Abstract
We consider a hybrid radio frequency (RF) / visible light communications (VLC) scenario where the RF link is empowered by the energy harvested during the VLC transmission. We take into account the power consumption of the access point (AP), which is composed of light emitting diodes (LEDs), while it is communicating with a far user over a two-hop hybrid RF/VLC link. In particular, we consider the energy efficiency of the end-to-end network in enhancing the energy-harvesting performance by choosing the optimal direct current (DC) bias, which is overlooked in the existing literature. To this end, we model the energy consumption of the commercially available LEDs, and formulate a joint energy- and spectral-efficiency optimization problem. The extreme cases of optimizing energy and spectral efficiency individually underscores the importance of optimizing the DC bias for a given joint (multi-objective) optimization problem.