eTAS: Enhanced Time-Aware Shaper for Supporting Nonisochronous Emergency Traffic in Time-Sensitive Networks
Moonbeom Kim, Doyeon Hyeon, Jeongyeup Paek
Abstract
To guarantee stringent real-time requirements of time-critical traffic in industrial systems, the IEEE time-sensitive networking (TSN) task group has standardized time-aware shaping (TAS) in IEEE 802.1Qbv, which schedules precise and periodic transmission times using preassigned traffic information. However, nonperiodic/unexpected but time-critical traffic, such as emergency events or alarms, may occur in real industrial scenarios, and TAS does not provision for performance of traffic that are unknown <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a priori</i> , nor the impact thereof on prescheduled traffic. Moreover, recalculating the schedule for every sporadic, nonisochronous event traffic is extremely difficult, complex, and costly. To address these challenges, we propose a novel enhancement to TAS, referred to as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eTAS</i> , which defines a new scheduling rule for immediate forwarding of emergency traffic to guarantee real-time performance, while dynamically extending the scheduled time windows to protect scheduled time-critical traffic from the interference of emergency traffic. We evaluate <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eTAS</i> through extensive simulations on OMNeT++ under an advanced driver assistance system (ADAS) scenario for autonomous driving to show that <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eTAS</i> effectively allows rapid transmission of event traffic with minimal impact on scheduled traffic, even for highly congested networks.