Radio Network Controller - Protocols

Protocols

Iub, Iu and Iur protocols all carry both user data and signalling (that is, control plane).

• Signalling protocol responsible for the control of the Node B by the RNC is called NBAP (Node-B Application Part). NBAP is subdivided into Common and Dedicated NBAP (C-NBAP and D-NBAP), where Common NBAP controls overall Node B functionality and Dedicated NBAP controls separate cells or sectors of the Node B. NBAP is carried over Iub. In order for NBAP to handle common and dedicated procedures, it is divided into: NodeB Control Port (NCP) which handles common NBAP procedures and Communication Control Port (CCP) which handles dedicated NBAP procedures.

• Control plane protocol for the transport layer is called ALCAP (Access Link Control Application Protocol). Basic functionality of ALCAP is multiplexing of different users onto one AAL2 transmission path using channel IDs (CIDs). ALCAP is carried over Iub and Iu-CS interfaces.

• Signalling protocol responsible for communication between RNC and the core network is called RANAP (Radio Access Network Application Part), and is carried over Iu interface.

• Signalling protocol responsible for communications between RNCs is called RNSAP (Radio Network Subsystem Application Part) and is carried on the Iur interface.