A Two-Stage Power Allocation-Based NOMA Architecture for Optical Camera Communication

Visible light communication (VLC) is an emerging technology that provides ubiquitous connectivity by complementing radio frequency communication for the fifth-generation (5G) wireless communication and beyond. However, inadequacies in modulation bandwidth of light-emitting diode (LED) reduce the achievable data rate for image sensor-based VLC, also known as optical camera communication (OCC). Hence, for densely deployed OCC networks, multiple channel access is a major challenge faced when supporting large numbers of users. This article proposes an optical nonorthogonal multiple access based OCC (NOMA-OCC) system, where each LED can transmit two separate signals of two different power levels by superimposing them into one signal. An image sensor based receiver system is designed to separate these two signals supporting two users by implying an intensity threshold. The distinct channel capacities for both the users as well as the sum rate of the LED access point were analyzed. In order to validate the proposed NOMA-OCC scheme, the bit error rate performance of the system is also investigated through simulation for both channels and then compared with the conventional frequency shift on-off keying scheme.