A range of radio frequencies between 4 GHz and 8 GHz. This includes the 5 GHz unlicensed band used for Wi-Fi, as well as the 3.7 – 6.4 GHz band that has long been used by commercial satellites.
In 2019-2023, the US FCC is conducting a process to re-allocate a part of this band for ground-based mobile cellular networks, which are expected to deploy 5G technology in this newly-available radio spectrum. The part being re-allocated for 5G is 3.7 – 3.98 GHz. The FCC will hold a public auction of new licenses in this band for wireless carriers, and use that money to compensate satellite operators, some of which will need to launch new satellites to make these frequencies available.