Bluetooth Low Energy-Based Indoor Positioning System for Mobile Devices

Abstract

In recent years, indoor positioning using Bluetooth Low Energy (BLE) technology has gained significant attention as a consequence of its low power consumption, wide availability, and compatibility with a variety of devices. In this thesis, a BLE-based positioning system introducing a server-based BLE positioning method utilizing received signal strength (RSS) measurements is developed. Here, mobile devices, for instance smartphones, act as broadcasting BLE beacons. The BLE signal is received by static BLE sniffers installed in the environment. The sniffers obtain the RSS of the signal and send the measurements to a server. The position of the mobile device is calculated at the server using a particle filter (PF). As a countermeasure to fading effects caused by multipath propagation and to enhance the distance and position estimation accuracy, each sniffer is equipped with multiple closely spaced BLE receivers. To further increase the positioning accuracy, the RSS measurements are smoothed by a two-staged smoothing filter and a fusion of inertial data from the mobile device. The developed system is evaluated by indoor measurements, where a positioning error with a root mean square error (RMSE) of 0.75 m for a mobile device carried by a robot and a RMSE of 1.1 m for a walking pedestrian is obtained.