Performance analysis and mitigation of turbulence effects using spatial diversity techniques in FSO systems over combined channel

Abstract

In this chapter, the average bit error rate (BER) and outage performance of a polarization shift keying (PolSK)-based FSO system is analyzed over moderate and strong atmospheric turbulences. By using wavelength and time diversity techniques, the performance of the system is enhanced. Also, the PolSK-based system is extended with spatial diversity and MIMO techniques using OC, EGC, and MRC combining schemes. The performance of SISO and MIMO FSO systems are analyzed in moderate and strong turbulence regimes, the results are compared and plotted. The better BER performance of 10-7 at SNR 1/4 30dB is achieved by using MIMO with MRC combining in weak turbulence without pointing errors. The performance degradation effect of atmospheric turbulence and pointing errors can be reduced by using MIMO scheme, that is by increasing the number of transmit and/or receive apertures. Through the analytical and numerical studies, it is observed that MIMO systems provide the better BER of 10-13 and 10-22 for moderate and strong turbulences at SNR at 60 dB, respectively.