Optimized Beam Size of Optical Ground-to-Satellite Link over Turbulence and Beam-Wandering

The performance of a laser beam traveling in uplink from a ground-to-satellite is subjected to turbulence, and beam wandering. This paper evaluates the performance of the optical uplink with the pulse position modulation (PPM) scheme in order to determine the optimum beam size that minimizes the symbol error rate (SER) and outage probability. Close-form expressions for SER and outage probability are derived by considering the combined effect of turbulence, and beam wandering. Appropriate simulation scenarios are applied, and numerical results are verified the accuracy of the derived close-form expressions. The results show that the optimum beam size is 2.5 with zenith angle changes from 0 to 30°. Furthermore, this paper studies the system performance on optimized beam size by considering the effect of changing the zenith angle, the transmitter power and the modulation orders.