Enhanced Coherent Optical OFDM FSO Link Using Diversity for Different Weather Conditions

One of the recent trends in communication is Free Space optics (FSO). These systems provide solution to the bottleneck problems of the RF communication systems, like Bandwidth scalability, cost effectiveness and portability. But, few of the challenging tasks in implementing this system are Line of sight, atmospheric conditions like fog, snow... etc. Actually the Coherent Optical OFDM orthogonal Frequency Division Multiplexing (CO OFDM) system in FSO is capable of transmitting data upto 0.22 km in dense fog weather conditions. This can be improved by reducing the fading due to free space. One of the efficient ways to reduce fading effects is spatial diversity. Spatial diversity will improve the received power and ensures the low Bit Error Rate (BER). The aim of this paper is to incorporate this Diversity technique into the FSO OFDM, so that an enhanced FSO link is established. The performance analysis is carried out in terms of BER, Constellation diagram, received power.