X-geocasting: Data dissemination to mobile sink groups in wireless sensor networks

Recently, group mobility support of mobile sinks has received increasing interest, and several mechanisms have been proposed. The mechanisms typically follow a strategy that simply adopts flooding. The strategy detects the currently located region of a mobile sink group in flooding, registers the current region to a source, and performs data flooding in the region to disseminate data to the sink group. However, this strategy might cause serious problems in terms of reachability and communication overhead. In the first, although a group could continuously move toward a target point for its own mission, the strategy discretely performs detecting the group region and updating the region information. Namely, data may be delivered the previously current region, i.e. already updated but changed the region. Moreover, in order to obtain the region information of the group, flooding is frequently fulfilled as well as the strategy utilizes flooding for data delivery to the group every time. Therefore, we propose a novel strategy for reachability and low overhead, called X-Geocasting. X-Geocasting merely finds out the region of a group when the group changes direction or movement velocity. Also, instead of fully flooding in group regions, X-Geocasting predictively and flexibly determines the restricted flooding area according to direction and movement velocity. Simulation results prove this proposed group mobility support strategy provides reachability and high energy-efficiency.