Optimized DTN-Routing for Urban Public Transport Systems

Communication is crucial to the coordination and efficient operation of public transport systems. However, deployment of infrastructure based communication systems is expensive, esp. due to long-term operational costs. Delay tolerant vehicular networks are a promising alternative since only very few infrastructure elements are required. This paper presents a DTN routing algorithm for urban public transport systems which exploits the knowledge about system characteristics and node mobility to improve the routing performance. Various DTN routing schemes are compared with the presented algorithm. Moreover, the impact of disturbances on the routing performance is examined

Deploying public surface transit to forward messages in DTN

Delay Tolerant Network (DTN) is a communication architecture enabling connectivity in a topology with unregular end-to-end network connection. DTN enables communication in environments with cross-connectivity, large delays and delivery time variations, and a high error rate. DTN can be used in vehicular networks where public transport get involved. This research aims to analyze the role of public transit as a DTN routing infrastructure. The impact of using public transit as a relay router is investigated by referencing the network performance, defined by its delivery ratio, average delay and overhead. The results show that public transit can be used as a backbone for DTN in an urban scenario using existing protocols. This opens insights for future researches on routing algorithm and protocol design

Robotic Wireless Sensor Networks

In this chapter, we present a literature survey of an emerging, cutting-edge, and multi-disciplinary field of research at the intersection of Robotics and Wireless Sensor Networks (WSN) which we refer to as Robotic Wireless Sensor Networks (RWSN). We define a RWSN as an autonomous networked multi-robot system that aims to achieve certain sensing goals while meeting and maintaining certain communication performance requirements, through cooperative control, learning and adaptation. While both of the component areas, i.e., Robotics and WSN, are very well-known and well-explored, there exist a whole set of new opportunities and research directions at the intersection of these two fields which are relatively or even completely unexplored. One such example would be the use of a set of robotic routers to set up a temporary communication path between a sender and a receiver that uses the controlled mobility to the advantage of packet routing. We find that there exist only a limited number of articles to be directly categorized as RWSN related works whereas there exist a range of articles in the robotics and the WSN literature that are also relevant to this new field of research. To connect the dots, we first identify the core problems and research trends related to RWSN such as connectivity, localization, routing, and robust flow of information. Next, we classify the existing research on RWSN as well as the relevant state-of-the-arts from robotics and WSN community according to the problems and trends identified in the first step. Lastly, we analyze what is missing in the existing literature, and identify topics that require more research attention in the future

IoB-DTN: a lightweight DTN protocol for mobile IoT Applications to smart bike sharing systems

International audienceInformation and communication are key to the intelligent city of tomorrow. Many technologies have been designed to connect smart devices to the Internet. In particular, public transport systems have been used to collect data from mobile devices. Public bike sharing systems have been introduced as part of the urban transportation system and could be used as the support of a mobile sensor network. In this paper, we introduce the "Internet of Bikes" IoB-DTN protocol which applies De-lay/Disruption Tolerant Network (DTN) paradigm to the Internet of Things (IoT) applications running on urban bike sharing system based sensor network. We evaluate the performance of three variants of IoB-DTN with four buffer management policies. Our results show that limiting the number of packet copies sprayed in the network and prioritizing generated packets against relayed ones, improves on low loss rate and delivery delay in urban bicycle scenario

A Survey on Multihop Ad Hoc Networks for Disaster Response Scenarios

Disastrous events are one of the most challenging applications of multihop ad hoc networks due to possible damages of existing telecommunication infrastructure.The deployed cellular communication infrastructure might be partially or completely destroyed after a natural disaster. Multihop ad hoc communication is an interesting alternative to deal with the lack of communications in disaster scenarios. They have evolved since their origin, leading to differentad hoc paradigms such as MANETs, VANETs, DTNs, or WSNs.This paper presents a survey on multihop ad hoc network paradigms for disaster scenarios.It highlights their applicability to important tasks in disaster relief operations. More specifically, the paper reviews the main work found in the literature, which employed ad hoc networks in disaster scenarios.In addition, it discusses the open challenges and the future research directions for each different ad hoc paradigm

iTETRIS: An Integrated Wireless and Traffic Platform for Real-Time Road Traffic Management Solutions

Wireless vehicular cooperative systems have been identified as an attractive solution to improve road traffic management, thereby contributing to the European goal of safer, cleaner, and more efficient and sustainable traffic solutions. V2V-V2I communication technologies can improve traffic management through real-time exchange of data among vehicles and with road infrastructure. It is also of great importance to investigate the adequate combination of V2V and V2I technologies to ensure the continuous and costefficient operation of traffic management solutions based on wireless vehicular cooperative solutions. However, to adequately design and optimize these communication protocols and analyze the potential of wireless vehicular cooperative systems to improve road traffic management, adequate testbeds and field operational tests need to be conducted. Despite the potential of Field Operational Tests to get the first insights into the benefits and problems faced in the development of wireless vehicular cooperative systems, there is yet the need to evaluate in the long term and large dimension the true potential benefits of wireless vehicular cooperative systems to improve traffic efficiency. To this aim, iTETRIS is devoted to the development of advanced tools coupling traffic and wireless communication simulators

Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges

With the rapid development of marine activities, there has been an increasing number of maritime mobile terminals, as well as a growing demand for high-speed and ultra-reliable maritime communications to keep them connected. Traditionally, the maritime Internet of Things (IoT) is enabled by maritime satellites. However, satellites are seriously restricted by their high latency and relatively low data rate. As an alternative, shore & island-based base stations (BSs) can be built to extend the coverage of terrestrial networks using fourth-generation (4G), fifth-generation (5G), and beyond 5G services. Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs. Despite of all these approaches, there are still open issues for an efficient maritime communication network (MCN). For example, due to the complicated electromagnetic propagation environment, the limited geometrically available BS sites, and rigorous service demands from mission-critical applications, conventional communication and networking theories and methods should be tailored for maritime scenarios. Towards this end, we provide a survey on the demand for maritime communications, the state-of-the-art MCNs, and key technologies for enhancing transmission efficiency, extending network coverage, and provisioning maritime-specific services. Future challenges in developing an environment-aware, service-driven, and integrated satellite-air-ground MCN to be smart enough to utilize external auxiliary information, e.g., sea state and atmosphere conditions, are also discussed

Unterbrechungstolerante Fahrzeugkommunikation im öffentlichen Personennahverkehr

Communication systems play an important role in the efficient operation of public transport networks. Recently, traditional voice-centric real-time communication is complemented and often replaced by data-centric asynchronous machine-to-machine communication. Disruption tolerant networking in combination with license-exempt high bandwidth technologies have the potential to reduce infrastructure investments and operating costs for such applications, because a continuous end-to-end connectivity is no longer required. In this thesis the feasibility of such a system is investigated and confirmed. First, realistic use-cases are introduced and the requirements to the communication system are analyzed. Then the channel characteristics of several WLAN-based technologies are experimentally evaluated in real public transport scenarios. Since the results are promising, the next step is gaining a deeper understanding of the special mobility properties in public transport networks. Therefore, we analyze existing traces as well as our own newly acquired trace. Our trace features additional operator meta-data that is not available for existing traces, and we report on unexpected properties that have not been quantified before. Then the trace is combined with the experimentally obtained channel parameters in order to analyze the characteristics of inter-vehicle contacts. We present the statistical distribution of situation-specific contact events and the impact of radio range on contact capacity. Then results of all steps above are used to propose a routing scheme that is optimized for public transport networks. In the final simulation-based evaluation we show that this router outperforms previously proposed algorithms.Kommunikationssysteme leisten einen wichtigen Beitrag zum effizienten Betrieb des öffentlichen Personennahverkehrs. Seit einigen Jahren wird dabei der Sprechfunk zunehmend durch asynchronen M2M-Datenfunk ergänzt und in vielen Anwendungsgebieten sogar vollständig ersetzt. Die Kombination aus unterbrechungstoleranten Netzwerken und lizenzfreien Drahtlostechnologien birgt ein erhebliches Potential zur Reduzierung von Infrastrukturinvestitionen und Betriebskosten, da für diese Anwendungen eine dauerhafte Ende-zu-Ende Verbindung nicht mehr erforderlich ist. In dieser Arbeit wird die Machbarkeit eines solchen Systems untersucht und belegt. Zunächst werden dazu Anwendungsfälle vorgestellt und deren Anforderungen an das Kommunikationssystem analysiert. Dann werden die Kanalcharakteristika mehrerer WLAN-Technologien im realen ÖPNV-Umfeld experimentell ermittelt und bewertet. Auf Grundlage der erfolgversprechenden Ergebnisse werden im nächsten Schritt die besonderen Mobilitätseigenschaften von ÖPNV-Netzen untersucht. Zu diesen Zweck analysieren wir existierende und eigene, neu aufgezeichnete Bewegungsdaten von ÖPNV-Fahrzeugen. Unsere Daten enthalten dabei zusätzliche Metadaten der Verkehrsbetriebe, die zuvor nicht verfügbar waren, so dass wir unerwartete Effekte beschreiben und erstmals quantifizieren können. Anschließend werden die Bewegungsdaten mit den zuvor experimentell erfassten Kanaleigenschaften kombiniert, um so die Kommunikationskontakte zwischen den Fahrzeugen genauer zu betrachten. Wir stellen die statistische Verteilung der situationsabhängigen Kontaktereignisse vor, sowie den Einfluss der Funkreichweite auf die Kontaktkapazität. Dann werden die Ergebnisse aller vorhergehenden Schritte verwendet, um ein neues, optimiertes Routingverfahren für ÖPNV-Netze vorzuschlagen. In der simulationsbasierten Evaluation belegen wir, dass dieser Router die Leistung bisher bekannter Verfahren übertrifft