Tutorials » GSM » GPRS Network Interfaces: Um, Gb, Gn, Gp, Gi, Gr, Gc, Gf, Gd, Gs

GPRS Network Interfaces: Um, Gb, Gn, Gp, Gi, Gr, Gc, Gf, Gd, Gs

gprs network interface transmission plane control plane protocol

This page covers GPRS (General Packet Radio Service) network interfaces used in both the transmission plane and the control plane. We’ll be looking at the Um, Gb, Gn, Gp, Gi, Gr, Gc, Gf, Gd, and Gs interfaces.

The transmission plane is responsible for the actual exchange of user data. The control plane, on the other hand, ensures the transmission plane is available and facilitates signaling between the Mobile Station (MS) and the GPRS network elements.

Transmission Plane Interfaces

Here’s a breakdown of the GPRS interfaces related to the transmission plane:

GPRS Interface TypeBetween What?Basic DescriptionProtocolReference
UmMS-BSSUsed between the Mobile Station (MS) and the Base Station Subsystem (BSS) for exchanging user and signaling information.Physical, RLC/MAC43.064/45.002, 44.060
UmMS-SGSNUsed between the MS and the Serving GPRS Support Node (SGSN) for exchanging user and signaling information.LLC, SNDCP44.064, 44.065
GbSGSN-BSSUsed between the SGSN and the BSS for data transfer and mobility management.Physical network service, BSSGP48.014, 48.016, 48.018
GnSGSN-GGSNUsed to support mobility when the Gateway GPRS Support Node (GGSN) and SGSN are located within the same Public Land Mobile Network (PLMN).GTP-U29.060
GpSGSN-GGSNUsed to support mobility when the GGSN and SGSN are located in different PLMNs.GTP-U29.060
GiGGSN-PDNUsed to exchange data with external packet data networks (PDN).IP29.061

Control Plane Interfaces

Now let’s examine the GPRS interfaces related to the control plane:

GPRS Interface TypeBetween What?Basic DescriptionProtocolReference
UmMS-BSSUsed between the MS and the BSS for exchanging user and signaling information.Physical, RLC/MAC43.064/45.002, 44.060
UmMS-SGSNUsed between the MS and the SGSN for exchanging user and signaling information.LLC, GMM, SM, SMS44.064, 24.008, 24.008, 24.011
GbSGSN-BSSUsed between the SGSN and the BSS for data transfer and mobility management.Physical network service, BSSGP48.014, 48.016, 48.018
GnSGSN-GGSNUsed to support mobility when the GGSN and SGSN are located within the same PLMN.GTP-C29.060
GpSGSN-GGSNUsed to support mobility when the GGSN and SGSN are located in different PLMNs.GTP-C29.060
GrSGSN-HLRUsed by the SGSN to obtain subscriber information from the Home Location Register (HLR).MAP29.002
GcGGSN-HLRUsed by the GGSN to retrieve information about the location and supported services for the MS to activate a packet data network address. This is an optional interface.MAP29.002
GfSGSN-EIRUsed by the SGSN to enable the Equipment Identity Register (EIR) to verify the IMEI retrieved from the MS. This is an optional interface.MAP29.002
GdSGSN-SMS-IWMSC / SGSN-SMS-GMSCUsed to deliver and receive short messages from the MS to the Short Message (SM) service center.MAP29.002
GsSGSN-VLRUsed for coordinating the functions of the SGSN and the Visitor Location Register (VLR) when a mobile has both GSM and GPRS services. This is an optional interface.BSSAP+29.016, 29.018