  A unified capacity analysis of a free-space optical (FSO) link that accounts
for nonzero boresight pointing errors and both types of detection techniques
(i.e. intensity modulation/direct detection as well as heterodyne detection) is
addressed in this work. More specifically, an exact closed-form expression for
the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO
transmission system is presented in terms of well-known elementary functions.
Capitalizing on these new moments expressions, we present approximate and
simple closed-form results for the ergodic capacity at high and low SNR
regimes. All the presented results are verified via computer-based Monte-Carlo
simulations.
