Description of Terminology:
Sub6

The radio waves used for 5G communications in Japan include the band below 6 GHz and the frequency band above 28 GHz.
Frequency below 6GHz are called “Sub6” while frequency bands above 28GHz are called “millimeter waves.”
Sub6 frequencies used for 5G communication are allocated to mobile phone operators in 100MHz band-width.
In addition, 4.6GHz – 4.9GHz 300MHz widths were allocated to local 5G in December 2020.
With less attenuation than higher frequency millimeter waves, Sub6 can deliver radio waves over wide areas and circumvent obstacles but is far inferior to millimeter waves in terms of speed and simultaneous connection performance.
Because of the proximity of Sub6 to wavebands used to date by 4G, existing technologies can be used.