Toward a Shared Sense of Time for a Network of Batteryless, Intermittently-powered Nodes
Toward a Shared Sense of Time for a Network of Batteryless, Intermittently-powered Nodes
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DOI：
10.1109/ipccc55026.2022.9894317
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发表时间：
2022-11
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影响因子：
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通讯作者：
Vishal Deep;Mathew L. Wymore;D. Qiao;Henry Duwe
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文献类型：
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作者：
Vishal Deep;Mathew L. Wymore;D. Qiao;Henry Duwe
完全由能量收集供电的无线传感器节点有望通过避免电池的脆弱性、成本和维护限制来实现真正普遍、长时间的传感。不幸的是，由于收集的能量的量通常显著小于设备的有效消耗，这些设备间歇地操作，对它们何时开启以及它们关闭多久的控制有限。这种不可控的不稳定性首先对传统的时间同步误差度量提出了挑战，因为节点不能以已知的间隔可靠地传递时间值，导致节点不同步的错觉。其次，长持续时间的关断时间可能超过间歇性节点依赖于测量关断时间的持久时钟的固有定时限制。长时间的突发组可能导致传统的时间同步机制缓慢地重新收敛，从而导致节点实际上不同步的高误差的显著时段。在本文中，我们定义了一个共享的意义上的时间的容错供电节点，并提出了两个容错意识的同步误差度量。然后，我们提出了一个容错弹性的时间同步机制，称为Levee，它在丢失时间后表现出更快的重新收敛，并且在48小时内最大时间同步误差减少了2.12倍。
Wireless sensor nodes powered solely by energy-harvesting show promise in enabling truly pervasive, long-duration sensing by avoiding the fragility, cost, and maintenance limitations of batteries. Unfortunately, since the amount of energy harvested is often significantly less than the active consumption of the device, these devices operate intermittently with limited control of when they are on and how long they are off. Such uncontrollable intermittency first poses a challenge for traditional time synchronization error metrics, since nodes cannot reliably communicate time values at known intervals, resulting in the illusion that nodes are out-of-sync. Second, long duration off-times can exceed the inherent timing limit of persistent clocks that intermittent nodes rely on to measure off-times. Bursty groups of long off-times can cause traditional time synchronization mechanisms to re-converge slowly, incurring significant periods of high error in which nodes are effectively out-of-sync. In this paper, we define the meaning of a shared sense of time for intermittently-powered nodes, and propose two intermittency-aware synchronization error metrics. We then propose an intermittency-resilient time synchronization mechanism, called Levee, that exhibits more rapid re-convergence after losing time and a 2.12× reduction in maximum time synchronization error for a 48-hour period.