Terrestrial free-space optical links with temporal diversity

In this work, the performance of subcarrier intensity modulated terrestrial free-space optical communication link is analysed in the presence of noise and atmospheric turbulence induced fading. To ameliorate channel fading we propose subcarrier time delay diversity (TDD) in which delayed versions of the original data are retransmitted on different subcarriers. The most efficient TDD is obtained with single re-transmission with an estimated gain of up to 4.5 dB in weak turbulence.