Link Budget

Loss	Formula
Free space path loss	$(\frac{λ}{4 π * d_{G S}})^{2}$
Transmitter pointing loss	$e^{- G_{t} * θ_{t}^{2}}$
Receiver pointing loss	$e^{- G_{r} * θ_{r}^{2}}$

Signal loss coefficients of a laser beam
where:
$λ$ wavelength of the laser beam
$d_{G S}$ satellite-OGS distance
$G_{t}$ transmitter's gain
$G_{r}$ receiver's gain
$θ_{t}$ transmitter's pointing error
$θ_{r}$ receiver's pointing error

Recommended Bibliography

Link Budget Analysis for Free-Space Optical Satellite Networks
Link budget calculation in optical LEO satellite downlinks with on/off-keying and large signal divergence: A simplified methodology
Free Space Optical Communications — Theory and Practices