Self-correcting time synchronization using reference broadcast in wireless sensor network

Time synchronization is one of the most fundamental services for numerous wireless sensor network applications. In this article the definition and basic concepts of time synchronization are introduced, and the related work is summarized in brief. Through analyzing the characteristics of the existing typical synchronization protocols and making a comprehensive comparison of the performance of various algorithms, we present a common guideline for designing the time synchronization protocol in WSN. Following this guideline, we develop a new time synchronization protocol called Self-Correcting Time Synchronization (SCTS), which converts the time synchronization problem into an online dynamic self-adjusting optimizing process to make the offset compensation and drift compensation simultaneously. The time and space complexities of the algorithm implementation are very low. In addition, the SCTS protocol fully exploits the inherent broadcast property of wireless channel, so the communication overhead is rather low. Because the algorithm implementation is based on the phase locked loop principle, an equivalent digital PLL without an actual voltage controlled oscillator is also proposed to avoid introducing the extra hardware required by a traditional PLL circuit. Finally, we validate SCTS on the Berkeley Mica2 experimental platform, and the performance is evaluated and compared to the existing typical time synchronization protocol.