LightSense: Exploiting smart bulbs for practical multimodal localization

Visible Light Positioning (VLP) is an exciting new approach but has to overcome considerable challenges before it becomes practical. In particular, the line-of-sight requirement which imports the constraint on the working condition of VLP and can not be solved by the VLP itself. This paper develops techniques to allow VLP to be augmented with traditional WI-FI approach by leveraging the WI-FI enabled smart bulbs which are now widely available. Those Smart bulbs offer several intriguing properties: a very dense deployment (roughly every 2 meters apart), ability to act as sensors that continually provide Wi-Fi signal strength measurements. We utilize these capabilities to not only build improved and practical Wi-Fi localization and Visible Light Positioning (VLP) techniques, but show that these two apparently-orthogonal techniques are symbiotic-i.e., they can mutually benefit by exploiting each other's capabilities. Moreover, we study a new VLP technique, based on modulation of a smart bulb's color temperature, that operates `out of the box' and that is compatible with camera on smartphones.