Performance analysis of Free Space Optical links encoded using Luby Transform codes

Free Space Optical (FSO) communication is an emerging transmission technique to transmit high data rates without using cables. This technology is expected to revolutionize the present communication system architectures both in the terrestrial and the in -space architecture. Atmospheric effects can significantly degrade the performance of FSO systems. This reduces the SNR and leads to impaired performance. FSO channels can be modeled using Gamma-Gamma, Weibull, Log-Normal, K distribution functions. Error control codes can help to mitigate atmospheric turbulence induced signal fading in free space optical communication links. Luby Transform codes belong to a class of error control codes called Fountain codes and are meant for erasure channels. In this paper, we propose encoding FSO links with Luby Transform (LT) codes for error channels. Decoding is done using belief propagation with Log Likelihood Ratio and results are obtained for different modulation schemes under different channel distributions.