# Advanced Security Framework for 6G Networks: Integrating Deep Learning and Physical Layer Security
## 2 System Model
### Simulation of Physical Layer Attacks  
In order to rigorously evaluate the robustness of the proposed PLS mechanisms, it is essential to simulate various attack scenarios. These scenarios are designed to reflect the types of threats that a 6G network might encounter. We focus on three primary types of attacks: jamming, eavesdropping, and spoofing. Each attack type is characterised by its unique method of disrupting communication, which helps in assessing the system's resilience. Table 1 summarises the simulated physical layer attacks with the implemented approach and their expected impact on the communication system. **Jamming attacks**: Jamming involves the introduction of interference into the communication channel to disrupt the signal transmission [32, 33]. This can be simulated by adding Gaussian noise to the received signal, thereby degrading the SNR. \[y_{\text{jammed}}=y+n_{j} \tag{6}\]  
where \(n_{j}\) is the jamming noise. **Eavesdropping attacks**: Eavesdropping attempts to intercept and decode the communication between legitimate users without authorisation [34, 35]. This attack can be modelled by introducing random bit flips in the transmitted signal, simulating the effect of an interceptor manipulating the signal. \[x_{\text{eavesdropped}}=x\oplus e \tag{7}\]  
where \(e\) represents the error vector due to eavesdropping. **Spoofing attacks**: Spoofing involves injecting false signals into the communication channel to deceive the receiver [36, 37]. This can be simulated by adding structured noise, such as a sinusoidal signal, to the original signal. \[y_{\text{spoofed}}=y+A\sin(2\pi ft) \tag{8}\]  
where \(A\) is the amplitude and \(f\) is the frequency of the sinusoidal spoofing signal. **Replay attacks**: Replay attacks can be defined as the adversary's interception of legitimate data and replaying it with the intention of misleading the receiver to accept it as an authentic message. This generally affects the system's whole operation depending on message sequencing or the timings, which would create disarray or unauthorised access. By reintroducing the previously transmitted data in the communication channel, the attacker makes the receiver process outdated or previously validated information, hence undermining the integrity of the whole communication process. \[y_{\text{replayed}}=y(t-\Delta t)\]  
where \(\Delta t\) is the time delay applied to the original signal before being replayed. **Signal fading**: Signal fading is essentially the process where the strength of a signal weakens due to multiple environmental factors, such as distance, obstacles, and interference. In this type of attack, an adversary can intentionally minimise the power of a signal such that it becomes very challenging for the receiver to decode the message with much accuracy. Therefore, the effect of the faded signal may be in the form of losses, delays, and communication errors. The latter can be emulated by multiplying the original signal with a fading coefficient \(h_{f}\), in which its amplitude is weakened. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Attack Type** & **Generation Method** & **Expected Impact** \\ \hline Jamming & Adding Gaussian noise & Degraded SNR, increased BER \\ \hline Eavesdropping & Introducing random bit flips & Compromised data confidentiality, increased BER \\ \hline Spoofing & Adding sinusoidal signal & False data reception, misleading information \\ \hline Replay Attack & Re-transmitting captured signals & Confusion in the communication flow, false timestamps \\ \hline Signal Fading & Reducing signal strength artificially & Loss of data, degraded communication quality \\ \hline Denial of Service (DoS) & Flooding the communication channel & Complete disruption of communication, inability to transmit data \\ \hline Man-in-the-Middle (MitM) & Intercepting and modifying signals & Unauthorised data manipulation, compromised integrity \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of simulated physical layer attacks with the implemented approach and their expected impact.