DRNC
Drift Radio Network Controller
When a UE (User Equipment), in the connected state is handed onto a cell associated with a different RNS (Radio Network Subsystem) it is said to have drifted. The RRC (Radio Resource Control) connection however still terminates with the SRNC (Serving RNC). In effect the DRNC acts as a switch, routing information between the SRNC and the UE.