Small mobile devices with networking capabilities are becoming more and more readily available and used. These devices can be used to form mobile ad hoc networks to communicate, where no infrastructure for network communication exist or where it has been destroyed or is overloaded e.g. in a natural disaster such as a hurricane. Such networks are almost never fully connected, and are part of the category of delay/disruption-tolerant networks (DTN) and suffer from limited resources e.g. bandwidth, storage and limited energy supply. The Opportunistic DTN Routing With Window-aware Adaptive Replication (ORWAR) is a delaytolerant protocol intended to be used in disaster relief efforts or emergency operations were a DTN could be a fast way to establish communication. In these kinds of scenarios high success rate together with efficient usage of the networks resources are critical to the success of such operations. ORWAR has been implemented and simulated on a high-level simulator, with promising results. To make a better assessment about what ORWARs performance would be in a real world network, more realistic and detailed simulations are needed. This Master's Thesis describes the design, implementation and evaluation of ORWAR in the network simulator ns-3, which simulates networks down to physical layer. The contributions of this thesis is a extension to ns-3 giving it an framework with support for the bundle protocol and delay-tolerant routing protocols and an evaluation of the ORWAR performance using more detailed simulations. The simulations represent a city scenario in down-town Helsinki city, Finland, were pedestrians, cars and trams form a network to communicate. The simulations with a higher level of detail has added to insight about the protocol. The obtained results showed that the high-level simulation may be overly optimistic and hides implementation details. On the other hand, some assumptions were found to be too pessimistic. For example we have shown that ORWAR actually performs better than the high level simulations, with regard to partial transmissions and that the high-level simulations have rather optimistic assumptions regarding the latency.

The Aim of this thesis is to implement the "Opportunistic DTN Routing with Window-aware Adaptive Replication" (ORWAR) protocol on the Android platform.Delay-Tolerant Networks (DTNs) are particular mobile ad-hoc network (MANET) architectures that try to solve the issues related to the lack of point to point connectivity between the nodes of the network or between its sub-networks (partitions). The general approach is based on techniques of store-carry-forward of the messages whereby delivery can be achieved even in partitioned networks, though with mobility-dependent delays. DTNs can be considered as a means of communication for scenarios where infrastructure-based networks cannot be deployed or get dysfunctional for some reasons, such as in the case of a natural disaster or highly overloaded infrastructure. ORWAR is a DTN protocol that tries to exploit knowledge about the context of mobile nodes (speed, direction of movement and radio range) to estimate the size of a contact window in order to avoid the energy waste deriving from partial transmissions. This report presents the design and the implementation of the protocol on the Android platform. It then describes some functional tests together with an analysis of the energy consumption and the performance reachable on our test device Android Development Phone 1.

Rapid urbanization burdens city infrastructure and creates the need for local governments to maximize the usage of resources to serve its citizens. Smart city projects aim to alleviate the urbanization problem by deploying a vast amount of Internet-of-things (IoT) devices to monitor and manage environmental conditions and infrastructure. However, smart city projects can be extremely expensive to deploy and manage partly due to the cost of providing Internet connectivity via 5G or WiFi to IoT devices. This thesis proposes the use of delay tolerant networks (DTNs) as a backbone for smart city communication; enabling developing communities to become smart cities at a fraction of the cost. A model is introduced to aid policy makers in designing and evaluating the expected performance of such networks and results are presented based on a public transit network data-set from Chapel Hill, North Carolina and Louisville, Kentucky. We also demonstrate that the performance of our network can be optimized using algorithms associated on set-cover and Influence maximization problems. Several optimization algorithms are then developed to facilitate the effective placement of gateways within the network model and these algorithms are shown to outperform traditional centrality-based algorithms in terms of cost-efficiency and network performance. Finally, other innovative ways of improving network performance in a low-cost smart city is discussed.

This thesis introduces approaches providing scalable delay-/disruption-tolerant routing capabilities in scheduled space topologies. The solution is developed for the requirements derived from use cases built according to predictions for future space topology, like the future Mars communications architecture report from the interagency operations advisory group. A novel routing algorithm is depicted to provide optimized networking performance that discards the scalability issues inherent to state-of-the-art approaches. This thesis also proposes a new recommendation to render volume management concerns generic and easily exchangeable, including a new simple management technique increasing volume awareness accuracy while being adaptable to more particular use cases. Additionally, this thesis introduces a more robust and scalable approach for internetworking between subnetworks to increase the throughput, reduce delays, and ease configuration thanks to its high flexibility.:1 Introduction 1.1 Motivation 1.2 Problem statement 1.3 Objectives 1.4 Outline 2 Requirements 2.1 Use cases 2.2 Requirements 2.2.1 Requirement analysis 2.2.2 Requirements relative to the routing algorithm 2.2.3 Requirements relative to the volume management 2.2.4 Requirements relative to interregional routing 3 Fundamentals 3.1 Delay-/disruption-tolerant networking 3.1.1 Architecture 3.1.2 Opportunistic and deterministic DTNs 3.1.3 DTN routing 3.1.4 Contact plans 3.1.5 Volume management 3.1.6 Regions 3.2 Contact graph routing 3.2.1 A non-replication routing scheme 3.2.2 Route construction 3.2.3 Route selection 3.2.4 Enhancements and main features 3.3 Graph theory and DTN routing 3.3.1 Mapping with DTN objects 3.3.2 Shortest path algorithm 3.3.3 Edge and vertex contraction 3.4 Algorithmic determinism and predictability 4 Preliminary analysis 4.1 Node and contact graphs 4.2 Scenario 4.3 Route construction in ION-CGR 4.4 Alternative route search 4.4.1 Yen’s algorithm scalability 4.4.2 Blocking issues with Yen 4.4.3 Limiting contact approaches 4.5 CGR-multicast and shortest-path tree search 4.6 Volume management 4.6.1 Volume obstruction 4.6.2 Contact sink 4.6.3 Ghost queue 4.6.4 Data rate variations 4.7 Hierarchical interregional routing 4.8 Other potential issues 5 State-of-the-art and related work 5.1 Taxonomy 5.2 Opportunistic and probabilistic approaches 5.2.1 Flooding approaches 5.2.2 PROPHET 5.2.3 MaxProp 5.2.4 Issues 5.3 Deterministic approaches 5.3.1 Movement-aware routing over interplanetary networks 5.3.2 Delay-tolerant link state routing 5.3.3 DTN routing for quasi-deterministic networks 5.3.4 Issues 5.4 CGR variants and enhancements 5.4.1 CGR alternative routing table computation 5.4.2 CGR-multicast 5.4.3 CGR extensions 5.4.4 RUCoP and CGR-hop 5.4.5 Issues 5.5 Interregional routing 5.5.1 Border gateway protocol 5.5.2 Hierarchical interregional routing 5.5.3 Issues 5.6 Further approaches 5.6.1 Machine learning approaches 5.6.2 Tropical geometry 6 Scalable schedule-aware bundle routing 6.1 Overview 6.2 Shortest-path tree routing for space networks 6.2.1 Structure 6.2.2 Tree construction 6.2.3 Tree management 6.2.4 Tree caching 6.3 Contact segmentation 6.3.1 Volume management interface 6.3.2 Simple volume manager 6.3.3 Enhanced volume manager 6.4 Contact passageways 6.4.1 Regional border definition 6.4.2 Virtual nodes 6.4.3 Pathfinding and administration 7 Evaluation 7.1 Methodology 7.1.1 Simulation tools 7.1.2 Simulator extensions 7.1.3 Algorithms and scenarios 7.2 Offline analysis 7.3 Eliminatory processing pressures 7.4 Networking performance 7.4.1 Intraregional unicast routing tests 7.4.2 Intraregional multicast tests 7.4.3 Interregional routing tests 7.4.4 Behavior with congestion 7.5 Requirement fulfillment 8 Summary and Outlook 8.1 Conclusion 8.2 Future works 8.2.1 Next development steps 8.2.2 Contact graph routing

With the miniaturization of satellites a fundamental change took place in the space industry. Instead of single big monolithic satellites nowadays more and more systems are envisaged consisting of a number of small satellites to form cooperating systems in space. The lower costs for development and launch as well as the spatial distribution of these systems enable the implementation of new scientific missions and commercial services. With this paradigm shift new challenges constantly emerge for satellite developers, particularly in the area of wireless communication systems and network protocols. Satellites in low Earth orbits and ground stations form dynamic space-terrestrial networks. The characteristics of these networks differ fundamentally from those of other networks. The resulting challenges with regard to communication system design, system analysis, packet forwarding, routing and medium access control as well as challenges concerning the reliability and efficiency of wireless communication links are addressed in this thesis. The physical modeling of space-terrestrial networks is addressed by analyzing existing satellite systems and communication devices, by evaluating measurements and by implementing a simulator for space-terrestrial networks. The resulting system and channel models were used as a basis for the prediction of the dynamic network topologies, link properties and channel interference. These predictions allowed for the implementation of efficient routing and medium access control schemes for space-terrestrial networks. Further, the implementation and utilization of software-defined ground stations is addressed, and a data upload scheme for the operation of small satellite formations is presented. / Mit der Miniaturisierung von Satelliten hat eine fundamentale Änderung in der Raumfahrtindustrie stattgefunden. Anstelle von einzelnen, großen, monolithischen Satelliten werden heutzutage immer mehr Systeme entworfen die aus mehreren Kleinstsatelliten bestehen die kooperativ zusammenarbeiten. Die geringeren Kosten für Entwicklung und Start sowie die räumliche Verteilung dieser Satellitensysteme ermöglichen die Realisierung neuer wissenschaftlicher Missionen und kommerzieller Dienstleistungen. Durch diesen Paradigmenwechsel entstehen neue Herausforderungen für Ingenieure, insbesondere in den Bereichen Funkkommunikation und Netzwerkprotokolle. Satelliten in erdnahen Umlaufbahnen und Bodenstationen bilden sogenannte Satelliten-terrestrische Netzwerke. Die Eigenschaften dieser Netzwerke unterscheiden sich wesentlich von denen anderer Netzwerke. Die resultierenden Herausforderungen in den Bereichen Systemdesign, Systemanalyse, Paketvermittlung, Routing und Medienzugriffskontrolle, sowie Herausforderungen in Bezug auf die Zuverlässigkeit und Effizienz der Funkkommunikation werden in dieser Dissertation behandelt. Die physikalische Modellierung von Satelliten-terrestrischen Netzwerken wird behandelt durch die Analyse von existierenden Satelliten- und Funkkommunikationssystemen, durch die Nutzung von Messungen an einer Bodenstation und einem Satelliten und durch die Implementierung eines Simulators für Satelliten-terrestrische Netzwerke. Die resultierenden System- und Kanalmodelle wurden als Basis für die Prädiktion der dynamischen Netzwerktopologien, Verbindungseigenschaften und Kanalinterferenzen genutzt. Diese Prädiktionen haben die Implementierung effizienter Verfahren für Routing und Medienzugriffskontrolle in Satelliten-terrestrischen Netzwerken ermöglicht. Darüber hinaus wird die Implementierung und Nutzung von Bodenstationen auf Basis von digitaler Signalverarbeitung behandelt und ein Datenübertragungsverfahren für den Betrieb von Kleinstsatellitenformationen beschrieben und evaluiert.

Ubiquitous connectivity plays an important role in improving the quality of life in terms of economic development, health and well being, social justice and equity, as well as in providing new educational opportunities. However, rural communities which account for 46% of the world's population lacks access to proper connectivity to avail such societal benefits, creating a huge "digital divide" between the urban and rural areas. A primary reason is that the Information and Communication Technologies (ICT) providers have less incentives to invest in rural areas due to lack of promising revenue returns. Existing research and industrial attempts in providing connectivity to rural communities suffer from severe drawbacks, such as expensive wireless spectrum licenses and infrastructures, under- and over-provisioning of spectrum resources while handling heterogeneous traffic, lack of novel wireless technologies tailored to the unique challenges and requirements of rural communities (e.g., agricultural fields). Leveraging the recent advances in Dynamic Spectrum Access (DSA) technologies like wide band spectrum analyzers and spectrum access systems, and multi-radio access technologies (multi-RAT), this dissertation proposes a novel Diverse Band-aware DSA (d-DSA) network architecture, that addresses the drawbacks of existing standard and DSA wireless solutions, and extends ubiquitous connectivity to rural communities; a step forward in the direction of the societal and economic improvements in rural communities, and hence, narrowing the "digital divide" between the rural and urban societies. According to this paradigm, a certain wireless device is equipped with software defined radios (SDRs) that are capable of accessing multiple (un)licensed spectrum bands, such as, TV, LTE, GSM, CBRS, ISM, and possibly futuristic mmWaves. In order to fully exploit the potential of the d-DSA paradigm, while meeting heterogeneous traffic demands that may be generated in rural communities, we design efficient routing strategies and optimization techniques, which are based on a variety of tools such as graph modeling, integer linear programming, dynamic programming, and heuristic design. Our results on realistic traces in a large variety of rural scenarios show that the proposed techniques are able to meet the heterogeneous traffic requirements of rural applications, while ensuring energy efficiency and robustness of the architecture for providing connectivity to rural communities.

耐延遲網路(Delay Tolerant Networks)上的路由協定可以區分為兩大類:flooding-based protocols 跟forwarding-based protocols。網路編碼(Network Coding)是一種編碼技術可以提高訊息傳輸的可靠度；並且運作時不需要知道整體網路的拓樸資訊。 我們提出的演算法結合了flooding-based protocols 跟forwarding-based protocol特性，最主要的概念是讓訊息不是被傳送給每一個節點，而是傳送給朝向目的地或是接近目的地的節點。當節點相遇時，我們的方法會利用節點的路徑、移動方向與速度去預測到達目的地的機率。同時我們利用網路編碼的技巧傳送編碼後的資料來代替訊息的片段，來避免重複傳送多餘的訊息；並讓通訊更加可靠。根據實驗模擬的結果，我們的機制有較好的效能，特別是在頻寬的使用上。 / The routing protocols of delay tolerant networks could be divided in two categories: flooding-based protocols and forwarding-based protocols. Network coding is an encoding technique that could make data transmission more reliable. It operates without the needed of information about the network topology. We proposed a routing protocol integrating the characteristic of flooding-based protocol and forwarding-based protocol. The main idea of our protocol is to let message would not be flooded to every node but to the nodes moving toward or moving closer to destination. When nodes contact with each other, our approach will use the path of node, node’s moving direction and its velocity to estimate the probability to reach the destination of message. At the same time, we exploit network coding to transmit coded block instead of message fragment in order to avoid sending redundant replication, make data transmit more reliable and more robust to packet losses or delays. From the result of simulation, we could see that our protocol have a higher performance especially in the bandwidth consumption compared to other protocols.

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Cette thèse traite de la dissémination de messages dans les réseaux tolérants aux délais (DTNs). Ce type d'environnements très contraints ouvre de nombreux défis parmi lesquels le routage qui exploite au mieux les critères de mobilité des noeuds, le routage utilisant un nombre réduit de copies du message à disséminer, le routage de messages respectant la vie privée des noeuds, le routage en présence de nœuds égoïstes. Ce sont ces défis que nous adressons dans le cadre de cette thèse. La première contribution de cette thèse consiste en un protocole de routage adaptatif pour les DTNs exploitant au mieux les critères de mobilité des nœuds. En particulier, ce protocole permet de déterminer à chaque fois qu'une décision de routage doit être prise, quel critère de mobilité augmente la probabilité que le message soit délivré à sa destination. Cette décision est prise grâce à une fonction d'utilité calculée par les nœuds après normalisation des valeurs décrivant les différents critères de mobilité. Le protocole est validé par des simulations faites en utilisant des traces de mobilité réelles et en comparaison avec des protocoles de l'état de l'art. Les résultats montrent de meilleures performances en terme de taux de délivrance de messages mais à coût plus élevé. La seconde contribution de cette thèse consiste en un protocole dont le but est d'adapter dynamiquement le nombre de copies de messages disséminés dans le réseau. Le protocole proposé dans cette thèse résout ce problème en pré-calculant un nombre de copies nécessaire pour atteindre une certaine probabilité de délivrance, puis en augmentant dynamiquement ce nombre au fur et à mesure que le délai d'expiration du message approche. Les résultats montrent que le protocole proposé offre un taux de délivrance équivalent aux protocoles les plus performants à un cout bien inférieur. La troisième contribution de cette thèse consiste en un protocole de routage dans les DTNs qui protège la vie privée des nœuds. En particulier, ce protocole protège les informations relatives à la mobilité des nœuds. Ceci est fait en se basant sur l'organisation des nœuds en communautés. En particulier, au lieu de comparer leur propres probabilités de rencontrer la destination d'un message donné, dans le protocole proposé, les nœuds comparent la probabilité qu'un nœud de leur communauté rencontre la destination. Afin de calculer cette probabilité au sein de la communauté de manière à préserver les valeurs individuelle, le protocole se base sur des algorithmes de cryptographie afin de calculer des produits de probabilité de manière à protéger les valeurs individuelles. Les résultats montrent que le protocole exhibe des performances équivalentes aux protocoles existants tout en étant le seul à respecter les informations confidentielles des usagers. / Mobile Delay Tolerant Networks (MDTNs) are wireless mobile networks in which a complete routing path between two nodes that wish to communicate cannot be guaranteed. A number of networking scenarios have been categorized as MDTNs, such as vehicular ad hoc networks, pocket switched networks, etc. The network asynchrony, coupled with the limited resources of mobile devices make message dissemination (also called routing) one of the fundamental challenges in MDTNs. In the literature, a large body of work has been done to deal with routing in MDTNs. However, most of the existing routing protocols are based on at least one of the following three assumptions: (1) all messages can be routed by relying on a single mobility property; (2) all messages can be routed using a single message allocation strategy; (3) users are willing to disclose their mobility information and relationships to others in order to improve the quality of the routing. We argue that the above three assumptions are not realistic because: (1) users can exhibit various social behaviors and consequently various mobility properties (e.g., they can have regular movements during week-days and exhibit non-predictable movements during week-ends); (2) some messages might need more or less copies to be delivered according to the localization of the source and the destination and to the urgency of the message; and (3) users mobility data can disclose sensitive information about the users. In this thesis, we relieve MDTN routing from the above three restrictive assumptions. Firstly, we propose an adaptive routing protocol for mobile delay tolerant networks. The proposed protocol can dynamically learn the social properties of nodes based on their mobility patterns, and exploit the most appropriate routing strategy each time an intermediate node is encountered. Simulations performed on real mobility traces show that our protocol achieves a better delivery ratio than existing state-of-the-art routing protocols that rely on a single mobility property. Secondly, we present a delay and cost balancing protocol for efficient routing in mobile delay tolerant networks. The presented protocol reasons on the remaining time-to-live of a message to dynamically allocate the minimum number of copies that are necessary to achieve a given delivery probability. Evaluation results show that the protocol can achieve a good balance between message delivery delay and delivery cost, compared with most of the existing routing protocols in the literature. Lastly, we propose an efficient privacy preserving prediction-based routing protocol for mobile delay tolerant networks. This protocol preserves the mobility patterns of a node from being disclosed by exploiting the mobility pattern of communities that node belongs to. Evaluation results demonstrate that this protocol can obtain comparable routing performance to prediction-based protocols while preserving the mobility pattern of nodes.

Le transport est devenu fondamental dans les villes pour le bon fonctionnement de l'économie et le bien-être de la population urbaine. Depuis plusieurs années, le transport est confronté à de nombreux problèmes tels que l'embouteillage, le taux élevé d'accidents, la vie malsaine due à la fumée et à la poussière, la pollution atmosphérique due aux émissions de carbone, etc. Pour faire face à ces problèmes, les recherches intègrent les technologies numériques au transport terrestre, connu sous le nom de système de transport intelligent (ITS). Les ITS peuvent détecter, analyser, collecter, contrôler et communiquer différentes données. Cette thèse étudie et propose un nouveau protocole pour les applications de collecte de données dans un environnement urbain. Nous faisons trois contributions principales. Tout d'abord, nous proposons un nouveau protocole dénommé le protocole "Internet of Bikes" IoB-DTN qui applique le paradigme DTN (Réseau tolérant aux délais) aux applications de l'Internet des objets (IoT) exécutant une application de collecte de données sur un système de partage de vélo urbain basé sur un réseau de capteurs. Le protocole est évalué sur un scénario réaliste en évaluant les politiques de gestion des buffers, le nombre de copies pulvérisé dans le réseau ainsi que le nombre des vélos utilisés. Deuxiément, une évaluation comparative des performances du protocole IoB-DTN multi-sauts avec une technologie de réseau étendu à basse consommation (LPWAN), de type LoRa/LoRaWAN est étudiée. LPWAN a été conçu pour fournir une connectivité à grande distance et rentable pour les applications IoT à faible débit: durée de vie de plusieurs années et une portée de multikilomètres pour les appareils mobiles alimentés par des batteries. Cette partie de notre travail vise à fournir aux concepteurs et aux managers de réseaux des idées sur la technologie la plus pertinente pour leurs applications urbaines pouvant fonctionner sur des systèmes de partage de vélos. Enfin, nous proposons un protocole efficace, IoB-DTN basé sur un mécanisme d’agrégation de données. Nous proposons trois variantes de IoB-DTN: IoB basé sur l'agrégation spatiale (IoB-SA), IoB basé sur l'agrégation temporelle (IoB-TA) et IoB basé sur l'agrégation spatio-temporelle (IoB-STA). Nous comparons les trois variantes avec le protocole multi-saut IoB-DTN sans agrégation et la technologie à faible puissance et longue portée, de type LoRa. Les résultats de la comparaison permettent de vérifier que les trois variantes de l’IoB-DTN basées sur l’agrégation de données améliorent plusieurs paramètres tels que le taux de livraison, la consommation d’énergie et le débit. / Transport has become fundamental in the cities to the well functioning of the economy and the welfare of the city population. For several years, transportation faces many issues such as traffic jamming, high accidents rate, unhealthy life due to smoke and dust, air pollution as a result of carbon emission, etc. To deal with these matters, researches integrate digital technologies to ground transportation which is known as Intelligent Transport System (ITS). ITS can sense, analyze, collect, control and communicate different data. This thesis investigates and proposes a new protocol for data collection applications in an urban environment. We make three main contributions: firstly, we propose a new protocol denoted the "Internet of Bikes" IoB-DTN protocol which applies Delay/Disruption Tolerant Network (DTN) paradigm to the Internet of Things (IoT) applications running a data collection application on urban bike sharing system based sensor network. The protocol is evaluated on a realistic scenario by assessing the buffer management policies, the number of copies sprayed in the network as well as the number of bicycles used. Secondly, a comparative evaluation of the performance of the multi-hop IoB-DTN protocol with a low-power wide-area network (LPWAN) technology, LoRa/LoRaWAN type is investigated. LPWAN have been designed to provide cost-effective wide area connectivity for small throughput IoT applications: multiyear lifetime and multikilometer range for battery-operated mobile devices. This part of our work aims at providing network designers and managers insights on the most relevant technology for their urban applications that could run on bike sharing systems. Finally, we propose an efficient IoB-DTN protocol based on data aggregation mechanism. We propose three variants of IoB-DTN: IoB based on spatial aggregation (IoB-SA), IoB based on temporal aggregation (IoB-TA) and IoB based on spatio-temporal aggregation (IoB-STA). We compare the three variants with the multi-hop IoB-DTN protocol without aggregation and the low-power long-range technology, LoRa type. Comparison results verify that the three variants of IoB-DTN based on data aggregation improve several metrics such as the delivery rate, energy consumption and throughput.