Don't Repeat Yourself: Seamless Execution and Analysis of Extensive Network Experiments

This paper presents MACI, the first bespoke framework for the management, the scalable execution, and the interactive analysis of a large number of network experiments. Driven by the desire to avoid repetitive implementation of just a few scripts for the execution and analysis of experiments, MACI emerged as a generic framework for network experiments that significantly increases efficiency and ensures reproducibility. To this end, MACI incorporates and integrates established simulators and analysis tools to foster rapid but systematic network experiments. We found MACI indispensable in all phases of the research and development process of various communication systems, such as i) an extensive DASH video streaming study, ii) the systematic development and improvement of Multipath TCP schedulers, and iii) research on a distributed topology graph pattern matching algorithm. With this work, we make MACI publicly available to the research community to advance efficient and reproducible network experiments

Current challenges and future trends in the field of communication architectures for microgrids

[EN] The concept of microgrid has emerged as a feasible answer to cope with the increasing number of distributed renewable energy sources which are being introduced into the electrical grid. The microgrid communication network should guarantee a complete and bidirectional connectivity among the microgrid resources, a high reliability and a feasible interoperability. This is in a contrast to the current electrical grid structure which is characterized by the lack of connectivity, being a centralized-unidirectional system. In this paper a review of the microgrids information and communication technologies (ICT) is shown. In addition, a guideline for the transition from the current communication systems to the future generation of microgrid communications is provided. This paper contains a systematic review of the most suitable communication network topologies, technologies and protocols for smart microgrids. It is concluded that a new generation of peer-to-peer communication systems is required towards a dynamic smart microgrid. Potential future research about communications of the next microgrid generation is also identified.This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and the European Regional Development Fund (ERDF) under Grant ENE2015-64087-C2-2. This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under grant BES-2013-064539.Marzal-Romeu, S.; Salas-Puente, RA.; González Medina, R.; Garcerá, G.; Figueres Amorós, E. (2018). Current challenges and future trends in the field of communication architectures for microgrids. Renewable and Sustainable Energy Reviews. 82(2):3610-3622. https://doi.org/10.1016/j.rser.2017.10.101S3610362282

On the benefits of applying experimental design to improve multipath TCP

Many scientific disciplines rely on "Experimental Design" to study various types of systems. Experimental design refers to a planned approach to experimentation that tries to provide statistical evidence to the outcome of experiments. The networking community rarely relies on such approaches, especially for real protocol implementations. Many improvements to protocols like TCP, including the recently proposed Multipath TCP, have been evaluated by considering a relatively limited set of simulations or experiments. Multipath TCP increases the goodput of a data transfer by simultaneously using multiple interfaces. It also improves load balancing thanks to dedicated congestion control. By applying experimental design, we conduct a large set of measurements inside Mininet with the Linux kernel Multipath TCP implementation, to measure its bandwidth aggregation and load balancing. Thanks to the experimental design approach, we are able to highlight several limitations of this implementation. We identify heuristics that lead to lower than expected performance and propose improvements

Optimizing transmission protocols for enhancement of quality of service in telemedical realtime applications

In der Dissertation mit dem Titel „Optimierung von Übertragungsprotokollen zur Verbesserung der Dienstgüte in telemedizinischen Echtzeitanwendungen“ geht es um die Entwicklung einer Protokollmodifikation für Multipath-TCP zur besseren Unterstützung von telemedizinischen Echtzeitanwendungen über das Internet in einem Szenario zwischen global verteilten Standorten. Das Ziel von redundantem Multipath-TCP (rMPTCP) ist es, mehrere Verbindungen gleichzeitig zu nutzen, um mithilfe von Redundanz Verzögerungsspitzen und Datenverluste auszugleichen und somit die Dienstgüte der Übertragung zu verbessern. Hierbei passt sich das Protokoll den aktuellen Gegebenheiten der Datenverbindung adaptiv an, indem es Redundanz, Leitungsqualität, benötigte Datenübertragungsrate sowie den durch das Netzwerk angebotenen Datendurchsatz in Relation setzt. Anwendungen in der Telemedizin unterscheiden sich in ihren kommunikativen und interaktiven Ausprägungen und damit in ihren Dienstgüteanforderungen. Zu diesem Zweck werden grundlegende Anwendungen in der Telemedizin sowie Spezifizierungen der Dienstgüteanforderungen der anfallenden Datenströme behandelt und klassifiziert. Dies geschieht in Hinblick auf ein zwischen der Universität Duisburg-Essen (UDE) und der Universiti Kebangsaan Malaysia (UKM) laufendes Forschungsszenario. Darauf folgt eine Darlegung von Dienstgüte-Mechanismen im Internet. Darin werden die elementaren Funktionsweisen sowie Möglichkeiten diese zu verbessern beschrieben. Die Übertragungsstrecke zwischen den beiden Universitäten wird entsprechend des Basisszenarios in Hinblick auf verschiedene Dienstgüteparameter mit entsprechenden Messwerkzeugen soweit ausgewertet, dass Gegebenheiten und Probleme identifiziert werden können. Eine Evaluierung der verschiedenen verfügbaren Verbindungen zwischen UDE und UKM dient der Ermittlung einer kombinierten Nutzungsweise und den Möglichkeiten bei einer Mehrfachverbindung. Die Modellierung und Entwicklung der Protokollmodifikation wird unter den vorher hergeleiteten Anforderungen durchgeführt. Es werden die grundsätzlichen mathematischen Zusammenhänge diskutiert und eine Einführung in die Funktionalitäten des Protokolls gegeben. Die Eigenschaften und Funktionen des neuen Protokolls werden modelliert und zusätzliche Hilfsmittel, die für die Anwendung innerhalb des Szenarios benötigt werden entwickelt. Die Funktionalitäten werden in praktischen Versuchen ausgewertet und eine abschließende Beurteilung diskutiert. Das Ergebnis dieser Dissertation ist die Entwicklung einer internetkompatiblen redundanten Protokollerweiterung für Multipath-TCP, die in der Lage ist, sich mithilfe verschiedener Algorithmen auf Situationen im Netzwerk anzupassen und verschiedene Maßnahmen bei Störungen zu ergreifen. Die Protokollerweiterung ist in der Lage, eine Dienstgüteverbesserung in Hinblick auf Verzögerungen sowie Verzögerungsvarianzen für Anwendungen mit „Nahe-Echtzeit“-Anforderungen zu erreichen.In the dissertation entitled "Optimization of Transmission Protocols to Improve Quality of Service in Telemedicine Real-Time Applications", the aim is to develop a protocol modification for Multipath-TCP to improve the support for telemedical real-time applications over the Internet in a scenario between globally distributed locations. The goal of redundant Multipath TCP (rMPTCP) is to use multiple connections at the same time to compensate for delay and data losses by means of redundancy and thus to improve the quality of service of the transmission. The protocol adapts to the current circumstances of the data connection by correlating redundancy, connection quality, required data transmission rate as well as the data throughput offered by the network. Applications in telemedicine differ in their communicative and interactive manifestations and thus in their quality of service requirements. For this purpose, basic applications in telemedicine as well as specifications of the quality requirements of the resulting data streams are treated and classified. This is done with regard to a research scenario running between the University of Duisburg-Essen (UDE) and the Universiti Kebangsaan Malaysia (UKM). It is followed by a presentation of quality of service mechanisms on the Internet. The basic functions as well as ways to improve them are described. The transmission distance between the two universities is evaluated according to the basic scenario with regard to different quality of service parameters with appropriate measuring tools in a way that conditions and problems can be identified. An evaluation of the various available connections between UDE and UKM is used to determine a combined usage and the possibilities for a multiple connection. The modeling and development of the protocol modification is performed under the previously-derived requirements. The basic mathematical connections are discussed and an introduction to the functionalities of the protocol is given. The properties and functions of the new protocol are modeled and additional tools developed for utilization within the scenario are designed. The functionalities are evaluated in practical tests and a final assessment is discussed. The result of this dissertation is the development of an Internet-compatible redundant protocol extension for multipath TCP, which is able to adapt to situations in the network by means of different algorithms and to take various measures in case of disturbances. The protocol extension is capable of achieving an improvement in service quality with regard to delays as well as delay variances for applications with "near real-time" requirements