This paper proposes a radio frequency (RF)/free space optics (FSO) communications hybrid system that will improve security and reliability of future sixth generation (6G) wireless communication network links with practical channel conditions. The system uses the composite Weibull-Lognormal (WLN) turbulence model for modeling the free-space-optics (FSO) link and incorporates the effects of both local fade events and global weather phenomena; it also uses Nakagami-m/Rayleigh fading to model the RF link. A hybrid link selection algorithm (HLA) is used to select the best available transmission link as a function of real-time channel characteristics. The performance of the proposed hybrid system is analyzed from three perspectives: secrecy capacity, bit-error-rate (BER), and outage probability under different fading/turbulence conditions through an exhaustive Monte-Carlo simulation process and supported by analytical results. These analyses show that this hybrid system has significant advantages over single-link systems employing either RF or FSO alone; these advantages include reduced outage probability, improved BER performance, and higher secrecy capacity especially when operating under high-turbulence conditions. These results show that a composite-fading architecture provides a reliable and secure framework for the development of fifth-generation (5G)-like communication systems which can be used in future sixth-generation (6G) wireless communication networks.
Kaushik et al. (Thu,) studied this question.