## 4 Methodology
### TMR Routing Protocol
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Time** & **QMR** & **ISR** & **TMR** \\ \hline
10 & 2.51 & 2.59 & 2.67 \\
20 & 2.21 & 2.39 & 2.5 \\
30 & 2.05 & 2.21 & 2.36 \\
40 & 1.89 & 2.08 & 2.24 \\
50 & 1.81 & 1.98 & 2.13 \\
60 & 1.72 & 1.91 & 2.06 \\
70 & 1.69 & 1.85 & 1.99 \\
80 & 1.67 & 1.83 & 1.96 \\
90 & 1.65 & 1.8 & 1.92 \\
100 & 1.62 & 1.78 & 1.9 \\ sum & 18.82 & 20.42 & 21.73 \\ gain (\%) & 15.5 & 6.4 & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Simulation time vs. throughput of Figure 24.

Figure 25: Comparison of ECSR, ISR, and proposed protocol TMR for PLR with simulation time. Through time, the network gets more congested, and consequently, the end-to-end delay increases which is the case in Figure 26; however, TMR has the lowest delay due to its route selection mechanism. The routing protocol needs to go through the route discovery phase when the PLR increases. TMR has the lowest PLR and therefore, the route discovery phase is initiated at a lower rate than other protocols. This in turn reduces the routing overhead ratio as shown in Figure 27. Additionally, an excessive amount of routing packets are sent to collect information about the network status such as head nodes selection in case of ISR and the next node in case of QMR. These routing packets are not used in the TMR and, therefore, QMR and ISR have worse routing overhead performance than TMR. #### 5.3.2 Assessment of the Simulation Results Based on Mobility Speed

The network topology is prone to change when the mobility speed increases. Consequently, the performance of protocols drops, as it is depicted in Figures 28 and 29. When

Figure 27: Comparison of EGSR, ISR, and proposed protocol TMR for routing overhead with simulation time. Figure 26: Comparison of EGSR, ISR, and proposed protocol TMR for end-to-end delay with simulation time. vehicles move at high speed, channels disconnect, and PLR increases. RSU has a wider transmission range than OBU and, therefore, RSU can find more alternative routes using TMR than OBU. The average end-to-end delay increases when mobility speed increases due to link failure and retransmission of data. The given justification is proven in Figure 30. As the result of the route selection mechanism based on the minimum RTT in TMR, the lowest end-to-end delay emerged for TMR, followed by ISR and QMR. Table 6 indicates that TMR saves end-to-end delay by 26.1 and 11.7 percent compared to QMR and ISR, respectively. According to Equation (4), the routing overhead is the result of two parameters: data and routing packets. Therefore, when the PLR increases, the number of successfully delivered data packets drops. Therefore, the routing overhead ratio increases. Additionally, the routing protocol has to go through the routing discovery phase in case of link failure, which produces more routing packets. The TMR has the lowest routing overhead in Figure 31, which proves the throughput and PLR result. With increasing mobility speed, the ISR and QMR routing overhead is distinguishable from TMR. Figure 28: Comparison of QMR, ISR, and proposed protocol TMR for throughput with mobility speed. Figure 29: Comparison of QMR, ISR, and proposed protocol TMR for PLR with mobility speed. Figure 31: Comparison of QMR, ISR, and proposed protocol TMR for routing overhead with mobility speed. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Speed** & **QMR** & **ISR** & **TMR** \\ \hline
10 & 0.92 & 0.89 & 0.85 \\
15 & 1.05 & 0.99 & 0.9 \\
20 & 1.24 & 1.12 & 1.01 \\
25 & 1.39 & 1.22 & 1.07 \\
30 & 1.62 & 1.36 & 1.19 \\
35 & 1.79 & 1.51 & 1.33 \\ sum & 8.01 & 7.09 & 6.35 \\ saving (\%) & 26.1 & 11.7 & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Mobility speed vs. end-to-end delay of Figure 30.

Figure 30: Comparison of QMR, ISR, and proposed protocol TMR for end-to-end delay with mobility speed. #### 5.3.3 Assessment of the Simulation Results Based on Number of Nodes

The network connectivity depends on the number of nodes in each area. Therefore, when the number of nodes increases, the network is more connected.