# Rethinking LEO Mega-Constellation Routing to Provide Fast Internet Access Services
###### Abstract  
In the realm of providing space-based internet access services, utilizing large-scale low Earth orbit (LEO) satellite networks have emerged as a promising solution for bridging the digital divide and connecting previously unconnected regions. The deployment of LEO satellites can augment terrestrial networks, with increased efficiency and reduced costs. However, as the size of LEO constellations continues to grow, the routing algorithm design of such networks faces numerous challenges. In this study, we present a novel routing algorithm, designated as Internet Fast Access Routing (IFAR), aimed at facilitating faster internet access for users. The algorithm consists of two main components. Firstly, we develop a formal model that calculates the minimum number of hops between any two satellites in the Walker-Delta constellation, along with the corresponding forwarding direction from source to destination. Then, a linear programming is formulated, to match each satellite to the visible satellite on the ground. Upon receipt of user data, each satellite then forwards the data only to the set of visible satellites that correspond to its own satellite. To validate the efficacy of IFAR, we conduct extensive simulation work, and the experimental results showcase the potential of IFAR to enhance the routing capabilities of LEO satellite networks and improve the overall quality of space-based internet access services.  
LEO mega-constellation; routing algorithm; space communications; satellite networks; linear programming 2023233207339  
succeed in fulfilling their intended purpose, e.g., GlobalStar [4] and Iridium [5]. The reasons behind their failure lay in their inability to compete with terrestrial telecommunications networks and insufficient funding to sustain the construction of such networks. The current focus on constructing LEO mega-constellations, aims to supplement terrestrial networks and provide internet access to remote regions, while also ensuring sustainable profitability.  
In the literature, various current routing algorithms for LEO satellite networks have been proposed, aiming to improve the network throughput through multi-path transmission or load balancing [6; 7; 8]. These studies use satellites to build a core network in space, that transmits large amounts of data over long distances, through ISLs. However, the terrestrial core network is reasonably robust and resource-abundant now, and multi-hop transmission, through unstable ISLs, would bring additional repeat request overhead. Therefore, how to use the LEO mega-constellation as the access network to provide ultra-reliable and low-latency communication (URLLC) services remains an open issue, which inspired our work.  
The main contributions of this paper include the following two aspects. First, we provide a theoretical model, to calculate the positions of satellites in the Walker constellation. This model is also used to derive a mathematical formula for the theoretical minimum number of hops between two satellites. The above calculation results are the basis of the satellite matching and forwarding strategy in IFAR algorithm. This algorithm operates in a distributed way and has low complexity, as only the routes between matching satellites need to be calculated.  
The remainder of the paper is as follows. Section 2 presents the existing routing algorithms and the satellite model. The Internet Fast Access Routing (IFAR) algorithm is described in Section 3. The performance evaluation of the proposed algorithm is presented in Section 4, followed by the conclusions of the paper in Section 5.