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An Improved Network Time Protocol for Industrial Internet of Things †

In the industrial Internet of Things, the network time protocol (NTP) can be used for time synchronization, allowing machines to run in sync so that machines can take critical actions within 1 ms. However, the commonly used NTP mechanism does not take into account that the network packet travel time...

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Autores principales: Hou, Ting-Chao, Liu, Lin-Hung, Lan, Yan-Kai, Chen, Yi-Ting, Chu, Yuan-Sun
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9269827/
https://www.ncbi.nlm.nih.gov/pubmed/35808516
http://dx.doi.org/10.3390/s22135021
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author Hou, Ting-Chao
Liu, Lin-Hung
Lan, Yan-Kai
Chen, Yi-Ting
Chu, Yuan-Sun
author_facet Hou, Ting-Chao
Liu, Lin-Hung
Lan, Yan-Kai
Chen, Yi-Ting
Chu, Yuan-Sun
author_sort Hou, Ting-Chao
collection PubMed
description In the industrial Internet of Things, the network time protocol (NTP) can be used for time synchronization, allowing machines to run in sync so that machines can take critical actions within 1 ms. However, the commonly used NTP mechanism does not take into account that the network packet travel time over a link is time-varying, which causes the NTP to make incorrect synchronization decisions. Therefore, this paper proposed a low-cost modification to NTP with clock skew compensation and adaptive clock adjustment, so that the clock difference between the NTP client and NTP server can be controlled within 1 ms in the wired network environment. The adaptive clock adjustment skips the clock offset calculation when the NTP packet run trip time (RTT) exceeds a certain threshold. The clock skew compensation addresses the inherent issue that different clocks (or oscillators) naturally drift away from each other. Both adaptive clock adjustment and clock skew compensation are environment dependent and device dependent. The measurement result in our experimental environment shows that the when the RTT threshold is set at 1.7 ms, the best synchronization accuracy is achieved.
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spelling pubmed-92698272022-07-09 An Improved Network Time Protocol for Industrial Internet of Things † Hou, Ting-Chao Liu, Lin-Hung Lan, Yan-Kai Chen, Yi-Ting Chu, Yuan-Sun Sensors (Basel) Article In the industrial Internet of Things, the network time protocol (NTP) can be used for time synchronization, allowing machines to run in sync so that machines can take critical actions within 1 ms. However, the commonly used NTP mechanism does not take into account that the network packet travel time over a link is time-varying, which causes the NTP to make incorrect synchronization decisions. Therefore, this paper proposed a low-cost modification to NTP with clock skew compensation and adaptive clock adjustment, so that the clock difference between the NTP client and NTP server can be controlled within 1 ms in the wired network environment. The adaptive clock adjustment skips the clock offset calculation when the NTP packet run trip time (RTT) exceeds a certain threshold. The clock skew compensation addresses the inherent issue that different clocks (or oscillators) naturally drift away from each other. Both adaptive clock adjustment and clock skew compensation are environment dependent and device dependent. The measurement result in our experimental environment shows that the when the RTT threshold is set at 1.7 ms, the best synchronization accuracy is achieved. MDPI 2022-07-03 /pmc/articles/PMC9269827/ /pubmed/35808516 http://dx.doi.org/10.3390/s22135021 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Hou, Ting-Chao
Liu, Lin-Hung
Lan, Yan-Kai
Chen, Yi-Ting
Chu, Yuan-Sun
An Improved Network Time Protocol for Industrial Internet of Things †
title An Improved Network Time Protocol for Industrial Internet of Things †
title_full An Improved Network Time Protocol for Industrial Internet of Things †
title_fullStr An Improved Network Time Protocol for Industrial Internet of Things †
title_full_unstemmed An Improved Network Time Protocol for Industrial Internet of Things †
title_short An Improved Network Time Protocol for Industrial Internet of Things †
title_sort improved network time protocol for industrial internet of things †
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9269827/
https://www.ncbi.nlm.nih.gov/pubmed/35808516
http://dx.doi.org/10.3390/s22135021
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