Robust and energy efficient clock synchronization scheme for wireless sensor networks

In this paper, a robust and energy efficient clock synchronization protocol for wireless sensor networks is introduced. In the proposed scheme a pair of nodes is synchronized by a sender-receiver synchronization protocol while the third node in their range can synchronize with them by overhearing the transmitted messages. This node is synchronized by a new receiver-receiver synchronization protocol without exchanging any extra messages which helps to save its energy. Then, using this fact that this three nodes form a loop, each pair of them can reduce their synchronization error by exchanging their estimated relative clock offsets. We show that the developed receiver-receiver scheme outperforms the classic liner regression based protocols in terms of synchronization accuracy by analysis. Also, the developed scheme is robust against the link delay variance by using the exact relation between the nodes' synchronization error in the loop. Simulation results are provided to justify the analytical derivation and comparisons with another scheme.