## 4 Research Methodology
### Search and Rescue Simulation Environment  
The primary application of this simulation study is a SAR operation in which a group of UAVs randomly explores a defined zone in search of a target. The ground base station is located at the edge of the simulation area, which can be found on top of Figure 3. One of the primary objectives of SAR is to search for and report the discovery of catastrophe victims [30; 31]. In this situation, the search is carried out by UAVs, which scan the whole \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No** & **Protocol Name** & **Main Feature** & **Technique** & **Route Selection** \\ \hline
1 & OLSR [9] & It uses MPRs to reduce the routing overhead. & The neighbor node selects 1-hop MPRs that cover 2-hop nodes. & The route is selected based on a short path using the Dijkstra algorithm. \\ \hline
2 & D-OLSR [26] & UAV is equipped with a directional antenna. & UAVs measure the distance to the destination, then use a directional or omni-directional antenna to select MPRs. & The route is selected based on the shortest path using the Dijkstra algorithm. \\ \hline
3 & ML-OLSR [27] & Added load-aware and mobility-aware algorithms to the original OLSR protocol. & The mobility-aware algorithm considers SDN and RDN metrics. The load-aware algorithm is based on the load of UAV in the MAC layer and neighbors UAV. \\ \hline
4 & P-OLSR [28] & It predicates the quality of wireless links between UAVs. & Utilize existing GPS data on board and multiply the expected transmission count (ETX) parameter by a formula that considers the direction and relative speed of the UAVs. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Similarities and differences between standard and modified OLSR protocols. region on a frequent basis. The UAVs are planned to include a straight-down camera that captures a rectangular area centered on the UAV to collect data. The UAV took pictures of the target and transmitted them to the base station so law enforcement could process them and locate the victims for prospective rescue teams. Neighboring UAVs become the relay. Figure 4 depicts the search and rescue mission considered in this paper. NS-3 simulator version 3.32 [32] was used during the simulation process with the implementation of OLSR and modified OLSRs using Gauss Markov (GM) as the UAV's mobility model [33]. We chose the GM mobility model because it supports three dimensions of flying for UAVs during the simulation, and the NS-3 simulator includes a model for GM. For the simulation, we assumed the use of a rotary UAV, also known as a quadcopter, such as the DJI Matric 210. They can fly in all directions, take off and land vertically, and hold a stationary position in the air during the SAR. A configurable number of UAVs are dispersed randomly over the simulated region because the location of the target is unknown, so the UAV needs to search the entire area and perform Monte Carlo searches. A UAV node involved in a packet transfer might take on the role of a multi-hop wireless router or the target UAV. To impose longer paths among UAVs than a square simulation area with such a similar UAV density would, a rectangle simulation field (3 \(\times\) 1.5 km) was deployed. A simulation time of 600 s was selected as it provided enough time to reach stationary behavior. The purpose of this network design is to examine how performance is impacted by UAV mobility and density. User Datagram Protocol (UDP) was considered in this simulation as it transports data packets faster than other transport protocols, such as TCP. Further, UDP does not need to establish three-way handshakes, thus providing a minimum delay, which is required in real-time applications. Being connectionless, UDP can also broadcast packets to be received by all devices on the subnet. The packet transmission rate was set to 4 packets/sec. During the simulation, considering certain points as targets (victims), whenever a UAV comes to this location and discovers it, it only begins to transfer packets to the base station.