An Empirical Survey of Autonomous Scheduling Methods for TSCH

Atis Elsts,Chongkwon Kim,Hyung-Sin Kim,Seohyang Kim

doi:10.1109/access.2020.2980119

Abstract

Time Slotted Channel Hopping (TSCH) is a link layer protocol defined in the IEEE 802.15.4 standard. Although it is designed to provide highly reliable and efficient service targeting industrial automation systems, scheduling TSCH transmissions in the time and frequency dimensions is left to the implementers. We evaluate the performance of existing autonomous scheduling approaches for TSCH on various traffic patterns and network configurations. We thoroughly investigate the pros and cons of each scheme; moreover, we propose the use of node based channel allocation to improve the performance of the best scheme, and demonstrate its practicality and reliability, with up to 6 percentage points better packet delivery ratio than the second best option while retaining a similar radio duty cycle. Finally, based on our extensive performance evaluation, we provide some guidelines on how to select a scheduler for a given network.

Highlights

The Time Slotted Channel Hopping (TSCH) protocol from the IEEE 802.15.4-2015 standard [1] brings highly reliable communications to the field of low-power wireless networks
Preliminary investigations showed that our adapted version of Orchestra with multiple channel offsets performs significantly better than the single channel offset version described previously [8], so we only report the results for the former. Report both the published version of ALICE, with link based channel allocation [9], and our modified one, with node based channel allocation, as we are interested in showing the tradeoffs, as well as the margin of improvement upon the current best state-of-the-art method
For a constant-size slotframe they do result in lower duty cycle; when the tradeoff between Packet Delivery Ratio (PDR) and Radio duty cycle (RDC) is explicitly considered as a function of slotframe size, other options achieve better PDR at a similar RDC

Summary

Introduction

The TSCH protocol from the IEEE 802.15.4-2015 standard [1] brings highly reliable communications to the field of low-power wireless networks. One aspect not specified in the IEEE 802.15.4 standard is the construction of a TSCH schedule. This task has attracted a large attention from the research community. With centralized scheduling [2], a central controller node builds the schedule and distributes it to other nodes. This controller is placed outside of the lowpower network. The attention of this paper is on autonomous scheduling – namely, on approach where the schedule is constructed by each node autonomously, typically (but not exclusively!) relying on routing information already present on the node

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Discussion

Conclusion