Reflecting the Light: Energy Efficient Visible Light Communication with Reconfigurable Intelligent Surface

This paper investigates the energy efficiency maximization problem in a downlink reconfigurable intelligent surface (RIS) assisted visible light communication (VLC) system. The energy efficiency maximization problem is formulated via jointly optimizing time allocation, power control, phase shit matrix under the unique power constraints in VLC. To solve this non-convex energy efficiency maximization problem, the original problem is first simplified to an equivalent problem with a smaller number of variables. Then, an alternating algorithm with low complexity is accordingly proposed to obtain a suboptimal solution via iteratively solving the joint time allocation and power control subproblem, and the phase shift matrix adjustment subproblem. The simulation results show that the proposed algorithm can achieve up to 0.127dB gain in terms of energy efficiency compared to the conventional interior point method.