This study explores the integration of orthogonal frequency division multiplexing (OFDM) with unmanned aerial vehicle (UAV)-based free-space optical (FSO) communication systems to enhance wireless communication links to ground sites, particularly in the context of 5G networks. The research introduces a 4-level quadrature amplitude modulation (4-QAM)-OFDM-FSO framework tailored for UAV-to-ground communication, aiming to mitigate atmospheric turbulence and improve signal integrity. Through simulations and theoretical analyses, the study demonstrates the system's efficacy in achieving high data transmission rates, enhancing spectral efficiency, and adapting to varying link distances. Key findings include the correlation between pointing errors, scintillation, and beam divergence angle, with adaptive beam divergence control and OFDM adaptive modulation significantly improving data rates and reducing scintillation effects. The proposed framework is validated through simulations, showing improved average spectral efficiency and reduced scintillation impact. The study also discusses the operational feasibility, scalability, and practical applicability of UAV-FSO systems, addressing challenges such as rapid deployment and spectrum accessibility. The results highlight the potential of this integrated system for future wireless network infrastructures, particularly in supporting high-throughput, agile, and resilient communication links.This study explores the integration of orthogonal frequency division multiplexing (OFDM) with unmanned aerial vehicle (UAV)-based free-space optical (FSO) communication systems to enhance wireless communication links to ground sites, particularly in the context of 5G networks. The research introduces a 4-level quadrature amplitude modulation (4-QAM)-OFDM-FSO framework tailored for UAV-to-ground communication, aiming to mitigate atmospheric turbulence and improve signal integrity. Through simulations and theoretical analyses, the study demonstrates the system's efficacy in achieving high data transmission rates, enhancing spectral efficiency, and adapting to varying link distances. Key findings include the correlation between pointing errors, scintillation, and beam divergence angle, with adaptive beam divergence control and OFDM adaptive modulation significantly improving data rates and reducing scintillation effects. The proposed framework is validated through simulations, showing improved average spectral efficiency and reduced scintillation impact. The study also discusses the operational feasibility, scalability, and practical applicability of UAV-FSO systems, addressing challenges such as rapid deployment and spectrum accessibility. The results highlight the potential of this integrated system for future wireless network infrastructures, particularly in supporting high-throughput, agile, and resilient communication links.