## 5 Performance Evaluation
### Numerical Results  
In this subsection, we present illustrative simulation results for the achievable performance of the proposed HPA-SR protocol approach. In particular, we set in the simulations parameter as shown in Table 4. We use the NS3 simulation program, where the algorithm is run with 200 s with 5 s each sessions. The simulation results in every figure are obtained with an average of 40 independent session. To illustrate the effectiveness of suggested algorithm (HPA-SR with ASCS), we will compare the performance of the suggested algorithm with AODV protocol (with or without combining ASCS clustering protocol). \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Value** \\ \hline Simulator & NS3 \\ Simulation area & 1000 \(\times\) 1000 m\({}^{2}\) \\ Packet size & 1024 bits \\ Mobility model & Group Mobility \\ Radio range & 250 m \\ Simulation time & 200 s \\ Session length & 5 s \\ Number of nodes & [30, 50, 100] \\ Node’s Speed Range & [20:20:80] (km/h) \\ Receive signal strength indicator (RSSI) threshold & \(-80\) dBm \\ MAC protocol & 802.11a \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Simulation Environments and Parameters. Figure 7 represents the comparison of the average number of cluster head changes in each session as a function of node speed to evaluate cluster stability. As can be seen in Figure 7, when the node speed increases, the average number of cluster head change is increased. One of possible reasons is that when the node speed is increased, the node location is changed frequently, which causes the broken of clustering. In addition, when the number of node in the network increases, the average number of cluster head change is increased. It can be explained as when the density of networks increase, the cluster head is changed. Nevertheless, the average number of cluster head change is less than one. It means that the number of cluster head change is less than one in each session. Thus, the proposed clustering is very stable. Figure 8 shows the comparison of the packet delivery ratio as a function of node speed. As can be seen in Figure 8, when the node speed increases, the packet delivery ratio is decreased. One of the possible reasons is that when the node speed is increased, the entire network becomes more unstable and dynamic as velocity reaches higher values, which causes packet loss. However, we can notice that the decrease in packet delivery ratio is significantly less in the case of HPA-SR with ASCS (HPA-SR+ASCS) protocol than in other cases. Thus, HPA-SR with ASCS protocol proved to be the most reliable in terms of packet delivery ratio. Figure 8: PDR as a function of node speed with difference scenarios. Figure 7: Average number of the cluster head change as a function of node speed. Figure 9 presents the comparison of the routing delay including latency time for cluster construction per session as a function of node speed. As can be seen in Figure 9, the pattern of routing delay is shown to increase when the node speed increases. This result can be explained as the route establishment spending more time because the node moves more dynamically. However, the proposed HPA-SR with ASCS (HPA-SR+ASCS) protocol only involves the CH and GW nodes to determine the route to be traversed by the packet. Thus, the HPA-SR+ASCS protocol can send packets with a minimum delay compared to other protocols. Figure 10 represents the comparison of the control overhead including the control overhead for cluster construction per node per session as a function of node speed. As shown in Figure 10, when the speed increases, the control overhead is increased little bits, but not significant. One of the possible reasons is that if node speed increases, the distance is increased, which causes the need for more packets to establish the route. However, ASCS clustering protocol can reduce the control overhead in our proposed routing protocol compared with other cases.