# Mobile Network Performance and Technical Feasibility of LTE-Powered Unmanned Aerial Vehicle
## 3 Aerial Channel Model  
The propagation condition and consequently the channel characteristics between BSs and UAVs are dramatically different with BSs and terrestrial UEs; one of the main differences is the _LOS_ or _NLOS_ propagation conditions. In this section, we present the large-scale path loss characteristics of communications channel between BS and drones and a complete characterization of propagation channel is out of the scope of this paper. It is highly beneficial to consider the large-scale characteristics of the propagation channel for understanding and analyzing the actual behavior of the communication link between BSs and drones. The propagation condition of _LOS_ and _NLOS_ can be determined based on _LOS_ probability, which is a function of heights and distance of transceivers. From the 3 GPP [44] the _LOS_ probability, \(P_{LOS}\), for aerial UEs (drones) in urban-macro scenario is given as,  
\[P_{LOS}=\left\{ \begin{array}{lcl}1&,&d_{2D}\leq 18\text{m}\\ \big{[}\frac{18}{d_{2D}}+\exp\Big{(}-\frac{d_{2D}}{68}\Big{)}\Big{(}1-\frac{1 8}{d_{2D}}\Big{)}\big{]}\Big{[}1+C^{\prime}(h_{UT})\frac{5}{4}\Big{(}\frac{d_{ 2D}}{186}\Big{)}^{3}\exp\Big{(}-\frac{d_{2D}}{186}\Big{)}^{3}\exp\Big{(}-\frac {d_{2D}}{186}\Big{)}^{3}\\ \end{array} \right.&,&d_{2D}\leq 18\text{m}\\ \end{array}\right. \tag{1}\]  
\[P_{LOS}=\left\{ \begin{array}{lcl}1&,&d_{2D}\leq d_{1}\\ \frac{d_{1}}{d_{2D}}+\exp\Big{(}\frac{-d_{2D}}{p_{1}}\Big{)}\Big{(}1-\frac{d_ {1}}{d_{2D}}\Big{)}&,&d_{2D}>d_{1}\\ \end{array} \right. \tag{2}\]  
\[P_{LOS}=1\quad 100\text{ m}<h_{UT}\leq 300\text{ m} \tag{3}\]  
where, \(d_{2D}\) is the horizontal distance between UAV and BS, \(h_{UT}\) is the height of drone, and  
\[C^{\prime}(h_{UT})=\left\{ \begin{array}{lcl}0&,&h_{UT}\leq 13\text{ m}\\ \Big{(}\frac{h_{UT}-13}{10}\Big{)}^{1.5}&,&13\text{ m}<h_{UT}\leq 22.5\text{ m}\\ \end{array} \right. \tag{4}\]  
\[p_{1}=4300\log_{10}(h_{UT})-3800\]  
\[d_{1}=\max(460\log_{10}(h_{UT})-700,18)\]  
Figure 9: Mapped waypoint for feasibility test. According to the above equations, the \(P_{LOS}\) for drone height up to 22.5 m is similar to terrestrial UEs in [45], and by increasing height to 100 the \(P_{LOS}\) will be increased and for height above 100 m the \(P_{LOS}\) is about 100%, which means the direct ray between transceivers is clear of obstacles. For modeling the path loss between drone and BS, information such BS height, \(h_{BS}\), drone height, 2D and 3D distances, as shown in Figure 10, are need to be known. From the 3 GPP [44] the path loss model for aerial UEs is given as:  
\[PL_{LOS}=\left\{ \begin{array}{cc}PL_{1},\ 10\ m\leq d_{2D}\leq d^{\prime}_{BP} &\\ PL_{2},\ d^{\prime}_{BP}\leq d_{2D}\leq 5\ \text{km}&\\ PL_{1}=28+22\log_{10}(d_{3D})+20\log_{10}(f_{c})&1.5\ \text{m}<h_{UT}\leq 22.5\ \text{m}\\ PL_{2}=28+40\log_{10}(d_{3D})+20\log_{10}(f_{c})&\\ -9\log_{10}\Bigl{(}\bigl{(}d^{\prime}_{BP}\bigr{)}^{2}+(h_{BS}-h_{UT})^{2} \Bigr{)}&\\ PL_{LOS}=28+22\log_{10}d_{3D}+20\log_{10}(f_{c})&\begin{array}{c}22.5\ \text{m}<h_{UT}\leq 300\ \text{m}\\ d_{2D}\leq 4\ \text{km}\end{array}\\ \end{array} \right. \tag{5}\]  
\[PL_{NLOS}=\max\bigl{(}PL_{LOS},PL^{{}^{\prime}}_{NLOS}\bigr{)},\ for\ 10\ m\leq d_{2D}\leq 5\ \text{km}\]  
\[PL^{{}^{\prime}}_{NLOS}=13.54+39.08\log_{10}(d_{3D})+20\log_{10}(f_{c}) &1.5\ \text{m}<h_{UT}\leq 22.5\ \text{m}\\ -0.6(h_{UT}-1.5)&\\ PL_{NLOS}=-17.5+\bigl{(}46-7\log_{10}(h_{UT})\bigr{)}\log_{10}d_{3D}+20\log_{1 0}\Bigl{(}\frac{40\pi f_{c}}{3}\Bigr{)}& \begin{array}{c}10\ \text{m}<h_{UT}\leq 100\ \text{m}\\ d_{2D}\leq 4\ \text{km}\end{array} \\ \end{array} \tag{6}\]  
where, \(f_{c}\) is the carrier frequency, \(d^{\prime}_{BP}\) is..., \(PL_{LOS}\) is LOS pathloss, and \(PL_{NLOS}\) is _NLOS_ pathloss. Large-scale pathloss is one of the most important factors for estimating the received signal power in a wireless system. The pathloss models in (5) and (7) are similar to terrestrial UEs in [45]. For the altitudes between 22.5 m and 100 m, where the drone is not in the _LOS_ of BS, the pathloss can be calculated based on (8).