# V2X Communications in Highway Environments: Scheduling Challenges and Solutions for 6G Networks
## 5 Performance Evaluation
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**UCs** & **Case 1: 40 Vehicles** & **Case 2: 60 Vehicles** & **Case 3: 80 Vehicles** \\ \hline HDM & 3 out of 5 & 3 out of 10 & 7 out of 15 \\ ToD & 3 out of 5 & 3 out of 10 & 7 out of 15 \\ AR & 2 out of 5 & 4 out of 10 & 6 out of 15 \\ RTSA & 12 out of 25 & 11 out of 30 & 11 out of 35 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Unsupported vehicles. Figure 3: HDM UL and DL mean throughput and delay. signal conditions.) Once again, SOVANET+ is much closer to meeting the set performance requirements for the ToD service. In Figure 5, the results regarding the mean values of mean throughput and delay for the AR UL and DL are illustrated. In the UL pathway, all schedulers exhibit similar performance in all traffic cases as AR is a non-delay-critical UC, and therefore no overprovisioning in resources is applied. However, in the DL, the throughput gain of the SOVANET+ scheduler against PF in the 80 vehicles case is 11% and the delay gain is 17.1%. This is attributed to the overall treatment of vehicles that experience bad signal conditions. In Figure 6, the results concerning the mean values of throughput and delay for RTSA UL and DL are illustrated. RTSA requires the least resources among the services in our study, resulting in similar throughput performance for all traffic cases in both UL and DL for all schedulers. The delay gain of the SOVANET+ in the UL reaches 9.1% against the PF scheduler while the corresponding DL delay gain is 13.7%. The purpose  
Figure 4: ToD UL and DL mean throughput and delay. Figure 5: AR UL and DL mean throughput and delay. of studying a non-demanding UC such as RTSA is to ensure that the proposed scheduler effectively differentiates critical and non-critical UCs, resulting in the conservation of network resources. Another important metric for evaluating a network's performance is mean jitter, which refers to the latency variation affecting the consistency of data delivery. In wireless networks, minimizing jitter is essential for applications with strict delay requirements, such as V2X UCs. In Figure 7, the mean values for jitter in the challenging UL direction are included for the studied UCs. Each scheduler is represented with a different color tint for each UC. PF is represented with a solid color, SOAVENT with a paler version, and SOVANET+ with the palest. The SOVANET+ implementation presents a significant reduction in mean jitter values in the case of 60 vehicles in the ToD, AR, and RTSA UCS. In the case of 80 vehicles, SOVANET+ exhibits jitter reduction in the HDM, ToD, and AR UCs. Achieving low jitter is crucial for delay-critical services during network congestion, where multiple packets contend for bandwidth. Based on the following results, our scheduling algorithm verifies the consistency and coordination of data packet transmissions. As shown in Figure 7, SOVANET+ outperforms the other schedulers except in the RTSA case, where the PF schedules perform better. This is, however, a small penalty to pay, as RTSA is not a critical application, and SOVANET jitter is fully acceptable. The last metric used in our evaluation is the PRR. In wireless networks, PRR refers to the rate at which packets are successfully received from the communication system. It is a crucial metric that indicates the quality of link reception in a network environment. In Figure 8, the UL PRR is illustrated for all studied UCs. The SOVANET+ scheduler exhibits the highest percentage values in the crucial PRR metric, ensuring that packets reach their intended destination with the highest success rate. Figure 6: RTSA UL and DL mean throughput and delay. In each studied scenario, some vehicles failed to receive or transmit any packets throughout the simulation. They are reported as unsupported vehicles and can be found classified per UC, in Table 6. Regardless of the scheduler used, the number of unsupported vehicles remains the same.