## 3 Results and Discussion
### Influence of the Obstacle Full Shadow and Half Shadow on Indoor VLC Systems
In addition, in Figure 6a,b, the mean square error of illumination and signal-to-noise ratio was smaller than when the number of obstacles was large. This was caused by the fact that the position of obstacles set in this paper was randomly generated in the room. Therefore, the shadow area generated when the number of obstacles was large was smaller than when the number of obstacles was small. To more clearly display the influence of the shadow effect of obstacles on the communication system performance, Figure 7 simulates and analyses the relationship between the link outrage probability and transmitted power and the number of obstacles (\(N=0,\,1,\,8,\,16\)) under different light sources and shade occlusion. Figure 6: (a) Mean square error simulation diagram of illumination; (b) Mean square error simulation diagram of SNR. As shown in Figure 7, with the same number of obstacles, the probability of system interruptions under any shadow occlusion can decrease with increasing transmitting power. When the transmission power was the same, the system outrage probability increased with the increase in the number of obstacles, and under the same number of obstacles, the outrage probability generated by half-shadow occlusions was always larger than that of full-shadow occlusions. When the transmission power was 6 W, as shown in Figure 7a, the outrage probability without obstructions was 0, and the outrage probability generated by full shadows and half shadows with 16 obstructions was 0.0952 and 0.2124, respectively. In Figure 7c, the outrage probability was 0 when there were no obstructions, and the outrage probability generated by full shadows and half shadows under 16 obstructions was 0.0332 and 0.1028, respectively. The results show that although increasing the light source could reduce the shadow effect caused by human obstacles, the outrage probability caused by half-shadow occlusion should not be ignored. Adaptive Simulation Analysis of Indoor VLC Channel Model with Shadow Occlusion under Multiple Light Sources  
To explore the applicability of the indoor VLC channel model with shadow occlusion under multiple light sources, the following is based on the applicability simulation analysis method of the indoor VLC channel model with the shadow occlusion of a single light source in the literature [12]. By changing the size of room size L, the applicability of a single light source shadow occlusion channel model and multiple light source shadow occlusion channel models in different communication room topologies could be analyzed. The outrage probability was still taken as the performance index to measure the communication quality of the system, and the simulation parameters in Table 2 remained unchanged. In the simulation of a single light source, it could be assumed that under different room topologies, the visible light source was located in the center of the ceiling of the room; that is, when the room size was \(5\) m \(\times\) 5 m \(\times\) 3 m, the specific coordinates of the visible light source were [2.5, 2.5, 3]. When the room size was \(6\) m \(\times\) 6 m \(\times\) 3 m, the coordinates of the visible light source were [3, 3, 3]; when the room size is \(7\) m \(\times\) 7 m \(\times\) 3 m, the coordinates of the visible light source were [3, 3.5, 3.5, 3]. In the simulation of multiple light sources, four light sources could be taken as an example. It was assumed that under different room topologies, four LED light sources were located around the room, and their coordinates remained unchanged. That is, when the room dimensions were, respectively, \(5\) m \(\times\) 5 m \(\times\) 3 m, 6 m \(\times\) 6 m \(\times\) 3 m and 7 m \(\times\) 7 m \(\times\) 3 m, the coordinates of the four LED light sources could be located in [1.25, 1.25, 3], [1.25, 3.75, 3], [3.75, 1.25, 3], [3.75, 3.75, 3]. In addition, in the simulation of a single light source and multiple light sources, it could be assumed that there were four obstacles randomly distributed in the room.