A Radio Network Controller (RNC) provides the interface between the wireless devices communicating through Node B transceivers and the network edge. This includes controlling and managing the radio transceivers in the Node B equipment, as well as management tasks like soft handoff.
The RNC performs tasks in a 3G wireless network analogous to those of the Base Station Controller (BSC) in a 2G or 2.5G network. It interfaces with GPRS Service Nodes (SGSNs) and Gateways (GGSNs) to mediate with the network service providers.
A radio network controller manages hundreds of Node B transceiver stations while switching and provisioning services off the Mobile Switching Center and 3G data network interfaces. The connection from the RNC to a Node B is called the User Plane Interface Layer and it uses T1/E1 transport to the RNC.
Due to the large number of Node B transceivers, a T1/E1 aggregator is used to deliver the Node B data over channelized OC-3 optical transport to the RNC. The OC-3 pipe can be a direct connection to the RNC or through traditional SONET/SDH transmission networks.
A typical Radio Network Controller may be built on a PICMG or Advanced TCA chassis. It contains several different kinds of cards specialized for performing the functions and interacting with the various interfaces of the RNC.