Power Allocation Optimization for NOMA based Visible Light Communications

In this paper, a power allocation strategy is investigated for visible light communications (VLC) in a nonorthogonal multiple access (NOMA) system. The purpose of this work is to maximize the downlink sum-rate under the constraints of quality of service (QoS), power consumption, and LED operating region (LOR). To this end, we first formulated the problem and then analyzed the convexity of the problem. Furthermore, with the help of variable transformation, auxiliary variables and the Taylor series, we approximated the non-convex problem successively with convex problems. Finally, an iterative optimization algorithm with low complexity in some cases was developed. Numerical results show that the proposed scheme can exhibit a higher sum-rate than the modified gain ratio power allocation (GRPA) algorithm.