Gamma Function Based Signal Compensation for Transmission Distance Tolerant Multilevel Modulation in Optical Camera Communication

Abstract

Data rate of optical camera communication is limited by low frame rate of the CMOS image sensor, so that multilevel modulation is required to improve its data rate. However, transmission performance may decrease with varying transmission distance between LED and image sensor due to nonlinearity occurred by saturation of received optical power. In this paper, we propose gamma function based signal compensation to overcome the nonlinearity and improve the performance of multilevel transmission. As an experimental demonstration, we transmitted maximum 16 pulse amplitude modulation signal and achieved data rate of 199.78 kb/s and symbol error rate (SER) under using the image sensor of 99.89 kfps with the transmission distance of 250 cm.

Keywords

• Image sensors
• light emitting diodes
• modulation
• optical camera communication
• optical wireless communication