# Two-Level Sharing and Extraction of Sensing Information with Hybrid V2X Communications
## 5 Performance Evaluation
### Evaluation Results  
Figure 5 shows the necessary number of vehicles that need a global report of results to the edge server in Scenario 1 regarding the proposed scheme. The number of global reports before the local exchange of sensing information is 30. After the first round of local exchange, there are 6 vehicles that need to report its sensing results to the edge server. After the second round of local exchange, there are 5 vehicles that need to report to the server, and this number of necessary reports does not change after the third round of exchange. We believe that the decrease in global report number is caused by the local extraction of object sensing information and the prohibition of unnecessary reports at each vehicle. \begin{table}
\begin{tabular}{l l} \hline \hline
**Parameters** & **Setup** \\ \hline Number of vehicles & 30 \\ \hline Number of BS/AP & 1 \\ \hline Global wireless-communication range & 1000 m \\ \hline Local wireless-communication range & 300 m, 100 m \\ \hline Number of lanes & 2 \\ \hline Maximum number of exchange rounds & 3 \\ \hline Period of an exchange round & 100 ms \\ \hline Number of simulation runs for average results & 10 \\ \hline Simulation Scenario 1 & One topology case with local communication range of 100 m \\ \hline Simulation Scenario 2 & 10 topology cases with local communication range of 100 m \\ \hline Simulation Scenario 3 & One topology case with local communication range of 300 m \\ \hline Simulation Scenario 4 & 10 topology cases with local communication range of 300 m \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Basic simulation setup. Figure 5: Number of necessary reports to the edge server in Scenario 1 regarding the proposed scheme (State 1 refers to the state in which the vehicle needs to report to the edge server). We further believe that the information exchange already brings about this effect after the second round of exchange, leading to little change in the number of necessary global reports after the second round of exchange. Moreover, the disconnectivity of the V2V network is considered to cause multiple reports form the vehicles to the edge server. It is impossible to exchange sensing information between vehicles in different V2V graph components. To confirm the connectivity among vehicles, we examined the graph features of the vehicles. Figure 6 shows the graph topology of the corresponding vehicles examined in Scenario 1. There are three components in the graph of vehicles that utilize a local communication range between them. Since each graph component requires at least one report after the local extraction of sensing information, the total number of global reports will be no less than 3 and cannot be further decreased by the increase in exchange rounds. Figure 7 shows the result of MinFactor, which was extracted at each vehicle during the exchange of sensing results among vehicles in Scenario 1 regarding the proposed scheme. Although the MinFactor at the vehicles were initially diverse before the exchange of sensing results, there was a significant decrease in the diversity of MinFactor values among vehicles after the first round of exchange. There were less than 10 different MinFactors. After the second round of exchange of sensing results, there were less than five different MinFactors among vehicles. As the number of rounds increased, the diversity of MinFactor information came to a stable number, without further decreases in the third round of exchange. Figure 8 illustrates the collection of reports at the edge server in Scenario 1. There were five reports collected at the edge server after the local extraction of sensing information. The final result of MinFactor was \(-99\). Figure 9 shows the average number of global results corresponding to each round of local exchange among vehicles in Scenario 2. After the first round exchange, the proposed scheme resulted in 5.8 vehicles that needed to report their sensing results to the edge server.