Multihop Free-Space Optical Communications Over Strong Turbulence Channels

TLDR

The study investigates the performance of multihop free‑space optical wireless systems over turbulence‑induced fading channels. We analyze amplify‑and‑forward and decode‑and‑forward relaying over Gamma‑Gamma turbulence, deriving outage and bit‑error probability expressions and validating them with numerical simulations. Exact outage probability expressions for AF relays and closed‑form results for DF relays are obtained, and simulations confirm that turbulence severity markedly degrades multihop FSO performance.

Abstract

In this paper, we study the performance of multihop free-space optical (FSO) wireless systems over turbulence-induced fading channels. The analysis is carried out for systems employing amplify-and-forward (AF) or decode-and-forward (DF) relays and for turbulence channels which can be modeled by the Gamma-Gamma distribution. An exact analytical expression for the end-to-end outage probability of AF systems is obtained, while a closed-form expression of DF systems is derived. The average bit-error probability of a dual-hop FSO system employing a DF relay is studied as a special case. Numerical examples are also presented to illustrate the proposed analysis and to further investigate the effects of the turbulence severity on the multihop FSO systems' performance.