WCDMA Protocol Structure for Iu CS

The WCDMA Iu CS overall protocol structure is depicted in below image. The three planes in the Iu interface share a common ATM (Asynchronous Transfer Mode) transport which is used for all planes. The physical layer is the interface to the physical medium: optical fiber, radio link or copper cable. The physical layer implementation can be selected from a variety of standard off-the-shelf transmission technologies, such as SONET, STM1, or E1.

WCDMA Iu CS Interface block diagram

WCDMA Iu CS Control Plane Protocol Stack

The Control Plane protocol stack consists of RANAP, on top of Broadband (BB) SS7 (Signaling System #7) protocols. The applicable layers are the WCDMA Signaling Connection Control Part (SCCP), the Message Transfer Part (MTP3-b) and SAAL-NNI (Signaling ATM Adaptation Layer for Network to Network Interfaces).

WCDMA Iu CS Transport Network Control Plane Protocol Stack

The Transport Network Control Plane protocol stack consists of the Signaling Protocol for setting up AAL2 connections (Q.2630.1 and adaptation layer Q.2150.1), on top of BB SS7 protocols. The applicable BB SS7 are without the WCDMA SCCP layer.

WCDMA Iu CS User Plane Protocol Stack

A dedicated AAL2 connection is reserved for each individual CS service.