Performance of channel coding on free space optical (FSO) communication link

The average loss power and the channel fading are among the major challenges of the free-space optical (FSO) communications through the turbulent atmosphere, resulting in the bit-error-rate (BER) performance degradation, or even communication link outage. For the same average received optical signal power, the degradation in BER performance is strongly dependent on the fading statistics. This thesis investigates the performance of channel coding to improve the FSO communication system performance and the communication distance by mitigating atmospheric turbulence. We derive a pairwise error probability (PEP) expression considering the recently introduced gamma-gamma turbulence model and then we drive the upper bounds for the bit-error probability for block codes through atmospheric turbulence channels, considering the gamma-gamma model. Also we present numerical results for the BER performance of different codes such as the Reed-Solomon (RS), Bose, Chaudhuri, and Hocquenghem (BCH) and Hamming codes under different turbulence conditions (weak, moderate, strong).