Robust data gathering method using controlled mobility in underwater sensor network

These days, underwater exploration demand is increasing in the field of industry, science, military, and so on. Hence, Underwater Sensor Network to collect data by scattering sensors in water has been attracted attention. However, there are various problems specific to underwater environments including the communication medium. In this paper, we focus on some problems on broken or degrading link between two neighboring nodes moving away from each other along with water current. To recover such links, we propose to introduce and control mobile nodes to relay communication between such two nodes. Existing studies dealing with the controlled mobility focused on the movement from the sea bed towards the water surface in order to avoid broken links caused by a shadow zone. On the other hand, the proposed method recovers broken and degrading links caused by movement of sensors by the water flow. Different from exiting works, limited number of smart mobile nodes move in any directions. In addition, because the cost of node movement in UWSN is higher than that of terrestrial network, this method also aims at reducing the movement distance of mobile nodes. Furthermore, the proposed method can measure and deal with the link disconnection proactively because the movement of mobile nodes is controlled while grasping the network condition. Finally, we show the effectiveness of the proposed method by computer simulation.