VLC smart lights work like an indoor GPS.

[TallDude]

The future of LED lighting has more than meets the eye. VLC (visual light communication) allows for data to exchange between 'Smart LEDs' and your phone. Outside, your phone utilizes GPS for tracking. Inside, your phone can now use VLC to lead you right to a product you want in a store. Target is one of the first using this technology in the US.

http://luxreview.com/article/2015/04/exclusive-us-retail-giant-target-leads-the-way-in-lighting-based-in-store-navigation-systems

http://www.mediapost.com/publications/article/279194/disneys-smart-light-innovations-adding-new-magic.html