# NR Sidelink Performance Evaluation for Enhanced 5G-V2X Services
## 4 Performance Evaluation
### Simulation Results  
When the average speed reduces, there is a decreased likelihood that the resource selection windows of various vehicles will overlap; this is shown in Figure 5a,b generated from simulations based on the parameters in Table 1. The duration of each resource reservation is set in milliseconds (ms) and is fixed for all RBs. As a result, there will be a greater difference in time or slots between the end of the selection window and the start of the subsequent reservation period. A reduction in average speed lessens the likelihood that the vehicles' selection windows will collide. Therefore, it results in a higher PRR when the speed is reduced and similarly shows comparatively poor results in the PRR when the speed of the vehicles is increased. Results shown in Figure 5a,b are significantly similar to the results shown in paper [30]. Figure 5: PRR for different NR-V2X configurations with varying vehicle speeds without retransmissions and varying vehicle numbers. (**a**) Highway and (**b**) Urban. \begin{table}
\begin{tabular}{c c c} \hline
**Parameter** & **Value** & **Unit** \\ \hline Simulator & NS-3/5G-LENA/SUMO & - \\ Packet Size & 500 & byte \\ Data Rate & 16 & Kbps \\ Simulation Time & 20 & s \\ Inter-Vehicle Distance & \(50,100,150,200\) & meter \\ Inter-Lane Distance & 4 & meter \\ Highway Length & 10 & kilometer \\ Number of Lanes (Urban) & 3 & - \\ Number of Lanes (Highway) & 5 & - \\ Number of Vehicles per Lane (Urban) & 2, 3, 5, 7, 8 & - \\ Number of Vehicles per Lane (Highway) & 2, 4, 6, 8, 10 & - \\ Average Speed (Urban Scenario) & 20, 25, 30 & mph \\ Average Speed (Highway Scenario) & 40, 60, 80 & mph \\ Sidelink Activation Time & 1 & ms \\ Sidelink Bandwidth & 40 & MHz \\ Transmission Power & 23 & dBm \\ Resource Reservation Period & 100 & ms \\ Resource Update Period & 500 & ms \\ \hline \end{tabular}
\end{table} 
Table 1: Simulation Parameters. Figure 6a,b show the results of varying vehicle density without retransmissions. Each packet requires increasingly fewer subchannels as the number of vehicles increases. As more resources become available for selection, there is a chance that the average interference will drop. Thus, in this scenario, as the number of vehicles increases, the packet reception ratio increases. There appears to be a positive correlation between the number of vehicles and the packet reception ratio in C-V2X communication. This correlation can be explained by a cooperative or relaying effect, in which a greater number of vehicles improves network coverage and raises the likelihood of a successful packet reception. However, it is important to note that this trend may not continue indefinitely. This phenomenon typically has a saturation point. The number of bandwidth and time slots that are available for communication may be limited as the number of vehicles increases. The network may eventually become congested, which would result in a decreased packet reception ratio. This saturation effect may be linked to various factors, including resource limitations, interference, and collisions. Consequently, even though adding additional vehicles might initially improve packet reception, there's undoubtedly a point at which doing so might not have a major impact on overall performance. The precise limit would be determined by the network infrastructure and the features of the communication environment. Figure 6: PRR for different NR-V2X configurations with varying vehicle speeds without retransmissions and varying inter-vehicle distances. (**a**) Highway and (**b**) Urban. On the other hand, when the speed increases and the vehicle numbers stay the same, the resource update period (which is fixed) is frequently started for new neighbor vehicles. This phenomenon decreases the packet reception ratio which follows a similar phenomenon compared to the results presented in papers [8, 16]. In addition to these two studies, this paper shows the comparison of results for varying speed of the vehicles. Figure 7a,b show the system throughput versus the number of vehicles.