Watch me if you can: Exploiting the nature of light for light-to-camera communications

With the proliferation of light emitting diodes (LEDs) and smartphone cameras, light-to-camera (L2C) communications have received attention as a complementary method to traditional RF wireless communications. In particular, a line-of-sight L2C communication system has the benefit of associating the received data with the light transmitter’s identity (or location) in a captured image. Thanks to the rolling shutter mechanism used in most smartphone cameras, a single image can include multiple light symbols, such as bright and dark bands within a light boundary, called a region of interest (RoI). The RoI size is important because we need a sufficient RoI size (number of light symbols) to decode a packet. In this paper, we present the feasibility of exploiting the nature of light to extend the communication range in L2C communications. By putting low-cost optical instruments on a smartphone camera, we can blur or diffuse the light captured in an image, and effectively increase the RoI size. Our preliminary experiment results demonstrate that our method extends the communication range 10-fold.