Bandwidth Aggregation Protocol and Throughput-Optimal Scheduler for Hybrid RF and Visible Light Communication Systems

In this paper, we propose a bandwidth aggregation protocol for hybrid visible light communication (VLC) and radio frequency (RF) communication systems. By efficiently combining the RF communication with the VLC, the proposed protocol compensates for the disadvantages of the VLC, e.g., unstable communication quality and a small coverage area, while enjoying the additional bandwidth provided by the VLC. In the hybrid VLC and RF communication system, packets which arrive at the system are scheduled to be transmitted via the VLC or RF communication. This scheduling decision has a profound impact on the overall performance of the system. Our proposed protocol employs a scheduling algorithm based on queue lengths, the goal of which is the throughput optimality. We define a Lyapunov function as a function of queue lengths and obtain the optimal scheduling policy by minimizing the drift of the Lyapunov function. We implement a real-life prototype of the hybrid VLC and RF communication system and conduct the experiments of the proposed protocol. The experimental results show that the proposed protocol is capable of successfully aggregating the bandwidth of the VLC and RF communication.