Joint AoI and Coverage Optimization for Earth-Moon Heterogeneous Orbital Relay Satellite Constellation Design

With lunar exploration attracting global attention, there is a growing interest in the design of relay satellite constellations for future lunar communication systems which is challenged by the huge distance between earth and moon. In this paper, we propose a novel hybrid combined Earth-Moon constellation network structure with Earth-Moon Libration 1/2 (EML1/L2) points Halo orbits, ordinary lunar orbits, and Geostationary Earth Orbit (GEO) to minimize both the total number of satellites and the average per-device Age of Information (AoI) as well as maximizing the coverage ratio of specific lunar surface regions to improve information freshness. This is formulated as a multiobjective optimization problem solved by the Nondominated Sorting Genetic Algorithm-II (NSGA-II). By simulating various constellation configurations, we can obtain the optimal configuration parameters for different total numbers of satellites. The simulation results show that our proposed combined constellation significantly outperforms traditional Walker Star and Delta constellations in both AoI and coverage performance.