Rolling-Shutter-Based QPSK by Spatial Luminance Distribution for Optical Camera Communication

Multilevel phase and amplitude modulation by spatial luminance distribution of an LED lighting is proposed and experimentally investigated to increase number of bits per symbol for optical camera communication (OCC). First, 256 quadrature amplitude modulation (QAM) and 64-QAM orthogonal frequency division multiplexing (OFDM) are experimentally demonstrated by spatial luminance distribution of two-dimensional LED image. When the symbol rate is lower than the frame rate, 80 and 78.5 bits per second (bps) is achieved using 30-frame-per-second (fps) image sensor with 256 QAM and 64-QAM OFDM, respectively. Next, rolling-shutter-based quadrature phase shift keying (QPSK) is experimentally demonstrated by adaptation of spatial luminance distribution of the LED image to each line of the rolling shutter to increase the symbol rate for OCC. When the symbol rate is much faster than the frame rate, 2657-bps error-free transmission is achieved using 30-fps image sensor with rolling-shutter-based QPSK.