The following sub-clauses describe how the logical ubiquitous charging architecture can be mapped onto physical components and interfaces within the scope of 3GPP standards.
The Figure 188.8.131.52
- Figure 184.108.40.206
below depict the mappings of the ubiquitous offline charging architecture onto physical implementations that are identified within the 3GPP standards. As stated previously in the present document, the CTF is a mandatory component of all NEs that have offline charging capabilities. In contrast, the CDF and the CGF may be implemented in any of the following ways:
CDF and CGF integrated in the NE. In this implementation, all network charging functions are embedded in the NE, i.e. the NE is fully self-contained in terms of offline charging. The (physical) NE itself produces the CDR files that are then transferred to the BD. Consequently, only the Bx reference point needs to be implemented as a physical interface.
CDF integrated in the NE, CGF in a separate physical element. In this implementation, the (physical) NE generates CDRs and sends them to an external CGF. Hence the Ga reference point must be implemented in the NE as a physical interface. If the CGF is a stand-alone entity, it must implement both the Ga and the Bx reference point as physical interface. As a variation of this construct, the CGF may be integrated in the BD, in which case the Bx reference point is internal to the BD.
CDF and CGF in two separate physical elements. This scenario represents the fully distributed implementation where all reference points must be implemented as physical interfaces on the NE, CDF and CGF, respectively. Again, as a variation of this approach, the CGF may be an integral component of the BD, in which case the Bx reference point becomes internal to the BD.
CDF and CGF in the same separate physical element. In contrast to scenario 3, there is no physical Ga interface, whereas the Rf and Bx reference points must exist as distinct interfaces in the same fashion as in scenario 3. The variation of the combined CDF/CGF being embedded in the BD is again possible, resulting in the Rf reference point being the only one that appears as a physical interface.
Details of the possible implementation options per domain / subsystem / service (usually a subset of the overall possible variants described above) are specified in the respective middle tier TS.
The CTF is a mandatory integrated component of all network elements that are involved in online charging as depicted in Figure 220.127.116.11
, with the exception of the S-CSCF (see clause 18.104.22.168.2
). If CDR generation by the OCS is required, as described in clause 22.214.171.124
, then a CDF is integrated in each OCF that is required to produce the CDRs. All other possibilities for physical mapping, including e.g.:
integrated versus distributed CGF in the OCS,
use of another CGF by the OCS,
IMS GWF integrated in S-CSCF or OCS, or a stand-alone entity,
are not specified within the 3GPP standards and are therefore implementation specific. The same is true for the composition of the OCS and its logical functions.