Simulations of vehicular optical wireless communication systems and comparisons with DSRC systems

Optical wireless communication (OWC) has been proposed as a complementary technique to radio frequency (RF) communications for vehicular applications. OWC systems can be categorized into two types based on the transmitters: the first one is the light-emitting diode (LED)-based OWC system, and the second is the laser diode (LD)-based OWC system. Simulations of both types of OWC systems are presented in this paper. To simulate the OWC systems precisely, outdoor experiments of OWC systems have been done and the measurements of background noise are applied in the simulations. In terms of the LED-based OWC system, the impulse responses are obtained by an improved ray tracing algorithm. To reduce the computational complexity, visibility graphs are applied in the improved ray tracing algorithm. Compared with the brute force algorithm, our improved algorithm is able to reduce the computational complexity from O(n³) to O(n²log⁡(n)), where n is the number of mobile terminals. In LD-based OWC systems, the performance and stability are highly dependent on the tracking system in vehicular applications. Therefore, this paper also analyzes the requirements of tracking accuracy in LD-based OWC systems. Finally, the simulated LED-based OWC system is compared with the dedicated short-range communication (DSRC) system under different traffic densities. Our experimental and simulation results have demonstrated that OWC can be a complementary technique for DSRC under conditions of high traffic density.