Non invasive time synchronization for ZigBee Wireless Sensor Networks

A precise time synchronization is essential in many wireless sensor networking applications, e.g. in order to correlate observations of the same event from different sites or to efficiently share the wireless channel. Generally, wireless sensors are designed having in mind low cost and low power. In the past, several protocols have been suggested, each one with its pros and cons, aiming at the maximization of the accuracy vs. consumption ratio. However, their performance have been generally tested on particular hardware setup and with proprietary communication protocols. In this paper we present a non invasive implementation of a synchronization protocol over a full ZigBee-compliant platform. Experimental evaluation on real prototypes has been performed in order to ensure feasibility and verify performances. Our approach preserves compatibility with this emerging standard still offering synchronization error on the order of few mus if synchronization procedure is executed every 4 s.