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Multi-Stream TSN Gate Control Scheduling in the Presence of Clock Synchronization

Aviroop Ghosh, Saleh Yousefi, Thomas Kunz

TL;DR

This work addresses the challenge of achieving deterministic, bounded end-to-end latency in TSN under clock drift and synchronization constraints. It analyzes four scheduling approaches (WCD, WCA, NCD, NCA) that differ in how they account for clock drift and queuing delays, formulating an ILP to compute gate-control offsets across a multi-hop network. The results show that WCA/NCA achieve zero jitter with minimum latency, while NCA provides substantial bandwidth efficiency gains over WCA; NCD improves jitter relative to WCD but cannot guarantee deadlines in all cases. The findings highlight the value of incorporating network-derived clock-drift measurements into gate-control scheduling and suggest future work on measurement errors, complex topologies, and adaptive synchronization periods to further optimize TSN performance.

Abstract

With the advancement of technologies like Industry 4.0, communication networks must meet stringent requirements of applications demanding deterministic and bounded latencies. The problem is further compounded by the need to periodically synchronize network devices to a common time reference to address clock drifts. Existing solutions often simplify the problem by assuming either perfect synchronization or a worst-case error. Additionally, these approaches delay the scheduling process in network devices until the scheduled frame is guaranteed to have arrived in the device queue, inducing additional delays to the stream. A novel approach that completely avoids queuing delays is proposed, enabling it to meet even the strictest deadline requirement. Furthermore, both approaches can be enhanced by incorporating network-derived time-synchronization information. This is not only convenient for meeting deadline requirements but also improves bandwidth efficiency.

Multi-Stream TSN Gate Control Scheduling in the Presence of Clock Synchronization

TL;DR

This work addresses the challenge of achieving deterministic, bounded end-to-end latency in TSN under clock drift and synchronization constraints. It analyzes four scheduling approaches (WCD, WCA, NCD, NCA) that differ in how they account for clock drift and queuing delays, formulating an ILP to compute gate-control offsets across a multi-hop network. The results show that WCA/NCA achieve zero jitter with minimum latency, while NCA provides substantial bandwidth efficiency gains over WCA; NCD improves jitter relative to WCD but cannot guarantee deadlines in all cases. The findings highlight the value of incorporating network-derived clock-drift measurements into gate-control scheduling and suggest future work on measurement errors, complex topologies, and adaptive synchronization periods to further optimize TSN performance.

Abstract

With the advancement of technologies like Industry 4.0, communication networks must meet stringent requirements of applications demanding deterministic and bounded latencies. The problem is further compounded by the need to periodically synchronize network devices to a common time reference to address clock drifts. Existing solutions often simplify the problem by assuming either perfect synchronization or a worst-case error. Additionally, these approaches delay the scheduling process in network devices until the scheduled frame is guaranteed to have arrived in the device queue, inducing additional delays to the stream. A novel approach that completely avoids queuing delays is proposed, enabling it to meet even the strictest deadline requirement. Furthermore, both approaches can be enhanced by incorporating network-derived time-synchronization information. This is not only convenient for meeting deadline requirements but also improves bandwidth efficiency.
Paper Structure (19 sections, 10 equations, 7 figures, 3 tables)

This paper contains 19 sections, 10 equations, 7 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Literature Survey
  3. Background and System Model
  4. Background on TSN Standard
  5. System Model
  6. GCL Formation
  7. Scheduling Approach with Worst-Case Error and Clock Drift
  8. Scheduling Duration and Clock Drift
  9. Scheduling Approaches
  10. Boundary Conditions:
  11. Non-Overlapping Condition:
  12. Consecutive Offsets:
  13. Scheduling Duration Constraint:
  14. Frame Arrival Constraint:
  15. End-to-End Latency:
  16. ...and 4 more sections

Figures (7)

  • Figure 1: Egress port GCL
  • Figure 2: Network model
  • Figure 3: GCL formation example
  • Figure 4: Illustration of scheduling duration delay and adjustment mechanisms
  • Figure 5: Case study network topology
  • ...and 2 more figures