Free Space Optical Channel Under Fog: Enhanced Performance Using MDRZ Technique

Data Transmission utilizing free space optics is becoming a promising solution for high-speedcommunication in the last mile, providing benefits such as high bandwidth and low bit error rates. However, itsperformance is affected by climate conditions, including rain, fog, and other factors. This study focuses on the designenhancement of the transmitter side to improve the channel quality, achieving longer propagation range with highreceived optical power (ROP), high rate, low bit error rate (BER) in short distances and low implementation costs.Our research showed the importance of selecting an appropriate modulation scheme to enhance the link quality overlonger distance, so the proposed MDRZ layout successfully extended the link distance to 1300 meters with the bestquality factor under light fog using Modified Duobinary Return to Zero (MDRZ) modulation format regardless oflosses. Through simulations conducted via OptiSystem software, the systems were tested under three modulationlayouts, Non-Return to Zero (NRZ), Return to Zero (RZ), and MDRZ at operating wavelength 1550 nm with varyingthe level of fog attenuation and link length.The study aims to analyze the effects of propagation range of the link and attenuation on the system performance,achieving the best ROP and evaluation of Q-factor when applying MDRZ and RZ modulation layouts while obtainingbetter and lower BER when utilizing the original NRZ modulation layout as it is applied for shorter distances. Theoutcomes confirm that the enhanced MDRZ modulation improves the transmission quality and extends thecommunication distance under foggy climate.