Optimal and Global Time Synchronization in Sensornets

Time synchronization is necessary in many distributed systems, but achieving synchronization in sensornets, which combine stringent precision requirements with severe resource constraints, is particularly challenging. This challenge has been met by the recent Reference-Broadcast Synchronization (RBS) proposal, which provides ondemand pairwise synchronization with low overhead and high precision. In this paper we introduce a model of the basic RBS synchronization paradigm that treats clock offset and clock skew on different time scales. Within the context of this model we derive the optimally precise and globally consistent clock synchronization. This approach can be used with any synchronization paradigm that produces pairwise synchronizations with independent errors.