Mobi-Sync: Configurable Time Synchronization for Mobile Multihop Networks

Maintaining a common notion of time among communicating nodes in mobile multihop networks is crucial to the correctness of many distributed real-time applications such as target tracking, data fusion, and environmental monitoring. Achieving both synchronization accuracy and efficiency (in terms of communication and energy overheads) are important goals of a time synchronization mechanism. While these goals have been addressed by numerous approaches for stationary or homogeneous networks that rely on uniform clock drift models and synchronization accuracy requirements, these existing approaches are not optimal when applied in networks that are mobile or where synchronization accuracies and clock drift rates differ among nodes. This paper proposes a novel opportunistic and on-demand synchronization mechanism called Mobi-Sync, which has two important characteristics. First, it avoids network-wide flooding or frequent reconstructing of rigid structures that are often unavoidable in other approaches when applied to mobile networks. Second, it (re-)synchronizes nodes only when necessary, thereby customizing the synchronization interval to each node´s specified accuracy requirement. Our results demonstrate that Mobi-Sync satisfies the nodes´ synchronization requirements in mobile networks, while significantly reducing the synchronization overhead compared to existing solutions.