CSMA/CA protocol design in hybrid network of Visible Light Communication and RF Femtocell systems

In this article, an access protocol based on the CSMA/CA algorithm and the IEEE 802.11n standard is proposed for a network composed of a hybrid Visible Light Communication (VLC) and Radio Frequency (RF) Femtocell in an indoor scenario. To evaluate the performance of the proposer protocol, a hybrid network comprised of VLC access points (APs) distributed on the ceiling, an RF AP located in the center of the room, and n users was modeled. The network considered that the VLC channel was used only for the downlink, while the RF Femtocell was used for the uplink, exchange of information with the server, and downlink. The benefits of solutions associated with hybrid Femtocells between VLC and RF that guarantee the natural use of the users are studied. The performance of the proposed protocol was studied in terms of delay, throughput, and transmission efficiency. Numerical results show that the increase in the number of users on the network leads to an exponential decrease in the average delay. In addition, it was observed that the throughput obtained by the hybrid VLC/RF Femtocell system was superior to the traditional throughput of both independent networks. The combination of VLC and RF Femtocell channels depending on the location of the users allow for increasing transmission efficiency of the hybrid VLC/RF Femtocell network.