# Coverage Area Decision Model by Using Unmanned Aerial Vehicles Base Stations for Ad Hoc Networks
## 3 Proposed UAVs-BS Network Coverage Model  
Cellular network coverage is always a challenge due to congested networks and the increased trend of users. Unmanned aerial vehicles (UAVs) in cellular networks have offered a reasonable solution to address the coverage issue. These networks use UAVs as a base station (BS) to improve cellular network coverage. With many positive features, these types of solutions have suffered from some constraints related to installation, optimization with the network, scalability, and link quality issues. Environmental factors have also affected UAV services and performance. The UAVs are controlled and managed for reallocation and position change per requirements. The UAVs have high line-of-sight (LoS), which makes them more realistic for the ground networks. The UAVs-BS is a more feasible solution for ground network users for providing the services and coverage and fulfilling the network requirements. The challenging task of UAVs is finding the optimal position in the microcell. The UAVs-BS is one of the flexible and low-cost solutions to improve the ground network \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**S\#**} & \multirow{2}{*}{**Ref.**} & \multicolumn{2}{c}{**Drone Placement**} & \multicolumn{3}{c}{**Drone Parameter**} & \multicolumn{3}{c}{**Placement Approach**} \\ \cline{3-10}  & & **Initial** & **Repositioning** & **User Density** & **Energy** & **Spectral Efficiency** & **Drone** & **Centralized** & **Distributed** & **Transit Mechanism** \\ \hline \hline \multicolumn{1}{c}{} & \multicolumn{1}{c}{**A Multitude of Done Base Stations**} & & & & & & & & & \\ \hline \hline \multirow{2}{*}{1} & 3D Placement of Drone [24] & \(\times\) & \(\surd\) & \(\surd\) & \(\surd\) & \(\times\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \hline \multirow{2}{*}{2} & Dynamic Base Station [26] & \(\times\) & \(\surd\) & \(\times\) & \(\surd\) & \(\times\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \hline \multirow{2}{*}{3} & Emergency Ad Hoc [8] & \(\surd\) & \(\times\) & \(\surd\) & \(\surd\) & \(\times\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \hline \multirow{2}{*}{4} & Backhaul-Aware [28] & \(\times\) & \(\times\) & \(\surd\) & \(\times\) & \(\times\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \hline \multirow{2}{*}{5} & User Association and & & & & & & & & & & \\  & Bandwidth Allocation & \(\times\) & \(\surd\) & \(\times\) & \(\times\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \cline{1-1}  & Model [29] & & & & & & & & & & \\ \hline \multirow{2}{*}{6} & IoT Connectivity in & & & & & & & & & & \\  & Radar Bands [30] & \(\times\) & \(\surd\) & \(\times\) & \(\times\) & \(\surd\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \hline \multirow{2}{*}{7} & Aerial-Terrestrial & & & & & & & & & & \\  & Communications In & \(\surd\) & \(\times\) & \(\times\) & \(\times\) & \(\surd\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \hline \multirow{2}{*}{8} & UAV-Assisted & & & & & & & & & & \\  & Heterogeneous Model & \(\times\) & \(\surd\) & \(\times\) & \(\times\) & \(\surd\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \cline{1-1}  & [35] & & & & & & & & & & \\ \hline \multirow{2}{*}{9} & Solar Energy & & & & & & & & & & \\  & Harvesting [38] & \(\surd\) & \(\times\) & \(\times\) & \(\times\) & \(\surd\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \hline \multirow{2}{*}{10} & SDN based & & & & & & & & & & \\  & managing topology & \(\surd\) & \(\times\) & \(\times\) & \(\times\) & \(\surd\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \cline{1-1}  & formation [39] & & & & & & & & & & \\ \hline \multirow{2}{*}{11} & Leveraging & & & & & & & & & & \\  & Communicating UAVs & \(\times\) & \(\surd\) & \(\surd\) & \(\times\) & \(\surd\) & \(\surd\) & \(\surd\) & \(\times\) & \(\times\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Technical comparison of discussed studies. connectivity and provide high data rate services.