Enhancing Real-Time and Determinacy for Network-Level Schedule in Distributed Mixed-Critical System

Jun Lu; Huagang Xiong; Feng He; Rongwei Wang

doi:10.1109/ACCESS.2020.2970266

IEEE Access (Jan 2020)

Enhancing Real-Time and Determinacy for Network-Level Schedule in Distributed Mixed-Critical System

Jun Lu,
Huagang Xiong,
Feng He,
Rongwei Wang

Affiliations

Jun Lu: ORCiD; School of Electronic and Information Engineering, Beihang University, Beijing, China
Huagang Xiong: ORCiD; School of Electronic and Information Engineering, Beihang University, Beijing, China
Feng He: ORCiD; School of Electronic and Information Engineering, Beihang University, Beijing, China
Rongwei Wang: ORCiD; School of Electronic and Information Engineering, Beihang University, Beijing, China

DOI: https://doi.org/10.1109/ACCESS.2020.2970266
Journal volume & issue: Vol. 8
pp. 23720 – 23731

Abstract

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Time-triggered Ethernet (TTE) is designed as a deterministic real-time network for mixed-critical real-time systems, such as industrial automation, aerospace, and aviation. Due to asynchrony between tasks and the network in end systems (ESes), time-triggered (TT) messages have to spend uncertain time in waiting for being scheduled after they are generated. The waiting time uncertainly increases end to end delays for TT messages and will degrade the real-time and determinacy of TT messages sequentially. The contribution of this paper is to present a new architecture SDTTE to minimize the end to end delays, so as to enhance real-time and determinacy of TT messages. More specifically, a frame-based network model is built to describe distributed network resources. Under the network model, the end to end delay model with asynchrony between tasks and the network is analyzed. To match the generated time with the triggered time for TT messages, the triggered mechanism of the TT traffic in ESes is regarded as event strategy to detect the generated time of TT messages automatically. Based on this, the software defined TTE (SDTTE) is presented to optimize TT schedule online in switches. Furthermore, a simplified algorithm based on Satisfiability Modulo Theories (SMT) is proposed to satisfy real-time computing requirements. Finally, experiments with three network sizes verify the availability of SDTTE and analyze its performance. The results show that end to end delays for TT messages in SDTTE are decreased by about 95% compared with those in TTE. And the delays for rate-constrained and best-effort messages in SDTTE are almost as well as those in TTE. The processing time is less than 10s. In general, SDTTE provides a method to optimize end to end delays for TT messages in TTE, thus SDTTE has more determinacy and real-time than TTE. Meanwhile, SDTTE makes dynamic reconfiguration possible in practice.

Published in IEEE Access

ISSN: 2169-3536 (Online)
Publisher: IEEE
Country of publisher: United States
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering
Website: https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=6287639

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