The Performance of Millimeter-Wave Over FSO Communication Systems Under Adverse Atmospheric Conditions for 6G Applications

Upgrading to the sixth generation (6G) network will bring new potential technologies for communication standards beyond the fifth generation (5G). Radio over free space optical (RoFSO) is a new version of optical communication that uses the atmospheric channel for high-data-rate transmission due to the large bandwidth it has. However, the signal attenuation caused by atmospheric conditions is the major factor that can affect the transmission of free space optics (FSO) and degrade ROFSO system performance. This paper investigates the performance of 60 GHz millimeter waves over FSO systems for ultradata rate delivery under different conditions, especially under the effect of oxygen (O
2
) absorption, as it considers the primary attenuation at approximately 60 GHz. A validation of the previous 5G-RoFSO research work is efficiently recognized to prove the effectiveness of our work on the 6G band over FSO in the presence of atmospheric factors. Incorporating a Mach-Zehnder modulator (MZM) into the 60 GHz RoFSO link enables the delivery of different data rates up to 70 Gbps, thereby improving the spectral efficiency of the 6G-RoFSO system. The design is performed using Optisystem v.19 software. The analysis depicted that 60 GHz offers 20 Gbps up to a distance of 2.2 km and shows increases in the data rate up to 60 Gbps for a distance of up to 2 km and 70 Gbps up to 1.4 km with a bit error rate (BER) less than -9 dB. A comparison analysis is performed between the 26 GHz 5G and 60 GHz 6G bands at the same 20 Gbps data rate. The analysis depicted a lower distance performance for the 60 GHz RoFSO link, reaching up to 2.2 km with -11 dB, compared to the 26 GHz RoFSO link, reaching up to 4 km with -11 dB. The results show that the 60 GHz-6G band can achieve a higher data rate of up to 70 Gbps than the 26 GHz-5G band, which achieves up to 20 GHz.