Mobile devices are often expected to perform computational tasks that may be beyond their processing or battery capability. Cloud computing techniques have been proposed as a means to offload a mobile device's computation to more powerful resources. In this thesis, we consider the case where powerful computing resources are made available by utilizing vehicles. These vehicles can be repositioned in real time to receive computational tasks from user-carried devices. They can be either equipped with rugged high-performance computers to provide both computation and communication service, or they can be simple message ferries that facilitate communication with a more powerful computing resource. These scenarios find application in challenged environments and may be used in a military or disaster relief settings. It is further enabled by increasing feasibility of (i) constructing a Mobile High Performance Computer (MHPC) using rugged computer hardware with form factors that can be deployed in vehicles and (ii) Message Ferries (MF) that provide communication service in disruption tolerant networks. By analogy to prior work on message ferries and data mules, one can refer to the use of our first schema, MHPCs, as computational ferrying. After illustrating and motivating the computational ferrying concept, we turn our attention into the challenges facing such a deployment. These include the well known challenges of operating an opportunistic and intermittently connected network using message ferries -- such as devising an efficient mobility plan for MHPCs and developing techniques for proximity awareness. In this thesis, first we propose an architecture for the system components to be deployed on the mobile devices and the MHPCs. We then focus on defining and solving the MHPC movement scheduling problem with sufficient generality to describe a number of plausible deployment scenarios. After thorough examination of the MHPC concepts, we propose a scheme in which MHPCs are downgraded to be simple MFs that instead provide communication to a stationary HPC with powerful computing resources. Similar to the MPHCs, we provide a framework for this problem and then describe heuristics to solve it. We conduct a number of experiments that provide an understanding of how the performance of the system using MHPCs or MFs is affected by various parameters. We also provide a thorough comparison of the system in the dimensions of Computation on the Move and Controlling the Mobility.

Submitted by Eric das Neves (evndeveloper@hotmail.com) on 2018-12-11T00:13:26Z No. of bitstreams: 3 Dissertação Versão Secretaria com ficha catalografica e folha de aprovação.pdf: 3156070 bytes, checksum: 27dc73ab25f883f2c6bd2faed11dd6e6 (MD5) 316 ATA de Defesa - Eric Vieira (Assinado).pdf: 478934 bytes, checksum: 8297a92876a93d2002070fab8e573ab2 (MD5) carta deposito.jpg: 881630 bytes, checksum: 1f98e977c3f922663009b11ea05b470a (MD5) / Approved for entry into archive by Secretaria PPGI (secretariappgi@icomp.ufam.edu.br) on 2018-12-12T01:14:34Z (GMT) No. of bitstreams: 3 Dissertação Versão Secretaria com ficha catalografica e folha de aprovação.pdf: 3156070 bytes, checksum: 27dc73ab25f883f2c6bd2faed11dd6e6 (MD5) 316 ATA de Defesa - Eric Vieira (Assinado).pdf: 478934 bytes, checksum: 8297a92876a93d2002070fab8e573ab2 (MD5) carta deposito.jpg: 881630 bytes, checksum: 1f98e977c3f922663009b11ea05b470a (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2018-12-12T13:54:35Z (GMT) No. of bitstreams: 3 Dissertação Versão Secretaria com ficha catalografica e folha de aprovação.pdf: 3156070 bytes, checksum: 27dc73ab25f883f2c6bd2faed11dd6e6 (MD5) 316 ATA de Defesa - Eric Vieira (Assinado).pdf: 478934 bytes, checksum: 8297a92876a93d2002070fab8e573ab2 (MD5) carta deposito.jpg: 881630 bytes, checksum: 1f98e977c3f922663009b11ea05b470a (MD5) / Made available in DSpace on 2018-12-12T13:54:35Z (GMT). No. of bitstreams: 3 Dissertação Versão Secretaria com ficha catalografica e folha de aprovação.pdf: 3156070 bytes, checksum: 27dc73ab25f883f2c6bd2faed11dd6e6 (MD5) 316 ATA de Defesa - Eric Vieira (Assinado).pdf: 478934 bytes, checksum: 8297a92876a93d2002070fab8e573ab2 (MD5) carta deposito.jpg: 881630 bytes, checksum: 1f98e977c3f922663009b11ea05b470a (MD5) Previous issue date: 2018-10-18 / Delay Tolerant Networks have emerged as a solution for communication in scenarios where the Internet does not have its basic premises met for proper operation. DTNs rely directly on their nodes for good performance because it uses the mobility of nodes to send messages to their destinations. However, due to factors such as resource economy, lack of interest in the message or simply the denial of collaboration, it negatively affects network performance. In this way, it is fundamental to consider the social factors, extended from the users to the network nodes, so that the best forwarding strategy is found, increasing the chances of delivering the messages. In this work a new protocol is proposed for the dissemination of messages in DTN networks, using the interests of the network nodes for the formation of level’s message passing. These levels are formed by grouping the nodes through machine learning techniques, KMEANS and EM clusters, according to the level of interest of the nodes by the message generated, directly or indirectly, passing the message by the groups formed up to the recipient of the node. Our results show that the proposal is promising, having superior results to the protocols well qualified in the literature. / As redes tolerantes a atrasos e desconexões surgiram como uma solução para a comunicação em cenários onde a internet não possui suas premissas básicas atendidas: conexão fim-afim, baixa latência e pouca perda de pacotes. As DTNs dependem diretamente da colaboração de seus nós para um bom desempenho, pois usa a mobilidade dos mesmos para fazer os repasses das mensagens até seus destinos. Entretanto, devido a fatores como economia de recursos: energia, armazenamento de dados, pouco interesse pela mensagem ou simplesmente a negação da colaboração, afeta de forma negativa o desempenho da rede. Dessa maneira é fundamental que se leve em consideração fatores sociais, que podem ser estendidos dos usuários e empregados aos nós da rede, para que se possa encontrar a melhor estratégia de repasses, aumentando as chances de entrega das mensagens. Portanto, este trabalho propõe um novo protocolo de disseminação de mensagens em redes DTN, usando os interesses dos nós da rede como fator social, para a formação de níveis de repasse de mensagens. Utilizou-se técnicas de aprendizagem de máquina para a formação dos níveis, que usam clusterizadores como o KMEANS e EM para agrupar os nós de acordo com o nível de interesse pela mensagem gerada, direto ou indireto. Dessa forma a mensagem é repassada através dos grupos formados até o nó destinatário. Resultados obtidos através de um conjunto de experimentos criteriosamente selecionados mostram que a proposta é promissora, apresentando um desempenho superior aos protocolos bem conhecidos da literatura.

<p>Technology has reached a point where it has become feasible to develop unmanned aerial vehicles (UAVs), that is aircraft without a human pilot on board. Given that future UAVs can be autonomous and cheap, applications of swarming UAVs are possible. In this thesis we have studied a reconnaissance application using swarming UAVs and how these UAVs can communicate the reconnaissance data. To guide the UAVs in their reconnaissance mission we have proposed a pheromone based mobility model that in a distributed manner guides the UAVs to areas not recently visited. Each UAV has a local pheromone map that it updates based on its reconnaissance scans. The information in the local map is regularly shared with a UAV’s neighbors. Evaluations have shown that the pheromone logic is very good at guiding the UAVs in their cooperative reconnaissance mission in a distributed manner.</p><p>Analyzing the connectivity of the UAVs we found that they were heavily partitioned which meant that contemporaneous communication paths generally were not possible to establish. This means that traditional mobile ad hoc network (MANET) routing protocols like AODV, DSR and GPSR will generally fail. By using node mobility and the store-carry-forward principle of delay-tolerant routing the transfer of messages between nodes is still possible. In this thesis we propose location aware routing for delay-tolerant networks (LAROD). LAROD is a beacon-less geographical routing protocol for intermittently connected mobile ad hoc networks. Using static destinations we have shown by a comparative study that LAROD has almost as good delivery rate as an epidemic routing scheme, but at a substantially lower overhead.</p> / Report code: LiU-Tek-Lic-2008:14

Delay-tolerant networks (DTNs) are dynamic networks in which senders and receivers are often completely disconnected from each other, often for long periods of time. DTNs are enjoying a burgeoning interest from the research community largely due to the vast potential for meaningful applications, e.g., to enable access to the Internet in remote rural areas, monitor animal behavioral patterns, connect participants in mobile search and rescue applications, provide connectivity in urban environments, and support space communications. Existing work in DTNs generally focuses either on solutions for very specific applications or domains, or on general-purpose protocol-level solutions intended to work across multiple domains. In this proposal, we take a more systems-oriented approach to DTNs. Since applications operating in these dynamic environments would like their connections to be supported by the network technology best suited to the combination of the communication session's requirements and instantaneous network context, we develop a middleware architecture that enables seamless migrations from one communication style to another in response to changing network conditions. We also enable context-awareness in DTNs, using this awareness to adapt communications to more efficiently use network resources. Finally, we explore the systems issues inherent to such a middleware and provide an implementation of it that we test on a mobile computing testbed made up of autonomous robots. / text

With the growth of Internet, the underlying protocols are increasingly challenged by new technologies and applications. The original Internet protocols were, however, not designed for wireless communication, mobility, long disconnection times, and varying bandwidths. In this thesis, we study challenged networking, and how well old and new protocols operate under such constraints. Our study is experimental. We build network testbeds and measure the performance of alternative protocols and architectures. We develop novel methodologies for repeatable experiments that combine emulations, simulations and real world experiments. Based on our results we suggest modifications to existing protocols, and we also develop a new network architecture that matches the constraints of a challenged network, in our case, an opportunistic network. One of our most important contributions is an Ad hoc Protocol Evaluation (APE) testbed. It has been successfully used worldwide. The key to its success is that it significantly lowers the barrier to repeatable experiments involving wireless and mobile computing devices. Using APE, we present side-by-side performance comparisons of IETF MANET routing protocols. A somewhat surprising result is that some ad hoc routing protocols perform a factor 10 worse in the testbed than predicted by a common simulation tool (ns-2). We find that this discrepancy is mainly related to the protocols’ sensing abilities, e.g., how accurately they can infer their neighborhood in a real radio environment. We propose and implement improvements to these protocols based on the results. Our novel network architecture Haggle is another important contribution. It is based on content addressing and searching. Mobile devices in opportunistic networks exchange content whenever they detect each other. We suggest that the exchange should be based on interests and searches, rather than on destination names and addresses. We argue that content binding should be done late in challenged networks, something which our search approach supports well.

Les réseaux tolérants aux délais sont aujourd’hui une alternative prometteuse aux réseaux traditionnels basés sur une infrastructure, encore peu déployée. Il existe plusieurs manières d’évaluer les performances d’un tel réseau : expériences de déploiement grandeur nature, modèles théoriques, simulation, émulation, jeu de traces. Chacune a ses avantages et inconvénients, tant en termes de coûts matériels, de réalisme, de temps nécessaire ou de capacité à gérer des noeuds réels. Cependant, aucune ne répond réellement aux besoins des développeurs d’applications. Dans cette thèse, nous nous focaliserons sur l’émulation. Dans une première partie, nous nous intéresserons aux entrées possibles pour un tel système. Nous proposons tout d’abord un modèle analytique pour prévoir le taux de pertes dans un réseau où les noeuds possèdent une mémoire limitée à un seul paquet. Ensuite, inspirés par les approches de mise à l’échelle de traces de la littérature, nous étudions les hypothèses prises pour l’analyse statistique de traces réelles, et montrons leur influence sur les lois de probabilité obtenues ainsi que les performances réseau observées. Nous étendons ensuite cette étude à la totalité du cycle de vie des traces réelles, en considérant la collecte de données, le filtrage et la mise à l’échelle de celles-ci. Dans une seconde partie, nous proposons une architecture possible d’un émulateur DTN hybride, c’est-à-dire comportant à la fois des noeuds réels sous forme d’intelliphones, et des noeuds virtuels. Le principal avantage ici est de pouvoir évaluer des applications réelles, éventuellement déjà existantes, dans un contexte DTN, et ce de manière aussi transparente que possible. Nous identifions les limites des approches existantes, ce qui nous permet d’établir une liste de spécifications pour notre système. Nous proposons ensuite un système, nommé HINT, permettant de remplir ces spécifications. L’ensemble est ensuite validé, puis appliqué à l’étude de quelques exemples. / Delay Tolerant Networks are currently a promising alternative to infrastructure-based networks, but they have not seen a wide deployment so far. There are several ways to evaluate the performance of such networks: field trials, theoretical models, simulation, emulation or replaying contact datasets. Each one has its advantages and drawbacks in terms of material cost, realism, required time or ability to manage real nodes. However, none of them effectively addresses the needs of application developers. In this thesis, we will focus on emulation. In a first part, we will deal with possible inputs for such a system. We first propose an analytical model to predict the drop ratio in a network where nodes have a one-packet buffer. Then, taking inspiration from trace scaling approaches from the literature, we study the hypotheses and assumptions taken for real traces statistical analyses, showing their impact on the obtained probability distributions and observed network performance metrics. We then extend this study to the whole life cycle of real traces, by considering data collection, filtering and scaling. In a second part, we propose a possible architecture for a hybrid DTN emulator, using both real nodes as smartphones and virtual nodes. The main advantage here is to be able to evaluate real applications, including preexisting ones, in a DTN context, doing so as transparently as possible. We identify the limitations of existing approaches, which helps us build a list of specifications for our system. Then, we propose a system called HINT which matches these specifications. HINT is validated, and applied to the study of some examples.

Technology has reached a point where it has become feasible to develop unmanned aerial vehicles (UAVs), that is aircraft without a human pilot on board. Given that future UAVs can be autonomous and cheap, applications of swarming UAVs are possible. In this thesis we have studied a reconnaissance application using swarming UAVs and how these UAVs can communicate the reconnaissance data. To guide the UAVs in their reconnaissance mission we have proposed a pheromone based mobility model that in a distributed manner guides the UAVs to areas not recently visited. Each UAV has a local pheromone map that it updates based on its reconnaissance scans. The information in the local map is regularly shared with a UAV’s neighbors. Evaluations have shown that the pheromone logic is very good at guiding the UAVs in their cooperative reconnaissance mission in a distributed manner. Analyzing the connectivity of the UAVs we found that they were heavily partitioned which meant that contemporaneous communication paths generally were not possible to establish. This means that traditional mobile ad hoc network (MANET) routing protocols like AODV, DSR and GPSR will generally fail. By using node mobility and the store-carry-forward principle of delay-tolerant routing the transfer of messages between nodes is still possible. In this thesis we propose location aware routing for delay-tolerant networks (LAROD). LAROD is a beacon-less geographical routing protocol for intermittently connected mobile ad hoc networks. Using static destinations we have shown by a comparative study that LAROD has almost as good delivery rate as an epidemic routing scheme, but at a substantially lower overhead. / <p>Report code: LiU-Tek-Lic-2008:14</p>

People all around the world have their internet access censored or monitored by governments or large corporations. Whistleblowers and human rights activists oftentimes need to communicate in secret to avoid persecution by the powerful organization monitoring their communications. Current anonymity systems often depend on the public internet, and as such are subject to some degree of interference. Cloak is a textual communication network created to hide the existence of the network itself from an outside observer, such as a repressive government or corrupt corporation. Cloak does not use the public internet, and as such would evade the majority of the monitoring in place today. Cloak also does not use any special infrastructure or create its own infrastructure, minimizing the risk of infrastructure attacks. Finally, Cloak provides plausible deniability for its users should they be investigated. Cloak works by hiding its messages inside of normal phone activity. Two Cloak nodes can identify each other by looking at wifi probe messages that are generated by phones in the vicinity of an open wifi hotspot. They can then connect to the hotspot and browse like normal, while hiding messages inside their browsing. Because this is open wifi, the other nodes can see the hidden messages and store them, and carry them closer to their destination. Cloak can hide its messages in a lot of ways. It can first send images with messages embedded in them. It can also use places where a website asks for data in a opaque format, such as YouTube video ids. Finally, if encrypted browsing is available, a Cloak node can just send the encrypted message and act like something went wrong with its encrypted browsing.

No description available.

This thesis presents the design and evaluation of routing protocols for efficient content delivery and dissemination in delay tolerant networks. With the advancement in technology, the communication devices with wireless interfaces become more and more universal. Delay tolerant networks (DTNs) are characterized by intermittent connectivity and limited network capacity. There exist several different application scenarios: connectivity of developing countries, vehicular DTN road communications, and social contact networks. In this thesis, we explore the characteristics in DTNs, such as mobility pattern, contact history information, and social feature information, to design efficient routing schemes. The research reported in this thesis investigates the technical challenges and their solutions of applying different DTN routing protocols. We design multicast schemes to forward the information to a group of destinations in DTN environment. We extend the delegation forwarding scheme in DTN multicasting. An non-replication multicast tree is also studied in this report. We also apply ticket-based and social-tie-based approaches in content distribution systems. We leverage the users' social feature information to study the hypercube-based routing schemes in social contact networks. We also study the resource management problem in DTNs. We design a joint replication-migration-based scheme to solve the storage congestion. These techniques are evaluated comprehensively in realistic simulation studies, by comparing the performance with state-of-the-art approaches in both synthetic and real traces. / Computer and Information Science