Clock Offset and Skew Estimation Using Hybrid One-Way Message Dissemination and Two-Way Timestamp Free Synchronization in Wireless Sensor Networks

In practical wireless sensor networks, time synchronization functions are usually integrated in existing network transmissions to minimize total energy consumption. In this letter, a hybrid synchronization scheme using one-way message dissemination and emerging timestamp-free synchronization is developed for wireless sensor networks without additional communication overhead, which not only estimates the fixed delay efficiently but also provides improved clock offset estimation. Under Gaussian delay model, the maximum likelihood estimator for the joint estimation of clock offset, skew and fixed delay is derived, as well as corresponding Cramer-Rao lower bounds. Simulation results demonstrate significant performance enhancement of the hybrid approach.