Local and broadcast clock synchronization in a sensor node

Energy constrained wireless sensor networks need to maintain network timing for coordinating event detection and processing, and to enable receiver duty cycling and communications rendezvous, in order to save energy. Motivated by this, we consider synchronization of a slow low-power local oscillator with an occasionally observed fast and highly accurate broadcast clock (such as GPS). Errors are modeled as quantization noise, incurred when comparing the slow and fast clocks. We consider estimation of the offset and skew between the clocks, detection of drift in the local clock, and prediction of the broadcast clock based on the locally observed times.