## 5 Simulations  
Computer simulations were conducted for the performance evaluation of the proposed method. The objective of the simulations was to examine the effectiveness of redundant packet delivery through multiple paths and redundancy mitigation by adjusting the number of paths. Through the simulations, the performance of the proposed method was compared to both conventional methods of path utilization: those involving single path-based communication and those involving multipath-based communication with a fixed number of paths. Therefore, the scenarios used for evaluation included (1) single-path communication; (2) multipath communication consisting of three active paths; and (3) the proposed method utilizing dynamic multipath communication with diverse offset values. The evaluation metrics included reliability, the average number of paths employed in a multipath connection, the number of path changes, and packet reception redundancy. The reliability metric represents the successful rate of packet delivery to the cloud in a multipath connection. The packet reception redundancy represents the average number of duplicated packets received at the cloud server for each source packet. To simplify the network's complexity, the evaluation employed a setup involving the probability of end-to-end packet loss on each path. Unless otherwise stated, the parameter setup used was as shown in Table 1. The maximum number of paths was set to 5, indicating the maximum number of wireless RF interfaces, such as LTE, DSRC, etc. The number of fixed paths in the simulations was set to 1 and 3. The target reliability was set to 90 percent. In the simulations, we set up the occurrence of packet loss on each path with predefined probabilities to simulate a general scenario of packet loss, regardless of the factors that caused it. The packet loss probabilities of the paths were set to 20 percent, 30 percent, 40 percent, 40 percent, and 70 percent for paths 1, 2, 3, 4, and 5, respectively. In the simulations, the selection of paths was in order from high reliability to low reliability. To simplify the management of reliability information at each path, we assumed that the reliability was monitored at every time unit for each path. Furthermore, we assumed that the cloud-to-vehicle communication was reliable and focused on examining the V2C operation. Figure 5a,b show the reliability of packet delivery with a fixed number of path(s). The blue line in the figure represents the target reliability. With only one path being employed, the average reliability was 0.776, which was far lower than the target reliability, even when using the best path among the five candidate paths. With three paths being employed, the average reliability was above 95 percent, which was much higher than the target threshold. Figure 5c shows the proposed method, employing the target reliability as the threshold for all adjustments of the path number. The average reliability was 0.903, which was close to the target reliability. The partial performance of reliability was sometimes lower than the target reliability. Figure 5d shows the proposed method, which utilized a threshold with an offset of 0.03 to decrease the number of paths. The average reliability was 0.908, which \begin{table}
\begin{tabular}{l l} \hline \hline
**Parameters** & **Setup** \\ \hline Maximum path number & 5 \\ \hline Initial route number in the proposed methods & 3 \\ \hline Time unit & 100 ms \\ \hline Period for the route adjustment & 50 time units \\ \hline Total evaluation time & 1000 time units \\ \hline Reliability target (packet successful delivery rate) & 90 percent \\ \hline Successful delivery probability at each path & 80, 70, 60, 60, 30 percent for paths 1, 2, 3, 4, 5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Simulation setup. Figure 5: Reliability performance. was a little higher than the target reliability most of the time. Sometimes, the reliability was lower than the target reliability.