Performance evaluation of hybrid radio frequency/free-space optical links using a fuzzy inference system

Naturally, free-space optical (FSO) links offer higher data rates and greater immunity to noise; however, their performance degrades under adverse weather conditions, such as dust storms and severe fog. By contrast, radio frequency (RF) links perform better in these conditions at the cost of high-noise susceptibility and scarce RF resources. A valuable amalgamation of both links, that is, hybrid RF/FSO links, has the potential to overcome the current challenges of reliability, bandwidth, and high traffic demand. However, optimal switching between RF and FSO is a major challenge for hybrid RF/FSO communication systems. Considering this challenge, we propose a soft-switching–based hybrid RF/FSO system, which has the ability to effectively handle bad weather conditions, including dust storms. The FSO link, being a primary link, will be switched to the RF link (as a backup link) using the fuzzy inference system (FIS) under severe atmospheric conditions. We present the evaluation of the attenuation level as a switchover decision metric. The uniqueness of the proposed solution lies in the close relation of adverse weather conditions with attenuation level and the application of FIS, which offers rapid response times adapted to dynamic channel conditions. For the performance analysis of the proposed model, we conducted extensive testing while considering the switchover decisions based on bad weather conditions and human factors. Through detailed simulation results, we demonstrate that the proposed model significantly outperforms the conventional hybrid RF/FSO link using hard switching. The proposed switchover achieves a reliability of more than 97%.