# SatEC: A 5G Satellite Edge Computing Framework Based on Microservice Architecture
## 4 Analysis, Comparisons, and Future Plans
### Simulation Results  
Example 1: The user is located in an extremely remote area and wants to communicate with another user. Using the 5G ground network, users need to walk to point A at least because of the \begin{table}
\begin{tabular}{c c c} \hline \hline
**Nodes** & **Quantity** & **Remarks** \\ \hline \multirow{2}{*}{Master node} & \multicolumn{2}{c}{Also used as common resource} \\  & 3 & nodes \\ Common resource node & 1 & — \\ FPGA resource nodes & 1 & — \\ GPU resource node & 1 & — \\ Storage resource node & 1 & — \\ Network resource nodes & 1 & — \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Resources in the test platform. Figure 4: Experimental simulation scenario. \begin{table}
\begin{tabular}{c c} \hline \hline
**Time Cost** & **Meaning** \\ \hline T1 & The time cost of moving to the coverage of communication networks \\ T2 & The time cost of forwarding data in terrestrial 5G network \\ T3 & The time cost of processing data in terrestrial 5G network \\ T4 & The time cost of uploading data \\ T5 & The time cost of forwarding data among intersatellite links \\ T6 & The time cost of downloading result \\ T7 & The time cost of forwarding data to data center \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The meaning of each time cost. physical requirements for connecting to the ground base station, so the time delay of users' access to the network is walking time T1+propagation time T2. However, if the 5 GsatEC network is used, the total time delay is only T4, without needing to consider user movement. Although T4 may be larger than T2, it remains basically the at the same time scale as T2, and much less than T1. According to the following settings, the time delays of the 5G satellite network and 5 GsatEC network are compared. 5G satellite altitude: 500 km-1200 km [21]; ground 5G base station coverage: 300 m [43]; electromagnetic wave velocity: 3.0 \(\times\) 108 m/s; distance from user to point A: 100 m; walking speed: 2 m/s. The delay between the ground 5G network and 5 GsatEC is shown in Table 3. Although we compare the time delay, it actually shows the difference in the coverage performance of the ground 5G network and 5 GsatEC networks. This is because timeliness is one of the characteristics of communication. When the delay exceeds a certain range, it is considered that the network cannot cover the area. Otherwise, when the delay was acceptable, the network was considered to have covered the area. In this experiment, the user can connect to the ground base station by his own movement, but the walking time is much longer than the ordinary communication time. It has bad timeliness. In fact, the ground network has no coverage for this user. We illustrate network coverage performance through the comparison of delay. It is a conversion from qualitative problem to quantitative problem. In addition, we refer to the constellation model of the Iridium communication system [44] and test the satellite communication coverage through the (Satellite Tool Kit) STK simulation software, as shown in Figures 5-7. Figure 5 shows a plan view of the global coverage of satellite networks. Figures 6 and 7 are obtained by calculation of STK's coverage analysis tool. Figure 6 shows that at each moment, the accumulative coverage of the satellite to the global region is 100%. Figure 7 shows that at different latitudes, the satellite coverage time ratio is 100%. Through the simulation of satellite coverage performance, it can be found that setting a reasonable satellite constellation can make up for the shortcomings that the network is difficult to cover in remote areas. Example 2: Users are located in extremely remote areas and want to achieve cloud processing of application data (suppose there is a lot of data to be processed, but the amount of data returned is very small, so the transmission delay of the return can be neglected). If traditional satellite communication is used, the data need to be sent to the remote data center. The total delay for the user to obtain the result is T4+T5+T6+T7+data processing delay.