Performance of Hybrid Cognitive RF/VLC Systems in Vehicle-to-Vehicle Communications

Visible Light Communication is a promising ubiquitous candidate that can be leveraged to serve the rapidly growing vehicle-to-vehicle communication (V2V) networks. This high interest in visible light communication is fundamentally due to its ability to transmit secure data at a high rate with no interference to its compartments. In contrast, VLC suffers from the fact that most of its applications are mainly based on line-of-sight (LOS) components. Therefore, recent literature has focused on the possibility of integrating this technology with the existing radio frequency communication (RF) to improve the performance of the networks. In this paper, we present a decode-and-forward based hybrid underlay cognitive radio frequency/visible light communication (CRF/VLC) cooperative system in vehicle-to-vehicle (V2V) communication networks. The system is composed of two links: direct link (DL) in parallel with a decode-and-forward based hybrid CRF/VLC cooperative link between the base station (BS) and the destination electric vehicle (EV2). The destination (EV2) employs a switching diversity technique which first selects a direct link. In case the signal quality for the direct link degrades, the destination (EV2) switches to the cooperative link in which the EV2 chooses either CRF link or VLC link based on the selection diversity technique. We further investigate the performance of the proposed system in terms of outage probability and bit error rate (BER). The closed-form analytical expression of the outage probability is derived. Our numerical and simulation results show that our system improves the performance in terms of lower outage probability and BER compared to employing the cognitive RF link stand alone. Our results show the advantage of less total transmission power allocation at the base station (BS). Finally, we study the impact of increasing the interference temperature power (Ip) on the outage probability performance.