Energy-Efficient Time Synchronization Based on Asynchronous Source Clock Frequency Recovery and Reverse Two-Way Message Exchanges in Wireless Sensor Networks

摘要

We consider energy-efficient time synchronization in a wireless sensornetwork where a head node (i.e., a gateway between wired and wireless networksand a center of data fusion) is equipped with a powerful processor and suppliedpower from outlet, and sensor nodes (i.e., nodes measuring data and connectedonly through wireless channels) are limited in processing and battery-powered.It is this asymmetry that our study focuses on; unlike most existing schemes tosave the power of all network nodes, we concentrate on battery-powered sensornodes in minimizing energy consumption for time synchronization. We present atime synchronization scheme based on asynchronous source clock frequencyrecovery and reverse two-way message exchanges combined with measurement datareport messages, where we minimize the number of message transmissions fromsensor nodes, and carry out the performance analysis of the estimation of bothmeasurement time and clock frequency with lower bounds for the latter.Simulation results verify that the proposed scheme outperforms the schemesbased on conventional two-way message exchanges with and without clockfrequency recovery in terms of the accuracy of measurement time estimation andthe number of message transmissions and receptions at sensor nodes as anindirect measure of energy efficiency.