AUTHOR=Singh Mehtab , Kříž Jan , Kamruzzaman M. M. , Dhasarathan Vigneswaran , Sharma Abhishek , Abd El-Mottaleb Somia A. 

TITLE=Design of a High-Speed OFDM-SAC-OCDMA-Based FSO System Using EDW Codes for Supporting 5G Data Services and Smart City Applications

JOURNAL=Frontiers in Physics

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2022.934848

DOI=10.3389/fphy.2022.934848

ISSN=2296-424X

ABSTRACT=A novel free space optical (FSO) system is introduced in this paper by combining orthogonal frequency division multiplexing (OFDM) with spectral amplitude coding optical code division multiple access (SAC-OCDMA) to be implemented in 5G technology and smart cities. Enhanced double weight (EDW) codes are used as signature codes while for detection technique, single photodiode detection (SPD) is applied for the SAC-OCDMA system. OFDM with four quadrature amplitude modulation (4-QAM) scheme is assigned to the three users in the SAC-OCDMA system, each transporting 15 Gbps. Adverse weather conditions, like clear, fog, haze, rain and dust storm that affect the FSO channel are considered. The performance of the proposed system is evaluated in terms of log of bit error rate and received power at different propagation distance. The simulation results show successful transmission of 3×15 Gbps with propagation range of 3.45 km under clear air, 1.316 km, 1.045 km, and 0.7 km under rain conditions (light, medium, and heavy rain) with received power of -12.6 dBm. As for haze conditions, the range and received power are 2.391 km with -13 dBm for low haze, 1.591 km with -12.7 dBm for medium haze and 1.025 km with -12.6 dBm for heavy haze.  The range is reduced and become 1.085 km, 0.784 km, and 0.645 km under fog conditions (light, medium, and heavy fog) with -12.6 dBm received power. Furthermore, the system achieved range of 0.681 km, 0.232 km, and 0.102 km under dust conditions (light, medium, and heavy dust) with received power of -16 dBm.