Relayed ground-to-satellite free-space-optical communications

A method for providing free space optical (FSO) ground-to-satellite communications, the method comprising:

• deploying an optical ground station;
• deploying a plurality of FSO relays, each being either a tropospheric FSO relay or a stratospheric FSO relay, the plurality of FSO relays comprising:
• a first FSO relay in optical communication with the optical ground station via a first FSO sub-link;
• and
• a second FSO relay in optical communication with a satellite via a second FSO sub-link;
• and
• transmitting optical signals from the optical ground station to the satellite optically via the plurality of FSO relays by communicating with the satellite via a ground-to-satellite FSO communication link that comprises at least three FSO sub-links including the first FSO sub-link and the second FSO sub-link, wherein:
• the transmitting involves a plurality of transmit nodes, including the optical ground station and at least some of the plurality of FSO relays, such that each of the plurality of transmit nodes participates in the transmission by transmitting at a respective partial transmit power over a respective FSO sub-link of the ground-to-satellite FSO communication link;
• the deploying the plurality of FSO relays comprises, for each of at least two transmit nodes, optimizing the respective partial transmit power based on decreasing an outage probability associated with the respective FSO sub-link in presence of predetermined attenuation factors.