Energy-efficient and robust-time synchronization is crucial for industrial Internet of things (IIoT). Some energy-efficient time synchronization schemes that achieve high accuracy have been proposed recently. However, some unsynchronized nodes namely isolated nodes exist in the schemes. To deal with the problem, this paper presents R-Sync, a robust time synchronization scheme for IIoT. We use a pulling timer to pull isolated nodes into synchronized networks whose initial value is set according to level of spanning tree. Then, another timer is set up to select backbone node and its initial value is related to the distance to parent node. Moreover, we do experiments based on simulation tool NS-2 and testbed based on wireless hardware nodes. The experimental results show that our approach makes all the nodes get synchronized and gets the better performance in terms of accuracy and energy consumption, compared with three existing time synchronization algorithms TPSN, GPA, STETS.

中文翻译：

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工业物联网的鲁棒时间同步方案

高效节能且时间稳定的同步对于工业物联网（IIoT）至关重要。最近已经提出了一些实现高精度的节能时间同步方案。但是，这些方案中存在一些非同步节点，即隔离节点。为了解决这个问题，本文提出了一种用于IIoT的鲁棒时间同步方案R-Sync。我们使用拉动计时器将隔离的节点拉入同步网络，该网络的初始值根据生成树的级别进行设置。然后，设置另一个计时器以选择骨干节点，其初始值与到父节点的距离有关。此外，我们基于仿真工具NS-2进行了实验，并基于无线硬件节点进行了测试台。