The Gamma-Gamma Channel Model - A Survey

Background: In Free space optical communication medium, the received signal envelope is affected by various impairments. The most dominating effect is turbulence induced fading. To model the turbulence there are fading channel models. Findings: In this paper the Gamma-gamma fading model is reviewed which gives impressive results under all types of turbulence conditions. The Gamma-gamma channel model statistics and its performance with spatial diversity techniques under correlation are reviewed. It has been shown that the Gamma-gamma channel model is able to perform better under correlation than other fading channel models. Improvements: The performance analysis of Gamma-gamma channel under pointing errors and its working with recent techniques in which FSO systems works with RF systems (Hybrid RF/FSO system) are also included in this paper.