The C-band is full band between 4 to 8GHz, which has been used for satellite since 1970s, now part of the band ranges is released for cellular companies.

The International Telecommunication Union (ITU) has divided C-band into three groups: band n77(3300~4200MHz), band n78(3300~3800MHz), and band n79(4400~5000MHz).

Most European and Asian countries currently use n78(3.3 to 3.8GHz).

The USA uses n77(3.3 to 4.2GHz), it means carriers can combine 3.45GHz, CBRS, and C-band for wider channels if they have the licenses available.

Japan also already uses n77.

In many countries, n77 (3700 MHz), or commonly referred to as the 3.7 GHz 5G band, or C-band 5G, is the most commonly tested and deployed 5G frequency. The n77 band’s popularity is due to its relatively common availability, compared to lower cellular spectrum (below 2700MHz) already widely in use by 3G and 4G networks.