## 3 Countermeasures
### Intrusion Detection-Based Countermeasures
Moreover, blockchain-based integrated security provides reliable service delegation in the 6G columniation environment [102]. SDN-enabled fog computing provides intelligent lightweight security infrastructure and an intelligent intrusion detection system in 6G networks [103]. The virtual representation of a 6G physical network, known as a digital twin, provides analyses and optimization of various synchronization solutions for IDS implementation [104]. Table 5 provides the summarized view of our analysis on IDS-based countermeasures in 6G communication. \begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Ref.** & **Threat Area** & **Countermeasure** & \multicolumn{2}{c}{**Attributes**} & \multicolumn{2}{c}{**Limitations**} \\ \hline
[88] & CIA3 & Simplified threat matrix & \(\bullet\) & Attack vector-based categorization & \(\bullet\) & Common agreement required \\  & & & & & \(\bullet\) & Compatibility issues \\ \hline
[89] & Authentication & Sparse Signatures matrix & \(\bullet\) & NOMA & & \\  & & & \(\bullet\) & Channel state information & \(\bullet\) & Covers only wireless domain \\  & & & \(\bullet\) & Linear minimum mean square error & \(\bullet\) & Compatibility issues with \\  & & & & & & non-NOMA IoTs \\ \hline
[90] & Availability & Routing scheme & \(\bullet\) & Identify Malicious Maneuver & \(\bullet\) & Specific to flooding attacks \\  & & & \(\bullet\) & Energy based Cluster head selection & & \\ \hline
[91] & Authentication & CSI & \(\bullet\) & Channel parameters-based & \(\bullet\) & Wireless domain only \\  & & & & authentication & \(\bullet\) & Backward Compatibility \\  & & & \(\bullet\) & Secret key distillation for physical & \(\bullet\) & Physical Layer Processing \\  & & & & layer security & \(\bullet\) & Degradation in \\  & & & & [PERSON] & & interference/jamming \\  & & & independence criterion & & \\ \hline
[48] & Confidentiality & Moving target defense & \(\bullet\) & Proactive defense & \(\bullet\) & Wireless domain \\  & & & \(\bullet\) & Standardization perspective & \(\bullet\) & Compatibility with upper layer \\  & & & & & in network \\ \hline
[51] & CIA3 & Machine Learning & \(\bullet\) & ML-based model & \(\bullet\) & Scalability issues \\  & & & \(\bullet\) & Covers seven different types of new and contemporary attacks & \(\bullet\) & Compatibility with \\ \hline
[98] & Confidentiality & Neural network-based prediction & \(\bullet\) & Transmit antenna selection & \(\bullet\) & Physical Layer Processing \\  & & & \(\bullet\) & Secrecy Outage Probability & \(\bullet\) & Compatibility with \\  & & & \(\bullet\) & Evaluation network secrecy performance & \(\bullet\) & heterogeneous devices \\ \hline
[102] & Integrity & Blockchain & \(\bullet\) & Service delegation & \(\bullet\) & Scalability issues \\  & & & \(\bullet\) & Secure communication environment & \(\bullet\) & Resource constraint \\ \hline
[103] & Availability & SDN-enabled fog & \(\bullet\) & Intelligent lightweight security & \(\bullet\) & Scalability issues \\  & & computing & \(\bullet\) & Intelligent resource scheduling & \(\bullet\) & SDN-based vulnerabilities \\  & & & \(\bullet\) & Collaborative trust model & \\ \hline
[104] & Authentication & Digital twin & \(\bullet\) & Public key update process & \(\bullet\) & Processing power intensive \\  & & & \(\bullet\) & Optimized synchronization & \(\bullet\) & Quantum Computing-based \\  & & & \(\bullet\) & Cryptogram validation & & Factorization \\ \hline \hline \end{tabular}
\end{table} 
Table 5: IDS-based countermeasures for 6G communication.