## 5 Performance Evaluation and Simulation Results
### Simulation Results  
Figure 4 shows the trend of system resource utilization with an increase in the network load. The proposed SPS-RBSP mechanism and dynamic scheduling mechanism achieve higher network resource utilization compared with static scheduling when there are more than 150 flows. When the number of scheduled traffic flows is more than 300 (i.e., under medium and high load), the resource utilization is higher than 80%. The traditional static scheduling algorithm reserves dedicated resources for ET flows with uncertain arrival times. However, other traffic cannot use these reserved RBs. It leads to a serious waste of resources when ET flows do not arrive for a long time, especially when the network load is heavy. The SPS-RBSP algorithm can share reserved resources with TT flows when reserved resources are idle, which greatly improves the resource utilization. In addition, dynamic scheduling for non-time-critical traffic improves the flexibility of resource allocation and increases the efficiency of resource utilization. The proportion of reserved resources has a significant impact on the resource utilization efficiency of SPS-RBSP. Figure 4a-c show the resource utilization ratio when the reserved RB ratio is 20%, 30%, and 40%, respectively. When the percentage of reserved RBs is 40%, the resource utilization ratio of SPS-RBSP greatly decreases. This is because there are far more reserved RBs than the actual number of RBs required for ET and TT flows. However, the power trade market flows cannot use the unused reserved RBs, resulting in a waste of resources. Figures 5 and 6 show the end-to-end delay performance comparison between the SPS-RBSP algorithm, the traditional static scheduling algorithm, and the traditional dynamic scheduling algorithm with different reserved RB ratios. The average end-to-end delays of \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Delay of core networks & 20 ms \\ Subcarrier spacing (SCS) & 15 kHz \\ Modulation mode & 64 QAM \\ Transmission time interval (TTI) & 1 ms \\ SPS period \(T_{S}\) & 50 ms \\ RB carrying data volume & 126 bytes \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulation parameters and values. the event-triggered flows are shown in Figure 5. Compared with the dynamic scheduling algorithm, the SPS-RBSP algorithm and the static scheduling algorithm have smaller end-to-end delay, which can meet the target delay requirements (50 ms) of three high-priority ET flows (emergency response, fast frequency regulation, and regular frequency regulation) in VPP systems. This is because the SPS-RBSP algorithm avoids the complex SR-SG process by preallocating resource blocks for high-priority ET flows. It greatly reduces the access delay in 5G systems. The uncertain arrival time of ET flows makes it difficult to accurately predict the scheduling period. The SPS-RBSP algorithm ensures prioritized transmissions of time-critical ET flows through a pre-emptive scheduling mechanism. It further reduces the end-to-end delay of ET flows. At the same time, it reduces the overhead of control signaling and it has higher computational efficiency. Additionally, it can be observed that when the percentages of reserved resources are 30% and 40%, SPS-RBSP has a similar delay to ET flows. When the percentage of reserved resources is 20%, the delay of SPS-RBSP is slightly higher, as shown in Figure 5a. This is because insufficient reserved RBs will lead to the queuing of ET flows, thereby increasing the end-to-end delay. Therefore, in order to achieve the deterministic low-latency scheduling of ET flows, it is necessary to reserve sufficient resources. Figure 6 shows the average end-to-end delay of the periodic time-triggered flows. The end-to-end delay of the SPS-RBSP scheme is slightly greater than that of static scheduling. The reason is that a small part of the TT flows in the SPS-RBSP scheme may be allocated resources through dynamic access.