Minimal cost clock synchronization using a sender-receiver protocol in Wireless Sensornets

Recent years have seen a tremendous growth in the development of small sensing devices capable of data processing and wireless communication through their embedded processors and radios. Wireless sensor networks (WSNs) are ad hoc networks consisting of such devices gaining importance due to their emerging applications. In WSNs, there is a need for a common notion of time among the wireless sensor nodes to accomplish major tasks such as data fusion. For the inactive nodes listening to a sender-receiver two-way timing message exchange between two nodes in an exponential link delay model, this paper derives the maximum likelihood estimate (MLE) for the clock offsets of such silent nodes. Since no data transmission is involved on the part of the inactive nodes, this clock synchronization is very attractive for the low power demanding WSN scenario due to reduced power consumption.