ServingGPRSSupportNode-SGSN

8/13/2019 ServingGPRSSupportNode-SGSN

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Serving GPRS Support Node (SGSN)

The SGSN main tasks can be summarized as follows:

– Session and mobility management

– Packet routing and transfer to and from the SGSN area.

– It serves all GPRS subscribers that are physically located within the geographical SGSN area. A GPRS subscriber may beserved by any SGSN in the network, all depending on its location.

– For WCDMA, the traffic is routed from the SGSN to an MS through a UMTS Radio Access Network (UTRAN).

– Security over radio access by means of ciphering and authentication.

– Output of charging data. The SGSN collects charging information for each MS related to radio network usage and events. Thecharging data (CDRs) can be transferred to the billing system via FTP or GTP

– Real-time charging control based on the CAMEL standards.

The diagram below shows a simplified overview of the GSM and WCDMA Network and also describes the interface names and

types associated with SGSN.



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Serving Support GPRS Node (GGSN)…..continued

Interfaces and Protocols

All interfaces with other GPRS network nodes in GSM and WCDMA Systems are shown in the diagram below



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Interfaces and Protocols…..continued

– Gb interface

The Gb interface connects the SGSN to BSSs and MSs allowing exchange of signaling and payload.

– Iu Interface

The Iu interface is used for transfer of User Plane (UP) payload encapsulated in GTP-U packets between SGSN and RNC andfor transfer of Control Plane (CP) signaling between SGSN and RNC as well as between SGSN and MS.

– Gn Interface

The Gn interface connects the SGSN to other SGSNs and to GGSNs within the same Public Land Mobile Network (PLMN),allowing exchange of signaling as well as payload on its way between an MS and an external network.

– The Gp Interface

The Gp interface connects the SGSN to other SGSNs and to GGSNs in other Public Land Mobile Network (PLMN), allowing

visiting subscribers to be routed through their home GGSN. – Gr Interface

The Gr interface connects the SGSN to the HLR and is used for download of subscriber data to the SGSN from the HLR.

– Gs Interface

The Gs interface makes it possible for the SGSN to handle location updates and paging also for circuit-switched services.(Gs is supported for GSM only.)

– Gd Interface

The Gd interface connects the SGSN to the SMS-IWMSC and SMS-GMSC providing SMS over GPRS. – Ge Interface

The Ge interface connects the SGSN to the CAMEL SCP making it possible to provide real-time charging for GPRS sessions.(CAMEL for WCDMA will first be available in a software update

– Gom interface

The Gom interface connects Operation and Maintenance (O&M) equipment to the SGSN, making it possible for an operator tocommunicate with the SGSN. The Gom interface also connects the SGSN to the Billing System (or a Mediation Gateway), andis used for transfering CDRs. Gom is an Ericsson proprietary interface.



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Payload Handling

– The payload handling (forwarding) mainly includes support for the GPRS protocol stacks and the forwarding of user payloadbetween the stacks.

– Protocols related to the Iu interface for WCDMA are:

GTP-U - GPRS Tunneling Protocol for the User plane

UDP - User Datagram Protocol

IP - Internet Protocol

ATM - Asynchronous Transfer Mode

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ServingGPRSSupportNode-SGSN