Localization In Mobile Underwater Wireless Sensor Network

Most localization algorithms are static methods in traditional UWSNs field. However, underwater sensor nodes are mobility due to water flowing and aquatic creatures touching. Some isolated sensor nodes appear, which moves outside the communication range of reference nodes and cannot obtain enough reference informations to locate themselves.In order to solve the isolated nodes problem, a multi-hop localization algorithm is proposed in this paper. Firstly, ordinary nodes between anchors(reference nodes) and unknown nodes(also the ordinary nodes) are set as routers to find a shortest paths by a greedy approach; secondly, the shortest paths are approximately fitted into a straight distance between two types of sensor nodes – unknown nodes and anchor nodes; finally, the positions of unknown nodes can be calculated by trilateration. The proposed algorithm is simulated and compared with other algorithms in terms of localization error, and the results are proven preferable.At the last part of paper, a simple prototype system of UWSNs localization which based ZigBee technology is realized. In this system, all of the sensor nodes chips program a Z-Stack protocol stack. Then nodes communicate with each other by AF and compute the positions by localization algorithms. Besides, an average localization accuracy is analyzed.