In the framework of satellite-to-ground laser downlinks, an analytical model describing the variations of the instantaneous coupled flux into a single-mode fiber after correction of the incoming wavefront by partial adaptive optics (AO) is presented. Expressions for the probability density function and the cumulative distribution function as well as for the average fading duration and fading duration distribution of the corrected coupled flux are given. These results are of prime interest for the computation of metrics related to coded transmissions over correlated channels, and they are confronted by end-to-end wave-optics simulations in the case of a geosynchronous satellite (GEO)-to-ground and a low earth orbit satellite (LEO)-to-ground scenario. Eventually, the impact of different AO performances on the aforementioned fading duration distribution is analytically investigated for both scenarios.

High-data-rate space-to-ground optical links are anticipated to be an alternative to radio-frequency spectrum congestion for the next generation of highthroughput geostationary satellites. An affordable site diversity system based on several optical ground stations (OGSs) and an optical fiber network is necessary to overcome cloud obstruction of the feeder link. In this paper, we report three promising sets of OGSs in the vicinity of existing ingress and egress points of a selected pan-European optical fiber network. These OGS networks are optimized for reaching at least 99.9% feeder link availability while minimizing the overall cost of the system. For the first time, the optical fiber network between OGSs is optimized using existing high-data-rate fiber links to limit its expense. The resulting cost estimates for each OGS network highlight the need to define a new cost model considering optical feeder link specificity. In addition, the link availability is simulated using a 2 year cloud mask data bank, taking into consideration practical cloud blockage forecasting duration and assuming optical transmission through thin ice clouds.

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