Wireless communications beyond 5G: Uncertainties of terahertz wave attenuation due to rain

Abstract

Statistical peculiarities of terahertz (THz) wave attenuation in heavy rain conditions are evaluated. The expected extreme densification of the infrastructure and the application of highly directional beams of 5th generation (5G) and beyond 5G (B5G) wireless networks were taken into account. Calculations were performed emulating both drop size distributions of the real rain and the laboratory-controlled rain described in literature. Simulation results revealed that absorbance fluctuations of more than one percent would occur if THz waves and raindrops interact within the 100 m3 volume. For much smaller volumes, short distances and narrow beams used for experiments with the laboratory-controlled rain, absorbance uncertainties could exceed the average absorbance value. A comparison of the simulation results at fixed average absorbance revealed that slightly lower uncertainties were expected in the case of a single raindrop size when compared to the Weibull distribution approximating the real rain. Nevertheless, in both cases the predicted deviations were substantially smaller than observed in the previously published experimental results. This fact predicts a new future application possibility for such laboratory-based experiments – they can be employed to predict the performance of wireless THz data transmission links when the resilience margin is required. Since much of the existing industrial test equipment is not designed to carry out calibrated over-the-air measurements of 5G/B5G wireless networks, such experiments can be employed to primarily predict the performance of data transmission links.