Nodes localization method based on the improved PSO algorithm without time synchronization

Location information in the application of underwater wireless sensor networks (UWSNs) plays a very important role. According to the features of underwater sensor networks, the ranging technology based on Round-trip Time of Flight (RTOF) without time synchronization was adopted to calculate the distance between the nodes. An improved PSO (Particle Swarm Optimization) method was adopted to locate the nodes in three dimensional space directly. The localization error of this method had been compared with USP method and the standard PSO method under the circumstance of different distance-measuring error and different numbers of beacon nodes and unknown nodes respectively. The simulation result indicates that the proposed method can effectively achieve better localization accuracy with less beacon nodes and faster convergence.