PERFORMANCE OF FREE-SPACE OPTICS TRANSMISSION SYSTEM USING ADVANCED MULTIPLEXING TECHNIQUES UNDER SAUDI ARABIAN WEATHER CONDITION

Abstract

Freespace optics (FSO) communication is a promising technology for high-speed and cost-effective data transmission in both terrestrial and non-terrestrial networks. This research evaluates the performance of advanced multiplexing techniques including orbital angular momentum (OAM), polarization division multiplexing (PDM), orthogonal frequency division multiplexing (OFDM), and in-phase/quadrature modulation (IQM) under representative Saudi Arabian atmospheric conditions. Visibility measurements from the Meteorological Department for Jazan and Riyadh were employed in this analysis. Atmospheric attenuation was modeled using the Kim, Kruse, and Al-Naboulsi approaches. OptiSystem and MATLAB were employed for system implementation and channel modeling, evaluating capacity gain and attainable distance range, with other performance metrics including bit error rate (BER), eye diagrams, and Q-factor evaluated for all objectives. The first objective examined OAM-based FSO systems, showing moderate capacity gains of up to 40 Gbps across 4 km under clear conditions. The second objective assessed OAM–PDM integration, effectively doubling capacity to 80 Gbps without extending the transmission range. The third objective investigated a hybrid IQM–OAM–PDM–OFDM design, achieving the highest performance: up to 640 Gbps over ~15 km under Kim and Kruse models, and ~7.25 km under the Al-Naboulsi model, with additional evaluation of Error Vector Magnitude (EVM) and Forward Error Correction (FEC) to further reduce BER. These findings confirm the sequential achievement of the research objectives and demonstrate that combining advanced multiplexing and modulation techniques, alongside probabilistic performance matrices, significantly enhances both capacity and transmission range. The results provide practical insights for the design of next-generation FSOs that are resilient to atmospheric impairments in Saudi Arabia.