Abstract
Low-Earth orbit (LEO) satellites are envisioned as a fundamental component in future 6G communications by virtue of their capability to provide global coverage with low-cost deployment. Most existing LEO satellite communication systems rely on terrestrial core networks to complete end-to-end data transmission. As LEO satellites are expected to be extensively deployed to serve the increased number of users, the satellite-terrestrial links will become more congested, resulting in degraded performance. Intersatellite links (ISLs) have emerged as a promising approach to deal with this challenge. Routing and resource allocation are two key designs for supporting efficient intersatellite communication, but they face challenges caused by the inherent characteristics of ISLs, such as the highly dynamic channel state and network topology. To this end, this article aims to present an easy-reading overview of routing and resource allocation for LEO intersatellite communications. It includes classification and discussion of intersatellite routing algorithms and in-depth analysis of key issues in intersatellite resource allocation, and it explores potential research directions for future satellite constellations.