Exact error rate analysis of free-space optical communications with spatial diversity over Gamma–Gamma atmospheric turbulence

Abstract

The error rate performances and outage probabilities of free-space optical (FSO) communications with spatial diversity are studied for Gamma–Gamma turbulent environments. Equal gain combining (EGC) and selection combining (SC) diversity are considered as practical schemes to mitigate turbulence. The exact bit-error rate (BER) expression and outage probability are derived for direct detection EGC multiple aperture receiver system. BER performances and outage probabilities are analyzed and compared for different number of sub-apertures each having aperture area A with EGC and SC techniques. BER performances and outage probabilities of a single monolithic aperture and multiple aperture receiver system with the same total aperture area are compared under thermal-noise-limited and background-noise-limited conditions. It is shown that multiple aperture receiver system can greatly improve the system communication performances. And these analytical tools are useful in providing highly accurate error rate estimation for FSO communication systems.

Keywords:

• atmospheric turbulence
• bit-error rate (BER)
• outage probability
• free-space optical communications
• Gamma–Gamma distribution
• spatial diversity

Additional information

Funding

This work was supported by the program of excellent team in Harbin Institute of Technology.