Application Platforms, Routing Algorithms and Mobility Behavior in Mobile Disruption-Tolerant Networks

Mobile disruption-tolerant networks (DTNs), experience frequent and long duration partitions due to the low density of mobile nodes. In these networks, traditional networking models relying on end-to-end communication cease to work. The topological characteristics of mobile DTNs impose unique challenges for the design and validation of routing protocols and applications. We investigate challenges of mobile DTNs from three different viewpoints: the application layer, a routing perspective, and by studying mobility patterns. In the application layer, we have built 7DS (7th Degree of Separation) as a modular platform to develop mobile disruption-tolerant applications. 7DS offers a class of disruption-tolerant applications to exchange data with other mobile users in the mobile DTN or with the global Internet. In the routing layer, we have designed and implemented PEEP as an interest-aware and energy efficient routing protocol which automatically extracts individual interests of mobile users and estimates the global popularity of data items throughout the network. PEEP considers mobile users' interests and global popularity of data items in its routing decisions to route data toward the community of mobile users who are interested in that data content. Mobility of mobile users impacts the conditions in which routing protocols for mobile DTNs must operate and types of applications that could be provided for mobile networks in general. The current synthetic mobility models do not reflect real-world mobile users' behavior. Trace-based mobility models, also, are based on traces that either represent a specific population of mobile users or do not have enough granularities in representing mobility of mobile users for example cell tower traces. We use Sense Networks' GPS traces that are being collected by monitoring a broad spectrum of mobile users. Using these traces, we employ a Markovian approach to extract inherent patterns in human mobility. We design and implement a new routing algorithm for mobile DTNs based on our Markovian analysis of the human mobility. We explore how the knowledge of the mobility improves the performance of our Markov based routing algorithm. We show that that our Markov based routing algorithm increases the rate of data delivery to popular destinations with consuming less energy than legacy algorithms

Improving Content Delivery and Service Discovery in Networks

Production and consumption of multimedia content on the Internet is rising, fueled by the demand for content from services such as YouTube, Netflix and Facebook video. The Internet is shifting from host-based to content-centric networking. At the same time, users are shifting away from a homogeneous desktop computing environment to using a heterogeneous mix of devices, such as smartphones, tablets and thin clients, all of which allow users to consume data on the move using wireless and cellular data networks. The popularity of these new class of devices has, in turn, increased demand for multimedia content by mobile users. The emergence of rich Internet applications and the widespread adoption and use of High Definition (HD) video has also placed higher pressure on the service providers and the core Internet backbone, forcing service providers to respond to increased bandwidth use in such networks. In my thesis, I aim to provide clarity and insight into the usage of core networking protocols and multimedia consumption on both mobile and wireless networks, as well as the network core. I also present research prototypes for potential solutions to some of the problems caused by the increased multimedia consumption on the Internet

A PEER-TO-PEER FILE SHARING SYSTEM FOR WIRELESS AD-HOC NETWORKS

Cataloged from PDF version of article.In recent years, we have witnessed an increasing popularity of peer-to-peer (P2P) networks. Especially, file sharing applications aroused considerable interest of the Internet users and currently there exist several peer-to-peer file sharing systems that are functional on the Internet. In the mean time, recent developments in mobile devices and wireless communication technologies enabled personal digital assistants (PDA) to form ad-hoc networks in an easy and automated way. However, file sharing in wireless ad-hoc networks imposes many challenges that make conventional peer-to-peer systems operating on wire-line networks (i.e. Internet) inapplicable for this case. Information and workload distribution as well as routing are major problems for members of a wireless ad-hoc network, which are only aware of peers that are within their communication range. In this thesis, we propose a system that solves peer-to-peer file-sharing problem for wireless ad-hoc networks. Our system works according to principles of peer-to-peer systems, without requiring a central server, and distributes information regarding the location of shared files among members of the network. By means of constructing a distributed hash table (DHT) and forming a tree shaped overlay network based on the topology of the network itself, the system is able to answer location queries, and also discover and maintain routing information that is used to transfer files from a source-peer to another peer.Sözer , HasanM.S

On-demand content delivery on spontaneous mobile mesh networks

Dissertação de mestrado em Engenharia InformáticaToday there is a vast number of mobile devices. These devices allow people to access services everywhere. Typically a network infrastructure is required to support these services, like a wireless access point or a 3G connection. Sometimes such infrastructure may not exist or may not be available, making services impossible to operate. Ad-hoc networks allow infrastructure-less communication where each device can communicate with other devices from the network without depending on some infrastructure. These networks can be explored in order to provide services. For example, content delivery in case there is no infrastructure available to support the communication. The main objective of this work is to take advantage of the potential of ad-hoc networks to provide some services related with content access. The goal is to achieve a framework that is able to explore ad-hoc networks to successfully deliver content to every interested user. Besides, it should be able to work in different devices and operating systems. In this work, a fully functional framework prototype was implemented, requiring minimal configuration. The result is an off-the-shelf application that needs only a Java Virtual Machine (JVM) to operate. In order to successfully forward content between nodes from the server to the destination, a new routing model was developed that is exclusively based on content IDs instead of addresses. We used HTTP as presentation layer of the framework. This way we enable the customization of the interface by the server. Each user that is already familiarized with HTML pages can easily interact with our system.Hoje em dia existe um grande número de dispositivos móveis que permitem o acesso a serviços em qualquer lado. Para suportar esses serviços é necessária uma infra-estrutura de rede, como por exemplo, um ponto de acesso sem fios ou uma ligação 3G. Quando essa infra-estrutura é inexistente ou não está disponível, os serviços tornam-se inacessíveis. As redes ad-hoc possibilitam a comunicação independente de qualquer infra-estrutura. Estas redes podem ser exploradas por forma a fornecer serviços, tais como o acesso a conteúdo, no caso de não existir uma infra-estrutura de comunicação. O objectivo principal é tirar partido das redes ad-hoc para fornecer serviços de acesso a conteúdo. Queremos obter uma plataforma capaz de fornecer conteúdos aos utilizadores interessados, explorando as redes ad-hoc. Para além disso, deve também ser capaz de operar em diferentes dispositivos e sistemas operativos. Neste trabalho foi implementado um protótipo da plataforma completamente funcional. O resultado final é uma aplicação pronta a ser utilizada, que necessita apenas de uma Java Virtual Machine (JVM). Foi desenhado um novo modelo de encaminhamento baseado, exclusivamente, em IDs de conteúdo, por forma a encaminhar o tráfego entre servidor e cliente. Utilizamos o HTTP como camada de apresentação, dessa forma, o servidor pode ‘desenhar’ o interface. A interacção com o sistema é bastante simples no caso do utilizador estar familiarizado com as páginas HTML

A study of mobile phone ad hoc networks via bluetooth with different routing protocols

The growth of mobile computing is changing the way people communicate. Mobile devices, especially mobile phones, have become cheaper and more powerful, and are able to run more applications and provide networking services. Mobile phones use fixed cellular infrastructure such as base stations and transmission towers to enable users to share multimedia content and access the internet at any time or place. However, using the internet is costly. Therefore, one of the solutions is to create impromptu ad hoc networks to share information among users. Such networks are infrastructureless and self-organising, much like mobile ad hoc networks. This dissertation therefore investigates how mobile phones with low-power Bluetooth technology can be used to create ad hoc networks that connect mobile phones and allow them to share information. The mobile phones should be able organise themselves for multi-hop communication. Routing becomes important in order to achieve effciency in data communication. Several existing routing protocols were developed and evaluated for this network to determine how effciently they deliver data and deal with network disruptions such as a device moving out of transmission range. Representative routing protocols in mobile ad hoc networking, peer-to-peer networks and publish/subscribe systems were evaluated according to performance metrics defidened in the research, namely total traffc, data traffc, control traffc, delay, convergence time, and positive response. Prototypes for Nokia phones were developed and tested in a small ad hoc network. For practical networking setup, a simple routing protocol that uses the limited mobile phone resources effciently would be better than a sophisticated routing protocol that keeps routing information about the network participants

Resilience-Building Technologies: State of Knowledge -- ReSIST NoE Deliverable D12

This document is the first product of work package WP2, "Resilience-building and -scaling technologies", in the programme of jointly executed research (JER) of the ReSIST Network of Excellenc

Mitigating Network Service Disruptions in High-bandwidth, Intermittently Connected, and Peer-to-Peer Networks

Users demand high-bandwidth, ubiquitous and low-cost network services. This demand has pushed ISPs and application providers to offer more bandwidth, allow users to access the Internet almost everywhere, and provide cheap or free network services using peer-to-peer networks. These three trends underlie the growing success of today's Internet. However, (1) high-bandwidth can empower more effective denial-of-service attacks; (2) Internet access is widespread, but still not ubiquitous; and (3) peer-to-peer network services need to solve the service discovery problem. This thesis addresses these three challenges. First, we tackle denial-of-service attacks. The high bandwidth available in many parts of the Internet allows denial-of-service attacks to be effective, and the large scale of the Internet makes detecting and preventing these attacks difficult. Anonymity and openness of the Internet worsens this problem because anyone can send anything to anybody. To prevent these denial-of-service attacks, we propose Permission-Based-Sending (PBS), a signaling architecture for network traffic authorization. PBS uses the explicit permission to give legitimate users the authority to send packets. Signaling is used to configure this permission in the data path. This signaling approach enables easy installation for granting authorization to flows, and allows PBS to be deployed in existing networks. In addition, a monitoring mechanism provides a second line of defense against attacks. Next, we strive to make Internet access more ubiquitous. When public transportation stations have access points to provide Internet access to passengers, public transportation becomes a more attractive travel and commute option. However, the Internet connectivity is intermittent because passengers can access the Internet only when a bus or train is within the networking coverage of an AP at a stop. To efficiently handle this intermittent network for the public transit system, we develop Internet Cache on Wheels (ICOW), a system that provides a low-cost way for bus and train operators to offer access to Internet content. Each bus and train car is equipped with a smart cache that serves popular content to passengers. The cache updates its content based on passenger requests when it is within range of Internet access points placed at bus stops, train stations or depots. This aggregated Internet access is significantly more efficient than having passengers contact Internet access points individually and ensures continuous availability of content throughout the journey. Finally, we consider peer-to-peer services. Typical service discovery mechanisms in peer-to-peer networks cause significant overhead, consuming energy and bandwidth: (1) in highly mobile networks, service discovery consumes the energy of mobile devices to discover services that newly joined members provide; and (2) peer-to-peer network systems consumes bandwidth during service discovery. To resolve and analyze these service discovery problems, (1) we design an efficient service discovery mechanism that reduces energy consumption of mobile devices; and (2) we evaluate the bandwidth consumption caused by service discovery in real-world peer-to-peer networks

Cooperative Data Backup for Mobile Devices

Les dispositifs informatiques mobiles tels que les ordinateurs portables, assistants personnels et téléphones portables sont de plus en plus utilisés. Cependant, bien qu'ils soient utilisés dans des contextes où ils sont sujets à des endommagements, à la perte, voire au vol, peu de mécanismes permettent d'éviter la perte des données qui y sont stockées. Dans cette thèse, nous proposons un service de sauvegarde de données coopératif pour répondre à ce problème. Cette approche tire parti de communications spontanées entre de tels dispositifs, chaque dispositif stockant une partie des données des dispositifs rencontrés. Une étude analytique des gains de cette approche en termes de sûreté de fonctionnement est proposée. Nous étudions également des mécanismes de stockage réparti adaptés. Les problèmes de coopération entre individus mutuellement suspicieux sont également abordés. Enfin, nous décrivons notre mise en oeuvre du service de sauvegarde coopérative. ABSTRACT : Mobile devices such as laptops, PDAs and cell phones are increasingly relied on but are used in contexts that put them at risk of physical damage, loss or theft. However, few mechanisms are available to reduce the risk of losing the data stored on these devices. In this dissertation, we try to address this concern by designing a cooperative backup service for mobile devices. The service leverages encounters and spontaneous interactions among participating devices, such that each device stores data on behalf of other devices. We first provide an analytical evaluation of the dependability gains of the proposed service. Distributed storage mechanisms are explored and evaluated. Security concerns arising from thecooperation among mutually suspicious principals are identified, and core mechanisms are proposed to allow them to be addressed. Finally, we present our prototype implementation of the cooperative backup servic