The Rf reference point supports interaction between a CTF and a CDF. The following information may flow across this reference point in real-time:
Charging events for offline charging from the CTF to the CDF;
Acknowledgements for these events from the CDF to the CTF.
The protocol(s) crossing this reference point shall support the following capabilities:
Real-time transactions;
Stateless mode ("event based charging") and statefull mode ("session based charging") of operation;
Provide its own reliability mechanisms, e.g. retransmission of charging events, to run also on unreliable transport.
In addition, the protocol should support changeover to a secondary destination (alternate CDF(s)) in case of the primary CDF not being reachable.
This interface application is defined in TS 32.299. The information contained in the charging events and the relevant chargeable events are specific to the domain / subsystem / service and are detailed in the respective middle tier TSs.
The Gz reference point is functionally equivalent to Ga for Legacy PS domain and to Ga or Rf for Evolved PS domain, and hence is replaced by Ga or Rf within the common charging architecture. See also clause 4.2.
The Ga reference point supports interaction between a CDF and a CGF. The following information may flow across this reference point:
CDRs are sent from the CDF to the CGF;
Acknowledgements for these CDRs are returned from the CGF to the CDF.
The protocol(s) crossing this reference point shall support the following capabilities:
Near real-time transactions;
Send one or more CDRs in a single request message;
Changeover to secondary destinations (alternate CGFs) in case of the primary CGF not being reachable;
Provide its own reliability mechanisms, e.g. retransmission of charging events, to run also on unreliable transport.
This interface application is defined in TS 32.295. The content of the CDRs, and the CDR trigger conditions, are specific to the domain / subsystem / service and are detailed in the middle tier TSs.
The Bx reference point supports interaction between a CGF and the BD. The information crossing this reference point is comprised of CDR files. A common, standard file transfer protocol (e.g. FTAM, FTP) shall be used, including the transport mechanisms specified for the selected protocol.
This interface application is defined in TS 32.297. The information contained in the files corresponds to the CDRs defined per domain/subsystem/service, as stated in clause 4.4.1.3.
The Gzn reference point is functionally equivalent to Ga or Rf in PS domain, and hence is replaced by Ga or Rf within the common charging architecture. See also clause 4.2.
The Ro reference point supports interaction between a CTF and an OCF. The following information may flow across this reference point:
Charging events for online charging from the CTF to the OCF.
Receive Acknowledgements for these charging events from the OCF to the CTF. The acknowledgement grants or rejects the network resource usage requested in the charging event, according to the decision taken by the OCS.
The protocol(s) crossing this reference point shall support the following capabilities:
Real-time transactions;
Stateless mode ("event based charging") and statefull mode ("session based charging") of operation;
Provide its own reliability mechanisms, e.g. retransmission of charging events, to run also on unreliable transport.
In addition, the protocol should support changeover to a secondary destination (alternate OCF(s)) in case of the primary OCF not being reachable.
This interface application is defined in TS 32.299. The information contained in the charging events and the relevant chargeable events are specific to the domain / subsystem / service and are detailed in the respective middle tier TSs.
The CAP reference point provides similar functionality for online charging as Ro, however, it is based on CAMEL techniques. It is kept within the overall charging architecture as CAMEL may be used in the CS and PS domains. See TS 23.078 for details on CAMEL.
The Re reference point supports interaction between the OCF and a Rating Function (RF) in order to determine the value of chargeable events in terms of monetary or non-monetary units. This interface application is defined in TS 32.296.
The Rc reference point allows the interaction between the OCF and an Account Balance Management Function (ABMF) in order to access the account of the subscriber on the OCS. See TS 32.296 for further information.
The common charging architectures are mapped into the specific domain/subsystem/service charging architectures in the respective middle tier TSs, which contain in their reference point representation, the following reference points:
N28:
Reference point between PCF and CHF defined in TS 23.501.
N40:
Reference point between SMF and the CHF in the same PLMN defined in clause 4.2 of TS 32.255.