LiPro: light-based indoor positioning with rotating handheld devices

In this paper, an indoor positioning method, namely LiPro, is proposed for handheld devices such as smartphones. Based on an empirical light intensity model, we propose a rotating multi-face positioning method that enables a receiver to locate itself in ill-conditioned scenarios which would otherwise make the traditional multilateration impossible—for example when less than three LED lamps are visible to the receiver. In this method, the user manually performs three rotations of the receiver around three orthogonal axes, in a manner similar to the calibration process of a compass. During this process, the receiver continuously collects RSS and magnetic field strength, which are then used to solve for the receiver’s position. LiPro can work with a single source of light, making it a more cost-effective and less demanding than previous approaches. Our experiments show that LiPro achieves a median error of 0.59 m in a corridor with linearly deployed LEDs, and 0.45 m in an office. Moreover, LiPro is shown to be robust against interference from ambient light sources.