## 7 Experimental Verification and Analysis
### Experimental Parameter Setting  
The primary parameter setting of the following experiments is summarized as follows, and mainly includes the setting of the BeiDou-3 system, non-cooperative cislunar targets (which will be denoted as lunarprobe-1), and CEI ground stations (which includes stations in Beijing and Kashi).  
The orbit types and specific parameters of the BeiDou-3 are shown in Table 2 and Table 3, respectively.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type** & **Number** & **Orbital Altitude** & **Orbital Inclination** \\ \hline MEO & 24 & 21,528 km & 55\({}^{\circ}\) \\ GEO & 3 & 35,786 km & 0\({}^{\circ}\) \\ IGSO & 3 & 35,786 km & 55\({}^{\circ}\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Parameter setting of the BeiDou-3 based scenario.  
station in the 2D simulation scenario is shown in Figure 8, which includes three CEI stations in Beijing (which have been denoted as B-1, B-2, and B-3 in Table 5) and another three in Kashi (which have been denoted as K-1, K-2, and K-3).  
The joint scenario simulation of the ground-based CEI station, the BeiDou-3 constellation, and the non-cooperative spacecraft in Earth-Moon space is shown in Figures 9-13, with the farthest simulation distance of \(4.9\times 10^{6}\) km from the center of the Earth, and the simulation start time is 24 March 2023 04:00:00.000, which ends at 24 April 2023 04:00:00.000.  
The spatial extent of the cislunar space studied in this paper (which highlights the Beidou-3 constellation) is presented in Figure 9, in earth inertial axes and moon inertial axes, respectively, followed by the simulation of a lunar exploration mission of the cislunar spacecraft (which will be called lunarprobe-1, from launch, maneuver to propagate (the whole process from launch in Earth, to Earth-Moon transfer maneuver, to the final lunar orbit)), which is illustrated in Figure 10. Figure 11 presents the significant performance indicators of lunarprobe-1 during the lunar exploration mission, which includes J2000 Classical Orbit Elements, inertial position and velocity, and LLA position.  
Figure 10: Simulation of lunar exploration mission of the cislunar spacecraft (from launch, maneuver, to propagate): (**a**) in earth inertial axes (**b**) in moon inertial axes.  
Figure 9: The spatial extent of the Earth–Moon studied in this paper (which highlights the Beidou-3-constellation): (**a**) in earth inertial axes (**b**) in moon inertial axes.  
To be closer to the real lunar exploration missions, the constraints during the spacecraft flight has been added, and the adjusted trajectory of the lunarprobe-1 with more constraints in 100 iterations is shown in Figure 12. On this basis, to facilitate the analysis of link budget and measurement accuracy of the proposed method, the simulation scenario of link budget anaysis in cislunar space based on the CEI and BeiDou-3 interstellar link has been constructed, as depicted in Figure 13.  
Figure 11: Key performance indicators of lunarprobe-1 during lunar exploration mission: (**a**) J2000 Classical Orbit Elements (**b**) inertial position and velocity (**c**) LLA position.  
Figure 12: The adjusted trajectory of lunar exploration mission of the cislunar spacecraft with more constraints (in 100 iterations): (**a**) in earth inertial axes (**b**) in moon inertial axes.  
Figure 13: Simulation of link budget analysis in cislunar space based on CEI and BeiDou-3 interstellar link: (**a**) in earth inertial axes (**b**) in moon inertial axes.