Scaling 5G-TSN Bridges: Operating Regimes, Scheduling, and Time Synchronisation Under Heterogeneous Industrial Traffic

2026-08-14

AI Summary

This study addresses the scalability and Quality of Service (QoS) challenges in 5G-TSN bridging under heterogeneous industrial workloads. Leveraging the nascTime framework, we model diverse traffic patterns and scheduling strategies to elucidate system dynamics and synchronization mechanisms. A QoS-aware Proportional Fair scheduling algorithm is proposed and validated via OMNeT++/Simu5G simulations. Results demonstrate that this algorithm reduces the P99 latency of critical flows by two orders of magnitude while significantly enhancing clock synchronization stability. Furthermore, doubling bandwidth doubles the saturation threshold, and the analysis identifies specific wireless configuration boundaries required to achieve sub-3ms latency. These findings provide a theoretical foundation for enabling reliable 5G industrial interconnection.

Abstract

3GPP Release 16 enables a 5G system to operate as a transparent IEEE 802.1 TSN bridge, but its scalability under heterogeneous industrial workloads remains insufficiently characterised. This paper uses the nascTime framework on OMNeT++/Simu5G to evaluate how many TSN endpoints a single 5G NR cell can bridge before per-flow QoS degrades. We model closed-loop control, machine vision, bulk telemetry, and IEEE 802.1AS traffic over a four-bearer SDAP architec- ture, varying the number of endpoints from 1 to 40, MAC scheduler, radio bandwidth (10 MHz and 20 MHz), and channel model. Results show three operating regimes. Below saturation, non-DRR schedulers perform similarly; near saturation, QoS- aware PF reduces critical-flow P99 latency by up to two or- ders of magnitude relative to channel-aware and fairness-based schedulers; and under overload, only QoS-PF maintains near- complete delivery for the highest-priority traffic. Across the two evaluated bandwidths, the saturation threshold approximately doubles when bandwidth doubles. We also show that isolating IEEE 802.1AS/gPTP traffic on a dedicated high-priority radio bearer reduces clock-servo instability, although endpoints carry- ing lower-priority data still experience elevated synchronisation delay under saturation because of reduced MAC scheduling frequency. Finally, the evaluated sub-6 GHz, 30 kHz-SCS con- figuration exhibits an effective latency floor of approximately 2.25 ms, indicating that sub-3 ms TSN deadlines may require radio-configuration changes such as configured grants or higher numerology

Problem

• 5G-TSN Bridge
• Scalability
• Heterogeneous Industrial Traffic
• QoS Degradation
• Time Synchronisation

Innovation

• 5G-TSN Bridge Scalability
• QoS-aware PF Scheduling
• Heterogeneous Industrial Traffic
• gPTP Traffic Isolation
• Latency Floor Characterization