4 Architecture considerations

32.2533GPPCharging managementControl Plane (CP) data transfer domain chargingRelease 17Telecommunication managementTS

4.1 High-level CP data transfer architecture

The overall architecture for Service Capability Exposure which enables the 3GPP network to securely expose its services and capabilities provided by 3GPP network interfaces to external 3rd party service provider applications is defined in 3GPP TS 23.682 [243], and figure 4.1.1 is an excerpt highlighting relevant 3GPP Nodes involved for Non-IP Data Delivery (NIDD) between the UE and the SCS/AS.

Figure 4.1.1: 3GPP Architecture Service Capability Exposure for Non-IP Data Delivery

For roaming case, the Interworking SCEF (IWK-SCEF) is optionally deployed and located in the VPLMN, as described in figure 4.1.2.

Figure 4.1.2: 3GPP roaming Architecture Service Capability Exposure for Non-IP Data Delivery

4.2 CP data transfer domain offline charging architecture

As described in TS 32.240 [1], the CTF (an integrated component in each charging relevant NE) generates charging events and forwards them to the CDF. The CDF, in turn, generates CDRs which are then transferred to the CGF.
Finally, the CGF creates CDR files and forwards them to the BD.

For offline charging the following Control Plane data transfer Charging Nodes (CPCN), functioning as the CTF, may generate accounting metrics sets for Control Plane data transfer CDRs:

– the SCEF, to record Control Plane data transfer;

– the IWK-SCEF, to record Control Plane data transfer;

– the MME, to record Control Plane data transfer (optional).

If the CPCN generating the charging information has an integrated CDF, then the CPCN can produce CDRs. The CGF may also be integrated in the CPCN, or it may exist as a physically separate entity.
If the CGF is external to the CPCN/CDF, then the CPCN/CDF forwards the CDRs to the CGF across the Ga interface. In this case, the relationship between CPCN/CDF and CGF is m:1.
If the CGF is integrated in the CPCN/CDF, then there is only an internal interface between the CDF and the CGF. In this case, the relationship between CPCN/CDF and CGF is 1:1. An integrated CGF may support the Ga interface from other CPCN/CDFs.

If the CDF is external to the CPCN, the charging events are transferred from the CPCN to the CDF via the Rf interface specified in TS 32.299 [50]. In this case, the relationship between CPCN and CDF is m:1.

When an external CGF is used, this CGF may also be used by other, i.e. non- Control Plane data transfer, network elements, according to network design and operator decision. It should be noted that the CGF may also be an integrated component of the BD – in this case, the Bcp interface does not exist and is replaced by a proprietary solution internal to the BD.

Figure 4.2.1 depicts the architectural options described above.

Figure 4.2.1: Control Plane data transfer offline charging architecture

It is mandatory to support at least one of the Rf, Ga or Bcp interfaces from the CPCN as described in the present document.

NOTE: Support of Control Plane data transfer charging is optional for the MME.

4.3 CP data transfer domain online charging architecture

Not specified in the present document.