Overview of MMW/THz Wireless Propagation

Millimeter-wave (MMW) and terahertz (THz) wireless links have recently attracted a significant interest because of their ultrahigh data rate. However, the application of MMW/THz wireless links is limited because of its propagation characteristics. The absorption of electromagnetic waves at MMW/THz bands by air and rain is considerably large, which limits the transmission distance of the wireless links for the MMW/THz bands. Moreover, the diffraction loss for the MMW/THz bands is significantly large, and a line-of-sight (LOS) environment is necessary for the MMW/THz wireless links. Based on the propagation characteristics, various use cases, such as a wireless backhaul/fronthaul link, mobile wireless access, wireless LAN, kiosk download, and intra- and inter-chip connections, have been proposed. It is important to construct propagation models applicable to this frequency band for using the MMW/THz band wireless systems practically, because these models are used to design the link budget of wireless systems and estimate interferences between the radio stations located in proximity. This chapter describes the features and subjects of MMW and THz band propagation for the major use cases of MMW/THz wireless links.