# Towards Deterministic-Delay Data Delivery Using Multi-Criteria Routing over Satellite Networks
## 3 Problem Modeling
### Routing Algorithm
The traffic distribution-based satellite Internet scheduling algorithm adjusts the link costs by balancing the load across the links, distributing non-time-sensitive traffic as evenly as possible across the network. This reduces congestion and utilizes the remaining bandwidth of the links to transmit time-sensitive services, leading to a higher throughput for time-sensitive services compared to the shortest path algorithm. Specifically, when the network load is 150 Tbit, the throughput of the traffic distribution-based satellite Internet scheduling algorithm reaches 661 Gbit, while the throughput of the shortest path algorithm is 547.1 Gbit. Figure 5: Packet loss rate comparison for time-sensitive services. In contrast, when the total daily traffic is less than or equal to 90 Tbit, the throughput of time-sensitive services in the traffic distribution-based satellite Internet scheduling algorithm and the optimization method are nearly identical. However, when the total daily traffic reaches 150 Tbit, the optimization method achieves a throughput of 705.56 Gbit, while the throughput of the proposed algorithm is 661.03 Gbit, resulting in a 6.3% difference. Table 2 shows the comparison of the time required to calculate the paths for time-sensitive and non-time-sensitive services under two algorithms with different numbers of tasks. As seen in Table 2, the runtime of the optimized method increases sharply as the number of tasks in the network grows. It takes 1640.34 s to plan the paths for 5112 tasks. In contrast, the runtime of the spatiotemporal distribution-based routing algorithm remains relatively stable as the number of tasks increases, requiring only 5.25 s to plan the paths for 5112 tasks. This makes it more suitable for deployment in the highly dynamic environment of the satellite Internet, allowing for real-time online path planning for services. In summary, through simulations comparing the load balancing performance, packet loss rate of time-sensitive services, and throughput of time-sensitive services between the shortest path algorithm and the satellite Internet service scheduling algorithm based on the spatiotemporal distribution of traffic, the effectiveness of the spatiotemporal distribution-based algorithm has been validated. Additionally, simulations provided insights into the differences between the spatiotemporal distribution-based algorithm and the optimized method in terms of time-sensitive service throughput and packet loss rate. The analysis of the runtime trends and the number of network tasks for both methods confirmed the real-time performance of the proposed satellite Internet service scheduling algorithm based on the spatiotemporal distribution of traffic. ## 6 Discussion

To address the limitations of existing load balancing methods in simultaneously ensuring load balance and meeting the quality of service (QoS) requirements for time-sensitive \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **500 Tasks** & **1000 Tasks** & **2000 Tasks** & **3000 Tasks** & **4000 Tasks** & **5112 Tasks** \\ \hline Algorithm proposed in the article & 0.05 s & 0.20 s & 0.79 s & 1.76 s & 3.13 s & 5.25 s \\ Optimization method & 2.83 s & 40.05 s & 63.2 s & 87.32 s & 165.17 s & 1640.34 s \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison table of the average runtime of the two algorithms. Figure 6: Throughput comparison chart for time-sensitive services. services, this paper proposes a multi-criteria routing algorithm based on the spatiotemporal distribution of service traffic. By constructing low-latency paths to reserve the bandwidth for time-sensitive services and optimizing link weight assignments, the algorithm ensures the QoS of time-sensitive services while achieving load balancing for non-time-sensitive services.