# V2X Communications in Highway Environments: Scheduling Challenges and Solutions for 6G Networks
## 5 Performance Evaluation  
In this section, we showcase the performance of the new SOVANET+ scheduler compared to the PF and SOVANET implementations for all the delay-critical UCs as presented in Table 1. Note that these UCs have different throughput and delay requirements for the UL and DL. The metrics used to evaluate the proposed scheme's performance are mean throughput, delay, jitter, and PRR. The requirement goals are summarized in Table 2. For the delay-sensitive UCs, timely and reliable communication is extremely critical as, on a highway, driving for 2 s with 150 km/h means covering 83 m, whereas in an urban environment, lower speed (e.g., 50 km/h) covers less distance (i.e., 27 m in 2 s). In Figure 3, the results concerning the mean throughput and delay for HDM UL and DL are illustrated. In this UC, all schedulers exhibit similar performance in throughput and delay in the case of 40 vehicles. However, the throughput gains for SOVANET+ vs. the PF scheduler in the UL case reach 5.2% for the 60 vehicles case and 4.5% for the 80 vehicles case. Against the SOVANET scheduler, the corresponding throughput gains are 1% and 6.1%, respectively. In the DL case, the throughput gains for SOVANET+ vs. the PF scheduler reach 21.1% for the 60 vehicles case and 21.6% for the 80 vehicles case. The corresponding delay gains in the UL against the PF scheduler are 36.5% and 28.5%, respectively. The delay gains against the SOVANET scheduler are 7.9% and 11.8%, respectively. The DL delay \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Channel model & 3 GPP TR 38.913 [23] \\ Channel bandwidth & 100 MHz \\ Carrier frequency & 4 GHz \\ Shadowing & Enabled \\ Beamforming method & No \\ MIMO & Yes \\ MCS & Adaptive \\ gNB Tx power & 49 dBm \\ UE Tx power & 33 dBm \\ Schedulers & Proportional Fair/SOVANET/SOVANET+ \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Network parameters. gains of SOVANET+ against PF are 20.9% and 36.7%. Against the SOVANET scheduler, they are 8.1% and 30.4%, respectively. It can be inferred that the SOVANET+ scheduler improves metrics in both UL and DL. As can be observed in loaded scenarios, compared to SOVANET+, the most significant performance improvement is in reducing delay (although the improvement in throughput is far from negligible). This is achieved because SOVANET+ uses an improved metric to calculate the overprovisioned resources and also avoids wasting resources on vehicles that have bad signal quality. Table 6 below offers more insight into vehicles that suffer from bad signal quality in the examined environment. In terms of the expected requirements for the HDM, SOVANET+ is the only scheduler that is closer to meeting them in the case of a loaded network. In Figure 4, the results concerning the mean values of throughput and delay for ToD UL and DL are illustrated. As in the previous UC, in the case of 40 vehicles, the performance of all three schedulers is similar in UL and DL. The UL throughput gains for SOVANET+ vs. the PF scheduler reach up to 13.3% for the 60 vehicles case and 14.9% for the 80 vehicles case. Against the SOVANET scheduler, the corresponding throughput gains are 7.8% and 8.9%, respectively. The DL throughput gains for SOVANET+ vs. the PF scheduler reach up to 9.4% for the 60 vehicles case and 35.3% for the 80 vehicles case. Against the SOVANET scheduler, the corresponding throughput gain is 45.9% for the case of 80 vehicles. The UL delay gains of the SOVANET+ scheduler against the PF are 32.5% and 8.2%, respectively. Against SOVANET, they are 31.2% and 10.2%, respectively. The DL delay improvements in the SOVANET+ scheduler against the PF are 8.3% and 10.5%, respectively. Against SOVANET, the improvements are 8.6% and 9.8%, respectively. As in the case of HDM, the performance improvements we have seen are due to two factors (i.e., the new performance metric and the treatment of vehicles with bad