TY - RPRT A1 - Großmann, Marcel A1 - Le, Duy Thanh T1 - Visualization of Network Emulation Enabled by Kathará T2 - KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023 (WueWoWAS’23) N2 - In network research, reproducibility of experiments is not always easy to achieve. Infrastructures are cumbersome to set up or are not available due to vendor-specific devices. Emulators try to overcome those issues to a given extent and are available in different service models. Unfortunately, the usability of emulators requires time-consuming efforts and a deep understanding of their functionality. At first, we analyze to which extent currently available open-source emulators support network configurations and how user-friendly they are. With these insights, we describe, how an ease-to-use emulator is implemented and may run as a Network Emulator as a Service (NEaaS). Therefore, virtualization plays a major role in order to deploy a NEaaS based on Kathará. KW - Network Emulator KW - Visualized Kathará KW - Containerization Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322189 ER - TY - RPRT A1 - Mazigh, Sadok Mehdi A1 - Beausencourt, Marcel A1 - Bode, Max Julius A1 - Scheffler, Thomas T1 - Using P4-INT on Tofino for Measuring Device Performance Characteristics in a Network Lab T2 - KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023 (WueWoWAS’23) N2 - This paper presents a prototypical implementation of the In-band Network Telemetry (INT) specification in P4 and demonstrates a use case, where a Tofino Switch is used to measure device and network performance in a lab setting. This work is based on research activities in the area of P4 data plane programming conducted at the network lab of HTW Berlin. KW - P4-INT Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322084 ER - TY - JOUR A1 - Liman, Leon A1 - May, Bernd A1 - Fette, Georg A1 - Krebs, Jonathan A1 - Puppe, Frank T1 - Using a clinical data warehouse to calculate and present key metrics for the radiology department: implementation and performance evaluation JF - JMIR Medical Informatics N2 - Background: Due to the importance of radiologic examinations, such as X-rays or computed tomography scans, for many clinical diagnoses, the optimal use of the radiology department is 1 of the primary goals of many hospitals. Objective: This study aims to calculate the key metrics of this use by creating a radiology data warehouse solution, where data from radiology information systems (RISs) can be imported and then queried using a query language as well as a graphical user interface (GUI). Methods: Using a simple configuration file, the developed system allowed for the processing of radiology data exported from any kind of RIS into a Microsoft Excel, comma-separated value (CSV), or JavaScript Object Notation (JSON) file. These data were then imported into a clinical data warehouse. Additional values based on the radiology data were calculated during this import process by implementing 1 of several provided interfaces. Afterward, the query language and GUI of the data warehouse were used to configure and calculate reports on these data. For the most common types of requested reports, a web interface was created to view their numbers as graphics. Results: The tool was successfully tested with the data of 4 different German hospitals from 2018 to 2021, with a total of 1,436,111 examinations. The user feedback was good, since all their queries could be answered if the available data were sufficient. The initial processing of the radiology data for using them with the clinical data warehouse took (depending on the amount of data provided by each hospital) between 7 minutes and 1 hour 11 minutes. Calculating 3 reports of different complexities on the data of each hospital was possible in 1-3 seconds for reports with up to 200 individual calculations and in up to 1.5 minutes for reports with up to 8200 individual calculations. Conclusions: A system was developed with the main advantage of being generic concerning the export of different RISs as well as concerning the configuration of queries for various reports. The queries could be configured easily using the GUI of the data warehouse, and their results could be exported into the standard formats Excel and CSV for further processing. KW - data warehouse KW - eHealth KW - hospital data KW - electronic health records KW - radiology KW - statistics and numerical data KW - medical records Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-349411 SN - 2291-9694 VL - 11 ER - TY - THES A1 - Bleier, Michael T1 - Underwater Laser Scanning - Refractive Calibration, Self-calibration and Mapping for 3D Reconstruction T1 - Laserscanning unter Wasser - Refraktive Kalibrierung, Selbstkalibrierung und Kartierung zur 3D Rekonstruktion N2 - There is great interest in affordable, precise and reliable metrology underwater: Archaeologists want to document artifacts in situ with high detail. In marine research, biologists require the tools to monitor coral growth and geologists need recordings to model sediment transport. Furthermore, for offshore construction projects, maintenance and inspection millimeter-accurate measurements of defects and offshore structures are essential. While the process of digitizing individual objects and complete sites on land is well understood and standard methods, such as Structure from Motion or terrestrial laser scanning, are regularly applied, precise underwater surveying with high resolution is still a complex and difficult task. Applying optical scanning techniques in water is challenging due to reduced visibility caused by turbidity and light absorption. However, optical underwater scanners provide significant advantages in terms of achievable resolution and accuracy compared to acoustic systems. This thesis proposes an underwater laser scanning system and the algorithms for creating dense and accurate 3D scans in water. It is based on laser triangulation and the main optical components are an underwater camera and a cross-line laser projector. The prototype is configured with a motorized yaw axis for capturing scans from a tripod. Alternatively, it is mounted to a moving platform for mobile mapping. The main focus lies on the refractive calibration of the underwater camera and laser projector, the image processing and 3D reconstruction. For highest accuracy, the refraction at the individual media interfaces must be taken into account. This is addressed by an optimization-based calibration framework using a physical-geometric camera model derived from an analytical formulation of a ray-tracing projection model. In addition to scanning underwater structures, this work presents the 3D acquisition of semi-submerged structures and the correction of refraction effects. As in-situ calibration in water is complex and time-consuming, the challenge of transferring an in-air scanner calibration to water without re-calibration is investigated, as well as self-calibration techniques for structured light. The system was successfully deployed in various configurations for both static scanning and mobile mapping. An evaluation of the calibration and 3D reconstruction using reference objects and a comparison of free-form surfaces in clear water demonstrate the high accuracy potential in the range of one millimeter to less than one centimeter, depending on the measurement distance. Mobile underwater mapping and motion compensation based on visual-inertial odometry is demonstrated using a new optical underwater scanner based on fringe projection. Continuous registration of individual scans allows the acquisition of 3D models from an underwater vehicle. RGB images captured in parallel are used to create 3D point clouds of underwater scenes in full color. 3D maps are useful to the operator during the remote control of underwater vehicles and provide the building blocks to enable offshore inspection and surveying tasks. The advancing automation of the measurement technology will allow non-experts to use it, significantly reduce acquisition time and increase accuracy, making underwater metrology more cost-effective. N2 - Das Interesse an präziser, zuverlässiger und zugleich kostengünstiger Unterwassermesstechnik ist groß. Beispielsweise wollen Archäologen Artefakte in situ mit hoher Detailtreue dokumentieren und in der Meeresforschung benötigen Biologen Messwerkzeuge zur Beobachtung des Korallenwachstums. Auch Geologen sind auf Messdaten angewiesen, um Sedimenttransporte zu modellieren. Darüber hinaus ist für die Errichtung von Offshore-Bauwerken, sowie deren Wartung und Inspektion eine millimetergenaue Vermessung von vorhandenen Strukturen und Defekten unerlässlich. Während die Digitalisierung einzelner Objekte und ganzer Areale an Land gut erforscht ist und verschiedene Standardmethoden, wie zum Beispiel Structure from Motion oder terrestrisches Laserscanning, regelmäßig eingesetzt werden, ist die präzise und hochauflösende Unterwasservermessung nach wie vor eine komplexe und schwierige Aufgabe. Die Anwendung optischer Messtechnik im Wasser ist aufgrund der eingeschränkten Sichttiefe durch Trübung und Lichtabsorption eine Herausforderung. Optische Unterwasserscanner bieten jedoch Vorteile hinsichtlich der erreichbaren Auflösung und Genauigkeit gegenüber akustischen Systemen. In dieser Arbeit werden ein Unterwasser-Laserscanning-System und die Algorithmen zur Erzeugung von 3D-Scans mit hoher Punktdichte im Wasser vorgestellt. Es basiert auf Lasertriangulation und die optischen Hauptkomponenten sind eine Unterwasserkamera und ein Kreuzlinienlaserprojektor. Das System ist mit einer motorisierten Drehachse ausgestattet, um Scans von einem Stativ aus aufzunehmen. Alternativ kann es von einer beweglichen Plattform aus für mobile Kartierung eingesetzt werden. Das Hauptaugenmerk liegt auf der refraktiven Kalibrierung der Unterwasserkamera und des Laserprojektors, der Bildverarbeitung und der 3D-Rekonstruktion. Um höchste Genauigkeit zu erreichen, muss die Brechung an den einzelnen Medienübergängen berücksichtigt werden. Dies wird durch ein physikalisch-geometrisches Kameramodell, das auf einer analytischen Beschreibung der Strahlenverfolgung basiert, und ein optimierungsbasiertes Kalibrierverfahren erreicht. Neben dem Scannen von Unterwasserstrukturen wird in dieser Arbeit auch die 3D-Erfassung von teilweise im Wasser befindlichen Strukturen und die Korrektur der dabei auftretenden Brechungseffekte vorgestellt. Da die Kalibrierung im Wasser komplex und zeitintensiv ist, wird die Übertragung einer Kalibrierung des Scanners in Luft auf die Bedingungen im Wasser ohne Neukalibrierung, sowie die Selbstkalibrierung für Lichtschnittverfahren untersucht. Das System wurde in verschiedenen Konfigurationen sowohl für statisches Scannen als auch für die mobile Kartierung erfolgreich eingesetzt. Die Validierung der Kalibrierung und der 3D-Rekonstruktion anhand von Referenzobjekten und der Vergleich von Freiformflächen in klarem Wasser zeigen das hohe Genauigkeitspotenzial im Bereich von einem Millimeter bis weniger als einem Zentimeter in Abhängigkeit von der Messdistanz. Die mobile Unterwasserkartierung und Bewegungskompensation anhand visuell-inertialer Odometrie wird mit einem neuen optischen Unterwasserscanner auf Basis der Streifenprojektion demonstriert. Dabei ermöglicht die kontinuierliche Registrierung von Einzelscans die Erfassung von 3D-Modellen von einem Unterwasserfahrzeug aus. Mit Hilfe von parallel aufgenommenen RGB-Bildern werden dabei farbige 3D-Punktwolken der Unterwasserszenen erstellt. Diese 3D-Karten dienen beispielsweise dem Bediener bei der Fernsteuerung von Unterwasserfahrzeugen und bilden die Grundlage für Offshore-Inspektions- und Vermessungsaufgaben. Die fortschreitende Automatisierung der Messtechnik wird somit auch eine Verwendung durch Nichtfachleute ermöglichen und gleichzeitig die Erfassungszeit erheblich verkürzen und die Genauigkeit verbessern, was die Vermessung im Wasser kostengünstiger und effizienter macht. T3 - Forschungsberichte in der Robotik = Research Notes in Robotics - 28 KW - Selbstkalibrierung KW - Punktwolke KW - Bildverarbeitung KW - 3D Reconstruction KW - Self-calibration KW - Underwater Scanning KW - Underwater Mapping KW - Dreidimensionale Rekonstruktion KW - 3D-Rekonstruktion Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322693 SN - 978-3-945459-45-4 ER - TY - RPRT A1 - Grigorjew, Alexej A1 - Schumann, Lukas Kilian A1 - Diederich, Philip A1 - Hoßfeld, Tobias A1 - Kellerer, Wolfgang T1 - Understanding the Performance of Different Packet Reception and Timestamping Methods in Linux T2 - KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023 (WueWoWAS’23) N2 - This document briefly presents some renowned packet reception techniques for network packets in Linux systems. Further, it compares their performance when measuring packet timestamps with respect to throughput and accuracy. Both software and hardware timestamps are compared, and various parameters are examined, including frame size, link speed, network interface card, and CPU load. The results indicate that hardware timestamping offers significantly better accuracy with no downsides, and that packet reception techniques that avoid system calls offer superior measurement throughput. KW - packet reception method KW - timestamping method KW - Linux Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322064 ER - TY - RPRT A1 - Raffeck, Simon A1 - Geißler, Stefan A1 - Hoßfeld, Tobias T1 - Towards Understanding the Signaling Traffic in 5G Core Networks T2 - KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023 (WueWoWAS’23) N2 - The Fifth Generation (5G) communication technology, its infrastructure and architecture, though already deployed in campus and small scale networks, is still undergoing continuous changes and research. Especially, in the light of future large scale deployments and industrial use cases, a detailed analysis of the performance and utilization with regard to latency and service times constraints is crucial. To this end, a fine granular investigation of the Network Function (NF) based core system and the duration for all the tasks performed by these services is necessary. This work presents the first steps towards analyzing the signaling traffic in 5G core networks, and introduces a tool to automatically extract sequence diagrams and service times for NF tasks from traffic traces. KW - signaling traffic KW - 5G core network Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322106 ER - TY - RPRT A1 - Vomhoff, Viktoria A1 - Geissler, Stefan A1 - Gebert, Steffen A1 - Hossfeld, Tobias T1 - Towards Understanding the Global IPX Network from an MVNO Perspective T2 - KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023 (WueWoWAS’23) N2 - In this paper, we work to understand the global IPX network from the perspective of an MVNO. In order to do this, we provide a brief description of the global architecture of mobile carriers. We provide initial results with respect to mapping the vast and complex interconnection network enabling global roaming from the point of view of a single MVNO. Finally, we provide preliminary results regarding the quality of service observed under global roaming conditions. KW - global IPX network Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322121 ER - TY - CHAP A1 - Abendschein, Robin A1 - Desai, Shital A1 - Astell, Arlene J. T1 - Towards Accessibility Guidelines for the Metaverse : A Synthesis of Recommendations for People Living With Dementia T2 - Conference on Human Factors in Computing Systems (CHI’23) : Workshop "Towards an Inclusive and Accessible Metaverse" N2 - Given the growing interest of corporate stakeholders in Metaverse applications, there is a need to understand accessibility of these technologies for marginalized populations such as people living with dementia to ensure inclusive design of Metaverse applications. We assessed the accessibility of extended reality technology for people living with mild cognitive impairment and dementia to develop accessibility guidelines for these technologies. We used four strategies to synthesize evidence for barriers and facilitators of accessibility: (1) Findings from a non-systematic literature review, (2) guidelines from well-researched technology, (3) exploration of selected mixed reality technologies, and (4) observations from four sessions and video data of people living with dementia using mixed reality technologies. We utilized template analysis to develop codes and themes towards accessibility guidelines. Future work can validate our preliminary findings by applying them on video recordings or testing them in experiments. KW - CHI Conference KW - Accessibility KW - Metaverse KW - extended reality KW - dementia KW - cognitive impairment KW - Human-centered computing / Access KW - Human-centered computing / Human computer interaction (HCI) / Interaction paradigms / Mixed / augmented reality KW - Human-centered computing / Human computer interaction (HCI) / Interaction paradigms / Virtual reality KW - Human-centered computing / Human computer interaction (HCI) / Interactiondevices KW - Human-centered computing / Human computerinteraction (HCI) / Interaction techniques Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-320199 UR - https://sites.google.com/view/accessiblemetaverse ER - TY - RPRT A1 - Martino, Luigi A1 - Deutschmann, Jörg A1 - Hielscher, Kai-Steffen A1 - German, Reinhard T1 - Towards a 5G Satellite Communication Framework for V2X T2 - KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023 (WueWoWAS’23) N2 - In recent years, satellite communication has been expanding its field of application in the world of computer networks. This paper aims to provide an overview of how a typical scenario involving 5G Non-Terrestrial Networks (NTNs) for vehicle to everything (V2X) applications is characterized. In particular, a first implementation of a system that integrates them together will be described. Such a framework will later be used to evaluate the performance of applications such as Vehicle Monitoring (VM), Remote Driving (RD), Voice Over IP (VoIP), and others. Different configuration scenarios such as Low Earth Orbit and Geostationary Orbit will be considered. KW - 5G KW - non-terrestrial networks KW - satellite communication Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322148 ER - TY - JOUR A1 - Seufert, Anika A1 - Poignée, Fabian A1 - Seufert, Michael A1 - Hoßfeld, Tobias T1 - Share and multiply: modeling communication and generated traffic in private WhatsApp groups JF - IEEE Access N2 - Group-based communication is a highly popular communication paradigm, which is especially prominent in mobile instant messaging (MIM) applications, such as WhatsApp. Chat groups in MIM applications facilitate the sharing of various types of messages (e.g., text, voice, image, video) among a large number of participants. As each message has to be transmitted to every other member of the group, which multiplies the traffic, this has a massive impact on the underlying communication networks. However, most chat groups are private and network operators cannot obtain deep insights into MIM communication via network measurements due to end-to-end encryption. Thus, the generation of traffic is not well understood, given that it depends on sizes of communication groups, speed of communication, and exchanged message types. In this work, we provide a huge data set of 5,956 private WhatsApp chat histories, which contains over 76 million messages from more than 117,000 users. We describe and model the properties of chat groups and users, and the communication within these chat groups, which gives unprecedented insights into private MIM communication. In addition, we conduct exemplary measurements for the most popular message types, which empower the provided models to estimate the traffic over time in a chat group. KW - communication models KW - group-based communication KW - mobile instant messaging KW - mobile messaging application KW - private chat groups KW - WhatsApp Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-349430 VL - 11 ER -