Hybrid Multiplexing-Based Free Space Optics System for High-Capacity Communication Under Rain-Induced Impairments

Free-Space Optics (FSO) is a high-speed communication technology that provides speed and bandwidth comparable to optical fiber. In terms of deployment time and cost, FSO is superior to optical fiber. However, variable weather conditions, such as rain, that impact the signal are one of the primary obstacles to FSO, as the signal is transmitted through the atmosphere. But, rainy weather substantially affects the efficacy of FSO links, resulting in diminished transmission quality and potential signal loss. The purpose of this research is to evaluate the performance of an FSO connection while considering the impairments induced by precipitation for the proposed data capacity. In light of these challenges and the benefits of FSO, this study proposed a hybrid multiplexing technique-based system that achieves data throughput of 0.344Tbps per WDM channel by combining coherent optical orthogonal frequency division multiplexing (CO-OFDM), polarization division multiplexing (PDM), and Wavelength division multiplexing (WDM). A quadrature amplitude modulation (4-QAM) scheme has also been used to achieve a total capacity of 1.38 Tbits/s and spectral efficiency of 3.4bps/HZ for four distinct WDM channels. Under situations of clear weather, light rain, medium rain, and heavy rain, the proposed system has been capable of supporting transmissions of up to 66.99 km, 5.049 km, 3.60 km, and 2.0498 km, respectively. The results show that the greatest link range could be achieved under the most difficult channel circumstances while maintaining a minimum acceptable bit error rate (BER) of log (BER) ⩽ -2.42, which has been accomplished by using pre- and post-optical amplification between FSO channels.