# End-to-End Performance Evaluation of MEC Deployments in 5G Scenarios
## 4 Performance Evaluation
Since there is only one VNF between the RAN and the MEC, the considered one-way latency is 100 \(\upmu\)s.  
Figure 7: RAN deployment (**left**) and urban-grid scenario (**right**). [credits to icograms.com]. The main simulation parameters are summarized in Table 2. We first run simulations with a varying number of UEs (24 to 40), increasing the video bitrate. Figure 9 shows the percentage of DL frame occupied in the 4G RAN, for the 4G and 5G NSA scenarios. The figure shows that this increases with the video bitrate, however keeping below 50%. In the 5G NSA case, the 4G DL is occupied even less, due to the gNB offloading. The difference in user experience is clarified in Figure 10, describing the frame latency and its breakdown. It is quite evident that, in the 4G scenario, both the RAN and the CN introduce a considerable delay. On the other hand, even high video bitrates are well tolerated in the 5G NSA scenario, and the 5G SA one exhibits negligible delays. In all the three scenarios, the MEC delay is negligible. Figure 11 shows the standard deviation of the frame latency, which measures the jitter, and is a meaningful indicator of user-perceived Quality of Experience. It is quite evident that, although the DL is far from being congested, in the 4G scenarios jitters comparable to twice the inter-packet time and more can occur, meaning that packets will need considerable buffering at the UE. This does not happen with either 5G NSA or 5G SA. These results show that the 4G network is going to represent the bottleneck for MEC services such as this, and that only deploying 5G will alleviate that. In order to find the point at which the MEC host starts acting as a bottleneck, we ran simulations with a considerably higher number of users (up to 248) in a 5G SA deployment. This time we used a low bitrate video, to avoid saturating the RAN. The results are shown in Figure 12, and they clearly show that the MEC host becomes congested around 200 users. However, before this occurs, the bulk of the latency is still due to the 5G RAN. Figure 8: LTE deployment with centralized EPC (**top**), 5G NSA deployment with distributed EPC (**center**), 5G SA deployment with distributed 5 GC (**bottom**). Figure 9: DL resource-block occupancy in the 4G and 5G-NSA scenarios. \begin{table}
\begin{tabular}{l l} \hline \hline
**Video Format** & **Bitrate** \\ \hline Bandwidth & 20 MHz (100 Resource Blocks) \\ Carrier Frequency & 2 GHz \\  & 6 GHz for gNBs in NSA \\ Numerology index (5G only) & 2 (60-kHz subcarrier spacing) \\ Tx Power & BS: 46 dBm; UE: 23 dBm \\ Fading effects & Enabled \\ Path loss model & [35] \\ UE mobility & Linear, \(\sim\)\(U\)(10,18) m/s \\ CN latency (one-way) & LTE: 15 ms \\  & 5G: 200 μs (NSA), 100 μs (SA) \\ X2 latency & 5 ms \\ Simulation time & 200 μs \\ UPF UL/DL bandwidth & 100 Gb/s \\ UPF-APP and APP-UPF delay & 5.4 μs \\ REQ processing time & 50 μs \\ Frame creation time & 200 μs \\ Frame size & [2000, 12,000, 24,000] bytes \\ Video duration & 8 s \\ Request period & 12 s \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Main Simulation parameters. Figure 11: Standard deviation of the inter-packet times at the UE. Figure 10: Frame-latency breakdown in a scenario with 24 UEs.