Uplink laser satellite-communication system performance for a Gaussian beam propagating through three-layer altitude spectrum of weak-turbulence

Uplink laser satellite-communication (satcom) system performance has been extensively studied under the assumption that atmospheric turbulence statistics obey a Kolmogorov power-law spectrum model. Unfortunately recent evidence has indicated that Kolmogorov spectrum is sometimes incomplete to describe atmospheric turbulence statistics properly, in particular in the upper atmosphere. In this paper, we use a three-layer attitude spectrum model that exhibits non-Kolmogorov properties in portions of the troposphere and stratosphere. Using this spectrum in weak turbulence, we analyze the bit-error rate (BER) performance of an uplink laser satcom system with a collimated untracked Gaussian beam subject to scintillation and beam wander impairments. Our theoretical results show that the difference in BER between the three-layer altitude spectrum and the Kolmogorov spectrum is not appreciable for smaller transmitter beam radius, but is significant at larger transmitter beam radius. Furthermore, for a given laser wavelength or zenith angle, the optimum transmitter beam radius that can minimize the BER is very different between the two turbulence spectrums.