Symbol error probability for coherent laser communications systems in atmospheric turbulence: Gaussian beam analysis

In this paper, we investigate how atmospheric turbulence impacts Symbol Error Probability (SEP) of free-space optical communication systems based on the phase-shift keying heterodyne coherent receiver scheme. The derivation assumes the validity of the Maréchal approximation and requires a high number of "coherence cells" at the receiver pupil (ergodic hypothesis). Results show that such conditions can both be satisfied at the same time when tip and tilt correction is applied. We also found that better performances in terms of SEP are possible when the receiver is located in the far field (supposing a collimated beam at the transmitter). Our analysis is valid for Gaussian beams affected by Kolmogorov turbulence.