Temperature-Assisted Clock Synchronization and Self-Calibration for Sensor Networks

Abstract

Synchronization is a pre-requisite for many sensor network applications. However, it remains challenging in sensor networks due to both the limited resources and the dynamic environments. In this paper, we propose a new two-phase clock synchronization scheme. The first one is the external clock synchronization phase, during which nodes update their clock by exchanging timestamp messages with the reference clock. Different from the conventional solutions, we propose to directly remove the clock skew during the external synchronization to achieve a higher synchronization accuracy and lower computational complexity. The second one is the clock selfcalibration phase, as the accumulated clock skew will make the synchronized clock drift away again, we need to compensate the clock skew to maintain the clock synchronization accuracy. However, the compensation is non-trivial as the clock skew may not be constant due to the changing environment. Thus we propose the temperature-assisted clock self-calibration (TACSC) to dynamically compensate the clock skew according to the working temperature. Extensive simulation demonstrates that the proposed synchronization scheme can achieve a much lower root mean square error in the external synchronization phase. Furthermore, during the clock self-calibration phase, the TACSC scheme can improve the synchronization accuracy by more than one order of magnitude, which is verified by both simulation and testbed experimentation.Index Terms-Time synchronization, clock skew, wireless sensor networks.

A Distributed Consensus-Based Clock Synchronization Protocol for Wireless Sensor Networks

“…Authors in [17] have employed a clustering technique, based on the LEACH [18] protocol, to deal with the problem of high communication traffic and low convergence speed of distributed consensus time synchronization protocols. In [19], the authors have designed a scheme that employs the measured temperature to assist network nodes to automatically compensate the effect of the clock skew. In order to increase the interval between two synchronization periods without losing synchronization accuracy, the authors of [20] have conducted measurements during several months to prove the correlation of clock frequency and temperature.…”

Accurate Clock Discipline For Long-Term Synchronization Intervals

“…In turn, M 0 accounts for production variability, i.e. the frequency tolerance (see [16] for a brief discussion). Generally, the main goal is to first compensate the latter effect, eliminating M 0 through an individual calibration process, and also periodically measuring Manufacturing tolerance.…”

Message Passing Based Time Synchronization in Wireless Sensor Networks: A Survey

“…Temperature-Assisted Clock Self-Calibration (TACSC) [52] compensates clock drift in a new way. As the clock drift changes over time based on the environment's temperature, TACSC relates the temperature and frequency of oscillator using a parabolic function before the nodes are deployed in the network.…”