A Proposal for Zigbee Clusters Interconnection based on Zigbee Extension Devices

WSNs are becoming an important topic in the research arena. Their low cost and the wide range of applications where wireless sensor networks can be applied, make them an important research and commercial field in the short term. Furthermore, the IEEE 802.15.4 standard for physical and MAC layer in addition with the Zigbee specification for the network and application layer, are an enforcement for WSNs. Much research in WSNs related topics such as energy-aware, MAC protocols, routing protocols, security, location, etc is being carried out nowadays. An open issue is the interconnection between wireless sensor networks where different approaches can be adopted: bridging (extension devices) and proxying (mainly middleware entities). This paper is focused in the bridging approach for Zigbee networks. Our objective is to establish a Zigbee Extension Device Network for the case where the different clusters can not be connected to the same Zigbee network by using the multihop routing protocol defined in Zigbee. A Zigbee cluster is a set of Zigbee nodes. This paper introduces three different solutions to join the disconnected clusters of the Zigbee Network: a central approach (based on the use of a central station) and two distributed approaches; one of them proposes that each Zigbee Extension Device stores the information of all the other Extension Devices within the network while the other uses a P2P Zigbee Extension Device Overlay Network to join the disconnected Zigbee Clusters. The paper includes the analysis of each solution and the comparison among them. Keywords— Zigbee, WSN, interconnection, cluster, overlay, p2p.