Bi-static Visible Light Backscatter Modelling and Tag Localisation

Backscattering visible light communication (VLC) is an emerging technology in the field of indoor communication and the internet-of-things. Here, bi-static topology has gained recent interest in radio-frequency (RF) backscatter communication systems due its longer range and higher scalability. However, the difference between VLC and RF systems raises the demand for new bi-static VLC backscatter models to accurately describe the characteristics. In this paper, we present two novel models designed with specular and diffuse reflectors respectively. We also present the global optimal tag location that maximises signal-to-noise ratio (SNR) for both models. Numerical simulations validated the analytical claims and demonstrate that the specular model outperforms the diffuse model in SNR despite extra effort required for alignment, and the relationship between optimal tag location and the system parameters in the specular model is different compared to the one in the diffuse model.