Mitigation Method for the Solar Irradiation Effect in Visible Light Communications

Among the environmental conditions that can alter the quality of the signal reception in visible light communications is the solar radiation which illuminates the optical receiver. To reduce the level of the background radiation, VLC systems use narrow bandpass optical filters that are placed in front of the photodiode. Considering that the data carrier in VLC is narrow-linewidth optical source and the power of the solar radiation represents the sum of a wide spectrum; the dispersion of sunlight can reduce the effect of background radiation on the optical receiver. Starting from this idea, the paper presents a method based on a prism that improves the ratio between the signal and the solar radiation by spatially distributing the solar power so that only limited spectrum reaches the receiver. The method was validated analytically by determining the dependency between the solar radiation intensity and the physical parameters of the optical system.