Performance of Convolutional Coded Subcarrier Intensity Modulation over Gamma-Gamma Turbulence Channels

Error rate performances of free-space optical communication are analyzed for irradiance modulation and direct detection systems using subcarrier intensity modulation with binary phase-shift keying and convolutional code. The analysis is carried out for Gamma-Gamma turbulence channels. For bit-by-bit interleaved channels, a highly accurate series solution is developed for the pairwise error probability, and this solution is used to formulate a simplified upper bound on the average bit-error rate (BER). We also study the BER performance for quasi-static fading channels of a convolutional coded system using block interleaving where each block experiences independent fading.