## 5 Evaluation Methodology and Simulation Scenarios  
In our work, the heuristics were developed in MATLAB, while IBM CPLEX [33] was used to compute the optimal solution of the MILP described in Section 2.1. The simulation scenarios considered a gNB sector area of 500 m radius overlaid with two SC clusters [25], as shown in Figure 5. Each cluster contained four possible SCs, which were randomly and uniformly placed in an 100-m-radius from the cluster centers. The minimum allowable distances are given in [25]. A subset of BSs, namely one SC (randomly selected) per cluster and the gNB, was assumed to have fiber access to the aggregation network. mmWave X-haul links could be deployed among BSs as long as their distance was lower than 200 m. The aggregation network consisted of two layers each one comprising four possible node positions, as shown in Figure 5. The aggregation layer nodes were connected among them and with the BSs via fiber so that there was no disconnected node. Hotspot UE traffic was also assumed [25]. We considered five different SFCs containing ordered combinations of the following VNFs: NAT (Network Address Translation), FW (Firewall), TM (Traffic Monitor), WOC (WAN Optimization Controller), IDPS (Intrusion Detection Prevention System), and VOC (Video Optimization Controller). For each SFC, the corresponding ordered VNF combination, data rate demand (uniformly distributed in the provided set), E2E delay requirement and share of the total SFC requests, are shown in Table 2. The data processing capacity as well as the GFLOPS requirement of each VNF type are given in Table 3. For a given number of UEs, we ran 10 different scenarios, with five different UE  
Figure 4: Orchestration Framework high-level architecture. We assumed 100 RBs allocated per gNB or SC (corresponding to \(\mu\) = 0 in 5G numerology). The operating frequency of the gNB and SCs was 2 GHz, assuming orthogonal channels between the gNB and the SCs. However, the SCs of different clusters could interfere with each other. The mmWave X-haul links operated at 60 GHz, with 200 MHz channel bandwidth. For the AN and the mmWave links, we employed the link budget equation and the link budget equation. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Type** & \multicolumn{2}{c}{**VNF Ordering**} & \multicolumn{2}{c}{**Throughput**} & **Delay** & **Share** \\  & & **(Mbps)** & **(ms)** & **(\%)** \\ \hline Web & NAT\(\rightarrow\)FW\(\rightarrow\)TM\(\rightarrow\)WOC\(\rightarrow\)IDPS & [0.6–1] & 500 & 20 \\ VoIP & NAT\(\rightarrow\)FW\(\rightarrow\)TM\(\rightarrow\)FW\(\rightarrow\)NAT & [0.404–0.64] & 100 & 20 \\ Streaming & NAT\(\rightarrow\)FW\(\rightarrow\)TM\(\rightarrow\)VOC\(\rightarrow\)IDPS & [5–24] & 100 & 39 \\ Gaming & NAT\(\rightarrow\)FW\(\rightarrow\)VOC\(\rightarrow\)WOC\(\rightarrow\)IDPS & [0.24–0.5] & 60 & 6 \\ Ultra RT AI/ML & NAT\(\rightarrow\)NAT & [15–25] & 1 & 15 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: SFC details [15]. Figure 5: Simulation scenario example topology. related parameter values of [25]. The number of CPU cores was equal to 8, 24, and 48 for each node at the MEC, 1 st, and 2 nd Aggregation layers, respectively. Parameter \(P_{y}^{(CPU,m)}\) was selected randomly from the set \(\{55,70\}\) for the MEC nodes, from \(\{150,220\}\) for the 1 st Aggregation Layer and from \(\{200,278\}\) for the 2 nd Aggregation Layer nodes, while the idle power was assumed to be equal to 10% of the assigned maximum power values. Each fiber link had a capacity of 10 Gbps, while the rest of the simulation parameters are summarized in Table 4.  
The optimal solution and the proposed heuristic (HERO) were compared with the following SoA algorithms [15]:  
* Holu: This algorithm first performed the VNF placement based on the node centrality (closeness) and the CPU utilization of computing nodes and then decided upon traffic routing targeting the minimization of power consumption, while satisfying the E2E service delay constraint.