title: Performance analysis of fiber-based free-space optical communications with coherent detection spatial diversity.
abstract: The performances of fiber-based free-space optical (FSO) communications over gamma-gamma distributed turbulence are studied for multiple aperture receiver systems. The equal gain combining (EGC) technique is considered as a practical scheme to mitigate the atmospheric turbulence. Bit error rate (BER) performances for binary-phase-shift-keying-modulated coherent detection fiber-based free-space optical communications are derived and analyzed for EGC diversity receptions through an approximation method. To show the net diversity gain of a multiple aperture receiver system, BER performances of EGC are compared with a single monolithic aperture receiver system with the same total aperture area (same average total incident optical power on the aperture surface) for fiber-based free-space optical communications. The analytical results are verified by Monte Carlo simulations. System performances are also compared for EGC diversity coherent FSO communications with or without considering fiber-coupling efficiencies.
authors.forename: Kangning
authors.initials: K
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Ma
authors.forename: Liying
authors.initials: L
authors.lastname: Tan
authors.forename: Siyuan
authors.initials: S
authors.lastname: Yu
authors.forename: Chao
authors.initials: C
authors.lastname: Zhai