# Cooperative Friendly Jamming Techniques for Drone-Based Mobile Secure Zone
## 3 Friendly Jamming Technique  
Equation (1) shows the information leakage rate (ILR) metrics defined for use as performance evaluation metrics of friendly jamming. The relationship between the bit error rate (BER) and friendly jamming was defined using the ILR. If the BER exceeds 0.5, then the ILR is 0, indicating that it is impossible to extract information because the BIR is high [24; 25; 26]. By contrast, if the BER is less than or equal to 0.5, then information extraction is possible, and ILR has a value greater than or equal to 0. As the ILR increases, the security decreases, indicating that more information can be extracted.  
\[\text{ILR}=0,\text{ if BER}>0.5\text{ILR}=1-\frac{\text{BER}}{0.5},\text{ if BER}\leq 0.5 \tag{1}\]  
Figure 1 shows the network configuration for verifying the security performance of friendly jamming. Figure 1a shows a friendly jamming technique model, which uses an open channel to send data (\(h_{sd}^{*}\)) to the sender node (Source, S) or receiver node (Destination, D) that uses a single antenna. Here, the eavesdropping device (Eve, E) also receives the data (\(h_{se}^{*}\)). A drone (Jammer, J) located near the source node transmits friendly jamming signals (\(h_{je}^{*}\)) to form a jamming zone. The eavesdropping quality of the eavesdropping device in the friendly jamming zone deteriorates as an effect of jamming, reducing the possibility of eavesdropping.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Paper Title** & **Research Topic** & \begin{tabular}{c} **Number of** \\ **Jammers** \\ \end{tabular} & **Main Idea** & **Limitation** \\ \hline UAV-enabled friendly jamming scheme to secure industrial Internet of Things & \begin{tabular}{c} Eavesdropping, \\ Internet of Things, \\ unmanned aerial \\ vehicles \\ \end{tabular} & Multiple & \begin{tabular}{c} Unmanned aerial \\ vehicles (UAV)-enabled \\ friendly jamming scheme \\ \end{tabular} & Need to study the optimal number of jammers \\ \hline A jamming approach to enhance enterprise Wi-Fi secrecy through spatial access control [16] & \begin{tabular}{c} Eavesdropping, \\ Wi-Fi networks \\ \end{tabular} & Multiple & \begin{tabular}{c} Defensive jamming \\ approach in Wi-Fi \\ networks secured by the WPA2 enterprise \\ mode \\ \end{tabular} & Need to study friendly jamming techniques in a mobile environment \\ \hline Achieving physical layer security with massive MIMO beamforming [17] & \begin{tabular}{c} Antenna arrays, \\ beamforming, \\ cylindrical arrays, \\ massive MIMO \\ \end{tabular} & Single & \begin{tabular}{c} Beamforming with \\ large cylindrical \\ antenna arrays \\ \end{tabular} & Need to study appropriate \\ \hline Friendly jammer against an adaptive eavesdrop in a relay-aided network [14] & \begin{tabular}{c} Relay-aided \\ single-input network, \\ adaptive eavesdropping, \\ outage probability \\ \end{tabular} & Single & \begin{tabular}{c} Simulations for \\ improvement in the \\ secrecy capacity and \\ SOP performances \\ owing to the presence \\ of friendly jamming \\ \end{tabular} & Need to study improved \\ \hline Friendly jamming for wireless secrecy [12] & \begin{tabular}{c} Cooperative jamming, \\ jamming coverage, \\ jamming efficiency, \\ eavesdropping \\ \end{tabular} & Single & \
\begin{tabular}{c} Cooperative/friendly \\ jamming on the secrecy \\ outage probability of a \\ quasi-static wiretap \\ fading channel \\ \end{tabular} &
\begin{tabular}{c} Need to study friendly \\ jamming techniques in a mobile environment, \\ mobile environment, \\ and the optimal number of \\ and the optimal number of \\ and the optimal number of \\ and the optimal number \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of prior studies on friendly jamming.