## 2 Integrating 5G and Satellite Networks for Enhanced IoT Applications in Smart Cities: A Review  
The convergence of 5G and satellite networks represents a significant advancement in telecommunications, combining the unique strengths of terrestrial and satellite systems to provide extensive coverage, improved connectivity, and reliability across various environments [23, 24, 25]. By integrating satellite networks, 5G technology overcomes the constraints of terrestrial infrastructure, enabling fast, responsive communication in remote and hard-to-reach areas, including oceans, airborne platforms, and space-borne environments. This hybrid approach is particularly advantageous for the Internet of Things (IoT), which demands reliable, widespread connectivity for various applications, from basic sensors to advanced autonomous systems [26]. The Internet of Things (IoT) comprises an expansive array of devices, including everything from simple environmental sensors to sophisticated autonomous vehicles and industrial automation systems [27, 28]. Consistent communication across different environments is critical to IoT functionality, especially in smart cities where large data volumes must be transmitted in real-time for urban management, environmental monitoring, and public safety. The 5G-satellite integrated network provides an ideal solution by leveraging the high data rates and low latency of 5G in dense urban areas, while satellite coverage ensures connectivity in remote regions where terrestrial infrastructure is sparse [29, 30]. The integration of 5G and satellite networks requires careful consideration of each system's distinct propagation characteristics. Primarily operating in the millimetre-wave (mmWave) spectrum, 5G utilizes frequencies between 24 GHz and 52 GHz, offering high data speeds but suffering from significant path loss in non-line-of-sight (NLOS) scenarios [31]. In real-world settings, the propagation environment includes not only direct line-of-sight (LOS) components but also multiple scattered components resulting from reflection, diffraction, and scattering. The Rician fading model, characterized by the Rician \(K\)-factor, is suitable for scenarios where both LOS and scattered components significantly impact signal strength [32]. High-frequency satellite communications, especially those in the Ka-band (26.5 GHz to 40 GHz) and V-band (40 GHz to 75 GHz), are subject to additional attenuation due to atmospheric gases and rain, critical factors that must be integrated into propagation models. The ITU-R models for rain attenuation and gaseous absorption provide frequency-dependent attenuation factors, allowing for more accurate modelling of signal degradation in hybrid environments [33, 34]. The two-ray model is commonly used to predict signal path loss by considering both direct and ground-reflected paths. Optimizing data transmission in 5G-satellite networks also requires efficient modulation schemes. Quadrature amplitude modulation (QAM) is widely used in both 5G and satellite communications due to its high spectral efficiency. The spectral efficiency \(\eta\) of an \(M\)-ary QAM system can be expressed as  
\[\eta=\log_{2}(M)\;\mathrm{bits}/\mathrm{s}/\mathrm{Hz} \tag{1}\]  
with the effective data rate \(R\) defined as  
\[R=\eta\cdot B=\log_{2}(M)\cdot B \tag{2}\]  
where \(B\) is the channel bandwidth. Higher-order QAM schemes, such as 64-QAM and 256-QAM, provide increased data rates but require higher signal-to-noise ratios (SNRs) to maintain reliability, making them susceptible to rain attenuation and atmospheric absorption effects [34]. The integration of these factors--FSPL, Rician fading, atmospheric absorption, rain attenuation, and the two-ray model--yields a comprehensive propagation framework for 5G-satellite networks. The proposed model provides a holistic approach to capturing signal variations across different environments, frequencies, and atmospheric conditions.