Car-to-car visible light communications

The light-emitting diode (LED)-based visible light communications (VLCs) have been gaining attraction in research and applications in recent years, thanks to its huge potential in future energy-saving lighting, display, and wireless data communications. With the ongoing development of white LED devices, the luminous efficiency of commercial white LEDs (WLEDs) has increased to 150 lm/w, which is almost 10 times that of the tungsten incandescent lamp [1]. In addition, WLEDs have an expected lifespan of over 15,000 hours, at least 10 times that of incandescent bulbs [2]. LEDs are much more compact and have higher energy efficiency. Furthermore, LEDs can be switched on and off at the speeds of sub-microseconds [3], thus offering functionalities such as data transmission, sensing, and localization beside illumination [4]. As a result, we are witnessing an explosive growth in the use of LED lamps as replacement for the conventional lamps, which creates huge opportunities for lighting and telecommunications industry, academia, and the way we will use lighting infrastructure in the future. The VLC technology, with its unique characteristics, is an alternative and complementary to the radio frequency (RF) wireless communications, not only for indoor applications but could also be used for outdoor applications such as vehicular communications (vehicle-to-vehicle communications or also known as car-to-car communications [C2C]), as part of the intelligent transportation systems (ITS) in future smart cities.