Bibliography | Haug, Lucas: Roaming with deterministic real-time guarantees in wireless Time-Sensitive Networking. University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Master Thesis No. 15 (2023). 91 pages, english.
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Abstract | As Cyber-Physical Systems (CPSs) become increasingly popular in various domains such as Industrial Internet of Things (IIoT) and autonomous vehicles, the demand for deterministic real-time communication with a high reliability and bounded network delay and delay variance (jitter) has grown. In CPSs with networked sensors and actuators, these deterministic real-time bounds are often crucial in order to provide safety guarantees. Major standardization organizations like the Institute of Electrical and Electronics Engineers (IEEE) have acknowledged the necessity for deterministic networks, resulting in a set of standards known as Time-Sensitive Networking (TSN), which enable deterministic communication in wired Ethernet networks. Many CPSs, however, necessitate mobility and therefore rely on wirelessly connected devices, such as a worker wearing an exoskeleton in order to carry heavy loads. To this end, the TSN standards will also be part of the upcoming Wi-Fi 7 standard (IEEE 802.11be). Although the increased flexibility offered by the mobility of devices in these scenarios is advantageous, it presents new challenges, such as controlling access to the shared wireless transmission medium and managing handovers such that deterministic real-time guarantees are maintained. In this work, we investigate these challenges and provide novel approaches to improve the reliability, delay and jitter in wireless TSN. We first modify an already existing Integer Linear Program (ILP) to generate schedules for the Time-Aware Shaping (TAS) in a wireless network environment. The necessity for this arises because the wireless transmission medium utilizes a shared access method, whereas existing approaches are limited to point-to-point Ethernet connections. Furthermore, we provide a novel seamless handover approach for wireless TSN utilizing two wireless interfaces in a single device and extend it with a proactive handover approach in order to allow for smoother handovers with a greater reliability. In order to analyze our approaches, we extend the INET framework of the OMNeT++ simulator with an implementation of our approaches. Our evaluation shows that delay and jitter are mainly influenced by the random back-off algorithm of the channel access procedure in Wi-Fi indicating research topics for future work. Moreover, we were able to significantly improve the reliability for wireless TSN by employing our proactive handover approach in the simulation.
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