Polarization-Based Visible Light Positioning

Abstract

Visible Light Positioning (VLP) provides a promising means to achieve indoor localization with sub-meter accuracy. We observe that the Visible Light Communication (VLC) methods in existing VLP systems rely on intensity-based modulation, and thus they require a high pulse rate to prevent flickering. However, the high pulse rate adds an unnecessary and heavy burden for receiving with cameras. To eliminate this burden, we propose the polarization-based modulation, which is flicker-free, to enable a low pulse rate VLC. In this way, we make VLP light-weight enough even for devices with a camera. This paper presents the VLP system PIXEL, which realizes our idea. In PIXEL, we developed 1) a novel color-based modulation scheme to handle user's mobility and 2) a sensor-assisted positioning algorithm to ease user's burden in capturing multiple location anchors. Our experiments based on the prototype show that PIXEL can provide $10$ cm-level real-time VLP for wearables and smartphones with camera resolution as coarse as 60 pixel × 80 pixel and CPU frequency as low as 300 MHz.