# Design of Mega-Constellations for Global Uniform Coverage with Inter-Satellite Links
## 4 Simulation and Results
### Simulation Studies and Results on Mega-Constellation Design
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sub-Constellation** & \(i\,NP\) & \
\begin{tabular}{c} **Sub-Constellation** \\ **Number** \\ \end{tabular} & \(i\,NP\) \\  & &
\begin{tabular}{c} **Number** \\ \end{tabular} & \(i\,NP\) \\ \hline Cons\_11 & 70\({}^{\circ}\) 187 11 & Cons\_34 & 24\({}^{\circ}\) 80 5 \\ Cons\_12 & 68\({}^{\circ}\) 182 13 & Cons\_35 & 22\({}^{\circ}\) 75 5 \\ Cons\_13 & 66\({}^{\circ}\) 173 173 & Cons\_36 & 20\({}^{\circ}\) 69 3 \\ Cons\_14 & 64\({}^{\circ}\) 184 23 & Cons\_37 & 18\({}^{\circ}\) 58 29 \\ Cons\_15 & 62\({}^{\circ}\) 173 173 & Cons\_38 & 16\({}^{\circ}\) 58 29 \\ Cons\_16 & 60\({}^{\circ}\) 173 173 & Cons\_39 & 14\({}^{\circ}\) 45 5 \\ Cons\_17 & 58\({}^{\circ}\) 168 14 & Cons\_40 & 12\({}^{\circ}\) 46 23 \\ Cons\_18 & 56\({}^{\circ}\) 164 41 & Cons\_41 & 10\({}^{\circ}\) 33 3 \\ Cons\_19 & 54\({}^{\circ}\) 160 16 & Cons\_42 & 8\({}^{\circ}\) 28 7 \\ Cons\_20 & 52\({}^{\circ}\) 156 13 & Cons\_43 & 6\({}^{\circ}\) 22 11 \\ Cons\_21 & 50\({}^{\circ}\) 152 19 & Cons\_44 & 4\({}^{\circ}\) 14 7 \\ Cons\_22 & 48\({}^{\circ}\) 148 37 & Cons\_45 & 2\({}^{\circ}\) 7 7 \\ Cons\_23 & 46\({}^{\circ}\) 148 37 & & \\ \hline
**Total** & & **5686** & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._To further demonstrate that the mixed [PERSON] constellation effectively compensates for the uneven distribution of the [PERSON] constellation along latitude, the sub-satellite point density of the two constellations along the latitude zone is calculated separately. The results are shown in Figure 8. In Figure 8a, the sub-satellite point density of the Walker constellation, which contains 5625 satellites, varies significantly across the latitude zones, with high latitudes being several times greater than low and middle latitudes. In contrast, the mixed Walker constellation of 5686 satellites has less difference in the density values of the sub-satellite points in each latitude zone, indicating a homogeneous distribution of satellites along latitude. It can be concluded that the mega-constellation designed in this paper effectively solves the problem of the uneven distribution of the Walker constellation on the latitudinal zone. Figure 7: 2D and 3D comparison diagrams of the mixed Walker constellation and Walker constellation at the same amount. (**a**) 3D schematic of the Walker constellation with 5625 satellites; (**b**) 2D schematic of the Walker constellation with 5625 satellites; (**c**) 3D schematic of the mixed Walker constellation with 5686 satellites; (**d**) 2D schematic of the mixed Walker constellation with 5686 satellites. The coverage performance is one of the most important indicators for evaluating the merits of a constellation design. The focus of the mega-constellation is on global coverage characteristics, for which the paper compares the N Asset Coverage of the Walker constellation with that of the mixed Walker constellation on a global scope. The resolution of the ground sampling points is \(1^{\circ}\times 1^{\circ}\), and the field of view of the satellite for ground coverage is set to \(50^{\circ}\). The simulation results are shown in Figure 9. In Figure 9a, the range of N Asset Coverage of the Walker constellation is 10-219, with a wide span of ground N Asset Coverage and more than 200 overlaps for the polar regions. However, in Figure 9b, the range of N Asset Coverage for the mixed Walker constellation is 18-25, with little variation in the number of duplicates covered across global regions. Figure 9c quantifies and compares the distribution of the N Asset Coverage between the two constellations, visually demonstrating the more concentrated distribution of the number of N Asset Coverage for the mixed Walker constellation. Furthermore, the N Asset Coverage distribution of the mixed Walker constellation peaks at 21 compared to 11 for the Walker constellation, indicating that for the same number of satellites, the mixed Walker constellation has a higher N Asset Coverage in most regions of the world.