# Deadline-Aware Scheduling for Transmitted RSU Packets in Cooperative Vehicle-Infrastructure Systems
## 5 Performance Evaluation  
The simulation experiment in this section follows two parts of the simulation experiment on DDPS proposed in this paper through MATLAB simulation software. The first part involves drawing curve images of the average system delay and packet queue length, which vary with the system's weight coefficient V and packet arrival rate. The second part compares this strategy model's performance to two commonly used packet scheduling strategies, Equal Allocation Strategy (EAS) and Queue-weighted Strategy (QS), regarding system average delay and packet queueing under constant simulation parameters. Table 1 shows the simulation parameters. In addition, Section 3 mentions the discontinuous Bernoulli distribution parameter \(\alpha=\beta=0.5\). The time, T, is set to 1500 s, the number of emergency data packet deadlines \(t_{n}^{H}\) is set to 1000 s, and the number of non-emergency data packet deadlines \(t_{n}^{L}\) is set to 1500 s.  
This paper considers that compared with the end-to-end delay, the end-to-end average delay fluctuates more stably, which can better measure the performance of the scheduling strategy. The lower the end-to-end average delay, makes the higher the transmission efficiency of data packets. The average end-to-end delay cannot exceed the data deadlines. In the second part of the comparative experiment, the EAS indicates that the number of packet transmissions between RSUs and vehicles is equal. QS indicates that the system allocates the transmission weight between vehicles according to the packet queue length in RSUs: the longer the queue length of RSU packets, the more data RSUs send to vehicles. Figures 3-5 show a DDPS simulation based on system performance. Figure 3 shows the curve trend of average delay in each time slot with the increase in weight coefficient \(V\). The simulation results show that the average delay decreases with the increase in weight coefficient \(V\). The results show that with the increase in weight coefficient \(V\), the average delay's impact on system performance increases gradually. Therefore, the system will adaptively reduce the average delay to ensure its overall performance. Figures 4 and 5 show that the high- and low-priority data queue lengths change with the increase in weight coefficient \(V\), which reduces the impact of queue length on system performance. System decisions tend to adjust the factors that greatly impact system performance; therefore, the system reduces the average delay and increases the length of high- and low-priority queues. The packet arrival rate will change accordingly when the system environment is different. Therefore, verifying whether the system's packet scheduling strategy can adaptively optimize packet scheduling under different arrival rates ensures online optimization. The results of this experimental scheme are as follows: The experimental scheme provides the weight value w, set to 0.8, 1, 1.2, multiplied by the packet arrival state \(h_{n}(t)\) of the system. Set the weight to \(V=2\). Figures 6-8 show the experimental results. As shown in Figure 6, the increase in packet arrival rate increases the average queue length and system delays accordingly. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** &
\begin{tabular}{c} **Notation/Units of** \\ **Measurement** \\ \end{tabular} & **Value** \\ \hline Highway mileage & L/m & 10,000 \\ RSU to Backbone RSU Spacing & \(L^{\prime}\)/m & 10,000 \\ RSU Spacing & L/m & 1000 \\ Speed limit range & \([V_{\text{min}},V_{\text{max}}]/(\text{m/s})\) & [16.67,33.33] \\ Speed expectation & \(\overline{V}/(\text{m/s})\) & 25 \\ Speed standard deviation & \(\sigma\) & 5.56 \\ Vehicle arrival rate & \(\lambda/(\text{vehicle/s})\) & 5.5 \\ Slot length & \(\tau/\text{s}\) & 1 \\ Maximum number of transmission packets & S & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The simulation parameters. Figure 3: The weight-dependent trend of average delay. We consider that the size of a single data packet is 1 MB.