Ground stations networks for Free-Space Optical communications: maximizing the data transfer.

Free-space optical communications are becoming a mature technology, but unlike current radio-frequency technologies, they are strongly impacted by clouds. In this paper, we aim to find a network of optical ground stations maximizing the amount of data that can be sent from a low-earth orbiting satellite to the Earth during its missions, taking into consideration cloud information. We present a Mixed Integer Linear Program (MILP) and a hierarchical method based on an exhaustive enumeration of the sets of ground stations and on a dynamic programming algorithm and compare them on real scenarios based on archived years of cloud data. Even if the MILP can solve scenarios over small time horizons in less than one hour, experiments show that the hierarchical approach outperforms it in term of CPU time while achieving optimality.