Energy-efficient time synchronisation based on odd-even periodic data transmission and acknowledgement in wireless sensor networks

Abstract

In the working process of wireless sensor networks (WSNs), it is challenging to realise precise and energy-efficient time synchronisation on resource-constrained WSNs nodes. In this paper, a fusion method of time synchronisation with periodical data transmission and acknowledgement is proposed for WSNs. Moreover, different response intervals are generated according to the parity characteristic of the measurement data's serial number. The maximum likelihood estimators (MLE) of clock skew and fixed delay, and the simplified MLE of clock skew under the Gaussian random delay are derived. Meanwhile, the corresponding Cramer-Rao Lower Bound is calculated. The two proposed MLEs of clock skew show that both of them can work independently of the fixed delay. Simulation results verify the efficiency of these two clock skew estimators and fixed delay estimator, especially the performance and effectiveness of the second simple and practical MLE.