# Multi-Satellite Observation-Relay Transmission-Downloading Coupling Scheduling Method
## 4 Simulation Results
### Scenario 2 Insufficient Data Transmission Resource Scenario  
Scenario 2 represented an insufficient data transmission resource scenario where the satellites have limited memory capacity and limited satellite-ground data transmission time windows. There were four satellites with sun-synchronous orbits. The orbital parameters of the satellites are shown in Table 5. The subsystem parameters of the four satellites were the same, as shown in Table 6.  
Figure 5: Iteration processes of different methods in a single condition of scenario 1. Figure 6: Observation and data transmission event diagram of CTSTD in scenario 1. Figure 7: Observation and data transmission event diagram of CTSRD in scenario 1. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter Name** & **Parameter Value** \\ \hline Attitude Maneuver Calculate Method & Trapezoidal Method \\ Max Attitude Maneuver Angular Velocity & \(1^{\circ}/\mathrm{s}\) \\ Max Attitude Maneuver Angular Acceleration & \(0.5^{\circ}/\mathrm{s}^{2}\) \\ Max Maneuvering Range Half-Cone Angle & \(45^{\circ}\) \\ Antenna Coverage Half-Cone Angle & \(70^{\circ}\) \\ Storage Capacity & \(500\) Gbit \\ Camera’s Data Generation Rate & \(2\) Gbps \\ Satellite-Satellite Data Transmission Rate & \(1\) Gbps \\ Satellite-Ground Station Data Transmission Rate & \(1\) Gbps \\ Battery Electrical Energy Capacity & \(5\times 10^{6}\) J \\ Battery Initial Electrical Energy & \(5\times 10^{6}\) J \\ Max Charging Electrical Power of Solar Arrays & \(1\) kW \\ Camera Electrical Power & \(1\) kW \\ Satellite-Satellite Data Transmission Devices Electrical Power & \(0.5\) kW \\ Satellite-Ground Station Data Transmission Devices Electrical Power & \(0.5\) kW \\ Satellite Attitude Maneuver Electrical Power & \(0.2\) kW \\ Satellite Normal Electrical Power & \(0.55\) kW \\ Observation time of a single target & \(20\) s \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Satellite subsystem parameters in Scenario 2. Figure 8: Observation and data transmission event diagram of ITSRD in scenario 1. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Satellite No** &
\begin{tabular}{c} **Semi-Major** \\ **Axis (m)** \\ \end{tabular} & **Eccentricity** & **Inclination (\({}^{\circ}\))** & **RAAN (\({}^{\circ}\))** & **Argument of** & **True** \\  & & & & **Perigee (\({}^{\circ}\))** & **Anomaly (\({}^{\circ}\))** \\ \hline
1 & 7,028,140 & 0 & 97.9908 & 40.348 & 0 & \(0\) \\
2 & 7,028,140 & 0 & 97.9908 & 80.348 & 0 & \(-30\) \\
3 & 7,028,140 & 0 & 97.9908 & 120.348 & 0 & \(-60\) \\
4 & 7,028,140 & 0 & 97.9908 & 160.348 & 0 & \(-90\) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Initial satellite orbit parameters in Scenario 2. In this scenario, five conditions are generated by randomly generating target points. The improvement effect of the proposed method in this article is explained by the statistical results comparison of each method in multiple conditions and the results comparison of each method in a single condition. The target number was set to 150. In this scenario, the longitude ranges were [80\({}^{\circ}\), 180\({}^{\circ}\)] and [\(-180^{\circ}\), \(-160^{\circ}\)], and the latitude range was [10\({}^{\circ}\), 50\({}^{\circ}\)]. The scenario included 2 ground stations with the following coordinates: (105\({}^{\circ}\), 20\({}^{\circ}\)), (110\({}^{\circ}\), 30\({}^{\circ}\)). The profit from the target points was randomly assigned between 0.9 and 1. The distribution of targets and ground stations is shown in Figure 9.  
The statistical results of the comparison of all six methods are shown in Table 7. The average optimal solution objective function values and the average optimal solution iteration time of each method are compared as follows: The optimal solution objective function values and the optimal solution iteration time of CTSRD and CTSTD are nearly the same. The optimal solution objective function value of CTSRD is 6% higher than that of CTSND. The optimal solution iteration time of CTSRD is 5.9% less than that of CTSND.