Comparative Performance Evaluation of Line Coding Schemes for Uplink Transmission in Single and WDM Channels FSO-HAP Systems Across Varied Altitude and Weather Scenarios

The demand for fast, reliable, and adaptable communication solutions has led to increased interest in wireless technologies. Free-Space Optical (FSO) communication systems with the integration of FSO with High Altitude Platforms (HAPs) presents unique opportunities for enhancing connectivity. However, challenges arise in optimizing system performance amidst varying altitude and weather conditions. This paper conducts a thorough comparative evaluation of line coding schemes for uplink transmission in FSO-HAP systems across diverse scenarios using OptiSystem. Results indicate NRZ as the top performer, excelling in both single-channel and Wavelength Division Multiplexing (WDM) setups due to its simplicity and spectral efficiency. RZ demonstrates optimal performance, particularly in WDM systems spanning up to 50km, while NRZ and RZ emerge as preferred options for long-distance optical communication. The Q-Factor for single channels recorded 39.067 for RZ and 59.926 for NRZ. Meanwhile, the average Q-Factor for WDM channels is 14.667 for RZ and 7.245 for NRZ. Caution is warranted in HAPs deployment, as current capabilities may be insufficient, particularly under adverse weather conditions.