Document Type : Research Paper


1 Materials Research Directorate, Ministry of Science and Technology, Baghdad, Iraq.

2 Electromechanical Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.


The performance and reliability of a free-space optical (FSO) communication system can be greatly increased using various methods. The primary goal of each technique is to reduce the effect of disturbances that lead to intensity or phase fluctuations in the system's receiver. Recent issues include increased data consumption and a crowded radio frequency spectrum, where free-space optical communication (FSOC) has changed the way people share information in a big way. In place of wired communication systems, it is possible to transport voice, video, and data effectively through air. High speed, cost savings, small buildings, low power consumption, energy economy, maximum transfer capacity, and adaptability are some of the main advantages of FSOC. Repair downtime can be reduced because of the quick advancement of high-speed connection technology. It is also now possible to quickly establish a backup network in an emergency or crisis. The design of FSO systems for two types of digital modulation techniques is the primary focus of this work. An examination of the FSO link's performance in various channel conditions using various modulation techniques is conducted. This analytical mechanism can aid a modulation strategy for various channel conditions. The results indicated that PSK modification is stronger against atmospheric turbulence than ASK modification in terms of quality factor and signal-to-noise ratio (SNR). In addition, the values of received power, quality factor, and signal-to-noise ratio were higher in the case of atmospheric turbulence during rain than in the case of fog, followed by dust conditions. The systems can operate using adaptive optics and evaluate the system's performance in the presence of atmospheric turbulence in terms of signal quality, received power, and signal-to-noise ratio.

Graphical Abstract


  • A design model with different modification types was simulated using Optisystem 7.0 software to evaluate its performance under different weather conditions to determine the best modification method.
  • Attenuation was calculated for each type of atmospheric turbulence.
  • The result of PSK and ASK modulation-based FSO systems used coupler-based delay line filters under various climatic conditions described.


Main Subjects

  1. A. Al-Gailani, M. F. Mohd Salleh, R. Q. Shaddad, N. A. Algeelani and T. A. Almohamad,  A Survey of Free Space Optics (FSO) Communication Systems, Links, and Networks, IEEE Access,  (2021) 7353- 7373.  
  2. De, and A A Bazil Raj, Experimental Study of Sand-Storm Effect on Digital FSO Communication Link, International Conf. Recent Trends Electr. Info. Comm. Technol., (RTEICT), (2020) 35-40.
  3. Mahajan, Investigation of the Performance Improvement of Free Space Optical Link in Atmospheric Conditions, Gharuan, Mohali, Punjab, India-140413, 2019.
  4. Kaymak , R. Rojas-Cessa , J. Feng, N. Ansari, M. Chu Zhou, and Tairan Zhang, A Survey on Acquisition, Tracking, and Pointing Mechanisms for Mobile Free-Space Optical Communications, IEEE Comm. Sur. Tutor., 20 (2018) 1104 -1123.
  5. National Aeronautics and Space Administration, 9.0 Communications, NASA, 2021.
  6. Sarkar and S. K. Metya, Effects of atmospheric weather and turbulence in MSK based FSO communication system for last mile users, Telecommun. Syst.,73 (2020) 87-93.
  7. Zhou, E. Li, and H. Zhang, Performance Analysis of Duobinary and AMI Techniques Using LG Modes in Hybrid MDM-WDM-FSO Transmission System, J. Opt. Commun., 43 (2019) 1-7.
  8. Krishnan, Performance Analysis of FSO Systems over Atmospheric Turbulence Channel for Indian Weather Conditions, IntechOpen, (2019) 5-16.
  9. S. Alatawi, A. A. Youssef , M.  Abaza, M. A. Uddin and A. Mansour, Effects of Atmospheric Turbulence on OpticalWireless Communication in NEOM Smart City, Photonics, 9 (2020) 262.
  10. Xu , G. Xu and Z. Zheng, BER and Channel Capacity Performance of an FSO Communication System over Atmospheric Turbulence with Different Types of Noise, Sensors, 21 (2021) 3454.
  11. T. Mushtaq, S.M. Yasir, M.S. Khan, A. Wahid and M.S. Iqbal, Analysis of Internal Design Parameters to Minimize Geometrical Losses in Free-Space Optical Communication Link, Acta Phys. Pol. Ser., a, 134 (2018) 275-277.
  12. M. Hassana, G M Rather, Free Space Optics (FSO): A Promising Solution to First and Last Mile Connectivity (FLMC) in the Communication Networks, Int. j. Wirel. Microw. Technol., 4 (2020) 1-15. https:/
  13. Khalil, F. Qamar, R. Shahzadi, M. Ali, M. F Nadeem, N. Qamar, I. A. Sajjad, FSO Communication: Benefits, Challenges, and its Analysis in DWDM Communication System, Sir Syed Uni. Res. J. Eng. Technol., 9 (2019).
  15. Dulamjav, B. Zundui, The Analysis of FSO Link Performance in Ulaanbaatar, ICT Focus, 1 (2022).
  16. Anuranjana, Sanmukh Kaur, Rakesh Goyal, Analysis of Terrestrial FSO link performance considering different fog conditions and internal parameters of the system, 6th Int. Conf. Proc. Integr. Networks (SPIN),  2019.
  17. Kh. Shaker, M. A. Aliy , and F. S. A. Ameer, Utilization of MIMO Concept for Optical Communication System under Fog Condition, ECTI Trans. Electr. Eng. Electr. Commun., 17 (2019) 130 – 135.
  18. A. Minhas, M. S. Khan , S. Henna, and M. S. Iqbal, Attenuation-based hybrid RF/FSO link using soft switching, Opt. Eng., 60 (2021) 056102.
  19. A. Ali, Z. H. Baqi and S. K. Rahi, On the Performance of Free Space Optical Communication Link Over Dust Environment, AIP Conf. Proc., 2213 (2020)