Particle swarm optimization-based low-complexity three-dimensional UWB localization scheme

To provide a location-based service (LBS), it is needed to obtain an exact location of communication terminals in sensor networks. Because the signal of global positioning system (GPS) cannot be received indoors, a triangulation-based location estimation using ultra-wide band (UWB) signals between more than three reference terminals and the target node is widely used. In particular, a time of arrival (TOA)-based least square (LS) estimation is popular because the balanced performance in terms of calculation complexity and the accuracy is obtained. However, when the height of reference terminals and the target node is close, the three-dimensional LS-based estimation tends to fall into a local-minimum solution and it needs an accurate initial value of search to keep the estimation performance, resulting in the calculation complexity increase. Therefore, in this paper, we adopt a particle swarm optimization (PSO) method which effectively searches in wide-area space and propose an LS-based localization scheme using the combination of PSO and Newton-Raphson method achieving lower calculation complexity. The improved performances are shown by computer simulations.