Vehicular Visible Light Communication With Low Beam Transmitters in the Presence of Vertical Oscillation

Abstract

The availability of light-emitting diodes (LEDs) in vehicle exteriors makes possible the use of visible light communication (VLC) as a vehicle-to-vehicle (V2V) wireless connectivity solution. Although high beam headlights offer higher illumination levels and further communication distances compared to low beam headlights, regulations restrict high beam utilization in many driving cases. These restrictions make low beam headlights a more suitable candidate for vehicular VLC systems. In this paper, we consider two heavy vehicles (e.g., trucks) on a road following each other. Low beam headlights of the follower truck act as wireless transmitters and the lead truck is equipped with a photodetector at its back. We first propose an accurate path loss model based on experimental measurements. The proposed model takes into account the presence of lateral shift between the trucks as well as the fact that headlamps and photodetector can be placed at different heights. Furthermore, we model the truck vertical oscillation experimentally at different speeds. Utilizing these models, we derive a bit error rate (BER) expression for VLC-based truck-to-truck communication system and investigate the effect of several system and channel parameters on the performance. In an attempt to mitigate the degrading effects of the vertical oscillation, we further investigate the proper selection of photodetector location in order to minimize the error rate performance.