Asymptotic analyses for coherent and subcarrier modulated wireless optical communications

Asymptotic error rates are presented for both coherent and subcarrier wireless optical communication systems in atmospheric turbulence channels. We consider the impacts of both additive noise and turbulence-induced fading in the asymptotic performance analyses for single receiver and diversity receiver cases. The general Gamma-Gamma distribution is used to model the turbulence-induced fading in the performance analyses. Furthermore, the diversity order and diversity gain are introduced for these wireless optical systems in Gamma-Gamma turbulence. These results allow a quantified description in terms of error performance of coherent and subcarrier wireless optical links in the large signal-to-noise ratio regimes.