Understanding Precision Time Protocol in Today's Wi-Fi Networks: A Measurement Study

Authors: 

Paizhuo Chen and Zhice Yang, ShanghaiTech University

Abstract: 

Emerging mobile applications involving distributed control and sensing call for accurate time synchronization over wireless links. This paper systematically studies the performance of Precision Time Protocol (PTP) in today's Wi-Fi networks. We investigate both software and hardware PTP implementations. Our study uncovers the root causes of software PTP synchronization errors. We show that with fine-tuned system configurations and an online calibration procedure, software PTP can achieve reasonable accuracy with off-the-shelf Wi-Fi devices. Hardware PTP requires a PTP hardware timestamper clock not contained in Wi-Fi NICs. We propose a method to make use of the hardware TSF counter to emulate the PTP clock. Rigorous tests traversing various conditions show that both software and hardware PTP implementations can achieve a 1-┬Ás level of accuracy in today's Wi-Fi networks.

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BibTeX
@inproceedings {273763,
author = {Paizhuo Chen and Zhice Yang},
title = {Understanding Precision Time Protocol in Today{\textquoteright}s {Wi-Fi} Networks: A Measurement Study},
booktitle = {2021 USENIX Annual Technical Conference (USENIX ATC 21)},
year = {2021},
isbn = {978-1-939133-23-6},
pages = {597--610},
url = {https://www.usenix.org/conference/atc21/presentation/chen},
publisher = {USENIX Association},
month = jul,
}

Presentation Video