Buffer requirements of an optical communication system in atmospheric turbulence

Expressions related to the buffer requirements of an optical communication system in atmospheric turbulence are developed from the channel signal fade time statistics. Laser irradiance data were recorded over the course of one day by a receiving aperture of variable diameter at the Townes Institute Science and Technology Experimentation Facility (TISTEF) 1km laser range located within the Kennedy Space Center at Cape Canaveral, FL. Fade statistics of collected data and scintillometer measurements were compared to the derived model gamma-gamma fade model. Parallel to the laser instrumentation was a commercial scintillometer unit which reported the refractive index structure coefficient, Cn2 and the inner-scale of atmospheric turbulence, l0. The atmospheric parameters inferred from the collected laser data and the commercial instruments were compared. Mean and variance of the fade times were found to agree well with theory for smaller apertures where effects of aperture averaging are not present and in cases where scintillation is weak to moderate. It is suggested that a more appropriate PDF, with a heavier focus on aperture averaging, may be applied in future studies of free space optical communication system fade statistics.