Distributed Cooperative Localization with Optimized Constraints for 3D WSNs

In three-dimensional (3D) Wireless Sensor Networks (WSNs), the localization suffers from localization accuracy and computation efficiency problem due to added dimension compared with 2D WSNs. Aiming at localizing WSNs in 3D way, we propose a distributed cooperative localization method with optimized constraints. The optimized constraints effectively limit the potential range where the unknown nodes are limited. By analyzing the positions of anchors which are within the communication radius of unknown node, the initial positions of unknown nodes are geometrically estimated in several situations. They link with each other and form a 3D cooperative network. Based on message passing (MP) theory, we extend the 2D cooperative localization to 3D distributed cooperative localization. In this process, optimized constraints derived from hop information and RSSI avoid the gross error and large deviation in the localization. Simulation results in various scenarios show the improvement of accuracy and efficiency compared with traditional methods.