## 4 Simulation Analysis
### Experimental Results
#### 4.3.4 Algorithm Robustness Analysis  
To explore the robustness of the 3-satellite alternate handover, we start from the model established in Sections 3.3-3.5 and conduct qualitative and quantitative analysis from the perspectives of multipath interference, NLOS interference, LOS interference, noise interference and satellite orbit disturbance. Our angles are explored separately: (1) the coexistence of multipath, NLOS, LOS and the effect of multimode noise on the algorithm. (2) Analysis of LEO satellite orbit disturbance. Without loss of generality, in all the above cases, we only consider two typical representative cases, which are 5 s with a shorter switching time and 60 s with a longer switching time. (1) Analysis of algorithm robustness under complex interference  
To more realistically simulate the navigation and positioning problem in a complex and challenging environment, we will consider multipath, NLOS, LOS and dual-modal Gaussian noise interference at the same time in this section, considering MLNSR = 0.1, \(C_{\beta}\) = 1 and MLNSR = 0.5, \(C_{\beta}\) = 5 and MLNSR = 1, \(C_{\beta}\) = 9, three complex interference scenarios. The simulation results are shown in Figure 10.  
In Figure 10a,b, we can see that due to the comprehensive interference from multipath, NLOS, LOS and dual-modal Gaussian noise, the positioning result of the algorithm fluctuates and jitter is relatively greater. It is not difficult for us to understand this result and the final positioning data with alternate switching times of 5 s and 60 s are statistically drawn into statistical Figure 11.  
In Figure 11a,b, we can see that in this type of complex interference environment, with the increase in MLNSR and dual-modal Gaussian noise intensity, the corresponding positioning error will increase, but the accuracy of the positioning algorithm can still be maintained at the meter level. (2) Analysis of LEO satellite orbit disturbance  
According to the model description in Section 3.5, combined with other relevant simulation parameters, we simulated the comprehensive perturbation factor model of the Earth's nonspherical perturbation and atmospheric drag perturbation. As a comparison, we added the simulation results without perturbation. The simulation results are shown in  
Figure 10: Navigation and positioning performance of algorithms under complex interference. (**a**) Error result. (**b**) Trajectory curve. Figure 12, where OP represents orbital perturbation and other acronyms have the same meaning as the preceding text. In Figure 12a,b, we can intuitively see that under different orbits, when the switching time is short, the orbital perturbation has little effect on navigation and positioning and when the switching time is long, we can see that the influence of orbital perturbation on navigation and positioning increases, but the effect is not particularly obvious. Under the same orbit, even in a short switching time, the result of orbital perturbation on navigation positioning is obvious and under a longer switching time, the impact of orbital perturbation shows a more serious trend. To facilitate quantitative analysis, we show the mean and standard deviation statistics of the corresponding navigation and positioning trajectory, as shown in Figure 13.  
In Figure 13a,b, we can see that, in general, the influence of orbital perturbation on the navigation and positioning results makes the algorithm worse than the navigation and positioning results in the case of no orbital perturbation, but there will be fluctuations in the standard deviation; for example, when the switching time is 5 s, the impact of orbital perturbation on different orbits will \"improve\" the navigation and positioning performance and, similarly, when the switching time is 60 s, the influence of orbit perturbation on the same orbit also makes the navigation and positioning performance \"improved\". This  
Figure 11: Algorithmic navigation and positioning results statistics under complex interference. (**a**) Mean statistics. (**b**) Standard deviation statistics.