UTRAN Protocol Model
The general protocol model for UTRAN Interfaces is shown below. The structureis based on the principle that the layers and planes are logically independentof each other. Therefore, as and when required, the standardisation body caneasily alter protocol stacks and planes to fit future requirements.
GeneralProtocol Model for UTRAN Interfaces
Horizontal Layers
The Protocol Structure consists of two main layers, Radio Network Layer,andTransport Network Layer. All UTRAN related issues are visible onlyin the Radio Network Layer, and the Transport Network Layer represents standardtransport technology that is selected to be used for UTRAN, but without anyUTRAN specific requirements.
Vertical Planes
The Control Plane Includes the Application Protocol, i.e. RANAP, RNSAPor NBAP, and the Signalling Bearer for transporting the Application Protocolmessages. Among other things, the Application Protocol is used for setting upbearers for (i.e. Radio Access Bearer or Radio Link) in the Radio NetworkLayer.
The User Plane Includes the Data Stream(s) and the Data Bearer(s) forthe Data Stream(s). The Data Stream(s) is/are characterised by one or moreframe protocols specified for that interface.
The Transport Network Control Plane does not include any Radio NetworkLayer information, and is completely in the Transport Layer. It includes theALCAP protocol(s) that is/are needed to set up the transport bearers (DataBearer) for the User Plane. It also includes the appropriate SignallingBearer(s) needed for the ALCAP protocol(s).
The Transport Network Control Plane is a plane that acts between theControl Plane and the User Plane. The introduction of Transport Network ControlPlane is performed in a way that the Application Protocol in the Radio NetworkControl Plane is kept completely independent of the technology selected forData Bearer in the User Plane. Indeed, the decision to actually use an ALCAPprotocol is completely kept within the Transport Network Layer.
Iur Interface Protocol Structure
Iurlayers
Further Reading:
Iurspecification numbers
Protocollayering specification numbers
More further reading: 3GPP TS 25.401, 25.420