Performance Improvement of SAC-OCDMA FSO System Under Rain and Snow Conditions Using Different Zero Cross-Correlation Codes

Free Space Optical (FSO) communication systems are gaining interest in the telecommunication field due to their significant advantages, including high bandwidth, wireless transmission instead of fiber optics, and no licensing requirement. Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) is one of the coding schemes that have been widely introduced in FSO communications due to their ability to eliminate Multiple Access Interference (MAI). The current paper focuses on the study of a SAC-OCDMA FSO system using various codes with zero cross-correlation value, namely: Zero cross-correlation (ZCC) and Double Weight-Zero Cross-Correlation (DW-ZCC) codes under the effect of different weather conditions, including rain and snow. This work reveals performance enhancement in comparison to some previous studies. The simulation results showed that the DW-ZCC code has a better performance compared to the ZCC code, and that the signal transmission quality is strongly dependent on weather conditions. The FSO transmission distance reached under the snow effect is shorter than that achieved under the rain effect. The proposed SAC-OCDMA FSO system of 7 users using DW-ZCC code achieves a maximum distance of 1.99 km under drizzle rain. Under wet and dry snow with a precipitation intensity of 2 mm/h, the maximum distance in free space is about 1.045 km and 675 m, respectively.