## 4 UAV Communication Network and Technology  
### Communication Solution Models  
* Direct communication between UAV and control station  
Each UAV is connected to transmit data directly to the control station based on a star network structure [59] (Figure 15). This structure allows the network to maintain operation when one device fails by redistributing tasks among the remaining UAVs. Figure 15: Direct communication between UAV and control station. \begin{table}
\begin{tabular}{p{56.9 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Type** & **Ref.** & **Algorithm** & **Main Contribution** & **Advantage** & **Limit** \\ \hline \multirow{4}{*}{\begin{tabular}{} \end{tabular} } & \multirow{4}{*}{[55]} & \multirow{4}{*}{APAR} & Deployment in different application models of UAV networks & Route selection is based on calculations of perceived distance, congestion level, and route stability & Requires complex computation to maintain network information; latency can increase in dynamic networks \\ \hline \multirow{4}{*}{\begin{tabular}{} \end{tabular} } & \multirow{4}{*}{[56]} & \multirow{4}{*}{FLM-IACO} & \multirow{4}{*}{\begin{tabular}{} \end{tabular} } & Ability to find flight routes for UAVs at lower cost; safer and more energy efficient, even in complex terrain and high-threat environments & High computational complexity due to integration of fuzzy logic memory mechanism; performance depends on accuracy of interaction model and parameter setup \\ \hline \multirow{4}{*}{\begin{tabular}{} \end{tabular} } & \multirow{4}{*}{[57]} & \multirow{4}{*}{\begin{tabular}{} \end{tabular} } & UAV networks with high node mobility; dynamically changing network structure and movement in 3D space & Optimize FANET routing by adapting to high dynamics, improving efficiency compared to traditional algorithms & Depends on node density and distribution; performance degrades in sparse or highly mobile networks \\ \hline \multirow{4}{*}{\
\begin{tabular}{} \end{tabular} } & \multirow{4}{*}{[58]} & \multirow{4}{*}{IABC} & \multirow{4}{*}{
\begin{tabular}{} \end{tabular} } & Ability to create smooth, optimal flight paths for UAVs in complex urban environments by combining advanced optimization strategies & Complex in designing objective function and tuning parameters; requires large computational resources \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Prominent swarm-based routing algorithms. However, this system has some limitations, such as requiring bandwidth capacity for each UAV separately. Therefore, when the UAV fleet expands, the bandwidth demand will increase accordingly. At the same time, in a network model with only one control station, serious incidents can occur if the station fails or is attacked. * Satellite communication  
This method has a limited transmission/reception distance of only 1500 km in both ground and sky transmission (Figure 16). In certain missions, UAVs must operate in special areas. They are not able to communicate directly with control stations. Therefore, to ensure that the requirement of continuous connectivity in the UAV network is maintained, the satellite can act as an intermediate node to control the UAV. The advantage of this method is the ability to promote and exchange important information within the UAV network and distribute the collected data to the ground control station even when it is far apart [60]. * UAV communication over mobile networks  
The application of a cellular-based model is considered a safe and reliable approach for many civil and military applications. In this model, cells use different frequency bands to communicate with each other [50]. When cells are linked in a specific area, a signal coverage area is created, allowing UAVs to communicate directly with each other or with the ground control station (Figure 17). However, deploying cellular networks can be expensive, especially in areas with complex terrain. In addition, the system is vulnerable to attacks at fixed control stations, leading to partial or complete loss of control of UAVs in the network.