A Wrapper-Based Approach to Sustained Time Synchronization in Wireless Sensor Networks

Time synchronization is an important service for wireless sensor network applications. Nodes in the network stay synchronized by exchanging periodic messages that carry local timestamps. Several algorithms have been proposed in the literature that are suited to different kinds of application scenarios. A common problem across these time synchronization algorithms is that the energy cost of message exchange is high. In fact, the cost of radio communication far outstrips the cost of performing local operations on the processor. If the message exchanges were stopped, nodes will fall out of sync, and may no longer be able to meet application requirements. In this paper, we present a wrapper-based approach to sustained time synchronization for wireless sensor networks. As such, our solution will act as a wrapper around a given time synchronization protocol, and will apply local corrector operations to extend the time duration between two message exchanges between nodes. Our wrapper performs at least as good as the original protocol provided, reduces the number of message exchanges on average, and consequently the energy consumed, significantly. We present an implementation of our wrapper for TinyOS and evaluate it on XSM motes in conjunction with TPSN, a popular time synchronization protocol for sensor networks.