4 Architecture considerations

32.2603GPPCharging managementIP Multimedia Subsystem (IMS) chargingRelease 17Telecommunication managementTS

4.1 High level IMS architecture

Figure 4.1.1 depicts the logical IMS architecture, as described in TS 23.002 [103]

Figure 4.1.1: IMS logical architecture

4.2 IMS offline charging architecture

The architecture for IMS offline charging is described in the following figure 4.2.1. The Rf interface is described in clause 6.1.1 and Bi in clause 6.1.2.

Figure 4.2.1: IMS offline charging architecture

4.3 IMS online charging architecture

The architecture for IMS online charging is described in the following figure 4.3.1. The Ro interface is described in clause 6.2 and ISC in TS 23.228 [201].

Figure 4.3.1: IMS online charging architecture

4.4 IMS converged charging architecture

The architectural options for IMS converged charging are depicted in figure 4.4.1 in service-based representation for CHF:

Figure 44.1: IMS converged charging architecture

In this architecture, IMS nodes, CHF, CGF and corresponding Billing domain are located in the same PLMN.

The IMS Nodes for which this architecture applies are the MRFC, IMS-GWF (connected to S-CSCF using ISC) and SIP AS, the architecture for MMTel AS is described in TS 32.275 [35]. In addition the MRFC and SIP AS may support offline only charging via Nchf interface.

Editor’note: whether other IMS Nodes use the Nchf interface is FFS.

The general architecture components can be found in TS 32.240 [2].

Ga is described in clause 5.4.5 and Bi in clause 5.4.6 of the present document, and Nchf is described in TS 32.290 [45].

Figure 4.4.2 depicts the IMS converged charging architecture in reference point representation:

Figure 4.4.2: IMS converged charging architecture in reference point representation

The architectural options of figure 4.4.1 apply to figure 4.4.2 with IMS node, CHF and corresponding Billing domain/CGF located in the same PLMN.

The different IMS architectures for the support of IMS services for roaming users are specified in TS 23.228 [201], and can be considered under two categories:

– without IMS-level roaming interfaces as per clause 4.15b, Annex M.2, Annex W and Annex Y.9.2 of TS 23.228 [201], with the P-CSCF located in HPLMN. All IMS Nodes are located in HPLMN and figure 4.4.1 and figure 4.4.2 apply.

– with IMS-level roaming interfaces as per clause 4.15a, Annex M.1 and Annex Y.9.3 of TS 23.228 [201], with the P-CSCF located in VPLMN. Figure 4.4.3 and figure 4.4.4 are applicable.

Figure 4.4.3 depicts the IMS converged charging architecture in service-based representation for CHF, in IMS with IMS-level roaming interfaces:

Figure 4.4.3: IMS converged charging architecture IMS-level roaming interfaces service based representation

Editor’note: whether P-CSCF use the Nchf interface is FFS.

The architectural options of figure 4.4.1 apply to figure 4.4.3 with IMS node, CHF and corresponding Billing domain/CGF located in the HPLMN.

Figure 4.4.4 depicts the IMS converged charging architecture in reference point representation for CHF, in IMS with IMS-level roaming interfaces:

Figure 4.4.4: IMS converged charging architecture IMS-level roaming interfaces in reference point representation

Editor’note: whether P-CSCF use the Nchf interface, therefore N45 is FFS.

The architectural options of figure 4.4.1 apply to figure 4.4.4 with IMS node, CHF and corresponding Billing domain/CGF located in the HPLMN.