TY - BOOK A1 - Tran-Gia, Phuoc A1 - Hoßfeld, Tobias T1 - Performance Modeling and Analysis of Communication Networks BT - A Lecture Note N2 - This textbook provides an introduction to common methods of performance modeling and analysis of communication systems. These methods form the basis of traffic engineering, teletraffic theory, and analytical system dimensioning. The fundamentals of probability theory, stochastic processes, Markov processes, and embedded Markov chains are presented. Basic queueing models are described with applications in communication networks. Advanced methods are presented that have been frequently used in recent practice, especially discrete-time analysis algorithms, or which go beyond classical performance measures such as Quality of Experience or energy efficiency. Recent examples of modern communication networks include Software Defined Networking and the Internet of Things. Throughout the book, illustrative examples are used to provide practical experience in performance modeling and analysis. Target group: The book is aimed at students and scientists in computer science and technical computer science, operations research, electrical engineering and economics. N2 - Dieses Lehrbuch bietet eine Einführung in gängige Methoden zur Modellbildung und analytische Leistungsbewertung von Kommunikationssystemen. Diese Methoden bilden die Grundlage für Verkehrstheorie und Systemdimensionierung. Die Grundlagen der Wahrscheinlichkeitstheorie, stochastische Prozesse, Markov-Prozesse und eingebettete Markov-Ketten werden vorgestellt. Grundlegende Warteschlangenmodelle werden mit Anwendungen aus Kommunikationsnetzwerken beschrieben. Es werden auch weiterführende Methoden vorgestellt, die in der jüngeren Praxis häufig verwendet wurden, insbesondere zeitdiskrete Analysealgorithmen, oder QoE und Energieeffizienz. Aktuelle Beispiele für moderne Kommunikationsnetze sind Software Defined Networking oder das Internet der Dinge. Im gesamten Buch werden anschauliche Beispiele verwendet, um praktische Erfahrungen in der Leistungsmodellierung und -analyse zu vermitteln. Zielgruppe: Das Buch richtet sich an Studierende und WissenschaftlerInnen aus den Bereichen Informatik und technische Informatik, Operations Research, Elektrotechnik und Wirtschaftswissenschaft. KW - performance modeling KW - Markovian and Non-Markovian systems KW - discrete-time models and analysis KW - communication networks KW - communication network KW - performance evaluation KW - Markov model KW - stochastic processes KW - queueing theory Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-241920 SN - 978-3-95826-152-5 SN - 978-3-95826-153-2 N1 - Parallel erschienen als Druckausgabe in Würzburg University Press, 978-3-95826-152-5, 65,00 Euro. PB - Würzburg University Press CY - Würzburg ET - 1st edition ER - TY - JOUR A1 - Borchert, Kathrin A1 - Seufert, Anika A1 - Gamboa, Edwin A1 - Hirth, Matthias A1 - Hoßfeld, Tobias T1 - In Vitro vs In Vivo: Does the Study's Interface Design Influence Crowdsourced Video QoE? JF - Quality and User Experience N2 - Evaluating the Quality of Experience (QoE) of video streaming and its influence factors has become paramount for streaming providers, as they want to maintain high satisfaction for their customers. In this context, crowdsourced user studies became a valuable tool to evaluate different factors which can affect the perceived user experience on a large scale. In general, most of these crowdsourcing studies either use, what we refer to, as an in vivo or an in vitro interface design. In vivo design means that the study participant has to rate the QoE of a video that is embedded in an application similar to a real streaming service, e.g., YouTube or Netflix. In vitro design refers to a setting, in which the video stream is separated from a specific service and thus, the video plays on a plain background. Although these interface designs vary widely, the results are often compared and generalized. In this work, we use a crowdsourcing study to investigate the influence of three interface design alternatives, an in vitro and two in vivo designs with different levels of interactiveness, on the perceived video QoE. Contrary to our expectations, the results indicate that there is no significant influence of the study’s interface design in general on the video experience. Furthermore, we found that the in vivo design does not reduce the test takers’ attentiveness. However, we observed that participants who interacted with the test interface reported a higher video QoE than other groups. KW - video QoE KW - crowdsourcing KW - study design KW - user study KW - distraction Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-235586 SN - 2366-0139 VL - 6 ER - TY - RPRT A1 - Blenk, Andreas A1 - Kellerer, Wolfgang A1 - Hoßfeld, Tobias T1 - Technical Report on DFG Project SDN-App: SDN-enabled Application-aware Network Control Architectures and their Performance Assessment N2 - The DFG project “SDN-enabled Application-aware Network Control Architectures and their Performance Assessment” (DFG SDN-App) focused in phase 1 (Jan 2017 – Dec 2019) on software defined networking (SDN). Being a fundamental paradigm shift, SDN enables a remote control of networking devices made by different vendors from a logically centralized controller. In principle, this enables a more dynamic and flexible management of network resources compared to the traditional legacy networks. Phase 1 focused on multimedia applications and their users’ Quality of Experience (QoE). This documents reports the achievements of the first phase (Jan 2017 – Dec 2019), which is jointly carried out by the Technical University of Munich, Technical University of Berlin, and University of Würzburg. The project started at the institutions in Munich and Würzburg in January 2017 and lasted until December 2019. In Phase 1, the project targeted the development of fundamental control mechanisms for network-aware application control and application-aware network control in Software Defined Networks (SDN) so to enhance the user perceived quality (QoE). The idea is to leverage the QoE from multiple applications as control input parameter for application-and network control mechanisms. These mechanisms are implemented by an Application Control Plane (ACP) and a Network Control Plane (NCP). In order to obtain a global view of the current system state, applications and network parameters are monitored and communicated to the respective control plane interface. Network and application information and their demands are exchanged between the control planes so to derive appropriate control actions. To this end, a methodology is developed to assess the application performance and in particular the QoE. This requires an appropriate QoE modeling of the applications considered in the project as well as metrics like QoE fairness to be utilized within QoE management. In summary, the application-network interaction can improve the QoE for multi-application scenarios. This is ensured by utilizing information from the application layer, which are mapped by appropriate QoS-QoE models to QoE within a network control plane. On the other hand, network information is monitored and communicated to the application control plane. Network and application information and their demands are exchanged between the control planes so to derive appropriate control actions. KW - Software-defined networking KW - Quality of Experience KW - SDN KW - QoE Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-207558 ER - TY - RPRT A1 - Grigorjew, Alexej A1 - Metzger, Florian A1 - Hoßfeld, Tobias A1 - Specht, Johannes A1 - Götz, Franz-Josef A1 - Schmitt, Jürgen A1 - Chen, Feng T1 - Technical Report on Bridge-Local Guaranteed Latency with Strict Priority Scheduling N2 - Bridge-local latency computation is often regarded with caution, as historic efforts with the Credit-Based Shaper (CBS) showed that CBS requires network wide information for tight bounds. Recently, new shaping mechanisms and timed gates were applied to achieve such guarantees nonetheless, but they require support for these new mechanisms in the forwarding devices. This document presents a per-hop latency bound for individual streams in a class-based network that applies the IEEE 802.1Q strict priority transmission selection algorithm. It is based on self-pacing talkers and uses the accumulated latency fields during the reservation process to provide upper bounds with bridge-local information. The presented delay bound is proven mathematically and then evaluated with respect to its accuracy. It indicates the required information that must be provided for admission control, e.g., implemented by a resource reservation protocol such as IEEE 802.1Qdd. Further, it hints at potential improvements regarding new mechanisms and higher accuracy given more information. KW - Echtzeit KW - Rechnernetz KW - Latenz KW - Ethernet KW - Latency Bound KW - Formal analysis Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-198310 ER - TY - RPRT A1 - Grigorjew, Alexej A1 - Metzger, Florian A1 - Hoßfeld, Tobias A1 - Specht, Johannes A1 - Götz, Franz-Josef A1 - Chen, Feng A1 - Schmitt, Jürgen T1 - Asynchronous Traffic Shaping with Jitter Control N2 - Asynchronous Traffic Shaping enabled bounded latency with low complexity for time sensitive networking without the need for time synchronization. However, its main focus is the guaranteed maximum delay. Jitter-sensitive applications may still be forced towards synchronization. This work proposes traffic damping to reduce end-to-end delay jitter. It discusses its application and shows that both the prerequisites and the guaranteed delay of traffic damping and ATS are very similar. Finally, it presents a brief evaluation of delay jitter in an example topology by means of a simulation and worst case estimation. KW - Echtzeit KW - Rechnernetz KW - Latenz KW - Ethernet KW - TSN KW - jitter KW - traffic damping Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-205824 ER - TY - RPRT A1 - Vomhoff, Viktoria A1 - Geißler, Stefan A1 - Hoßfeld, Tobias T1 - Identification of Signaling Patterns in Mobile IoT Signaling Traffic T2 - Würzburg Workshop on Next-Generation Communication Networks (WueWoWas'22) N2 - We attempt to identify sequences of signaling dialogs, to strengthen our understanding of the signaling behavior of IoT devices by examining a dataset containing over 270.000 distinct IoT devices whose signaling traffic has been observed over a 31-day period in a 2G network [4]. We propose a set of rules that allows the assembly of signaling dialogs into so-called sessions in order to identify common patterns and lay the foundation for future research in the areas of traffic modeling and anomaly detection. KW - Datennetz KW - IoT Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-280819 ER - TY - RPRT A1 - Loh, Frank A1 - Geißler, Stefan A1 - Hoßfeld, Tobias T1 - LoRaWAN Network Planning in Smart Environments: Towards Reliability, Scalability, and Cost Reduction T2 - Würzburg Workshop on Next-Generation Communication Networks (WueWoWas'22) N2 - The goal in this work is to present a guidance for LoRaWAN planning to improve overall reliability for message transmissions and scalability. At the end, the cost component is discussed. Therefore, a five step approach is presented that helps to plan a LoRaWAN deployment step by step: Based on the device locations, an initial gateway placement is suggested followed by in-depth frequency and channel access planning. After an initial planning phase, updates for channel access and the initial gateway planning is suggested that should also be done periodically during network operation. Since current gateway placement approaches are only studied with random channel access, there is a lot of potential in the cell planning phase. Furthermore, the performance of different channel access approaches is highly related on network load, and thus cell size and sensor density. Last, the influence of different cell planning ideas on expected costs are discussed. KW - Datennetz KW - LoRaWan Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-280829 ER - TY - JOUR A1 - Loh, Frank A1 - Mehling, Noah A1 - Hoßfeld, Tobias T1 - Towards LoRaWAN without data loss: studying the performance of different channel access approaches JF - Sensors N2 - The Long Range Wide Area Network (LoRaWAN) is one of the fastest growing Internet of Things (IoT) access protocols. It operates in the license free 868 MHz band and gives everyone the possibility to create their own small sensor networks. The drawback of this technology is often unscheduled or random channel access, which leads to message collisions and potential data loss. For that reason, recent literature studies alternative approaches for LoRaWAN channel access. In this work, state-of-the-art random channel access is compared with alternative approaches from the literature by means of collision probability. Furthermore, a time scheduled channel access methodology is presented to completely avoid collisions in LoRaWAN. For this approach, an exhaustive simulation study was conducted and the performance was evaluated with random access cross-traffic. In a general theoretical analysis the limits of the time scheduled approach are discussed to comply with duty cycle regulations in LoRaWAN. KW - LoRaWAN KW - IoT KW - channel management KW - scheduling KW - collision Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-302418 SN - 1424-8220 VL - 22 IS - 2 ER - TY - RPRT A1 - Grigorjew, Alexej A1 - Diederich, Philip A1 - Hoßfeld, Tobias A1 - Kellerer, Wolfgang T1 - Affordable Measurement Setups for Networking Device Latency with Sub-Microsecond Accuracy T2 - Würzburg Workshop on Next-Generation Communication Networks (WueWoWas'22) N2 - This document presents a networking latency measurement setup that focuses on affordability and universal applicability, and can provide sub-microsecond accuracy. It explains the prerequisites, hardware choices, and considerations to respect during measurement. In addition, it discusses the necessity for exhaustive latency measurements when dealing with high availability and low latency requirements. Preliminary results show that the accuracy is within ±0.02 μs when used with the Intel I350-T2 network adapter. KW - Datennetz KW - latency Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-280751 ER - TY - RPRT A1 - Raffeck, Simon A1 - Geißler, Stefan A1 - Hoßfeld, Tobias T1 - DBM: Decentralized Burst Mitigation for Self-Organizing LoRa Deployments T2 - Würzburg Workshop on Next-Generation Communication Networks (WueWoWas'22) N2 - This work proposes a novel approach to disperse dense transmission intervals and reduce bursty traffic patterns without the need for centralized control. Furthermore, by keeping the mechanism as close to the Long Range Wide Area Network (LoRaWAN) standard as possible the suggested mechanism can be deployed within existing networks and can even be co-deployed with other devices. KW - Datennetz KW - LoRa Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-280809 ER -