A Comparative Study for Indoor Factory Environments at 4.9 and 28 GHz

The industrial Internet of Things (IIoT) has benefited from the fifth-generation (5G) wireless network and is providing much-needed impetus to stimulate economic growth. Because of a very wide frequency range of 5G wireless network, the microwave and millimeter wavebands will constitute hybrid wireless communication systems, thus it is essential to have a thorough knowledge of the propagation characteristics in industrial scenarios at different frequencies. In this paper, we provide a comparative study of channel characteristics, i.e., the path loss and Ricean K-factor, at 4.9 and 28 GHz in indoor factory environments based on channel measurements. The analysis results consistently indicate that rich reflection paths occur in industrial scenarios, relative to indoor office environments. Also, severer attenuation and lower multipath richness occur at 28 GHz. Meanwhile, the impact of antenna height on the propagation channel is studied. These results are helpful for the frequency band selection and antenna height design of IIoT systems.