Performance of annular beams in weak atmospheric turbulence for satellite laser communications

摘要

In a weakly turbulent medium, average bit error rate ((BER)) performances of annular beams used in satellite communication systems in vertical paths are investigated by using Rytov method. (BER) is evaluated by utilizing the on-axis scintillation index and the log-normal distributed intensity. The scintillation indices and (BER) of collimated annular beams are compared against the propagation lengths, source sizes, zenith angle and the average signal to noise ratio ((SNR)) with selected thickness and focusing length for paths including uplink and downlink. The effect of the thickness of this annular beam model is apparent for uplink, while it is unclear for downlink, except for minor differences. The behaviors of this beam model are different for one because of the index structure constant which is directly influenced by a height in these up/down link models. While the minimum source size that can be used is about 8 cm for uplink, it is about 42 cm for downlink.