# Adaptive Access Selection Algorithm for Large-Scale Satellite Networks Based on Dynamic Domain
## 1 Introduction
The simulation results show that CFDAMA--CLSTMTL reduces the end-to-end delay. In Literature [21], a combined free/demand assignment multiple access schemes employing a combined round robin/piggybacking request strategy (CFDAMA-RPR) is proposed to improve the throughput and reduce the end-to-end delay of satellite networks. The improved algorithm based on CFDAMA improves the network throughput to a certain extent and reduces the end-to-end delay. However, implementing these algorithms requires the interaction between satellites and ESs, increasing the cost of network resources. In fact, simple processing of acknowledgment packages (ACKs) can somewhat reduce the number of interactions between satellites and ES. The above access selection algorithm reduces the switching failure rate, blocking rate, and outage probability to some extent. However, the multi-satellite coverage of the above algorithm is mostly small constellations, the inter-satellite collaboration is not considered when selecting the access satellite, and the characteristics of satellite networks such as predictable trajectory are not fully utilized. Because of the shortcomings of existing access selection algorithms in large-scale satellite networks, we propose a dynamic domain-based adaptive access algorithm (DAA). The main contributions of the DAA algorithm proposed in this paper are as follows:  
* The strategy of large-scale satellite network dynamic domain is proposed. Based on the predictable characteristics of satellite position, the ES determines the communication domain according to the minimum elevation angle, and the satellites in the communication domain change dynamically with time. Before the ES sends data packets, it calculates each satellite's position information and coverage time in the communication domain through the stored ephemeris information. The calculation and storage costs of this process are all from the ES, and there is no need for information interaction between satellites and the ES, reducing resource-constrained satellites' storage and calculation costs. * This paper proposes an adaptive access selection algorithm based on the dynamic domain. Firstly, the ES determines access satellites according to the relationship between satellite coverage time and ES traffic volume. Then the ES determines the backup access satellite according to the prior knowledge. ES can quickly switch to a backup satellite when switching access satellite is required. * To reduce the routing overhead caused by switching the ESL to the backup access satellite, the DAA algorithm preferentially selects backup access satellites in the original path. When there is no satellite in the original path to meet the access requirements, this paper proposes the concept of a virtual destination address. The backup access satellite first transmits the data packet to the virtual destination address. Then the satellite corresponding to the virtual destination address transmits the data packet to the destination node. * To verify the effectiveness of the DAA algorithm, we model and analyze the access selection of the StarLink constellation. Modeling and analysis methods provide a reference for subsequent research on large-scale constellations. The organization of the remainder of this article is as follows: Section 2 describes the system model and defines the problems such as communication domain and coverage time. Section 3 describes the specific implementation of the DAA algorithm. Section 4 simulates and analyzes the performance of the DAA algorithm. Finally, Section 5 summarizes this article.