# Cooperative Friendly Jamming Techniques for Drone-Based Mobile Secure Zone
## 5 Experiment
### Simulation
#### 5.1.2 Evaluation Environments
First, the signal that the destination node receives from the source node in Equation (3) can be expressed based on the distance between the source and destination nodes (\(h_{sd}^{*}\)), the distance between the jammer drones and the destination node (\(h_{jl}^{*}\)), the maximum transmission power of the receiver (\(P_{s}\)), the maximum transmission power of the jammer drones (\(P_{j}\)), and the noise (\(n_{d}\)) [28]:  
\[y_{e}=G\sqrt{P_{s}}h_{sd}^{*}s+\sqrt{P_{j}}\ h_{jl}^{*}q+n_{d} \tag{3}\]  
where the channel coefficient \(h\) is shown by Equation (4). In addition, \(d\) is the distance between the two communication nodes, \(e\) is a uniformly distributed random number \(a+bi\), and \(c\) is the path loss exponent. \[h=(d)^{\frac{-c}{2}}e \tag{4}\]  
The amplification scale vector \(G\) can be shown through Equation (5), where \(N\) refers to the Gaussian noise. \[G=\frac{1}{\sqrt{P_{s}\left|h_{sd}^{*}\right|^{2}+N}} \tag{5}\]  
Finally, the signal received by the eavesdropper in Equation (6) can be represented by the distance between the source node and the eavesdropper (\(h_{se}^{*}\)), the distance between the jammer drones and the eavesdropper (\(h_{je}^{*}\)), the maximum transmission power of the receiver (\(P_{s}\)), the maximum transmission power of the jammer drones (\(P_{j}\)), and the noise (\(n_{d}\)). \[y_{e}=G\sqrt{P_{s}}h_{se}^{*}+\sqrt{P_{j}}h_{je}^{*}q+n_{e} \tag{6}\]  
For the BER of the eavesdropper node in each experiment, we used an average of 1000 times, as shown in Equation (7). In Figure 4a,c, where there is no jamming signal, \(G\sqrt{P_{j}}h_{je}^{*}*JamSymbols\) is calculated as zero. \[y_{e}=G\sqrt{P_{s}}h_{se}^{*}*\ TrsutSymbols+G\sqrt{P_{j}}h_{je}^{*}*JamSymbols \tag{7}\]  
Table 4 shows the definitions of the parameters used in the simulation pseudo-code, and Algorithm 1 shows the simulation pseudo-code itself. The detailed operating principle of Algorithm 1 is as follows. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Case** & **Figure 4a** & **Figure 4b** & **Figure 4c** & **Figure 4d** \\ \hline Mobility & X & X & O & O \\ friendly jamming & X & O & X & O \\ Source-Destination distance (m) & 48.413 & 48.413 & 2 & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Environment setting of Figure 4.  
In line 1-5, the distance between the jamming drones and eves is measured, and the measured distance is used for the influence of jammer on eve. Line 6 refers to the number of simulation repetitions, and the average BER is evaluated by repeating 1000 times. The c of line 7 is the path loss index and is used to evaluate the channel coefficient. Line 8-24 is a function of calculating the average BER of the eavesdropper and is repeatedly performed by a value specified in line 6. This function receives the size of data to be transmitted, the path loss index, the maximum source power of jammer, and the distance between source node and eavesdropper, source node and destination node, and jammer and receiver as parameters. The e of line 10 is a random number in the form of a complex number and is used to evaluate the channel coefficient. In line 11-13, channel coefficients are calculated using c and e. The G of line 14 is a scaling coefficient amplified according to the distance between the source node and the destination node. In line 15-16, 0 and 1 are randomly generated as the size of the data to be transmitted and then mapped in a complex number form. In line 17-18, data to be used as jamming signals are randomly generated and then mapped in complex number form. Line 19 refers to a signal received by the eavesdropper, and line 20 refers to the bit formed as signals. In line 21, the BER is calculated using the