Connecting Vehicles to the Internet - Strategic Data Transmission for Mobile Nodes using Heterogeneous Wireless Networks

With the advent of autonomous driving, the driving experience for users of connected vehicles changes, as they may enjoy their travel time with entertainment, or work productively. In our modern society, both require a stable Internet access. However, future mobile networks are not expected to be able to satisfy application Quality of Service (QoS) requirements as needed, e.g. during rush hours. To address this problem, this dissertation investigates data transmission strategies that exploit the potential of using a heterogeneous wireless network environment. To this end, we combine two so far distinct concepts, firstly, network selection and, secondly, transmission time selection, creating a joint time-network selection strategy. It allows a vehicle to plan delay-tolerant data transmissions ahead, favoring transmission opportunities with the best prospective flow-network matches. In this context, our first contribution is a novel rating model for perceived transmission quality, which assesses transmission opportunities with respect to application QoS requirement violations, traded off by monetary cost. To enable unified assessment of all data transmissions, it generalizes existing specialized rating models from network selection and transmission time selection and extends them with a novel throughput requirement model. Based on that, we develop a novel joint time-network selection strategy, Joint Transmission Planning (JTP), as our second contribution, planning optimized data transmissions within a defined time horizon. We compare its transmission quality to that of three predominant state-of-the-art transmission strategies, revealing that JTP outperforms the others significantly by up to 26%. Due to extensive scenario variation, we discover broad stability of JTP reaching 87-91% of the optimum. As JTP is a planning approach relying on prediction data, the transmission quality is strongly impaired when executing its plans under environmental changes. To mitigate this impact, we develop a transmission plan adaptation as our third contribution, modifying the planned current transmission online in order to comply with the changes. Even under strong changes of the vehicle movement and the network environment, it sustains 57%, respectively 36%, of the performance gain from planning. Finally, we present our protocol Mobility management for Vehicular Networking (MoVeNet), pooling available network resources of the environment to enable flexible packet dispatching without breaking connections. Its distributed architecture provides broad scalability and robustness against node failures. It complements control mechanisms that allow a demand-based and connection-specific trade-off between overhead and latency. Less than 9 ms additional round trip time in our tests, instant handover and 0 to 4 bytes per-packet overhead prove its efficiency. Employing the presented strategies and mechanisms jointly, users of connected vehicles and other mobile devices can significantly profit from the demonstrated improvements in application QoS satisfaction and reduced monetary cost

Beitrag zur Selbstorganisation in der Intralogistik

In der Natur existieren viele dezentral organisierte Systeme. Ein bekanntes Beispiel hierfür ist eine Insektenkolonie, bei dem jedes Insekt die ihm lokal verfügbaren Informationen für eine eigene Handlung oder für die Interaktion mit anderen Insekten verwendet. Gemeinsam arbeiten diese an komplexeren, globaleren Zielen der Kolonie. Es entsteht eine Emergenz auf Basis von einfacher Interaktion. Hieraus ergibt sich Frage, weshalb die Intralogistik und der darin enthaltene Materialfluss bisher nicht dezentral organisiert sind. Denn die immer komplexer werdenden materialflusstechnischen Abläufe benötigen neue Ansätze, damit sie idealerweise effizient gelöst werden können. Ein möglicher Ansatz hierfür ist eine Erhöhung der Autonomie der einzelnen Teilnehmer, die konsequente Dezentralisierung der Prozesse und insbesondere der Kommunikation. Somit muss neben der Interaktion der Teilnehmer auch die Kommunikation zwischen diesen auf der Organisationsebene betrachtet werden. In der vorliegenden Dissertation wird ein Konzept für einen selbstorganisierenden Materialfluss vorgestellt und umgesetzt. Grundlage hierfür ist eine konsequente Modularisierung, was zu einer Dezentralisierung eines monolithischen Systems führt. Dabei wird die Gesamtintelligenz des Systems aufgeteilt und auf seine Teilnehmer verteilt. Konkret bedeutet dies, dass der Materialfluss mithilfe einer domänenspezifische Sprache beschrieben und formalisiert wird. Aufbauend hierdrauf erfolgt eine Virtualisierung des Materialflusses, sodass eine eigenständige Entität entstehen kann, welche mit Fahrerlosen Transportfahrzeugen in Verhandlung tritt und sich über die zu leistenden Transportaufträge abstimmt. Gemeinsam verfolgen alle Teilnehmer das globale Ziel der (effizienteren) Abarbeitung von Transportaufträgen und tragen somit zur Selbstorganisation in der Intralogistik bei. Die eingeführte Selbstorganisation hat allerdings auch einen Einfluss auf die Kommunikation. Denn mit der Erhöhung der Autonomie, wie in der Natur zu beobachten, steigt der Bedarf zur Synchronisation der Teilnehmer und daher auch der Kommunikationsaufwand. Dies hat zur Folge, dass die Kommunikation mit der Anzahl an Teilnehmern skalieren muss. Hierfür wird die inhärente Fähigkeit zur Kommunikation der Teilnehmer ausgenutzt, um ein dezentral organisiertes Kommunikationsframework auf Basis einer nullbalancierten, vollständigen Baumstruktur zu entwickeln. Unter Verwendung eines quelloffenen Simulationsframeworks für Rechnernetze wird das dezentral organisierte Kommunikationsframework und seine Bestandsteile analytisch und simulativ ausgewertet. Anhand zweier Anwendungsfällen wird die Anwendbar- und Machbarkeit das Konzepts eines selbstorganisierenden Materialflüssen in der Intralogistik gezeigt und die aus der Interaktion der Teilnehmer entstandene Kommunikation unter Verwendung des dezentral organisierten Kommunikationsframeworks evaluiert

Monitoring and Management of Peer-to-Peer Systems

The peer-to-peer paradigm has had large success in content distribution and multimedia communication applications on the Internet. In a peer-to-peer network, the participating nodes create an infrastructure to provide a desired functionality and offer their resources to host an application in a distributed manner. Besides the functional requirements of an application, the non-functional requirements to achieve a high service quality are also an important part of successful peer-to-peer networks and a major challenge is to meet these requirements in networks with unreliable nodes. In contrast to traditional centralized approaches where the quality can be measured and controlled, in a distributed environment it is challenging both to capture the status and performance of the whole distributed system in one point of time and to control its general behavior. In this dissertation, we focus on the monitoring and management of peer-to-peer systems. We systematically engineer SkyEye.KOM, a fully decentralized monitoring mechanism that provides both a precise status snapshot of the peer-to-peer system and enables queries for peer capacities, such as bandwidth or storage capacities, in a large-scale peer-to-peer system. It considers individual load limits of the peers and ensures that no peer is overloaded. The core tree topology of SkyEye.KOM is established and maintained solely with protocol-relevant messages. It is based on local peer identifier calculations and using the underlying peer-to-peer overlay. As a second step, we focus on the management of peer-to-peer systems and introduce P3R3O.KOM and SkyNet.KOM, two solutions to manage both the reservation of available capacities in the peer-to-peer system and the system behavior in a fully decentralized and efficient manner. P3R3O.KOM is a peer-to-peer protocol for reliable long-term resource reservation that overcomes the limitations of traditional peer-to-peer services, which typically are host only by single peers and cease once the service providing peer fails. Resource reservations are fulfilled with adjustable guarantees (even 100\%) in the presence of strong churn through the automated and fully decentralized management of the resource provision redundancy. With SkyNet.KOM, we present a fully decentralized approach for automated management of peer-to-peer systems following the principles of autonomic computing. It allows the user or system provider to set service quality goals for the peer-to-peer system, which are automatically verified by the monitoring solution SkyEye.KOM and analyzed, aligned and enforced by the other components of SkyNet.KOM. Preset quality goals for the peer-to-peer system are reached and held through automated systematic re-configuration of the individual components of the peer-to-peer system. At the end, we present LifeSocial.KOM, a peer-to-peer-based platform for online social networks that incorporates the proposed monitoring mechanism to show the feasibility and application scope of the monitoring and management solutions