Accuracy-Driven Synchronization Protocol

Sensor nodes are small-size, low-cost embedded systems capable of local processing and RF communication. In a sensor network, nodes need to organize their operations to perform distributed sensing tasks, and need therefore to be time synchronized to a common reference. In this paper we present a time-synchronization approach for wireless sensor networks(WSNs), denoted as accuracy-driven synchronization protocol(ADSP). ADSP is based on the "always-on" model of time synchronization, and offers customizable accuracy level, using a novel method to reduce the transmit-to-receive time delay. The time reference is provided by a master node frequently broadcasting packets that the nodes use to synchronize themselves, and then to improve their synchronization. Nodes estimate their own clock characteristics with respect to the master node, thus keeping themselves synchronized even when the master node is not transmitting. The one-way broadcast scheme adopted by ADSP guarantees extremely low energy consumption.