# FANET Routing Protocol Analysis for Multi-UAV-Based Reconnaissance Mobility Models
## 6 Discussion
### Remaining Issues  
There are four remaining issues that we have not experimented with yet. The first issue is an energy-efficient analysis, the second issue is an analysis of the altitudes of UAVs, the third issue is an analysis of different routing protocols, and the last issue is an analysis of the physical characteristics of UAVs. When it comes to the first issue, a flying ad hoc network (FANET) requires an energy-efficient routing protocol due to the limited battery life of unmanned aerial vehicles (UAVs). In FANETs, UAVs communicate with each other without centralized infrastructure support. Therefore, the energy efficiency of routing protocols is critical to the overall performance and longevity of the network. There are routing protocols that are energy-inefficient and energy-efficient. Energy-inefficient routing protocols may waste energy by selecting paths that are not optimal in terms of energy consumption. It can rapidly deplete battery life, leading to UAV failures and network outages. Energy-efficient routing protocols can choose a route that minimizes energy consumption while maintaining network connectivity. It can extend a UAV's battery life. Overall, energy-efficient routing protocols are essential to the successful operation of FANETs and can significantly improve the reliability and longevity of networks. To evaluate the performance of FANET routing protocols in terms of energy efficiency, we need to consider several factors, such as the residual energy of a UAV, the distance between nodes, and the quality of the communication link. We leave such an evaluation as future work. When it comes to the second issue, the choice of altitude for a reconnaissance mission depends on a number of factors such as objectives, threat environment, and capabilities of the reconnaissance UAVs. If a UAV operates at a higher altitude, the UAV's camera has a wider field of view and can observe a larger area. However, lower image resolution can make it more difficult to identify specific objects. On the other hand, if a UAV operates at a lower altitude, the UAV's camera may provide a better image resolution. Furthermore, we need to consider the risks of UAVs being detected by air defense systems or enemy forces. We have not experimented with the diversity of altitudes, leaving it as future work. When it comes to the third issue, there are continuously evolving technologies such as hierarchical swarm scenarios [37] and hybrid routing methods of topology-based routing and geocast routing [28]. As a different direction from the topology-based routing protocols used in this paper, we can set up a new reconnaissance scenario with such technologies. With swarm scenarios, various reconnaissance scenarios could be identified. For example, a reconnaissance scenario in which a fixed wing flies at a high altitude and a rotary wing performs a mission at a lower level could be possible. In this case, we can consider forming a hierarchical network according to the operating altitudes of UAVs. In another case, such as geocast routing, we can consider routing protocols using GPS information maintained by UAVs for various reconnaissance scenarios. When it comes to the last issue, the physical aspects of a UAV can affect its performance in reconnaissance scenarios. In reconnaissance scenarios, UAVs are used to collect information about a target or area of interest. The UAV's physical characteristics can affect its ability to perform this effectively. For example, the size, shape, and color of a UAV can affect its ability to covertly collect information without being detected. A UAV's propulsion system and battery life can affect its ability to stay in the air for a long period of time and cover a large area. A UAV's payload capacity can also affect the determination of the type and the number of sensors or cameras it can carry to collect information. A UAV's weight and aerodynamics can affect its stability and maneuverability, which are essential for capturing high-quality images.