Free-space optical communication with M-ary pulse position modulation under gamma-gamma and negative exponential atmospheric turbulence model

Free space optical (FSO) communication offers an attractive alternative to the radio frequency (RF) channel for the purpose of transmitting data at very high rates. Atmospheric turbulence can degrade the performance of FSO links, particularly over ranges of the order of 1 km or longer. The performance of the FSO link can be improved by employing an appropriate modulation scheme and channel model which makes a good compromise between complexity and performance. In this view, we consider in this paper the M-ary pulse position modulation (PPM) which has the interesting advantage of being average-energy efficient with gamma-gamma and negative exponential atmospheric turbulence model under turbulent condition. The performance results are evaluated in terms of symbol error probability (SEP) for different type of channel model.