Communication Scheme to Support Sink Mobility in Multi-hop Clustered Wireless Sensor Networks

In wireless sensor networks, the studies that support sink mobility without global position information exploit a Backbone-based Virtual Infrastructure (BVI) to avoid the routing structure construction per each mobile sink by full network flooding. The BVI approach typically considers one-hop clusters and a backbone structure-based tree configured by the cluster heads (CHs). For data dissemination to a mobile sink, the head of the cluster where the mobile sink exists registers the backbone structure on behalf of the sink, and then source nodes generate the data to their CHs via the tree. Finally, the CHs deliver the data to the mobile sink. However, the one-hop cluster makes the tree organized by too many CHs so that it causes large location registration overhead according to movement of the sink. Moreover, the data delivery via the tree with a large number of CHs might lead to data delivery from source nodes to the sink though detour paths due to always delivering data via the tree. Namely, although the source nodes exist at nearest clusters from the cluster attached by the sink, if they are located in different branch of the tree, the data should be delivered via detour paths on the tree. Therefore, we propose a novel BVI-based communication protocol to support sink mobility without global position information. To reduce the number of CHs, we consider multi-hop clusters. Also, to avoid the location registration of a mobile sink to the whole CHs, we uses a rendezvous CH on which queries of the mobile sink and reporting data of a source node meet. However, such a manner also has data detour problem that the source node sends data packets to the mobile sink via the rendezvous CH. Thus, we present a scheme to find a path with fewer hop-counts between CHs where the source node and the mobile sink are located in. Simulation results show that the proposed protocol is superior to the existing protocols in terms of the control overhead and the data delivery hop counts.