## 2 Applications of U-WSN
### Functionalities of UAV as a Communication Node  
In WSN applications, one of the objective is to obtain meaningful information through sensors deployed in the region of interest. Traditionally, the data gathering issues were implemented in multi-hops in which the sensors that are closer to the base station will selected as the relay nodes for those sensors that deployed far away from the base station. As a result, these relay nodes consume energy much faster than other nodes. As the network connectivity depends on these relay nodes, this will result in a shorter network life-time. To address these issues, mobile vehicles were introduced.  
Generally, it has limited conditions, such as limited velocity, and obstacles due to actual movement environment, when the mobile vehicles move on the ground. It would be  
\begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Category** & **Mass (kg)** & **Range (km)** & **Flight alt. (m)** & **Endurance (h)** \\ \hline Micro & \(<\)5 & \(<\)10 & 250 & 1 \\ Mini-UAV & \(<\)20/25/30/150 1 & \(<\)10 & \(150/250/300\) & \(<\)2 \\
**Tactical** & & & & \\ Close range (CR) & 25–150 & 10–30 & 3000 & 2–4 \\ Short range (SR) & 50–250 & 30–70 & 3000 & 3–6 \\ Medium range (MR) & 150–500 & 70–200 & 5000 & 6–10 \\ MR endurance (MRE) & 500–1500 & \(>\)500 & 8000 & 10–18 \\ Low altitude deep penetration (LADP) & 250–2500 & \(>\)250 & 50–9000 & 0.5–1 \\ Low altitude long endurance (LALE) & 15–25 & \(>\)500 & 3000 & \(>\)24 \\ Medium altitude long endurance (MALE) & 1000–1500 & \(>\)500 & 3000 & 24–48 \\
**Strategic** & & & & \\ High altitude long endurance (HALE) & 2500–5000 & \(>\)2000 & 20,000 & 24–48 \\ Stratospheric (Strato) & \(>\)2500 & \(>\)2000 & \(>\)20,000 & \(>\)48 \\ Exo-stratospheric (EXO) & TBD & TBD & \(>\)30,500 & TBD \\
**Special task** & & & & \\ Unmanned combat AV (UCAV) & \(>\)1000 & 1500 & 12,000 & 2 \\ Lethal (LET) & TBD & 300 & 4000 & 3–4 \\ Decoys (DEC) & 150–250 & 0–500 & 50–5000 & \(<\)4 \\ \hline \hline \end{tabular}
\end{table}
Table 1: UAV categorization for differentiation of existing systems.  
\begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Number** & \(T_{GI}\)**a** & **MTOW** & **Name** & **Note** \\ \hline
0 & \(10^{2}\) & Less than 1 kg & Micro & Most countries do not regulate this category since these vehicles pose minimal threat to human life or property \\
1 & \(10^{3}\) & Up to 1 kg & Mini & These two categories roughly correspond to R/C model aircraft \\
2 & \(10^{4}\) & Up to 13.5 kg & Small & Airworthiness certification for this category may be based either on ultralights (FAR b bpart 103), LSA c (Order 8130), or even normal aircraft (FAR Part 23) \\
4 & \(10^{6}\) & Up to 4332 kg & Normal & Based on MTOW these vehicles correspond to normal aircraft (FAR Part 23) \\
5 & \(10^{7}\) & Over 4332 kg & Large & These vehicles best correspond to the transport category (FAR Part 25) \\ \hline \hline \end{tabular}  
* a \(T_{GI}\) is the minimum time between ground impact accidents. b Federal Aviation Regulations. c Light Sport Aircraft.  
\end{table}
Table 2: Classifications of UAVs based on the MTOW and the ground impact risk.  
a huge challenge if the traditional mobile vehicles are used in specific applications that are dangerous for human participation. Thus, UAV which has high extensive and flexible and do not need human on board, is a better choice in these similar applications. In this section, we will analyze and study the functionalities of UAV when it works as a communication node in WSN.  
As previously described, UAV has been extensively applied in many areas. In this section, we analyze the existing applications and propose the main functionalities of the UAV in WSN.