# Enhancing Tactile Internet Reliability: AI-Driven Resilience in NG-EPON Networks
## 4 Proposed Architecture
### Mean Packet Delay  
Figure 10 shows the mean packet delay of Expedited Forwarding (EF), Assured Forwarding (AF), and Tactile Internet (TI) with different traffic proportions. Four scenarios are depicted: Normal: delay of no faults in the network (blue line); 1 Fault_Average: delay with one fault in the network, which represents a single fault occurring in one branch of the ODN; 3 Fault_Average: delay with three faults in the network, representing multiple faults distributed across different branches of the ODN; 1 Fault_BackupNode: delay at a specific backup node handling the affected ONU with one fault; and 3 Fault_BackupNode: delay at specific backup nodes handling the affected ONU with three faults. As seen in Figure 10a, the EF delay under normal conditions increases gradually with the traffic load, showing an expected behavior where higher traffic leads to higher delay. However, in the 1 Fault_Average and 3 Fault_Average scenarios, when the traffic loads are below 70%, the delay remains close to the normal operation but increases more significantly as the traffic load exceeds 70%. This highlights the compounded effect of multiple faults on the network performance. The green lines (1 Fault_BackupNode and 3 Fault_BackupNode) show that the EF delay at specific backup nodes handling the affected ONU is slightly higher than the normal operation but much lower than the 1 Fault_Average line, demonstrating the effectiveness of the backup node in mitigating the impact of the faults on the affected ONU \begin{table}
\begin{tabular}{l l} \hline \hline
**Parameters** & **Value** \\ \hline Number of ONUs in the System & 32 \\ Upstream/downstream link capacity & 1 Gbps \\ OLT-ONU distance (uniform) & 10–20 km \\ Maximum transmission cycle time & 1 ms \\ Guard time & 1 \(\upmu\)s \\ DBA computation time & 10 \(\upmu\)s \\ Control message length & 0.512 \(\upmu\)s \\ Number of Faults & 1, 3 Faults \\ Traffic Proportion of Expedited Forwarding (EF) & 14\% of link capacity \\ Traffic Proportion of AF, BE, and TI Scenarios & (50\%:20\%:30\%)/(40\%:20\%:40\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulation parameters. In terms of TI delay, shown in Figure 10b, when there is one fault in the network, the 1 Fault_BackupNode and 3 Fault_BackupNode manage to stay close to the normal operation levels, even at higher traffic loads. This again demonstrates the effectiveness of the backup node in mitigating the impact of the fault, ensuring that TI delay remains well below 2 ms up to 90% and slightly exceeds 2 ms at 100% load. In the 3 Fault_BackupNode scenario, the delay remains relatively low at moderate traffic loads but spikes dramatically beyond 80% load, reaching up to 5 ms at 100% load. This indicates that while backup nodes help manage the delay better than without them, multiple faults still pose a significant challenge, especially under high-traffic conditions. Figure 10c,d illustrate the AF and BE delay, respectively. AF delay, much like EF, shows a minimal increase with rising traffic loads in the normal scenario. BE traffic, typically given the lowest priority, shows non-congested conditions under normal conditions. However, as the traffic load increases, the limited available resources are allocated preferentially to  
Figure 10: Mean packet delay of EF, TI, AF and TI traffic. higher-priority traffic; therefore, once the traffic load surpasses 70%, the resources available for AF and especially BE packets become increasingly constrained. When faults are present, resources are redistributed to maintain service levels for critical applications, exacerbating delays for AF and BE traffic. Consequently, the proposed RDBA mechanism successfully ensures that delays for EF and TI packets remain below critical thresholds, i.e., below 2 ms [4; 37], maintaining high QoS for real-time and tactile internet applications. The results show that under normal and fault conditions, the RDBA can keep the delays well managed.