32.2523GPPCharging managementRelease 9Telecommunication managementTSWireless Local Area Network (WLAN) charging
As described in 3GPP TS 32.240 , 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 Billing Domain.
The following WLAN network elements are involved in WLAN charging process – the WLAN Access Network, the WLAN AAA Proxy/Server, and the PDG, implying that they have an integrated CTF. The distribution of the CDF and CGF logical functions differs from network element to network element. For the purposes of this TS, the distributions in figure 4.2 are considered.
WLAN AN: The CTF is integrated in to the WLAN AN. The CDF and the CGF are external to the WLAN AN.
Editor’s note: The CTF … TBD
3GPP AAA Proxy: The 3GPP AAA Proxy proxies the charging information received from the WLAN AN over the Wa reference point to a CDF in the visited network over a Wf reference point, and, to a 3GPP AAA Server in the subscriber’s home network over the Wd reference point. The 3GPP AAA Proxy is relevant only in a roaming case.
3GPP AAA Server: A 3GPP AAA Server proxies the charging information received from the WLAN AN over the Wa reference point (in a non-roaming case) or charging information received from the 3GPP AAA Proxy Server located in a visited network over the Wd reference point (in a roaming case) to the CDF over the Wf reference point.
WLAN PDG: The CTF and CDF are integrated in the PDG; however, the CGF may exist as a physically separate entity or integrated to the PDG. If the CGF is external to the PDG, then the CDF forwards the CDRs to the CGF across the Ga interface.
NOTE 1: This is a purely function architecture and it does not distinguish between a roaming and non-roaming case.
NOTE 2: Any physical co-location of CGF, CDF and AAA Server / Proxy is possible.
Figure 4.2: Functional WLAN offline charging architecture
The Diameter based Rf interface on which the Wf interfaces are based on is described in 3GPP TS 32.299 .