# Application and Performance Evaluation of Resource Pool Architecture in Satellite Edge Computing
## 4 Experiment and Analysis
### Results Comparison  
#### 4.2.1 Task Response Time  
Firstly, the hardware in the loop simulation experiments of the three modes is carried out in Figure 2. In the isolated mode, the task is only submitted to the satellite which is visible to the ground, and the task is not migrated. When the satellite leaves the visible window, the task of _App2_ fails because it leaves the target area. The task of _App1_ is unaffected and ends when the execution time is finished. In the cooperative mode, the ground station submits a task to a satellite visible to the ground. When the resources of one satellite are exhausted, that satellite sends a task request to other satellites and selects the nearest satellite to execute it. In the pooled mode, \(k_{\alpha}^{*}\) satellites are calculated according to (1), and the resources of \(k_{\alpha}^{*}\) satellites are used together. At the same time, with the satellite movement, satellites will join or exit to maintain the balance of the resource pool. The results of the average response time of tasks in the three modes on our platform are shown in Figure 7. It can be seen that the response time increases with the number of tasks under the three modes. In the isolated mode, the average response time of tasks is approximately 9.28 s (device count: 60-500). Even when the number of tasks is small, the response time is too long because tasks can only be processed locally, which is approximately 11.49 s (device count: 1-60). In the pooled mode and cooperative mode, when the number of tasks is small, they can be quickly executed without waiting too long, and the time is approximately 6.63 s (device count: 1-60). It is worth noting that the average waiting time drops after the device count increases beyond 180. This is because the task success rate has increased, and due to delay the task failure rate decreases, as can be seen in Figures 9 and 11. In contrast, there are fewer waiting tasks in the queue, and therefore the waiting time is decreased. The average response time of the last three modes tends to be the same, because when the workload reaches the cluster load, it enters a balanced state. Figure 6: Structure diagram of sample demonstration satellite system. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & _App1_ & _App2_ & _App3_ \\ \hline Max. delay (s) & 5 & 5 & 200 \\ Container size (KB) & 2500 & 9000 & 13,000 \\ Task length (MI) & 60,000 & 15,000 & 200,000 \\ Required core (PE) & 3 & 2 & 2 \\ Required memory (MB) & 100 & 500 & 300 \\ Required sensor & SDR & camera & Microwave \\ Poission interarrival (s) & 40 & 10 & 30 \\ remarks & No target area & Target area & Visible to another satellite \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Application resource configuration table. The results of the average waiting time and task success rate are shown in Figures 8 and 9. It can be seen that in the isolated mode, the average waiting time of tasks is 17.84 s (device count: 60-500). Even when the number of tasks is small, the waiting time is long because the required resources must wait for local processing. In pooled mode and cooperative mode, when the number of tasks is small, they can be executed quickly without waiting for too long. However, when the number of tasks becomes larger, the waiting time becomes approximately twice the average waiting time of the isolated mode due to the time spent waiting for the task to be sent and received. We first make it clear that the task success rate refers to the ratio of the number of successfully executed tasks to the total number of initiated tasks in the simulation time. In terms of task success rate, it can be seen from Figure 9 that through resource sharing, both the pooled mode and the cooperative mode have greatly improved the task success rate, from 26.21% of the isolated mode to 45.73%, increased by 19.52%. This is because resource sharing results in more tasks being assigned to resources, while tasks have to wait for resources in the isolated mode, which improves resource utilization and task success rate.