Optimised optical wireless car-to-traffic-light communication

Intelligent transport systems have become the major technology for increasing road safety and traffic efficiency, as well as for reducing the number of road casualties. Radio frequency and optical wireless communication technologies have been proposed as a means for establishing communication between vehicular and road infrastructure, such as traffic lights, billboards and road infrastructures and for providing inter-vehicular communication. These technologies provide one-way or two-way short-range to medium-range wireless communication links that are specifically designed for the automotive sphere. The technology that is analysed in this paper is optical wireless communication. This technology modulates optical data on top of the illumination in the traffic lights and in the automotive lighting and detects the information using fast imaging sensors. Using knowledge of the amplitudes of the signal and the noise in each pixel, we tune adaptively and separately the gain of each individual pixel in the imaging sensor for communication signals. Tuning the gain is based on the mathematical model derived in this research. Comparison is made between the adaptive model and the standard model. From the mathematical analysis and the results of the comparison, it is clear that this model significantly improves communication system performance. In our numerical calculation for a given set of parameters, the signal-to-noise ratio of the standard system and the adaptive system changes from more than 7x10(-4) to more than 7 and less than 2x10-3 to more than 30 for a change in transmitter power from 10 to 100watts respectively. Copyright (c) 2014 John Wiley & Sons, Ltd.