Information theoretic analysis of DF based dual-hop mixed RF-FSO communication systems

The information theoretic study of decode-and-forward based mixed radio frequency-free space optical (RF-FSO) cooperative communication system is performed in this paper. The RF link is assumed to be Nakagami-m distributed and the FSO link is modeled by the Gamma-Gamma distributed turbulence, pointing error, and path loss. Novel closed-form analytical expressions of the average channel capacity are derived for the considered asymmetric system under various adaptive transmission policies, i.e., optimal rate adaptation (ORA), simultaneous optimal power and rate adaptation (OPRA), and truncated channel inversion with fixed rate (TCIFR) in terms of Meijer G-function and Extended Bivariate Generalized Meijer-G function. Simulation results validate the proposed analysis. The effect of atmospheric conditions and pointing errors is analyzed by using the average channel capacity expressions. It is observed that the capacity under OPRA scheme outperforms capacity under other schemes.