Impact of Control-Plane Uplink in Asymmetric RF/RIS-Aided VLC Indoor System

Apart the well-known benefits of Visible Light Commmunications (VLC), some drawbacks still limit its realworld deployment and market penetration, such as the need of link alignment, shadowing, and blockage. Radio Frequency (RF) technology is traditionally adopted to alleviate such limitations, acting as uplink support in asymmetric RF/VLC systems. Specifically, the downlink is established using VLC direct links, while a RF link is deployed to guarantee uplink data and control transmissions. In this paper, we investigate a Medium Access Control (MAC) protocol for a hybrid asymmetric RFVLC indoor system, enhanced by a Reconfigurable Intelligent Surface (RIS) device, which is able to redirect the impinging wireless signal to the desired destination thus solving any VLC blockage occurrence. We evaluate the impact of the proposed MAC protocol in which packets can collide among them within an RF transmission link, and we derive the expressions for the RF, VLC direct, and RIS-aided VLC throughput when a blockage occurs.