# SatScope: A Data-Driven Simulator for Low-Earth-Orbit Satellite Internet
## 5 Evaluating LEO Satellite Internet with SatScope: Case Studies
### Single-Shell Satellite Network Service Performance  
The distribution of satellite ground stations and end-users is influenced by regional policies, economic development levels, and geographic conditions. Previous studies primarily rely on GDP data to model these factors. Utilizing SatScope, our approach bypasses the need for such modeling, enabling us to obtain large-scale, real-time connectivity information between satellite network ground nodes at a low cost. By treating satellites from different shell layers as nodes within a single-shell network, we conducted continuous simulations of varying durations for each shell layer. After geolocating IP addresses, we derived the distribution of ground nodes that aligns with real-time network conditions. Table 3 presents the ground node coverage rate and average number of users served per satellite under identical ground node distributions for different shell layers. To comprehensively understand and evaluate the communication characteristics of different shell layers, we introduce two new metrics: IP coverage rate of ground nodes and the number of IPs served per satellite. First, we perform geolocation on all IP addresses to obtain their latitude and longitude. A ground node is considered covered if it can connect to at least one satellite. Let \(N\) denote the total number of IP addresses at any given time, \(C_{t}\) represent the number of covered \begin{table}
\begin{tabular}{c|c c c c c} \hline
**Index** & **Shell Height** & **Shell Inclination** & **Number of Satellites** & **Simulation Duration (s)** & \(C_{g}\) & \(\overline{\Pi}\) \\ \hline
1 & 364.72 & 53.16 & 232 & 9000 & 27.26\% & 301.50 \\
2 & 447.88 & 43.00 & 483 & 9000 & 50.43\% & 234.61 \\
3 & 478.44 & 53.16 & 330 & 9000 & 56.15\% & 415.94 \\
4 & 491.49 & 43.00 & 163 & 9000 & 26.48\% & 420.63 \\
5 & 546.81 & 53.21 & 1519 & 9000 & 95.26\% & 164.99 \\
6 & 563.02 & 43.00 & 1345 & 9000 & 82.07\% & 159.78 \\
7 & 575.24 & 97.66 & 232 & 9000 & 30.15\% & 345.89 \\
8 & 582.55 & 70.00 & 391 & 9000 & 46.05\% & 307.59 \\ \hline \end{tabular}
\end{table} 
Table 3: Shell satellite coverage and utilization table. ground nodes at time \(t\), \(S\) be the number of satellites, and \(T\) the total number of time intervals during the simulation. The IP coverage rate of ground nodes and the number of IPs served per satellite are calculated as follows:  
\[C_{g}=\frac{1}{T}\sum_{t=1}^{T}\frac{C_{t}}{S} \tag{5}\]  
\[\overline{U}=\frac{1}{T}\sum_{t=1}^{T}\frac{C_{t}}{N} \tag{6}\]  
where \(C_{g}\) indicates the average IP coverage rate of ground nodes during the simulation, while \(\overline{U}\) represents the average number of satellite service IPs during the simulation. These formulas allow us to evaluate the coverage and service capability of the satellite network for ground nodes. The number of satellites is not the sole determinant of IP coverage for ground nodes and the number of IPs served per satellite, even when the distribution of ground nodes remains constant. For instance, despite the eighth shell having 118.48% more satellites than the third shell (Table 3), its IP coverage rate is only 91.31% that of the third shell, indicating that increased satellite numbers do not necessarily lead to higher coverage. Similarly, while the third shell has 142.24% more satellites than the first shell, it serves only 137.96% more IPs, suggesting an imbalance in load distribution. The average altitude and inclination of a shell also influence IP coverage and the number of IPs served per satellite. Therefore, assessing the network performance of a shell requires considering both the IP coverage rate and the number of IPs served per satellite. Researchers should select the priority shells for satellite network construction based on the distribution of target ground nodes. Given that the average latitude in the United States is around 37 degrees and that of EU countries is typically around 50 degrees, these regions are primary service areas for Starlink.