What is RAN? Radio access network: the part of a telecommunications system that implements a radio technology (e.g. UTRA, Evolved UTRA, CDMA2000, DECT, GERAN) to access the Core Network. The radio access network conceptually resides between user equipment (i.e. mobile phones and other devices) and the Core Network. Mavenir's cloud-based version is Cloud RAN.
What is RRH? Radios placed on top of roof tops or towers. These are the core parts of the macroCell and Small cell transmission technology. As an MEC application, Private LTE is considered a small cell.
What is RRU? A remote radio transceiver that connects to an operator radio control panel. Is used interchangeably with RRH (remote radio head), with RRH being the more common of the two.