Re-synchronization in a Synchronized IEEE 802.15.4 Cluster-tree Network

In an IEEE 802.15.4 cluster tree network, a synchronization scheme achieves beacon synchronization among coordinators that allow devices to schedule their beacons in a non-overlapping way. This prevents unnecessary data frame collisions as well as allows devices to enter sleep periods, thereby increasing the overall network performance and lifetime, respectively. Synchronization schemes proposed in the literature primarily focused on either schedulability, overhead, or MAC goodput. But, none of these schemes analyze the factors that may affect synchronization among the devices. In this paper, we identify and analyze the impact of such factors and show that the absence of mechanisms to handle the issue of loss of synchronization will result in high network overhead. Since the goal of a low-rate wireless network (based on IEEE 802.15.4 standard) is to maximize network lifetime, it is highly desirable to explore all possible energy-conserving avenues and address them. In this regard, we propose lightweight re-synchronization mechanisms that address the issue of lost synchronization with minimal overhead.