The protocols used in Wireless Sensor Networks are subject to very strict temporal synchronization constraints. Radio Duty Cycle (RDC) protocols in particular are characterized by their very high synchronization accuracy requirements. In these protocols, synchronization errors are primarily caused by the natural clock drift observed in real nodes. The impact of the clock drift on the desynchronization issues can be investigated by the use of low-level node simulators.

In this paper, we show the limitation of the COOJA simulator to evaluate the impact of the clock drift. We show that its current mote execution model does not faithfully reproduce the requested clock drift. We identify the root cause of these inaccuracies and present a new algorithm that is able to precisely reproduce any requested clock drifts in simulation. On the basis of our understanding, we build a mathematical model of the clock drift error allowing previous authors to estimate the error caused by clock drift inaccuracies in their studies and its impact on their results.

To demonstrate the new algorithm, we consider a well-documented RDC protocol issue where the clock drift would cause periodic communication blackouts. This phenomenon was observed on real nodes, but was previously impossible to reproduce by simulation. Our new algorithm not only allows to reproduce the blackouts but also provides additional insights that help to confirm the initial analysis of the phenomenon. Finally, we use our algorithm to implement dynamic clock drift models to simulate the behavior of a clock drift evolving through time. We illustrate this using our linear model to push a RDC protocol to its limits.

无线传感器网络中使用的协议受到非常严格的时间同步约束。无线电占空比（RDC）协议特别具有很高的同步精度要求。在这些协议中，同步错误主要是由在实际节点中观察到的自然时钟漂移引起的。时钟漂移对失步问题的影响可以通过使用低级节点模拟器来研究。

在本文中，我们展示了COOJA仿真器在评估时钟漂移影响方面的局限性。我们表明其当前的微粒执行模型不能如实再现请求的时钟漂移。我们确定了这些不准确性的根本原因，并提出了一种新算法，该算法能够在模拟中精确再现任何要求的时钟漂移。在我们的理解的基础上，我们建立了时钟漂移误差的数学模型，使以前的作者可以估计由于他们研究中的时钟漂移不准确所引起的误差及其对结果的影响。

为了演示新算法，我们考虑了一个有据可查的RDC协议问题，其中时钟漂移会导致周期性的通信中断。在实际节点上可以观察到这种现象，但是以前不可能通过仿真来重现。我们的新算法不仅可以重现停电，而且还可以提供其他见解，有助于确认现象的初步分析。最后，我们使用算法来实现动态时钟漂移模型，以模拟时钟漂移随时间演变的行为。我们使用线性模型将RDC协议推向极限，对此进行了说明。