Implementation of the ZigBee Network Layer with Cluster-tree Support

Abstract

While the IEEE 802.15.4/Zigbee protocol stack is being considered as a promising technology for low-cost low-power Wireless Sensor Networks (WSNs), several issues in their specifications are still open. One of those ambiguous issues is how to build a synchronized cluster-tree network. In fact, the current IEEE 802.15.4/Zigbee specifications restrict the synchronization in the beacon-enabled mode (by the generation of periodic beacon frames) to star-based networks, while they support multi-hop networking using the peer-to-peer mesh topology, but with no synchronization. Even though both specifications mention the possible use of cluster-tree topologies the description on how to effectively construct such a network topology is missing. This technical describes the implementation details of the ZigBee Network Layer on top of our implementation IEEE 802.15.4 for nesC/TinyOS. This implementation enables the cluster-tree network topology with our proposed mechanism for beacon scheduling in order to enable an efficient use of synchronized cluster-tree networks. This implementation induces minor changes to our IEEE 802.15.4 implementation, the open-ZB (www.open-zb.net), in order to implement our proposed Time Division Beacon Scheduling approach. This technical report describes the implemented mechanisms and gives an intuition how to effectively use this implementation with a ZigBee Cluster-tree network topology.