BER performance of MIMO free-space optical links

Free space optical (FSO) communications is a cost-effective and high bandwidth access technique, which has been receiving growing attention with recent commercialization successes. Spatial diversity, which involves the use of multiple laser transmitters/receivers, can be used over FSO links to mitigate turbulence-induced fading, resulting in error-rate-performance improvement. In this paper, we investigate BER (bit error rate) performance of MIMO (multiple-input multiple-output) FSO links over lognormal atmospheric turbulence fading channels, assuming both independent and correlated channels among transmitter/receiver apertures. Our derivations clearly demonstrate the effect of diversity in a lognormal channel, which turns out to be much different from a Rayleigh fading channel, which is frequently used to model radio-frequency (RF) wireless fading channels.