Convergecast in ZigBee tree-based wireless sensor networks

Convergecast is a fundamental operation in wireless sensor networks. This paper uses ZigBee tree-based, beacon-enabled networks to support convergecast. In the network, ZigBee routers form a tree backbone and ZigBee end devices connect to routers. Some previous works have discussed to use ZigBee tree networks to support regular data reporting. In this work, we further consider the event data reporting scenario, where the network may randomly have urgent events. We assign each router a regular mode slot and several event mode slots. To support regular data reporting, routers and their child devices periodically wake up in their regular mode slots to sense and to report. When an event happens, devices nearby the event can wake up more times in their event mode slots, and routers can collect more event data from child devices and report more frequently. In this paper, we design tree formation algorithms, slot assignment rules, and event mode operations to support event data reporting. Simulation results show that our designs can indeed support both regular and event data reporting.