Analysis of Rayleigh fading channel in FSO system with respect to Eb/N0 for different modulation schemes

Free Space Optics (FSO) is an emerging and promising communication system which provides very high speed transmission of data, without the use of any hardware channel. The channel is atmosphere, which is turbulent in nature and causes degradation of optical signal. This paper focuses on investigating the system performance when the optical signal is passed through Rayleigh fading channel. Bit Error Rate (BER), Outage Probability and Power Margin expressions are expressed in terms of E
b
/N
0
, for BPSK, QPSK and 16-QAM modulation schemes and investigations are carried out to determine the system performances in case of all three modulations. At the end, based on the investigations it is concluded that the performance of 16-QAM is poorer than the other two techniques and hence should be least used in case of Rayleigh fading channel in FSO.