Impact of Vehicle Headlights Radiation Pattern on Dynamic Vehicular VLC Channel

Abstract

This article develops a statistical large-scale fading (path loss) model of a dynamic vehicular visible light communication (VVLC) system. The proposed model combines the impact of inter-vehicle spacing and the radiation intensity distribution as a function of the irradiance angle which changes with the traffic conditions. Three models (Lambertian, Gaussian, and empirical) are utilized to examine the impact of vehicles headlights radiation pattern on the statistical path loss of VVLC system. The analytical model of channel path loss is validated by Monte Carlo simulation with the headlight model simulated with a raytracing software. The path loss values of the Gaussian model differ by 2 dB compared to the Lambertian model, irrespective of the traffic conditions while it differs by 24.6 dB during late night and 8.15 dB during rush hours compared to the empirical model of a Toyota Altis headlight. This variation shows that the radiation intensity distribution should be modelled for each vehicle's headlights from each manufacturer to ensure accurate VVLC channel model. The proposed Gaussian model provides a close approximation to describe such radiation pattern and can easily be adapted to model for different manufacturers' headlights.