Heterogeneous Multi-Layer Constellation for Future Satellite Internet: Framework, Optimization, and Evolution Vision

The alternative strategy for future space-based satellite (SAT) internet development involves a potential transition from single-layer low Earth orbit (LEO) system to sophisticated heterogeneous multi-layer constellations (HMLCs). HMLC integrates SATs from different orbital layers, including very low Earth orbit, LEO, medium Earth orbit, and geostationary orbit, potentially incorporating communication, navigation, and remote sensing (CNR) capabilities, with the ability to enhance coverage, communication capacity, geometric dilution of precision, resilience, resolution, etc., then offering the diversification of service functions. Realizing this potential hinges on multi-SAT collaboration driven by key technologies including inter-satellite link, advanced antenna technology, on-board processing, topology-aware routing, and artificial intelligence. Designing these sophisticated systems inevitably involves multi-objective optimization problem (MOP) to trade-off conflicting performance metrics, especially in optimizing integrated CNR services. In addition, HMLC's structural flexibility and integration capabilities also provide an important foundation for future mission configurations extending into deep space. This article explores the HMLC framework, enabling technologies, and the MOP paradigm. Furthermore, it outlines a vision towards intelligent and agile HMLCs, emphasizing future directions in rapid constellation assessment using surrogate models and dynamic in-orbit adaptation to meet evolving demands, paving the way for building adaptive and efficient intelligent space-based networks to support future deep space missions such as Earth-Moon collaboration.