GPRS/UMTS Group Domain roaming

GPRS-UMTS group domain roaming is conceptually similar to GSM roaming-it allows users to access the network at any time with GPRS/UMTS coverage, through domestic and international roaming agreements signed between different regional networks or operators. The signed business information of the mobile user is permanently stored in the HLR, when the mobile user roams to visit the network, the network access control is managed by the visiting place SGSN, it will authenticate the user and check the user information to determine the business that the user contracted. Through the corresponding roaming protocols, mobile users will be able to access the UMTS/GPRS business when they roam the country or the world within the network coverage. --Editor

From the network structure point of view, UMTS and GPRS roaming are no different. Like GSM, HLR is responsible for the network access Control (authentication) and the traffic path management. SGSN communicates with HLR through a standardized interface (called the GR Interface) using Gsmmap.

Vaa parameters (allowing access to PLMN addresses) enable GPRS-UMTS operators to control the establishment of data sessions through attribution GGSN or by visiting GGSN.

The APN parameter represents a combination of application services that the mobile network provides to the user. Different APN represent a combination of different application services. In a UMTS/GPRS network, GGSN is a gateway that connects users to external data networks and different application service platforms. Therefore, different APN also represent different Ggsns. General UMTS/GPRS Access, the network through the DNS server to the mobile user required APN to resolve to determine the use of the GGSN. (Computer science)

The Boundary Gateway (BG) is defined in 3gppts29.061. BG is the core network element, which is interconnected with two GPRS-UMTS networks to support GPRS-UMTS packet domain roaming. BG allows interconnection between Gprs-umts and PLMN via a low security external IP network. BG can use BGP4 (a large network routing protocol) and IPSec (Secure Tunneling Protocol) as a Routing and Security tool. IPSec is encrypted for GTP signaling and business data, enabling it to be securely routed through an external IP network.

The GP interface is defined in 3gppts23.060, which is actually the same as the GN interface. The only difference in the standard is that the GP interface is used to communicate between the plmn of the GSN. GP contains all GTP signaling information that supports GN, but the path management capabilities of the GN interface are not used to monitor the availability of all SGSN in the roaming partner PLMN.

The GP interoperability between Nortel Network VSGSN and Nortel Network HGGSN is guaranteed, but in order to ensure successful roaming in multi-vendor environments, the GP interface requires testing interoperability between GSN in roaming partner PLMN. Nortel recommends multiple vendor IoT testing between the SGSN/HLR (Gr) and vs GSN/HGGSN (Gp) interfaces.

To achieve this, Nortel Networks completed IoT testing with most major vendors and repeated these tests when new versions were introduced. According to NDA, Nortel can provide detailed results for IoT tests (interfaces, versions, and test results) with specific vendors.

The billing information is collected in the GSN network element of the GPRS-UMTS group Domain core network. Both SGSN and GGSN can collect billing information and support the GA interface that connects the central CGF (Billing gateway function). The records collected by CGF from SGSN are called S-cdr and M-cdr, and records collected from GGSN are called G-CDR. CGF is not only responsible for collecting billing data, but is also responsible for centralizing the billing data into a total record (per user) and transferring the record down to BS (billing system) for later processing. BS will convert the record format into an ITU-compliant TAPV3 record.

Roaming between UMTS/GPRS systems usually means that when an UMTS mobile user enters a region that is only GPRS-covered, it can also successfully log in and use the GPRS network. The most basic requirement for roaming between UMTS/GPRS Systems is a dual-mode terminal that supports UMTS and GPRS. When the UMTS mobile user enters the GPRS network scope, the dual-mode terminal will log in the GPRS network by the GPRS way. In the 3GPP standard, when UMTS mobile users enter the GPRS network and require login, 3GHLR to provide mobile users and GPRS network to meet the GPRS requirements of the authentication parameter group. In addition, because GPRS and UMTS network have a great difference in QoS support, when UMTS mobile users roam to GPRS network, they can only enjoy the lower level QoS.