eTAS: Enhanced Time-Aware Shaper for Supporting Nonisochronous Emergency Traffic in Time-Sensitive Networks

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 pre-assigned traffic information. However, non-periodic/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 a priori, nor the impact thereof on prescheduled traffic. Moreover, recalculating the schedule for every sporadic, non-isochronous event traffic is extremely difficult, complex, and costly. To address these challenges, we propose a novel enhancement to TAS, referred to as eTAS, 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 eTAS through extensive simulations on OMNeT++ under an advanced driver assistance system (ADAS) scenario for autonomous driving to show that eTAS effectively allows rapid transmission of event traffic with minimal impact on scheduled traffic, even for highly congested networks.