# User-Information-Aware D2D Multicast File Distribution Mechanism
## 7 Simulation Analysis
### Effects of Various Parameters on Performance of All Four Schemes  
#### 7.3.1 Effects of Various Parameters on Utility  
In the above Section 7.2, we analyzed the proposed scheme's performance through putting different number of potential requesters in different communication environments. In order to fully verify the superiority of the proposed scheme, in this subsection, the proposed scheme is compared with other schemes under different communication environment. The relationships between utility value and the number of service requesters are shown in Figure 5. In Figure 5a, the value of \(P_{th}^{accept}\) is set to 0.5, the first curve and the second curve represent the performance of the proposed scheme when the value of \(\lambda\) is set to 0.3 and 0.7, respectively. And in Figure 5b, the value of \(\lambda\) is set to 0.6, the first curve and the second curve represent the performance of the proposed scheme when the value of \(P_{th}^{accept}\) is set to 0.3 and 0.7, respectively. As shown in Figure 5, with the increase of service requesters, the utility value of four schemes also rises with varied degrees, and the rise of the proposed scheme is slightly larger than the other three schemes. As the process of \(|U_{R}|\) increases, the performance of the proposed scheme is obviously superior to the other schemes. Scheme 2 with the consideration of social information and scheme 3 with the consideration of interference information have similar performances, and the performance of scheme 4 by selecting cluster head randomly is the worst. For the proposed scheme, when \(\lambda\) is set to 0.7, its performance is better than when \(\lambda\) is set to 0.3. This is because the larger the \(\lambda\), the greater the weight of the video popularity in the calculation of the user's request probability. This will increase the similarity of the request probability vectors of different users, and thus the social relationship strength value will become larger. Further, the utility value becomes larger. The choice of threshold \(P_{th}^{accept}\) is an important factor affecting the number of the potential requesters who meet the condition \(P_{pi,I}^{accept}>P_{th}^{accept}\). As shown in Figure 5b, when \(P_{th}^{accept}\) is set to 0.7, the performance of the proposed scheme is much lower than when \(P_{th}^{accept}\) is set to 0.3. It is gratifying that the performance of the proposed scheme under different parameter settings is always better than the comparison schemes. As noted above, when the number of video files \(|F|\) increases, the popularity of individual video shows decrease, making that the weight of user's interest in the calculation of video request probability increases, further resulting in a decrease in the similarity of the video request probability between users, in turn the strength of social relationships between users decreases. What's more, in the proposed user's information awareness scheme, the increase of \(|F|\) can cause low probability of potential requesters to accept the pushed videos, and then the number of users who meet the condition \(P_{pi,I}^{accept}>P_{th}^{accept}\) also decreases. Therefore, Figure 6 shows that the utility value of all four schemes decreases dramatically as the number of video files increases. Due to the decrease of both the intensity of social relations and the number of potential servicing users, the decrease speed of the proposed scheme is faster than the other three schemes, but the utility value of the proposed scheme is still greater than the other three schemes. For the same reason mentioned above, the performance of the proposed scheme differs under different parameter settings. To summarize, in the proposed user-information-aware D2D multicast file distribution mechanism, the video is pushed to potential service requesters when distributing video for service requesters.