Transmit Diversity for FSO/RF-Based Multiuser Networks

In this paper, we consider multi-aperture multiuser dual-hop amplify-and-forward (AF) free-space optical/radio frequency (FSO/RF) communication systems. The FSO-RF channels are assumed to follow Málaga- M/shadowed κ-μ fading models with pointing errors on the FSO links. Under the assumption of transmit aperture selection at the source and opportunistic user scheduling at the destination, we derive exact closed-form expressions for the outage probability and average symbol error probability (SEP). Additionally, the system performance is studied at the high signal-to-noise ratio (SNR) regime where an approximate expression for the system outage probability is derived, in addition to deriving the system diversity order and coding gain.