## 1 Introduction  
The Internet of Things (IoT) is expanding rapidly, with tens of billions of devices expected to be connected in the near future [1]. Wireless communication systems play a pivotal role in meeting the demands of intelligent IoT networks, which require a high bandwidth and exceptional performance when delivering real-time services to mobile users. These systems underpin a wide range of applications, including intelligent transportation systems [2], parking occupancy information services [3], air quality monitoring [4], and self-configuring and self-organizing industrial wireless sensor networks [5], as well as video surveillance and target localization in scenarios characterized by emergencies, challenging terrains, or a limited transport infrastructure [6]. The majority of network traffic is now generated by wireless devices [7, 8]. Radio Frequency (RF) technology is a well-established and widely utilized medium for communication, supporting applications ranging from space communication systems to indoor networks and beyond. However, RF communication is inherently susceptible to interference due to its propagation characteristics. To mitigate interference and ensure coexistence among RF-dependent systems, local and international regulatory bodies govern the RF spectrum. These regulations influence the availability and performance of RF communication, as the spectrum becomes increasingly congested, scarce, and costly to access [7]. Additionally, conventional technologies such as WiMAX and LTE are ill-suited to IoT applications due to their high power consumption [9]. More broadly, RF technologies face persistent challenges in ensuring security, reliability, and scalability [10; 11], which necessitate ongoing innovation and adaptation. In response to these challenges, academia and industry are actively exploring enhancements to existing wireless technologies and the development of novel solutions to address emerging demands. Free-space optical (FSO) communication represents a reasonable alternative to traditional RF technologies, merging the high capacity of optical communication systems with the flexibility of wireless connectivity. Operating across a broad spectrum, including near-infrared, visible light, and ultraviolet ranges, FSO systems leverage their extremely short wavelengths, in comparison to the radio range, to achieve immunity to multipath fading--an issue prevalent in RF channels. According to a number of authors, beyond its unregulated spectrum, FSO technology offers additional advantages: the optical components used in FSO systems are generally smaller, lighter, more energy-efficient, and more cost-effective compared to their RF counterparts [12; 13; 14]. As FSO technology gains traction and competition intensifies within the communication services market, the cost of FSO solutions is expected to decline further, while their performance and efficiency continue to improve. Hybrid Free Space Optics and Radio Frequency (FSO/RF) systems [15; 16] leverage the strengths of both RF and FSO, switching seamlessly between them depending on the environmental conditions. This ensures consistent and reliable IoT connectivity, even during adverse weather or line-of-sight disruptions. FSO provides a high bandwidth for the transmission of heavy data, while RF serves as a backup in scenarios where the performance of FSO is degraded (e.g., fog or snow), ensuring uninterrupted communication. This dual approach minimizes the cost of infrastructure compared to purely optical or RF systems. FSO can enhance security, while RF ensures redundancy [17]. This ensures that hybrid systems fulfil the requirements of secure and reliable IoT applications such as healthcare, financial services, and critical infrastructure. By dynamically switching between RF and FSO depending on the network conditions, hybrid systems optimize the consumption of energy, which is critical for IoT devices with limited power resources. Despite their promise, hybrid FSO/RF systems present several challenges.