## 2 UAV-Enabled ITS Framework
### Second Layer: Communication Networks for Traffic Monitoring
#### 2.2.1 Communication Networks
UAVCN design considerations are often dynamic and require a higher level of coordination, making the system highly complex. The following factors must be considered while designing a UAV network to avoid unwanted interruptions during the mission. * Mobility: UAV networks often have high node mobility and speed, which could result in several communication design challenges. The degree of mobility of UAVs would vary depending on the application. For disaster management, the UAVs would fly over the designated area and provide communication at a slow or dynamic speed. On the other hand, the UAVs could cover a large area with more dynamic links while used for surveillance. * Adaptability: UAV network parameters can be changed considering the applications and circumstances. UAV networks should be able to adapt to common changes, such as the locations of the UAVs, the distance between UAVs, and the routes. Moreover, UAV networks are often affected by unexpected weather changes. In most applications, UAV networks need to adjust to any of these changes. * Reliability: UAV networks are vulnerable to various natural phenomena or human attack, which can diminish performance. To withstand such attacks, UAV networks need to be robust and reliable, and reliability depends on the application-specific parameters. Comprehensive analyses, delay-tolerant functionalities, and recovery algorithms are required to ensure high reliability in the network. Moreover, the degree of reliability of UAV networks could also vary depending on the task. * Scalability: UAV networks should be highly scalable to allow the addition or subtraction of UAVs with minimal restoration and reorganization costs. The scalability of a UAV network depends on both the nodes and the resources. The scalability of UAV networks could be increased by hiding any obstacles around the coverage area and adding more relay nodes. * Bandwidth requirements: The bandwidth of a communication system should align with the transfer rate requirements of the UAV's specific application. ITS applications that involve high-resolution video streaming, real-time data transfer, or complex sensor data generally require higher bandwidth to function effectively. * Power consumption or Energy considerations: UAV network power depends on the UAV's energy source. Most UAVs are battery-operated with a limited energy source. A mission's power consumption significantly impacts the network's lifespan. Therefore, designing an energy-efficient network configuration is essential to ensure longevity and optimal performance. * Coverage: The design of a UAV system must ensure comprehensive area and network coverage within budget and time limits. This includes accounting for the UAVs' movement patterns to avoid gaps in monitoring and maintain reliable communication. An adequate coverage design balances operational needs with constraints to optimize performance. * Security and Privacy: UAV networks can be viewed as cyber-physical systems (CPSs) because they integrate physical components (such as sensors and actuators) with digital systems (such as communication equipment and the internet). Securing the data and providing the user with the required privacy is challenging. The variety of components adds to the network's complexity, making it more vulnerable to potential security issues. \begin{table}
\begin{tabular}{c c c} \hline
**Features** & **Single-UAV System** & **Multi-UAV System** \\ \hline Control Complexity & Low & High \\ Cost & Medium & Low \\ Survivability & Poor & High \\ Failure Impact & High & Low \\ \hline \end{tabular}
\end{table} 
Table 2: Cont.