Dual camera-based split shutter for high-rate and long-distance optical camera communications

Smartphones have been very versatile communication devices. Cameras fitted in smartphones are primarily used to capture photographs and for relevant multimedia functions. Recently, smartphone cameras have been studied for short-range wireless communications. Camera-based optical wireless communication, termed optical camera communication (OCC), is a form of visible light communication. In the OCC, a camera is employed as the receiver, while either a light emitting diode or a liquid crystal display (LCD) is used as the transmitter. This paper proposes a downlink OCC scheme with a dual camera (receiver) and an LCD (transmitter) is employed, using a unique capture method called split shutter method. The split shutter method combined with dual camera offers a significantly increased capture rate as well as increased coverage distance. Experiments were conducted to verify the proposed dual camera-based split shutter OCC scheme. Compared with a standard camera shutter, it is found that the proposed method effectively increases the transmission rate by a factor of two under identical experimental conditions, achieving a maximum of 11,520 bits per second and a distance of up to 2 m using a 1280 x 720 pixels camera resolution. When compared with conventional rolling shutter OCCs, the proposed method offers four times farther the coverage distance at an identical resolution. It is also demonstrated that the data rate can be further increased when a larger number of transmitters are employed. (C) 2016 Society of PhotoOptical Instrumentation Engineers (SPIE).