presence. For the particular LTE network we have worked with we would recommend to use shallow multi-layer perceptron architectures as far as deep learning models are concerned.

Mobile Video streaming has become popular with the arrival of high capability smart phones on Mobile Networks. Users are streaming high definition (HD) videos and have high expectations on Mobile Quality of Experience (QoE). Fourth Generation Mobile Networks are being deployed recently in many regions of the world and have capability to efficiently handle high definition video traffic. YouTube is one of the most extensively used Video on Demand Service on smart phones where wide range of people do video streaming. Most of the QoE experiments on 4g networks have been conducted in lab environment but they do not capture the daily routine of user experience on viewing videos. The user experiments in this thesis are conducted in natural life settings to capture Quality of Experience based on context of the user location. User experiments are designed and conducted for collecting Mean Opinion scores (MOS) in four different context based locations and have been collected using Experience Sampling Method (ESM). The Contribution of thesis is applying linear mixed effect Modeling on data collected to develop Quality of Experience (QoE) models of video streaming for Mobile YouTube on 4G Network. This thesis is one of the first works on modeling QoE experience at different context based physical locations in natural settings for mobile YouTube video streaming in 4G networks.

The wide-spread coverage and ubiquitous presence of mobile networks has propelled the usage and adoption of mobile phones to an unprecedented level around the globe. The computing capabilities of these mobile phones have improved considerably, supporting a vast range of third party applications. Simultaneously, Peer-to-Peer (P2P) overlay networks have experienced a tremendous growth in terms of usage as well as popularity in recent years particularly in fixed wired networks. In particular, Distributed Hash Table (DHT) based Structured P2P overlay networks offer major advantages to users of mobile devices and networks such as scalable, fault tolerant and self-managing infrastructure which does not exhibit single points of failure. Integrating P2P overlays on the mobile network seems a logical progression; considering the popularities of both technologies. However, it imposes several challenges that need to be handled, such as the limited hardware capabilities of mobile phones and churn (i.e. the frequent join and leave of nodes within a network) intensive mobile networks offering limited yet expensive bandwidth availability. This thesis investigates the feasibility of extending P2P to mobile networks so that users can take advantage of both these technologies: P2P and mobile networks. This thesis utilises OverSim, a P2P simulator, to experiment with the performance of various P2P overlays, considering high churn and bandwidth consumption which are the two most crucial constraints of mobile networks. The experiment results show that Kademlia and EpiChord are the two most appropriate P2P overlays that could be implemented in mobile networks. Furthermore, Network Address Translation (NAT) is a major barrier to the adoption of P2P overlays in mobile networks. Integrating NAT traversal approaches with P2P overlays is a crucial step for P2P overlays to operate successfully on mobile networks. This thesis presents a general approach of NAT traversal for ring based overlays without the use of a single dedicated server which is then implemented in OverSim. Several experiments have been performed under NATs to determine the suitability of the chosen P2P overlays under NATed environments. The results show that the performance of these overlays is comparable in terms of successful lookups in both NATed and non-NATed environments; with Kademlia and EpiChord exhibiting the best performance. The presence of NATs and also the level of churn in a network influence the routing techniques used in P2P overlays. Recursive routing is more resilient to IP connectivity restrictions posed by NATs but not very robust in high churn environments, whereas iterative routing is more suitable to high churn networks, but difficult to use in NATed environments. Kademlia supports both these routing schemes whereas EpiChord only supports the iterating routing. This undermines the usefulness of EpiChord in NATed environments. In order to harness the advantages of both routing schemes, this thesis presents an adaptive routing scheme, called Churn Aware Routing Protocol (ChARP), combining recursive and iterative lookups where nodes can switch between recursive and iterative routing depending on their lifetimes. The proposed approach has been implemented in OverSim and several experiments have been carried out. The experiment results indicate an improved performance which in turn validates the applicability and suitability of ChARP in NATed environments.

Les réseaux cellulaires ont connu une croissance phénoménale du trafic alimentée par les nouvelles technologies d'accès cellulaire. Cette croissance est en grande partie tirée par l'émergence du trafic HTTP adaptatif streaming (HAS) comme une nouvelle technologie de diffusion des contenus vidéo. Le principe du HAS est de rendre disponible plusieurs qualités de la même vidéo en ligne et que les clients choisissent la meilleure qualité qui correspond à leur bande passante. Chaque niveau d'encodage est segmenté en des chunks, qui dont la durée varie de 2 à 10 secondes. L'émergence du HAS a introduit des nouvelles contraintes sur les systèmes de livraison des contenus vidéo en particulier sur les systèmes de caches. Dans ce contexte, nous menons une analyse détaillée des données du trafic HAS collecté en France et fournie par le plus grand opérateur de téléphonie mobile du pays. Tout d'abord, nous analysons et modélisons le comportement des clients qui demandent des contenus VoD et live. Ces analyses nous ont permis d'identifier les facteurs qui impactent la performance des systèmes de cache et de proposer un nouveau algorithme de remplacement de contenus qu'on appelle WA-LRU. WA-LRU exploite la localité temporelle des chunks dans le contenu et la connaissance de la charge du trafic dans le réseau afin d'améliorer la performance du cache. Ensuite, nous analysons et modélisons la logique d'adaptation entre les qualités vidéo basés sur des observations empiriques. Nous montrons que le changement fréquent entre les encodages réduit considérablement la performance des systèmes de cache. Dans ce contexte, nous présentons CF-DASH une implémentation libre d'un player DASH qui vise à réduire les changements fréquents entre qualités, assure une bonne QoE des clients et améliore la performance des systèmes de caches. La deuxième partie de la thèse est dédié à la conception, simulation et implémentation d'une solution de préchargement des contenus vidéo sur terminaux mobiles. Nous concevons un système que nous appelons «Central Predictor System (CPsys)" qui prédit le comportement des clients mobiles et leurs consommations des vidéos. Nous évaluons CPSys avec des traces de trafic réel. Enfin, nous développons une preuve de concept de notre solution de préchargement. / Recently, cellular networks have witnessed a phenomenal growth of traffic fueled by new high speed broadband cellular access technologies. This growth is in large part driven by the emergence of the HTTP Adaptive Streaming (HAS) as a new video delivery method. In HAS, several qualities of the same videos are made available in the network so that clients can choose the quality that best fits their bandwidth capacity. This strongly impacts the viewing pattern of the clients, their switching behavior between video qualities, and thus beyond on content delivery systems. In this context, we provide an analysis of a real HAS dataset collected in France and provided by the largest French mobile operator. Firstly, we analyze and model the viewing patterns of VoD and live streaming HAS sessions and we propose a new cache replacement strategy, named WA-LRU. WA-LRU leverages the time locality of video segments within the HAS content. We show that WA-LRU improves the performance of the cache. Second, we analyze and model the adaptation logic between the video qualities based on empirical observations. We show that high switching behaviors lead to sub optimal caching performance, since several versions of the same content compete to be cached. In this context we investigate the benefits of a Cache Friendly HAS system (CF-DASH) which aims at improving the caching efficiency in mobile networks and to sustain the quality of experience of mobile clients. Third, we investigate the mobile video prefetching opportunities. We show that CPSys can achieve high performance as regards prediction correctness and network utilization efficiency. We further show that CPSys outperforms other prefetching schemes from the state of the art. At the end, we provide a proof-of-concept implementation of our prefetching system.

The architecture of the network is undergoing a series of structural changes from the core network to the user to pave the way for 5G. New infrastructure elements are being massively deployed, thus making 5G more heterogeneous. This emerging paradigm, along with new services and handheld devices, creates a massive, highly mobile, heterogeneous environment with hard constraints in throughput, latency, resilience, and power consumption. This dissertation presents Agile MEC (AMEC), a shift in the concept of MEC to support user's mobility with the rapid relocation of services; and Network-coded Cooperation (NCC), a new system for massive content distribution in cellular networks. In summary, AMEC provides a mobility framework that reliably reduces the latency and power consumption in the system, and NCC improves network throughput, network resilience, and power consumption by offloading cellular traffic to underlay networks. / Die Architektur des Netzes durchläuft eine Reihe von strukturellen Veränderungen vom Kernnetz bis zum Benutzer, um den Weg für 5G zu ebnen. Neue Infrastruktur Elemente werden massiv eingesetzt, wodurch 5G heterogener wird. Dieses aufkommende Paradigma bildet zusammen mit neuen Diensten und Handheld-Geräten eine massive, hochmobile, heterogene Umgebung mit harten Einschränkungen in Bezug auf Durchsatz, Latenz, Belastbarkeit und Stromverbrauch. In dieser Dissertation werden Agile MEC (AMEC), eine Verschiebung des MEC-Konzepts zur Unterstützung der Mobilität der Benutzer durch die schnelle Verlagerung von Diensten, und Network-coded Cooperation (NCC), ein neues System zur massiven Verteilung von Inhalten in zellularen Netzwerken, vorgestellt. Zusammenfassend lässt sich sagen, dass AMEC einen Mobilitätsrahmen bietet, der die Latenzzeit und den Stromverbrauch im System zuverlässig reduziert, und NCC verbessert den Netzwerkdurchsatz, die Netzwerkstabilität und den Stromverbrauch, indem es den zellularen Datenverkehr auf unterlagerte Netzwerke verlagert.

New developments in web transport such as HTTP/2 and first and foremost QUIC promise fewer connections to track as well as shorter connection setup times. These protocols have proven themselves on modern reliable connections with a high bandwidth-delay-product, but how do they perform over cellular connections in rural or crowded areas where the connections are much more unreliable? A lot of new users of the web in todays mobile-first usage scenarios are located on poor connections. A testbench was designed that allowed for web browsing over limited network links in a con- trolled environment. We have compared the network load time of page loading over the protocols QUIC, HTTP/2 and HTTP/1.1 using a variety of different network conditions. We then used these measurements as a basis for suggesting which protocol to use during different conditions. The results show that newer is not always better. QUIC in general works reasonably well under all conditions, while HTTP/1.1 and HTTP/2 trade blows depending on connection conditions, with HTTP/1.1 sometimes outperforming both of the newer protocols.

La pénétration du marché des appareils mobiles a connu une croissance impressionnante ces dernières années. Smartphones, tablettes et ordinateurs portables sont devenus soit producteurs soit consommateurs de contenus générés par les utilisateurs. Les communications opportunistes permettent une couverture étendue dans les endroits où il n'existe aucune infrastructure réseau disponible et des stratégies de délestage de données pour aider les opérateurs à soulager la charge de leurs infrastructures. Dans cette thèse, nous considérons le cas de la diffusion opportuniste de plusieurs grands contenus d'un point de vue expérimental. Dans la première partie nous commençons par implémenter EPICS, un protocole réseau conçu pour l'échange opportuniste de grands contenus, dans des terminaux Android. Après sa évaluation nous proposons DAD, un nouveau protocole, qui envoie une rafale de paquets de données de façon adaptative. Nous comparons les deux protocoles expérimentalement et, à l'aide des traces de contacts, soit réelles, soit synthétiques, nous obtenons des gains importants avec cette nouvelle approche. La deuxième partie est dédiée au passage à l'échelle des systèmes de surveillance passive. Nous proposons deux approches. La première est basée sur la similarité des traces et des algorithmes de détection de communautés. La deuxième est basée sur des mesures collaboratives. / The market penetration of mobile devices has experienced an impressive growth. Smartphones, tablets, and laptops have become both producers and consumers of user-generated contents. They also motivate novel communication paradigms such as the possibility to establish, in an opportunistic fashion, direct device-to-device links whenever two mobile nodes enter within the wireless range of each other. In this thesis, we consider the case of opportunistic dissemination of multiple large contents from an experimental point of view. This implies revisiting, among others, the common assumption that contacts have enough capacity to transfer any amount of data.In the first part of this thesis, we start from an Android implementation of EPICS, a network protocol designed for exchanging large contents in opportunistic networks, on off-the-shelf devices. After an deep analysis of application-level logs and captured wireless traces we found out limitations and uncovered improving possibilities. We then propose DAD, a new content dissemination protocol that adaptively sends bursts of data instead of the per-fragment transmission strategy of EPICS.The second part of this thesis deals with the scalability of legacy WLAN monitoring systems. We propose two original approaches. With the first one, based on trace similarity and community detection algorithms, we are able to identify how many monitor we need in a target area and where to place them. The second approach in based on collaborative measurements. In this case we face the risk of biased measures due attacks of malicious users generating adulterated traces. We then propose a method to detect such malicious behaviors.