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.

Α dual‐hop equivalent structure of a generalised multi‐hop free‐space optics network

“…Here, we provide some typical numerical results for the FSO configuration as illustrated in Figure 3 operating over weak or moderate turbulent channels. By properly using Equations (5) to (7), we estimate the values for the parameters of both distributions. More precisely, for the gamma case, we consider weak turbulence conditions, C 2 n = 7 × 10 −15 m −2∕3 , with L = 7 km,…”

“…Free-space-optics (FSO) has attracted increasing research and commercial interest mostly due to the benefits against other wireless technologies, including radiofrequency or millimetre wave systems, in cases where point-to-point connections are required [1][2][3][4]. The most important of them is the high bandwidth access, the operation in the unlicensed spectrum, the low installation and operation cost, the enhanced security provision and the immunity to the electromagnetic interference [5][6][7]. However, the operation of FSO links strongly depends on several impairments, including scintillation caused by atmospheric turbulence effect [4].…”