Fifth-generation (5G) communication provides a substantial increase in data transmission capacity because of more available bandwidth and advanced communication techniques. It opens the door to a range of new applicatio. Fifth-generation (5G) communication provides a substantial increase in data transmission capacity because of more available bandwidth and advanced communication techniques. It opens the door to a range of new applications, such as 4K/8K video streaming, Internet of Things, autonomous vehicles, unmanned aerial vehicles, and more. However, atmospheri. High data rate, ultra-low latency, and massive connection requirements in fifth-generation (5G) services have substantially promoted the development of telecommunications1,2,3,4,5,6,7,8. The development of 5G signals through fibre-free-space optics (FSO)-wireless communications (as shown in Fig. 1) has greatly accelerated this global trend. One of the technical challenges of 5G wireless communications is high atmospheric attenuation. 5G communication experiences severe signal loss as 5G signals propagate through the atmosphere, limiting their coverage. Reducing high atmospheric attenuation is a substantial challenge in deploying 5 G communication. A promising solution to address this limitation is the deployment of FSO links. It overcomes the coverage limitations of 5. Atmospheric attenuation and laser light alignment for FSO linksWhen optical signals travel through free space, atmospheric turbulence causes the optical signals to attenuate in the atmosphere. For FSO links, atmospheric attenuation varies with weather conditions. Over a 1-km FSO link, atmospheric attenuation changes from 2 dB (clear weather) to 50 dB (bad weather). Severe atmospheric turbulence caused by severe weather strongly affects FSO link performance. In this demonstration, approximately 2.6 dB of atmospheric attenuation occurs (clear weather) due to a 1 km FSO link. However, under severe weather conditions such as heavy rain and fog, FSO link performance will drastically deteriorate. In severe weather, neverthel. 5G MMW/sub-6 GHz signals through two-way fibre–FSO–wireless communicationsThe architecture of 5G MMW/sub-6 GHz signals through two-way fibre–FSO–wireless communications employing polarisation-orthogonal modulation is offered and realised in Fig. 5a. A real experimental setup rather than a simulated one is established. And further, a photo of the experimental setup is exhibited in Fig. 5b. A light source, including a DFB LD, a PR and an MZM, is deployed at the transmission site. The light sent out from a DFB LD (with 1545.62 nm centre wavelength) is supplied to an MZM through a PR. The MZM is worked at the minimum transmission point and is driven by integrated 1-Gbps/2.2-GHz and 10-Gbps/19-GHz 16-QAM-OFDM signals thr. The data in this manuscript are available from the corresponding author upon reasonable request. The source data for Figs. 2a, b, 4a, and b are provided as Supplementary Data 1–4, respectively.