On the Performance Analysis of V2N Mixed RF and Hybrid FSO/RF Communication System

Vehicular communications allow vehicles to connect with other vehicles and network infrastructures in order to facilitate the transfer of real-time information and dependable transportation. This paper proposes a system that connects vehicles to the network (base station) in two phases using transceivers-equipped roadside infrastructures, such as signboards, traffic lights, and street lights, as intermediary relay nodes. In the first phase, the information transfer occurs from vehicles to infrastructure using a radio-frequency (RF) link. The second phase includes establishing communication from the infrastructure to the base station using hybrid free-space optics (FSO)/RF link. In modeling the FSO link, we consider factors like atmospheric attenuation, pointing errors, and atmospheric turbulence-induced fading, which can affect FSO performance. For this set-up, we derive the accurate expressions for the outage probability, system throughput, average symbol error rate, and average end-to-end delay. Numerical results corroborate the dependency of the time allocation factor $\alpha$ for the vehicle-to-infrastructure link on the vehicle transmit power. Furthermore, the results elucidate the impact of the length of the transmitted packet and FSO link distance on average end-to-end delay performance. The increase in distance between infrastructure and base station can be compensated by reducing the length of packets to achieve desirable delay performance.