User Cooperation and Link Selection in Hybrid VLC/RF Systems With NOMA

This letter presents three downlink transmission and user cooperation (UC) methods for visible light communication (VLC)/ radio frequency (RF) systems with non-orthogonal multiple access (NOMA), including NOMA-based VLC, simultaneous wireless information and power transfer-NOMA-based VLC/RF, and direct RF. Then, we propose an adaptive quality of service-oriented UC and link selection strategy, in order to improve the user experience. Besides, the cooperation transmission matrix is defined and the closed-form expression for the system throughput is derived. Simulation results show that the proposed strategy can significantly improve the system throughput regardless of residual interference in NOMA or VLC link blockage.