# Research on Multi-Strategy Routing Protocol in Flying Ad Hoc Networks
## 5 Experimental Results and Discussion
In terms of the average delay, AODV had significant growth, while greedy, PSO-GLFR, AntHocNet, and RGF had a little growth, among which RGF's growth was the smallest. In terms of the re-routing cost, RGF's cost was higher than that of AODV, and greedy's cost was the highest but basically stable. Figures 17-19 show the comparison experiments of each index of the five protocols under different node numbers. Figure 17 demonstrates that as the number of nodes in the network increased, the weaker the network sparsity became; therefore, the delivery rate for all protocols improved significantly. For ADOV, the increase in the number of nodes made the network less prone to segmentation and so improved the delivery rate, but the lack of location awareness and the high dynamics of the topology still left a significant number of packets unnecessarily lost during transmission, so the improvement to AODV was the smallest of the four protocols. For the greedy, GLFR, and AntHocNet routing protocols, the increase in the number of nodes reduced the probability of routing holes in the network, so that forwarding could  
be executed more smoothly, and the delivery rate was higher than that of AODV. RGF relied more on greedy forwarding to transmit packets in highly dynamic networks, so the improvement was similar to that of greedy. Because it could rely on projection face forwarding to jump out of routing holes, the final delivery rate was higher. As can be seen in Figure 18, the average delay of all protocols decreased significantly with an increase in the number of nodes, which is related to an increase in the delivery rate of these protocols. For AODV and greedy, the increase in the number of nodes allowed the existence of multiple paths to the destination node in the network, and even if the current route was broken, a new transmission path could be found, reducing the delay waiting in between due to the retransmission of control messages. For GLFR and AntHocNet, the increase in the number of nodes made packet forwarding less prone to encountering local minima, and route holes existed for shorter periods of time, thus reducing the waiting time for hole recovery and decreasing the latency. The increase in RGF with the number of nodes allowed the reactive mechanism to have the opportunity to establish more stable transmission paths, and greedy forwarding could be performed more smoothly. Figure 17: The effect of the number of nodes on the delivery rate. Figure 18: The effect of the number of nodes on the average delay. The variation in the routing overhead with the number of nodes is shown in Figure 19. With an increase in the number of nodes, the routing overhead grew rapidly for greedy, with almost no growth for AODV and only a small increase for RGF, GLFR, and AntHocNet. For AODV, since route discovery required the network-wide flooding of RREQs, the increase in the number of nodes led to an increase in the number of flooded RREQ messages in the network, but because the delivery rate also increased, the routing overhead remained essentially the same. For greedy, it was clear that the number of successfully received packets did not keep up with the number of control packets as the number of nodes increased due to the need to flood HELLO messages across the network, so the routing overhead increased the most. In contrast, GLFR, RGF, and AntHocNet did not require network-wide flooded HELLO messages, so the growth in the routing overhead was lower than that of greedy. The experimental results for node number changes are basically close to the results for the node speed changes. From the experimental results, it can be seen that RGF has obvious advantages over AODV, greedy, PSO-GLFR, and AntHocNet in terms of delivery rate, average end-to-end delay, and routing overhead in a three-dimensional high-dynamic topology, at a low density, and when there is an uneven distribution of nodes in the flight ad hoc network. In the high-speed and low-density scenarios, the RGF routing performance improved the communication ability of the FANET.