Algorithm 1 Trajectory Planning Algorithm for Problem (P3).

1:Initialization: Initial trajectory of the base station UAV is $Q_U^0$, initial value of energy efficiency $\mu =0$, maximum threshold $ϵ>0$, and number of iterations $r=0$. 2:Solve problem (P2.3) given UAV trajectory $Q_U^r$ and system secret energy efficiency value $\mu$, and obtain optimal solutions $Q_U^{*}$, ${\eta }^{*}$, and $z_I^{1\left(*\right)},z_I^{2\left(*\right)},X_I^{*},Y_I^{*},{\phi }_U^{*},\mathrm{and}{{\omega }^{*}}_I$. 3:Calculate ${\eta }^{*}-\mu E_{\mathrm{total}}^{*}$. If ${\eta }^{*}-\mu E_{\mathrm{total}}^{*}<ϵ$, then the algorithm converges, obtains the optimal solution, and outputs $Q_U^{*}$, ${\eta }^{*}$, $z_I^{1\left(*\right)},z_I^{2\left(*\right)},X_I^{*},Y_I^{*},{\phi }_U^{*},{{\omega }^{*}}_I$. Otherwise, continue with steps 4–5. 4:Make ${\mu }^{*}=\frac{{\eta }^{*}}{E_{\mathrm{total}}^{*}}$, update parameters $\mu ={\mu }^{*}$, and update UAV trajectory $Q_U^{r+1}=Q_U^{*}$. 5:Update the number of iterations $r=r+1$. Then, execute step 3 again to check whether the algorithm converges.