STARLIT: 3D indoor positioning with smartphones and reflection light

This paper presents STARLIT, a system that enables a single LED to localize smartphone to within sub-meter. The LED transmits its coordinates encoded in human-imperceptible optical pulses. Different from the existing camera-based approaches, which need to capture images of the luminaires within a short light-to-camera distance, we utilize the reflection light from the floor for positioning. As the camera sensor contains millions of pixels, it can be considered as a sensor array. By exploiting the rolling shutter mechanism in the smartphone cameras, we propose a solution to extract the received signal strengths (RSSs) of sampled pixel rows from the captured images. Given the measured RSSs, we establish an equation set with Lambertian model and the camera projection model to solve the location of the smartphone. We have implemented STARLIT and evaluated its performance in a lab room. Our experiments demonstrate that STARLIT can achieve average positioning error around 40 cm and 80-percentile error around 55 cm.