First results of ground to GEO optical links channel monitoring with FEELINGS

In the coming decade, optical GEO feeder links should form the backbone of future spatialized high-data rate networks, provided that atmospheric propagation channel influence can be adequately mitigated. Currently foreseen mitigation strategies (interleaving and error correcting codes) rely on strong hypothesis on the statistics of the transmitted optical power, the latter being particularly dependent on the atmospheric channel models considered to tune them. Atmospheric transmission is affected by thin clouds (cirrus), aerosols and contrails, resulting in a several dB uncertainty in the link budget. Atmospheric turbulence causes fluctuations in the transmitted power, with properties highly dependent on the turbulence distribution along the line of sight and its temporal characteristics. Though well-documented in the favorable propagation environments of astronomical observatories, the compatibility of propagation channel properties with very high data rates still needs to be demonstrated for ground segments located closer to densely populated areas. In order to characterize the relationship between challenging optical propagation and optical link performance, ONERA has built the FEELINGS ground station, a 600 mm based adaptive optics (AO) corrected demonstrator equipped with a 50 W optical booster. Located in the periphery of Toulouse, FEELINGS' primary objective is to address the scientific and technological uncertainties associated with optical links and their application in realistic environments. The aim is to pave the way for future operational Optical Ground Stations (OGS) systems. The TELEO payload developed by Airbus, composed of a TOP-M laser terminal with a 260 mm diameter telescope, a 5 W optical amplifier and a 10 Gbaud compatible data transceiver, enables both uplink and downlink 10 Gbaud data transmission. Recently put into orbit, it offers a unique opportunity to confront atmospheric propagation channel models to the challenges of regular high data rate operations. This paper will present the first results of optical links between TELEO and ONERA's ground segment with a specific focus on the propagation channel analysis and modeling for the uplink.