Comparative Analysis of Topology Changes in FSO and RF Spatial Networks Under Node Mobility and Weather Variability

In recent years, Radio Frequency Spatial Networks (RF-SNs) have struggled to meet the increasing demand for higher data rates due to their limited bandwidth. To address this challenge, Free Space Optical Spatial Networks (FSO-SNs) have been proposed as a promising solution that aims to fulfill the stringent requirements for high data rates, enhanced security, and global coverage. Despite their potential, FSO-SNs face significant challenges due to their dynamic nature caused by the mobility of spatial nodes and fluctuating weather conditions, leading to frequent topology changes and inefficient routing. However, in RF-SNs, the dynamicity is mainly attributed to node mobility, since Radio Frequency (RF) is more robust to weather impairments. Consequently, the topology changes in RF-SNs are less frequent and do not pose routing issues as in FSO-SNs. This paper presents a comparative analysis of the dynamicity in RF-SNs and FSO-SNs, providing valuable insight into the rate of topology change. The analysis reveals that, on average, topology changes occur every 43.6 seconds in FSO-SNs, with a total of 1981 topology changes during a period of 24 hours, 61.4% of which occur within 41 seconds after the previous change. In contrast, RF-SNs experience only 441 topology changes, with only 20.6% of these occurring before 41 seconds after the previous change. Furthermore, we analyze the impact of weather conditions on the maximum achievable data rates for both FSO-SN and RF-SN technologies, observing drastic fluctuations in Free Space Optical (FSO) systems. This study provides a solid foundation for developing tailored routing solutions for FSO-SNs.