Radio Unit (RU)
The Radio Unit is the part of a split base station, next to the antenna, that handles radio frequency processing and the lowest part of the physical layer.
What is Radio Unit (RU)?
In 5G's CU/DU/RU split, the RU converts digital signals to radio and back, carries out beamforming in some designs, and connects to the DU over the fronthaul. The source calls it a "Remote or Radio Unit", reflecting both names in use.