4 Architecture considerations
32.2993GPPCharging managementDiameter charging applicationsRelease 17Telecommunication managementTS
4.1 High level architecture
4.1.0 General
The Rf and the Ro are reference points from the Charging Trigger Function (CTF) to the Charging Data Function (CDF) and the Online Charging Function (OCF) respectively, and are intended for the transport of charging events. Rf is used for offline charging whereas Ro is used for online charging.
Figure 4.1.0.1 and figure 4.1.0.2 depict the position of the Rf and Ro reference points within the overall 3GPP online and offline charging architecture.
CTF: Charging Trigger Function
CDF: Charging Data Function
CGF: Charging Gateway Function
BD: Billing Domain. This may also be a billing mediation device / post-processing system.
Figure 4.1.0.1: Logical ubiquitous offline charging architecture
CTF: Charging Trigger Function
OCF: Online Charging Function
CGF: Charging Gateway Function
BD: Billing Domain. This may also be a billing mediation device / post-processing system.
Figure 4.1.0.2: Logical ubiquitous online charging architecture
Different mappings of the ubiquitous offline charging functions, CTF, CDF and CGF, onto physical implementations are possible. Further details of the configuration refer toTS 32.240 [1]. Details of the implementation options per domain / subsystem / service (usually a subset of the overall possible variants described above) are specified in the respective middle tier TSs.
4.1.1 Charging related transfer requirements
Each CTF would have CDF and OCF address list to which it can send its charging events and/or charging requests.
The list is organized in address priority order. If the primary charging function is not available (e.g. out of service) then the CTF shall send the charging information to the secondary charging function and so on.
Within the scope of this release, each Network Element that generates charging information sends the information only to the charging entities of the same PLMN, and not to charging entities in other PLMNs.
To implement roaming unbundling for EU roaming regulation III, an architectural solution known as the Single IMSI architecture has been defined. In this architecture a specific Service-NE (known as a Proxy Function) uses the Ro reference point for sending charging information to an OCF in another network. The details of this architecture are defined in Annex B of TS 32.240 [1].
To implement PS domain online charging for roaming context, PCEF in the VPLMN uses the Gy reference point, and TDF in the VPLMN uses the Gyn reference point, both based on Ro interface and specified in TS 32.251[11], for sending charging information to an OCS in the HPLMN. A simplified profile is provided in Annex E of TS 32.251[11] for deployment purposes.
Each CDF in the PLMN may know of other CDFs’ network addresses (e.g., for redundancy reasons, to be able to recommend another CDF address with the Redirection Request message). This is achieved by OAM&P configuration facilities that enables each CDF to have a configurable list of peer CDF addresses.