An effective and robust time synchronization scheme is essential for many wireless sensor network (WSN) applications. Conventional synchronization methods assume the use of highly accurate crystal oscillators (10--100 ppm) for synchronization, only correcting for small errors. This paper suggests a novel method for time synchronization in a multi-hop, fully-distributed WSN using imprecise CMOS oscillators (up to 15,000 ppm). The DiStiNCT technique is power-efficient, computationally simple, and robust to packet loss and complex topologies. Effectiveness has been demonstrated in simulations of fully connected, grid and uni-directional ring topologies. The method has been validated in hardware on a grid of nine sensor nodes, synchronizing to within a mean error of 6.6 ms after 40 iterations.
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