# VANET Clustering Based Routing Protocol Suitable for Deserts
## 6 Simulation and Results
### Results and Discussion
CBVRP outperforms AODV because of the store route as backup and built-in route maintenance (RM) properties, while in the case of AODV, the routing mechanism searches for a new route at every request and when a route failure has occurred. The use of RM increases the packet delivery ratio, saves route rediscovery flooding traffic and reduces overall route acquisition delay. The PDR is too low in the beginning of the curves due to the random initiation of the simulation program. Figure 15 shows a number of sent packets _versus_ end-to-end delay for CBVRP, AODV, CBRP and DSR. In the figure, we can observe that the average end-to-end delay of CBVRP is the best among the others. The packet delivery delay time is affected by the route search algorithm and the packet delivery process itself. CBVRP end-to-end delay is better than that of others because the CBVRP route search algorithm is done only once and remains stable until the cluster structure changes. This decreases the time needed for the whole process of packet delivery. AODV requires more time to establish a connection, and the initial communication required for finding a route is dense; however, it has no extra traffic for communication along existing links. For that reason, it has more advantage over DSR and CBRP, and its AD is less than that of DSR and CBRP; moreover, its AD decreases with time. Other protocols had a longer delay because the route finding process takes more time, as every  
Figure 14: PDR _versus_ numbers of vehicles for CBVRP, CBRP, DSR. Figure 15: CBVRP, CBRP and DSR number of sent packet _versus_ end-to-end delay for 20 vehicles. intermediate node tries to extract information before forwarding the reply, while the protocol tries to search for a new route. We also investigated the effect of the communication distance on the performance of the proposed routing protocol, and we compared it to AODV, CBRP and DSR. The results are shown in Figure 16. As is clear from the figure, the PDR performance deteriorated with the increase of distance. Meanwhile, the proposed protocol demonstrated a superior performance compared to the others. This result clearly indicates the suitability of this protocol for desert and similar scenarios. According to Figure 17, we noticed that the routing cost of CBVRP, AODV, CBRP and DSR increases with respect to the increase of the number of vehicles; this is because the increase in the number of vehicles directly increases the number of hops, thereby increasing congestion in the routing process. In the case of fewer vehicles, the CBVRP routing cost is more than CBRP and DSR, because in CBVRP, the initiation of the route finding process is very complicated. It takes more time in the initialization of the process. However, this calculation is done once and remains steady until the cluster structure changes. Hopefully, the increase in the number of vehicles will increase the opportunity of more backup routes in CBVRP, which enhances the route maintenance process. The AODV problem is that the increase of the  
Figure 16: The PDR of CBVRP, CBRP, AODV and DSR _versus_ the communication distance. Figure 17: CBVRP, CBRP, AODV and DSR routing cost _versus_ the number of vehicles. intermediate nodes can lead to inconsistent routes when the source sequence number is very old and the intermediate nodes have a higher, but not the latest destination sequence number, thereby having none existent or stale entries. In the case of more vehicles, CBRP and DSR have a higher routing cost, because they use a flooding approach with all of the vehicles to determine the destination route, while in CBRVP, only vehicles in the request cluster that have the capability of finding the destination are able to participate in the routing process.