Hierarchical Scheduling Mechanism Based on Relaxed Constraints for Complex Industrial Scenes

The rise of Time-Sensitive Networking (TSN) has sparked a significant transformation in the domain of industrial networks. Concurrently, industrial networks have established new benchmarks for communication quality, characterized by stringent requirements for low latency, minimal jitter, and enhanced reliability. In this context, the TSN subcommittee under the IEEE 802.1 working group has released a comprehensive collection of protocol standards. These standards are intricately crafted to ensure deterministic low latency in inherently unpredictable Ethernet environments. To enhance deterministic Quality of Service (QoS) in industrial networks and increase the flexibility of network scheduling paradigms, emerging technologies that combine TSN with Software-Defined Networking (TSSDN) have gained significant attention. Nevertheless, due to the complex and multifaceted nature of factory workflows and the varying scheduling requirements at different hierarchical levels, current industrial scheduling methods encounter challenges in efficiently managing network traffic in real-world factory environments. In this paper, we present a systematic framework designed for the scheduling of factory traffic. Additionally, we introduce two distinct scheduling mechanisms, each based on a framework with relaxed constraints. These mechanisms correspond to intra-level and inter-level traffic transmission in industrial networks. According to our experimental results, we observe an increase of 12.6% to 25.32% in the relaxed constraint scheduling mechanism when compared to the single scheduling scheme, along with a 9% reduction in the proportion of occupied queues.