## 4 Results and Discussion
### Packet Delivery Ratio  
In this section, the proposed solution is evaluated in terms of packet delivery ratio. The packet delivery ratio is evaluated in the presence of different IoT devices on the ground and the packet delivery ratio is observed when the UAVs' nodes collect the data from IoT devices. As seen in Figure 6, the proposed DR-UAVIoT protocol achieved a higher data delivery ratio as compared with the existing routing protocols, AODV and GyTAR. The proposed DR-UAVIoT protocol was designed for UAVs and IoT devices to collect the data especially when more nodes were present on the IoT network side. As a result, the AODV had a slightly better performance when the density of the nodes was around 150 nodes whereas the GyTAR performance dropped in the presence of 150 nodes compared with the AODV. We also noticed that when the number of IoT devices increased from 150 to 350 then the performance of the AODV dropped due to its routing table and topology information-sharing mechanism. On the other hand, the GyTAR performance was better due to its path selection strategy. The proposed DR-UAVIoT protocol is better in dense situations due to its control messages handling strategy by using RREQ and RREP. Figure 6 shows the packet delivery ratio of the proposed protocol compared with the existing solutions.  
\begin{table}
\begin{tabular}{c c c} \hline
**S\#** & **Parameters** & **Value** \\ \hline
1 & Network Size & 4 \(\times\) 4 Km \\
2 & Time & 900 s \\
3 & Mobility Model & SUMO \\
6 & Drone Speed & 0 to 60 Km/h \\
7 & Communication Range & 300 m for BS and 1000 m for UAVs \\
8 & Data size & 1 to 1024 B \\
9 & UAV Altitude & 200–500 Feet \\
10 & UAV Transmission Power & 35 dBm \\
11 & System Bandwidth & 10 MHz \\
12 & Active Users & 400 \\
13 & Number of Macro Cell Base Station & 10 \\
14 & MAC Type & IEEE 802.15.4 \\
15 & Channel Type & Wireless \\
16 & Traffic Source & CBR \\
17 & Antenna Type & Omnidirectional \\ \hline \end{tabular}
\end{table}
Table 1: Simulation Parameters.  
In the second experiment, again we evaluated the proposed protocol in terms of the packet delivery ratio with a different scenario. The packet delivery ratio was evaluated in the presence of different UAVs nodes' velocities in the sky when the UAVs' nodes were communicating with each other, such as UAV-to-UAV data communication. As seen in Figure 7, the proposed DR-UAVIoT protocol achieved a higher data delivery ratio compared with existing routing protocols AODV and GyTAR. The proposed DR-UAVIoT protocol is designed for UAVs and IoT devices to collect the data especially when more nodes are present on the IoT network side. As result, the AODV degraded its performance because this protocol was designed for static nodes and was not feasible for mobility parameters. Whereas the GyTAR performance was better in this parameter because it was designed for vehicular networks which have mobility factors as well. In the presence of 12 km per hour speed, the proposed solution achieved better results and dropped less packets as compared with the AODV and GyTAR. We also noticed, the UAV's velocity was increased so the packet delivery was better due to the UAV covering limited areas with more mobility and having more chances to achieve better results. On the other hand, the GyTAR performance was better due to its path selection and mobility support strategies. The proposed DR-UAVIoT protocol is better in velocities and node movement situations due to its RREQ and RREP strategy. Figure 7 shows the packet delivery ratio of the proposed protocol as compared with the existing solutions.  
Figure 6: Packet Delivery Ratio in the Presence of Different Number of IoT Devices.  
Figure 7: Packet Delivery Ratio in the Presence of Different UAVs Nodes Velocity.