Realization of OFDM based free space optics

OFDM(Optical Frequency Division Multiplexing) provides a promising solution for delivering high data rate , large link range for Free space optical link even for worse atmospheric condition like fog, haze, rain etc. With the help of OFDM high spectral efficiency can be achieved as the data is distributed over large number of orthogonal carrier. This paper investigate the performance of Orthogonal Frequency Division Multiplexing (OFDM) based Free Space optical (FSO) Communication System. By using 4-Level QAM and OFDM Modulation, 20Gbps data is transmitted through the FSO system under different weather condition. Further improvement in the link rage can be done by use of SOA (semiconductor optical amplifier). In the current work maximum link range achieved is 260km for clear weather (attenuation 0.11dBm) whereas for heavy fog(attenuation 22dBm) the maximum distance achieved is 4 km.