Power Allocation for Downlink Hybrid Power Line and Visible Light Communication System

Light-emitting diode (LED)-based visible light communication (VLC) is a great promising high-speed wireless access solution due to its low power consumption, no electromagnetic interference, large available bandwidth, and no authentication required. However, visible light cannot be used directly as an information source, and must be combined with other communication technologies to avoid becoming an information island. In hybrid power line and visible light communication (HPV) system, power line communication (PLC) can be used to deliver data to VLC transmitters. Multiple users can share the same time and frequency resources to provide higher spectral efficiency using non-orthogonal multiple access (NOMA) method than traditional multiple access method. Therefore, we investigate the power allocation strategy for a downlink of HPV system based on NOMA. Our goal is to maximize achievable sum rate of the HPV system while considering user fairness. To solve this optimization problem, we present an optimal power allocation (OPA) algorithm that finds optimal solution by transforming the non-convexity of the original formulated model into the convex programming. Numerical results show that the proposed OPA algorithm significantly outperforms the gain ratio power allocation (GRPA) and the fixed power allocation (FPA) algorithm in terms of the sum rate, and improves the fairness among users.