## 4 Experimental Results and Analysis
### Impacts of the Orbital Parameters on LEO-LEO Occultation Events
#### 4.1.3 Impact of the Inclination  
As shown in Figure 2a, the number of 3-month occultation events varies with the Rx and Tx orbital inclination greatly in the range 0-5500 and, accordingly, the orbits with an inclination between 65\({}^{\circ}\) and 115\({}^{\circ}\) were defined as 'near-polar orbits' (NPOs), the orbits with an inclination in the 0-45\({}^{\circ}\) and 135-180\({}^{\circ}\) intervals were defined as 'near-equator orbits' (NEOs), and orbits with an inclination in other intervals were defined as'medium-inclination orbits' (MIOs). For the NPO constellations, when the inclinations of the Rx and Tx orbits are equal, the number of occultation events has a peak area, and the peak width is about 30\({}^{\circ}\); when they are supplementary, the number of occultation events is reduced obviously. The NEO constellations also have an occultation event number peak area when the inclinations of the Rx and Tx orbits are supplementary, and the peak width is about 40\({}^{\circ}\). However, the MIO constellations do not have an occultation event number peak area. To further explore the spatial-temporal distribution of the NPO, NEO, and MIO constellation occultation events and the reason why the 3-month occultation numbers are different, Figures 3 and 4 show the global coverage and the occultation number trend beside the GCF trend of the occultation events for nine representative constellations, i.e., Rxi90-Txi90, Rxi100-Txi100, Rxi80-Txi100, Rxi60-Txi60, Rxi120-Txi120, Rxi120-Txi60, Rxi40-Txi40, Rxi140-Txi40, and Rxi170-Txi10. Figure 2: The variation in the 3-month accumulated LEO-LEO occultation event number (color scale) with the Rx and Tx orbital elements of inclination (**a**), RAAN (**b**), and height (**c**). Figure 4: The accumulated time dependence of the LEO-LEO occultation event number (orange lines) and the global coverage fraction (GCF) (blue lines) for the representative LEO-LEO constellations composed of a Rx satellite and a Tx satellite with particular orbital inclinations. Figure 3: The global coverage of LEO-LEO occultation events for representative constellations composed of a Rx satellite and a Tx satellite with particular orbital inclinations, illustrating the occultation numbers per 5\({}^{\circ}\times 5^{\circ}\) latitude and longitude grid cell, while the GCFs were calculated using grid cell areas according to Equation (12). As shown in Figure 3a-c, the NPO constellation easily provides global coverage of occultation events, and the 3-month occultation global coverage fractions of Rxi90-Txi90, Rxi100-Txi100, and Rxi80-Txi100 are 98%, 96%, and 41%, respectively. Comparing (a,b) with (c), one can see that the occultation number and the global coverage fractions of the NPO constellations with the same Tx and Rx inclination are larger than those of the NPO constellations with supplementary Tx and Rx inclinations. As shown in Figure 3d-f, the occultation events of the MIO constellation are mainly distributed in the low and middle latitude zones, and the global coverage fractions are relatively low. Comparing (d,e) with (f), one can see that the occultation number and the global coverage fractions of the MIO constellations with the same Tx and Rx inclination are relatively small. As shown in Figure 3g-i, the occultation events of the NEO constellation are mainly distributed in the low latitude zone, and the global coverage fractions are relatively low. Comparing (g) with (h,i), the NEO constellations with the same Tx and Rx inclination have a small occultation number and a small global coverage fraction, while the NEO constellations with supplementary Tx and Rx inclinations have a large occultation number but very small global coverage fractions. With the decrease in the dihedral angle between the LEO plane and the equatorial plane, the global coverage fraction decreases, and the global coverage fraction of Rxi170-Txi10 is only 24%.