## 4 Performance Evaluation
### Simulation Results
Figure 3a illustrates scenarios with unlimited RBs and varying speeds to observe the collision probabilities at different packet generation times: 100 ms, 60 ms and 20 ms. At a generation time of 100 ms, the collision probability remains notably low across varying speeds. It seems that the availability of unlimited RBs coupled with lower packet generation frequency significantly mitigates the potential for packet collisions. The collision probability subtly increases as the speed elevates; however, the impact is minimal, maintaining a stable and reliable communication environment. With a decrease in generation time to 60 ms, a slight increase in collision probability is observed, particularly at higher speeds. The faster packet generation seems to mildly saturate the available RBs. Nevertheless, the availability of unlimited RBs continues to cushion the collision probability, ensuring the sustenance of seamless communication. Moving to a generation time of 20 ms, we observe a more pronounced impact on collision probability, especially at elevated speeds. The swift packet generation leads to a more extensive utilization of the available RBs, thus inducing a higher probability of collisions. Even with unlimited RBs, the system experiences intervals of elevated collision risks due to the high-frequency packet introductions coupled with increased speeds. In Figure 3b, the impact of a single RB on collision probabilities was examined at different speeds, with packet generation times of 100 ms, 60 ms and 20 ms. In the scenario with a generation time of 100 ms, we observe a moderate increase in collision probability, even at lower speeds. The constrained environment of a single RB, combined with the infrequent packet generation, leads to a gradual increase in collision instances as the speed escalates, reflecting the system's sensitivity to speed variations in a limited-resource scenario. Reducing the generation time to 60 ms brings a notable rise in collision probabilities across all speeds. The faster generation of packets, coupled with the constraint of a single RB, leads to more frequent collisions. The heightened sensitivity to speed variations underlines the challenges posed by rapid packet introductions in a constrained communication scenario, with collision risks escalating swiftly at higher speeds. At the lowest generation time of 20 ms, the simulation unveils a substantial surge in collision probabilities throughout the speed spectrum. The accelerated packet introduction in an environment restricted to a single RB invariably leads to high collision probabilities. The rapidly increasing speed exacerbates the situation, reflecting a heightened state of contention and subsequent collision in the restricted-resource scenario. The implementation of a single RB presents significant challenges, especially with decreasing generation times and increasing speeds. The constraint posed by a single RB distinctly highlights the system's susceptibility to elevated collision probabilities, revealing the critical need for advanced resource allocation strategies and collision mitigation techniques to manage the interplay between speed, generation time and available resources in 5G NR sidelink C-V2X communications. In Figure 4a, there are plenty of resource blocks available, and the distance between the two UEs gradually increases from 50 to 400 m in increments of 50 m. In this scenario, the packet reception ratio noticeably increases. The path loss effects grow more obviously as the UEs are placed farther apart, reducing interference and, hence, the likelihood of packet collisions. Here, the path loss effect essentially refers to the reduction in signal strength as it travels over a distance, especially in wireless communications. This phenomenon occurs due to the dispersion and absorption of the signal's energy as it traverses through the environment, encountering obstacles, reflections and other interferences.