IMPLEMENTATION OF AN EFFECTIVE FSO WDM SYSTEM UNDER DIFFERENT ATMOSPHERIC CONDITIONS WITH DIFFERENT CODING SCHEMES

Abstract

In different atmospheric conditions, Free Space Optical (FSO) transmission is vital because it sends data via light beams through the atmosphere. This technique transmits data quickly and efficiently with low signal attenuation in clear weather. This makes it ideal for short- to medium-range communication, especially in urban areas where cables or radio frequency spectrum are impractical. However, fog, rain, and snow can absorb or disperse the light signal, reducing transmission range and reliability for FSO. This research creates an effective FSO system that supports many channels and transmission distances. The suggested system will be tested in four weather conditions (light air, light rain, medium rain, and heavy rain) with attenuation values of 0.47, 1.988, 5.844, and 9.29 dB/km. Optisystem program version 21 designs and evaluates system performance based on QF, BER, and other criteria. In this research, multiple modulation formats are evaluated for best performance. QF exhibited a reversal relationship with distance, while BER showed a direct one. The suggested system can transmit for 25 km, 12 km, 10 km, and less than 6 km in light air, light rain, medium rain, and severe rain. This research also examines system performance under NRZ and RZ modulation formats. NRZ modulation is better for light air and clear weather transmission than RZ modulation since it requires less equipment and is easier to install. Since NRZ modulation requires no clock recovery overhead, bandwidth efficiency is usually higher. In light rain, RZ modulation minimizes optical fiber dispersion, extending transmission distances and improving signal quality. NRZ excels within 10 kilometers. NRZ works for 6 km and 4 km in medium and severe rain, although RZ's dispersion tolerance and synchronization make it better for longer transmission distances. For short distances, NRZ is suitable, but for longer distances, RZ is more resilient due to its better dispersion management and signal transmission.