Opportunistic Shortcut Tree Routing in ZigBee Networks

The shortcut tree routing has been proposed to provide near optimal routing path as well as maintaining the advantages of the ZigBee tree routing, such as resource-free multi-hop routing capability. However, in spite of the efforts to provide an efficient and reliable protocol, the unicast routing itself has the fundamental limitation in wireless environment due to lossy, time-varying, and broadcast nature of wireless medium. For example, even one lossy link on a path may result in the failure of end-to-end packet delivery in wireless network environment. In this paper, we propose the opportunistic shortcut tree routing that combines the shortcut tree routing and the opportunistic routing. Instead of specifying a next hop node, the opportunistic shortcut tree routing allows the receiving nodes to compete to forward a packet with the priority of remaining hops. Since it has inherited advantages of both routing protocols, it can provide reliable packet delivery service without any resources for multi-hop routing and forwarder candidate selection for opportunistic routing. The performance evaluation proves that the opportunistic approach significantly enhances diverse network performances, while suppressing duplicate forwarding effectively with a metric of the remaining hops and the one-hop neighbor table.