Design and Analysis of HDMA-assisted Visible Light Communication System Based on Transmitting and Reflecting RIS

For this article, a hybrid domain multiple access (HDMA)-assisted visible light communication (VLC) system based on transmitting and reflecting reconfigurable intelligent surface (TR-RIS) is studied. HDMA is a new multiple access technology enjoying multi-domain signal information, which can effectively improve the system performance by carrying more users' information on the light emitting diodes (LEDs). Contrapose to the problem of multi-LED interference in the system, this paper introduces a transmitting RIS (T-RIS) angle diversity receiver (RADR) model, using the electronically controlled refractive index characteristics of the T-RIS and the angle diversity of the spatial optical signal, which can effectively alleviate interference problem between multiple LEDs. Furthermore, a system optimization model is proposed in this paper. Considering various constraints of the system, an optimization objective is established to maximize the communication capacity by optimizing the power distribution ratio and reflecting RIS (R-RIS) unit. The simulation results show that the proposed scheme can effectively improve the VLC system capacity compared to the existing ones.