SISO and MIMO FSO based links under different weather conditions: system evaluation

Free space optics (FSO) systems are the terrestrial point-to-point optical wireless communications (OWC) systems, also known as one of the most advanced wireless technologies. FSO communication is one of the best cost saving ways to send and receive data with high data transmission capacity and security. In this paper, a channel distance of 1 km at the wavelength of 1550 nm is utilized. Different modulation schemes are analyzed to improve OWC system performance under different weather conditions. The effect of the number of transmitters and receivers on the performance of the proposed FSO system is investigated and evaluated through the evaluation parameters including the quality factor (Q-factor), power received and bit error rate (BER). The effect of the pointing error is also studied under different weather conditions using multiple input multiple output (MIMO) systems with different modulation schemes. Among these schemes, we focus on: on-off keying-non-return to zero (OOK-NRZ), carrier suppressed non-return to zero (CSNRZ), duobinary non-return to zero (DBNRZ) and modified duobinary non-return to zero (MDBNRZ)). The obtained results reveal that, the received signal power of both CSNRZ and DBNRZ in MIMO systems is improved by 21% compared to single input single output (SISO) systems. It is also found that, the MDBNRZ received signal power increases by similar to 22% in MIMO system compared to SISO system at a beam divergence angle of 1 mrad. The performance the OOK-NRZ is enhanced by 23% in SISO system and by 25% in MIMO system than that in literature.

Automated summary

This paper investigates the performance of point-to-point optical wireless communication using Free Space Optics (FSO) systems under different weather conditions. Through analyzing different modulation schemes, it is found that in MIMO systems, the received signal power of CSNRZ and DBNRZ is improved by 21%, MDBNRZ increases by approximately 22%, and OOK-NRZ is enhanced by 23% in SISO systems and 25% in MIMO systems compared to literature.