Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Programmable Cycle-Specified Queue for Long-Distance Industrial Deterministic Packet Scheduling

Yudong Huang, Shuo Wang, Shiyin Zhu, Guoyu Peng, Xinyuan Zhang, Tao Huang, Xinmin Liu

TL;DR

Evaluation results show that PCSQ can schedule tens of thousands of time-sensitive flows and strictly guarantee $ms$-level delay and us-level jitter, and the queue coordination and cycle mapping mechanisms are delicately designed to solve the cycle-queue mismatch problem.

Abstract

The time-critical industrial applications pose intense demands for enabling long-distance deterministic networks. However, previous priority-based and weight-based scheduling methods focus on probabilistically reducing average delay, which ignores strictly guaranteeing task-oriented on-time packet delivery with bounded worst-case delay and jitter. This paper proposes a new Programmable Cycle-Specified Queue (PCSQ) for long-distance industrial deterministic packet scheduling. By implementing the first high-precision rotation dequeuing, PCSQ enables microsecond-level time slot resource reservation (noted as T) and especially jitter control of up to 2T. Then, we propose the cycle tags computation to approximate cyclic scheduling algorithms, which allows packets to actively pick and lock their favorite queue in a sequence of nodes. Accordingly, PCSQ can precisely defer packets to any desired time. Further, the queue coordination and cycle mapping mechanisms are delicately designed to solve the cycle-queue mismatch problem. Evaluation results show that PCSQ can schedule tens of thousands of time-sensitive flows and strictly guarantee $ms$-level delay and us-level jitter.

Programmable Cycle-Specified Queue for Long-Distance Industrial Deterministic Packet Scheduling

TL;DR

Evaluation results show that PCSQ can schedule tens of thousands of time-sensitive flows and strictly guarantee -level delay and us-level jitter, and the queue coordination and cycle mapping mechanisms are delicately designed to solve the cycle-queue mismatch problem.

Abstract

The time-critical industrial applications pose intense demands for enabling long-distance deterministic networks. However, previous priority-based and weight-based scheduling methods focus on probabilistically reducing average delay, which ignores strictly guaranteeing task-oriented on-time packet delivery with bounded worst-case delay and jitter. This paper proposes a new Programmable Cycle-Specified Queue (PCSQ) for long-distance industrial deterministic packet scheduling. By implementing the first high-precision rotation dequeuing, PCSQ enables microsecond-level time slot resource reservation (noted as T) and especially jitter control of up to 2T. Then, we propose the cycle tags computation to approximate cyclic scheduling algorithms, which allows packets to actively pick and lock their favorite queue in a sequence of nodes. Accordingly, PCSQ can precisely defer packets to any desired time. Further, the queue coordination and cycle mapping mechanisms are delicately designed to solve the cycle-queue mismatch problem. Evaluation results show that PCSQ can schedule tens of thousands of time-sensitive flows and strictly guarantee -level delay and us-level jitter.
Paper Structure (22 sections, 2 theorems, 11 equations, 18 figures, 4 tables, 2 algorithms)

This paper contains 22 sections, 2 theorems, 11 equations, 18 figures, 4 tables, 2 algorithms.

Table of Contents

  1. Introduction
  2. Observations
  3. Task-oriented On-time Packet Delivery
  4. The Trends of Cyclic Scheduling
  5. Motivation
  6. Packet Scheduling Dilemmas
  7. Challenges for implementing PCSQ
  8. Packet Scheduling using Programmable Cycle-Specified Queue
  9. PCSQ Framework
  10. High-Precision Rotation Dequeuing
  11. Queue Coordination in Nodes
  12. Cycle Mapping Between Nodes
  13. Cycle Tags Computation
  14. Evaluation
  15. Microbenchmarks
  16. ...and 7 more sections

Key Result

Theorem 1

If the input flow to any network node is smooth ($s^{'}_{f}$) or uniform ($u^{'}_{f}$), then both the internal buffer and delay of that node are bounded.

Figures (18)

  • Figure 1: The on-time packet delivery is highly required to co-transmit the time-sensitive flows and best-effort traffic in typical industrial network scenarios.
  • Figure 2: A testbed for TSN interconnection. The master PLC sends pulse signals across the emulated WAN to synchronize the position angle of the slave servo motor. $\left| Pos_{1}-Pos_{2} \right|$ is the measured metric of the position error.
  • Figure 3: The impact of delay and jitter (delay/ $\pm$ jitter) on the remote control of servo motor. Out-of-order is disabled for the second half of samples.
  • Figure 4: The impact of network jitter. The delay is set to 10 ms and out-of-order is disabled.
  • Figure 5: DetNet improves Ethernet's deterministic transmission capabilities and is more flexible than proprietary fieldbuses. Compared with Asynchronous Transfer Mode (ATM), DetNet reduces the technical complexity and has better compatibility with existing networks.
  • ...and 13 more figures

Theorems & Definitions (2)

  • Theorem 1
  • Corollary 1