Clock Skew Estimation of Listening Nodes with Clock Correction upon Every Synchronization in Wireless Sensor Networks | IEEE Journals & Magazine | IEEE Xplore

Clock Skew Estimation of Listening Nodes with Clock Correction upon Every Synchronization in Wireless Sensor Networks


Abstract:

Time synchronization is a significant component in Wireless Sensor Networks (WSNs) for maintaining synchrony among nodes. Most time synchronization protocols in WSNs util...Show More

Abstract:

Time synchronization is a significant component in Wireless Sensor Networks (WSNs) for maintaining synchrony among nodes. Most time synchronization protocols in WSNs utilize dedicated synchronization packets for clock accuracy optimization. However, in practical WSNs, the joint design of time synchronization and Media Access Control layer protocols should be considered. One approach is adding timestamps directly into data packets and the corresponding acknowledgements (ACKs). Therefore, communication and energy overhead could be saved greatly and time synchronization could be seamlessly integrated into networks. In this letter, we investigate the time synchronization scheme of listening nodes overhearing the neighboring two-way timing packet exchange based on periodical ACK mechanism and present an efficient clock skew estimation algorithm with clock correction upon every synchronization. The Maximum Likelihood Estimator (MLE) of clock skew for Gaussian random packet delay is derived, and the corresponding Cramer-Rao Lower Bound (CRLB) is obtained. In addition, the MLE shows that the clock skew could be estimated without any prior knowledge of the fixed packet delay and the time of adjustment. Simulation results verify that the MLE is efficient.
Published in: IEEE Signal Processing Letters ( Volume: 22, Issue: 12, December 2015)
Page(s): 2440 - 2444
Date of Publication: 15 October 2015

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