Performance of FSO system using PPM and MSK sub-carrier intensity modulation scheme

Performance analysis of FSO system using pulse position modulation (PPM) and minimum shift keying (MSK) subcarrier intensity modulation (PPM-MSK-SIM) is done in this paper. Performance of system has been analyzed for different values of APD gain over varying turbulence strength and link ranges. Noise sources considered are shot noise, thermal noise and back ground noise. Results reveal that by selecting proper average APD gain, the channel capacity and bit error rate (BER) of system improves considerably.