A Passive Indoor Tracking Scheme With Geometrical Formulation

Passive tracking that aims to track targets without assistant devices, i.e., device-free targets, is addressed as an emerging field recently. This letter proposes a novel passive tracking algorithm with several pairs of position-known wireless terminals (WTs) and access points (APs), which can be implemented in wireless local area network environments. In the proposed scheme, we formulate the crossing point estimation on the line-of-sight paths (LOSPs) between APs and WTs of third parties, which reveal trajectory of the device-free target, as a geometrical optimization problem. Then, the optimization problem is solved by the particle swarm optimization algorithm. As essential knowledge, we first explore the characteristics of the wireless propagation radio frequency tomography, under LOSP. The tracking performance of the proposed scheme is evaluated via computer simulations as well as experiments in a (5 × 12)-m 2 monitored area. The experimental results show that the proposed scheme can provide remarkable tracking accuracy of as high as decimeters.