Compensating Image Overlay QPSK Modulation by Dual Camera for Rolling Shutter-Based Screen Camera Communication

Rolling shutter (RS)-based screen camera communication (SCC) has been studied to increase data rates. Among modulation schemes for RS-based SCC, phase shit keying (PSK) is most suitable for M-ary modulation. However, PSK is vulnerable to pixel value variations on the image overlay screen. A method has been proposed to compensate for the image overlay degradation of PSK modulation using dual camera. In this study, type of overlay standard image and the ratio of exposure time to symbol length are changed to demonstrate the effectiveness of compensating method using dual camera for quadrature PSK (QPSK) modulation. The compensation method using dual camera enabled to suppress mean square error of constellation points of QPSK modulation to a nearly constant value regardless of overlay image difficulty.