GPRS Transmission Mechanism - Control Plane

The control plane consists of protocols for control and support of the user plane functions:

-     Controlling the GPRS network access connections, such as attaching to and detaching from GPRS

-     Controlling the attributes of an established network access connection, such as activation of a PDP address

-     Controlling the routing path of an established network connection in order to support user mobility

-     Controlling the assignment of network resources to meet changing user demands.

The following control planes are used in both A/Gb mode and Iu mode unless specifically indicated.

MS – SGSN (A/Gb mode)

Control Plane MS - SGSN in A/Gb mode

Legend:

-     GPRS Mobility Management and Session Management (GMM/SM): This protocol supports mobility management functionality such as GPRS attach, GPRS detach, security, routeing area update, location update, PDP context activation, and PDP context deactivation, as described in clauses "Mobility Management Functionality" and "PDP Context Activation, Modification, Deactivation, and Preservation Functions".

  

MS – SGSN (Iu mode)

Control Plane MS - SGSN in Iu mode

Legend:

-     Iu mode Mobility Management and Session Management (GMM/SM): GMM supports mobility management functionality such as attach, detach, security, and routeing area update, as described in clause "Mobility Management Functionality". SM supports PDP context activation and PDP context deactivation, as described in clause "PDP Context Activation, Modification, Deactivation, and Preservation Functions".

-               Radio Access Network Application Protocol (RANAP): This protocol encapsulates and carries higher-layer signalling, handles signalling between the 3G‑SGSN and Iu mode RAN, and manages the GTP connections on the Iu interface.

-               Radio Link Control (RLC): The RLC protocol offers logical link control over the radio interface for the transmission of higher layer-signalling messages and SMS.

 

SGSN - HLR

Control Plane SGSN ‑ HLR

Legend:

-               Mobile Application Part (MAP): This protocol supports signalling exchange with the HLR.

SGSN ‑ MSC/VLR

Control Plane SGSN ‑ MSC/VLR

Legend:

-               Base Station System Application Part + (BSSAP+): A subset of BSSAP procedures supports signalling between the SGSN and MSC/VLR, 

SGSN ‑ EIR

Control Plane SGSN ‑ EIR

Legend:

-     Mobile Application Part (MAP): This protocol supports signalling between the SGSN and the EIR, as described in clause "Identity Check Procedures".

GSN ‑ GSN

Control Plane for SGSN – GGSN and SGSN – SGSN Interfaces

 

Legend:

-     GPRS Tunnelling Protocol for the control plane (GTP‑C): This protocol tunnels signalling messages between SGSNs and GGSNs (Gn), and between SGSNs in the backbone network (Gp).

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GGSN ‑ HLR 

This optional signalling path allows a GGSN to exchange signalling information with an HLR. There are two alternative ways to implement this signalling path:

-     If an SS7 interface is installed in the GGSN, the MAP protocol can be used between the GGSN and an HLR.

-     If an SS7 interface is not installed in the GGSN, any GSN with an SS7 interface installed in the same PLMN as the GGSN can be used as a GTP-to-MAP protocol converter to allow signalling between the GGSN and an HLR.

  

1- MAP-based GGSN ‑ HLR Signalling

Control Plane GGSN ‑ HLR Using MAP

Legend:

-     Mobile Application Part (MAP): This protocol supports signalling exchange with the HLR, as described in clause "Network-Requested PDP Context Activation Procedure".

2-GTP and MAP-based GGSN ‑ HLR Signalling

Control Plane GGSN ‑ HLR Using GTP and MAP

Legend:

-     GPRS Tunnelling Protocol for the control plane (GTP‑C): This protocol tunnels signalling messages between the GGSN and the protocol-converting GSN in the backbone network.

-     Interworking: This function provides interworking between GTP and MAP for GGSN ‑ HLR signalling.