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End-to-End Reliability in Wireless IEEE 802.1Qbv Time-Sensitive Networks

S. Egger, J. Gross, J. Sachs, G. P. Sharma, C. Becker, F. Dürr

TL;DR

This work addresses the challenge of achieving end-to-end reliability in wireless TSN by revealing that end-to-end QoS cannot be guaranteed by 5G internal reliability alone when using conventional 802.1Qbv scheduling. It introduces Full Interleaving Packet Scheduling (FIPS), a robust, wireless-friendly TAS scheduler that leverages 5G Packet Delay Budgets (PDBs) to provide formal end-to-end QoS guarantees and fault isolation. By allowing controlled batching and an incremental ordering approach, FIPS significantly increases schedulability (up to 45x) and prevents cascading QoS violations, even under 5G delay variations. Evaluation with realistic 5G delay histograms and an AGV-oriented topology demonstrates that FIPS maintains high end-to-end reliability ($ ext{e.g., }$ $99.99\%$) while outperforming strict isolation strategies in throughput and scalability. This work thus advances dependable wireless TSN by delivering provable end-to-end QoS and scalable, fault-tolerant scheduling in the presence of 5G uncertainties.

Abstract

Industrial cyber-physical systems require dependable network communication with formal end-to-end reliability guarantees. Striving towards this goal, recent efforts aim to advance the integration of 5G into Time-Sensitive Networking (TSN). However, we show that IEEE 802.1Qbv TSN schedulers that are unattuned to 5G packet delay variations may jeopardize any reliability guarantees provided by the 5G system. We demonstrate this on a case where a 99.99% reliability in the inner 5G network diminishes to below 10% when looking at end-to-end communication in TSN. In this paper, we overcome this shortcoming by introducing Full Interleaving Packet Scheduling (FIPS) as a wireless-friendly IEEE 802.1Qbv scheduler. To the best of our knowledge, FIPS is the first to provide formal end-to-end QoS guarantees in wireless TSN. FIPS allows a controlled batching of TSN streams, which improves schedulability in terms of the number of wireless TSN streams by a factor of up to x45. Even in failure cases, FIPS isolates the otherwise cascading QoS violations to the affected streams and protects all other streams. With formal end-to-end reliability, improved schedulability, and fault isolation, FIPS makes a substantial advance towards dependability in wireless TSN.

End-to-End Reliability in Wireless IEEE 802.1Qbv Time-Sensitive Networks

TL;DR

This work addresses the challenge of achieving end-to-end reliability in wireless TSN by revealing that end-to-end QoS cannot be guaranteed by 5G internal reliability alone when using conventional 802.1Qbv scheduling. It introduces Full Interleaving Packet Scheduling (FIPS), a robust, wireless-friendly TAS scheduler that leverages 5G Packet Delay Budgets (PDBs) to provide formal end-to-end QoS guarantees and fault isolation. By allowing controlled batching and an incremental ordering approach, FIPS significantly increases schedulability (up to 45x) and prevents cascading QoS violations, even under 5G delay variations. Evaluation with realistic 5G delay histograms and an AGV-oriented topology demonstrates that FIPS maintains high end-to-end reliability ( ) while outperforming strict isolation strategies in throughput and scalability. This work thus advances dependable wireless TSN by delivering provable end-to-end QoS and scalable, fault-tolerant scheduling in the presence of 5G uncertainties.

Abstract

Industrial cyber-physical systems require dependable network communication with formal end-to-end reliability guarantees. Striving towards this goal, recent efforts aim to advance the integration of 5G into Time-Sensitive Networking (TSN). However, we show that IEEE 802.1Qbv TSN schedulers that are unattuned to 5G packet delay variations may jeopardize any reliability guarantees provided by the 5G system. We demonstrate this on a case where a 99.99% reliability in the inner 5G network diminishes to below 10% when looking at end-to-end communication in TSN. In this paper, we overcome this shortcoming by introducing Full Interleaving Packet Scheduling (FIPS) as a wireless-friendly IEEE 802.1Qbv scheduler. To the best of our knowledge, FIPS is the first to provide formal end-to-end QoS guarantees in wireless TSN. FIPS allows a controlled batching of TSN streams, which improves schedulability in terms of the number of wireless TSN streams by a factor of up to x45. Even in failure cases, FIPS isolates the otherwise cascading QoS violations to the affected streams and protects all other streams. With formal end-to-end reliability, improved schedulability, and fault isolation, FIPS makes a substantial advance towards dependability in wireless TSN.

Paper Structure

This paper contains 31 sections, 6 theorems, 46 equations, 11 figures, 1 table.

Table of Contents

  1. Introduction
  2. Related Work
  3. Scheduling in Time-Sensitive Networks
  4. Scheduling with Uncertainty in Related Domains
  5. Background and System Model
  6. Time-Sensitive Networking
  7. The 5G System as a Logical TSN Bridge
  8. System Model and Notation
  9. Modelling TSN Runtime Behavior
  10. Problem Description
  11. Robust and Feasible TSN Configurations
  12. 5G Packet Delay Budgets
  13. Design Rationale
  14. 5G PDB Contracts
  15. Robust and Feasible TSN Configurations
  16. ...and 16 more sections

Key Result

Theorem 1

A TSN configuration $\mathcal{C}$ feasibly schedules a stream $F \in \mathcal{F}$ (according to Definition def:reliability) if

Figures (11)

  • Figure 1: Port-to-port model of TSN bridges with Per-Stream Filtering and Policing (PSFP) and the Time-Aware Shaper (TAS).
  • Figure 2: Integration of 5G and TSN, as standardized by 3gpp.23.501.
  • Figure 3: Packet delay characteristics, measured by downlink_example_histogram.
  • Figure 4: Frame reordering in a TSN configuration for time-triggered streams can nullify any end-to-end QoS guarantee.
  • Figure 5: 5G Packet Delay Budgets $[\mathbf{d}^{min}, \mathbf{d}^{max}]$ from a 5G perspective (left) and from a TSN perspective (right).
  • ...and 6 more figures

Theorems & Definitions (8)

  • Definition 1: End-to-End QoS
  • Definition 2: Robustness
  • Theorem 1: Feasibility
  • Theorem 2
  • Corollary 1
  • Lemma 1
  • Lemma 2
  • Theorem 3