Performance analysis of hybrid RF/FSO link over Nakagami-m fading and Chi-square–inverse Gamma atmospheric turbulence with pointing errors

This paper introduces a novel statistical model for the performance analysis of hybrid RF/FSO (radio frequency/free-space optics) communication systems. The RF channel is modeled using the Nakagami-m fading distribution, while the FSO channel is characterized by a Chi-square–inverse Gamma distribution to account for atmospheric turbulence and pointing errors. A closed-form expression for the cumulative distribution function (CDF) of a one-hop hybrid RF/FSO system is derived under a selective combining scheme, formulated as a function of the average signal-to-noise ratio (SNR). The resulting CDF is expressed in terms of the extended generalized bivariate Meijer-G function (EGBMGF). Furthermore, new analytical expressions for the average bit error rate (ABER) are obtained for both the hybrid RF/FSO system and its FSO-only counterpart under coherent binary phase-shift keying (CBPSK) modulation. A detailed comparative analysis is performed across varying channel parameters and turbulence conditions. Numerical results, presented graphically, demonstrate the superior robustness of the proposed hybrid scheme under severe turbulence and misalignment effects.