Image transmission performance analysis through free space optical communication link using coherent QPSK modulation under various environmental conditions

Abstract

Free space optics (FSO) technology has been used recently in many applications due to its various advantages such as high bandwidth, easy deployment, high security, free installation license and immunity to electromagnetic interference. However, this type of communication is vulnerable to meteorological conditions such as rain, haze and fog which significantly degrade the system's efficiency. To enhance the effectiveness of the FSO systems, Quadrature Phase Shift Keying (QPSK) modulation based on coherent detection constitutes a promising technique for achieving high spectral efficiency and long‐distance FSO links with the characteristics of low‐cost implementation and simple design. This work aims to investigate the performance of FSO communication links on image transmission under the presence of atmospheric attenuations. A comparative study has been made using QPSK modulation scheme and on–off‐keying (OOK) modulation scheme to estimate the maximum range that was used to recover an RGB transmitted image over an FSO link under different meteorological weathers. The obtained results clearly show that the quality of the received image has degraded significantly during transmission through free space yielding to limit the propagation range. Moreover, the proposed FSO communication system performs well when using QPSK modulation rather than OOK modulation in different environmental conditions. Thus, to improve the quality of the received image under adverse fog weather condition, high power and small beam divergence angle have been suggested to increase system's performance. The proposed solution increases the communication range of the FSO link by 230 m and 100 m for moderate and heavy fog, respectively.

Performance Enhancement of FSO Communication System Under Rainy Weather Environment Using a Novel Encryption Technique

“…Amina et al in [21], evaluated the performance in terms of PSNR, SNR, and SSIM for a colored image transmission in FSO systems under the impact of MR and HR. In [22], a transmission for AVB-T image over an FSO channel under different turbulence was proposed for Single Input Single Output (SISO) and Multi Input Multi Output (MIMO) systems. The performance was carried out in terms of SSIM.…”

Performance of Cipher Image Transmission in Free Space Optics Under Foggy Weather

“…In [27], authors evaluated the Q-factor, PSNR, and SNR for images propagated in FSO channel affected by fog conditions. In [28], the performance of images modulated using quadrature phase shift keying (QPSK) and on-off keying (OOK) using non-return-to-zero (NRZ) pulse format was investigated under the impact of fog conditions in a FSO channel, where Q-factor, PSNR, and SSIM are used as performance metrics. Although the above-mentioned studies discussed image transmission in the FSO system, neither of them encrypted the image before transmitting it.…”