Overcoming Atmospheric Turbulence Using OFDM-FSO System:A Review

Nowadays, Free Space Optics (FSO) is gaining a lot of popularity, as it offers more advantages than other communication systems like licence-free operation, high data transmission rates etc. The major drawback of this system is the atmospheric turbulence since the medium that is used in this system is air. Orthogonal frequency-division multiplexing (OFDM) is a method of digital signal modulation in which a single data stream is divided into several separate narrowband channels at different frequencies. One of the main advantages of OFDM is that it is more resistant to frequency selective fading because it divides the overall channel into multiple narrowband signals that are affected individually as flat fading sub-channels. Using FSO system in combination with Orthogonal Frequency Division Multiplexing (OFDM) scheme, the bad influence of atmosphere can be overcome. There are different methods to mitigate the bad influence of turbulence in OFDM-FSO system which is discussed in this paper.