Informatik-Oberseminar: Design and Evaluation of an Ultra-Reliable Low-Latency Wireless Network Protocol
Mittwoch, 14.06.2017, 09.00 Uhr
Ort: Raum 9007, Gebäude E3, Ahornstr. 55
Referent: Dipl.-Ing. Christian Dombrowski
With the rise of wireless communication networks in industrial use-cases, the deficiencies of previous wireless technologies becomes apparent. Since these technologies have been developed with the demands of private users in mind, they fail to meet the stringent requirements of industry. This relates in particular to the achievable latency and reliability of individual data transmissions. Thus, this work address the design, the implementation, and the evaluation of a newly developed wireless technology, specifically tailored to industrial use-cases. The developed medium access protocol, called EchoRing, allows to realize latency requirements of below 10ms and reliability levels beyond 1e-7 over typical distances, utilizing a standard Physical Layer. To achieve this, the well-known token-passing medium access scheme is complemented with cooperative and stability enhancing elements, yielding a significant increase in reliability. In this context, various cooperation strategies are evaluated with respect to their practical applicability, their incurred overhead, and their resulting performance gain. With respect to methodology, the design, implementation, and evaluation process is accompanied with different tools. From a theoretical perspective, a framework is developed that accounts for temporal protocol effects in the derivation of the achievable performance. Including the performance of two reference technologies in a comparison enables the evaluation of the EchoRing protocol. It is shown that EchoRing outperforms these technologies in the vast majority of anticipated scenarios. Additionally, extensive measurement campaigns of EchoRing and two other reference protocols have been conducted in an office environment, validating the theoretical observations. Despite inevitable imperfections of real-world embedded systems, we are able to demonstrate EchoRing’s superiority in practically feasible scenarios. For certain configurations we did not observe a single lost data packet in spite of measurements covering multiple days. Since industrial applications have to ensure safety to prevent damages and human or monetary losses, the developed technologies have to comply to norms and regulations. This significantly influences the development process since functional correctness of the design has to be assured in early development stages to avoid unnecessary costs and risks. To do so, we examine the approach of integrating a model-based technique to guide early development, e. g., by proving the formal correctness of the complex distributed EchoRing protocol. Furthermore, we can show that model-based techniques lend themselves to be applied at design stages to estimate the system performance with adequate accuracy. In this context it is shown how different protocol variants and wireless channel models affect the performance. Ultimately, this integrated approach allows not only to shorten the development cycle but also to support the accompanying certification process.
Es laden ein: Die Dozenten der Informatik