RFGPRS Network Interfaces: Um, Gb, Gn, Gp, Gi, Gr, Gc, Gf, Gd, Gs
gprs
network interface
transmission plane
control plane
protocol
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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 Type | Between What? | Basic Description | Protocol | Reference |
|---|---|---|---|---|
| Um | MS-BSS | Used between the Mobile Station (MS) and the Base Station Subsystem (BSS) for exchanging user and signaling information. | Physical, RLC/MAC | 43.064/45.002, 44.060 |
| Um | MS-SGSN | Used between the MS and the Serving GPRS Support Node (SGSN) for exchanging user and signaling information. | LLC, SNDCP | 44.064, 44.065 |
| Gb | SGSN-BSS | Used between the SGSN and the BSS for data transfer and mobility management. | Physical network service, BSSGP | 48.014, 48.016, 48.018 |
| Gn | SGSN-GGSN | Used to support mobility when the Gateway GPRS Support Node (GGSN) and SGSN are located within the same Public Land Mobile Network (PLMN). | GTP-U | 29.060 |
| Gp | SGSN-GGSN | Used to support mobility when the GGSN and SGSN are located in different PLMNs. | GTP-U | 29.060 |
| Gi | GGSN-PDN | Used to exchange data with external packet data networks (PDN). | IP | 29.061 |
Control Plane Interfaces
Now let’s examine the GPRS interfaces related to the control plane:
| GPRS Interface Type | Between What? | Basic Description | Protocol | Reference |
|---|---|---|---|---|
| Um | MS-BSS | Used between the MS and the BSS for exchanging user and signaling information. | Physical, RLC/MAC | 43.064/45.002, 44.060 |
| Um | MS-SGSN | Used between the MS and the SGSN for exchanging user and signaling information. | LLC, GMM, SM, SMS | 44.064, 24.008, 24.008, 24.011 |
| Gb | SGSN-BSS | Used between the SGSN and the BSS for data transfer and mobility management. | Physical network service, BSSGP | 48.014, 48.016, 48.018 |
| Gn | SGSN-GGSN | Used to support mobility when the GGSN and SGSN are located within the same PLMN. | GTP-C | 29.060 |
| Gp | SGSN-GGSN | Used to support mobility when the GGSN and SGSN are located in different PLMNs. | GTP-C | 29.060 |
| Gr | SGSN-HLR | Used by the SGSN to obtain subscriber information from the Home Location Register (HLR). | MAP | 29.002 |
| Gc | GGSN-HLR | Used 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. | MAP | 29.002 |
| Gf | SGSN-EIR | Used by the SGSN to enable the Equipment Identity Register (EIR) to verify the IMEI retrieved from the MS. This is an optional interface. | MAP | 29.002 |
| Gd | SGSN-SMS-IWMSC / SGSN-SMS-GMSC | Used to deliver and receive short messages from the MS to the Short Message (SM) service center. | MAP | 29.002 |
| Gs | SGSN-VLR | Used 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 |
