Weakly-Hard Real-Time Flow Scheduling in Time-Sensitive Networks

Abstract

Time-Sensitive Networking (TSN) offers deterministic transmission through mechanisms such as the Time-Aware Shaper (TAS), but existing scheduling approaches assume hard real-time semantics where all packets must meet deadlines, leading to inefficiency under high utilization or overload. In contrast, numerous cyber-physical systems operate under “weakly-hard” timing models that permit bounded deadline violations. This paper introduces a design-time scheduling framework that integrates weakly-hard requirements into TSN by categorizing packets as mandatory or optional and synthesizing Gate Control Lists (GCLs) that guarantee timing constraints for all mandatory packets while maximizing admission of optional traffic. We propose both a computationally efficient heuristic algorithm (named Lazy Search) and an Integer Linear Programming (ILP) formulation for GCL construction. We further systematically analyze the trade-off between serving optional packets through a dedicated priority queue versus multiplexing them within their nominal traffic class. Through synthetic workload evaluation and hardware validation on a commodity TSN switch, we demonstrate that the proposed framework substantially improves optional packet service rates without compromising timing guarantees of mandatory packets.