Extension of pairwise broadcast clock synchronization for multicluster sensor networks

Time synchronization is crucial for wireless sensor networks (WSNs) in performing anumber of fundamental operations such as data coordination, power management,security, and localization. The Pairwise Broadcast Synchronization (PBS) protocolwas recently proposed to minimize the number of timing messages required forglobal network synchronization, which enables the design of highly energy-efficientWSNs. However, PBS requires all nodes in the network to lie within the communicationranges of two leader nodes, a condition which might not be availablein some applications. This paper proposes an extension of PBS to the more generalclass of sensor networks. Based on the hierarchical structure of the network,an energy-efficient pair selection algorithm is proposed to select the best pairwisesynchronization sequence to reduce the overall energy consumption. It is shown thatin a multicluster networking environment, PBS requires a far less number of timingmessages than other well-known synchronization protocols and incurs no loss in synchronizationaccuracy. Moreover, the proposed scheme presents significant energysavings for densely deployed WSNs.