H.3 EPC-based Trusted WLAN Access with S2a

23.2033GPPPolicy and charging control architectureRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

In an EPC-based trusted WLAN Access with S2a, the PCEF is located in the PDN-GW and the BBERF does not apply.

NOTE: Gxa interface is not used for S2a-PMIP in Trusted WLAN within this Release of the specification.

From the network scenarios listed in clause 7.1, the Case 1 (no Gateway Control Session) applies.

Specific event triggers applicable are listed in table H.3.

Table H.3: TWAN access specific event/credit reauthorization triggers

Event/Credit reauthorization trigger	Description	Reported from	Condition for reporting
RAT type change.	The characteristics of the air interface, communicated as the radio access type, have changed.	PCEF	PCRF/OCS

For an IP-CAN session set-up over a Trusted WLAN Access with S2a:

– at IP‑CAN Session Establishment the PCEF provides TWAN location information (TWAN ID and/or UE Time Zone as described in clause 16 of TS 23.402 [18]), IP-CAN type , RAT Type, PLMN identifier and an indication that access is trusted to the PCRF (over Gx). The TWAN ID may include the identifier of the operator of the TWAN as defined in clause 16 of TS 23.402 [18]. This occurs at step 3 of Figure 7.2-1 (IP‑CAN Session Establishment). This information is also provided by the PCEF to the charging entities as described in TS 32.251 [9].

– The Access Network Information Report event trigger defined in clause 6.1.4 applies. The user location information within the Access Network Information reporting contains the TWAN ID and/or UE Time Zone as described in clause 16 of TS 23.402 [18]. This information is sent when a bearer over Trusted WLAN access is activated or modified or deactivated and when the IP-CAN session is terminated. When the bearer over Trusted WLAN access is deactivated or the IP-CAN session is terminated the user location information corresponds to the last known UE location. When the IP‑CAN session is terminated a TWAN Release Cause (if available) is also provided to the PCRF.

The IP-CAN type change, the PLMN change event triggers defined in clause 6.1.4 and RAT type event trigger applies. The PCEF reports to the PCRF when a Create Session Request is received including information that the UE moved to a trusted WLAN access. This information is also provided by the PCEF to the charging entities as described in TS 32.251 [9].

When the PCRF subscribes to any of the listed above event triggers using the Provision of PCC Rules procedure, the PCEF provides the parameter values in the response back to the PCRF, as defined in clause 6.1.4.

It shall be possible for the PCRF to authorize the QCI and ARP of the default EPS bearer to be enforced by the PCEF immediately or at a specific point in time by providing the default EPS bearer related policy information as defined in clause A.4.3.4.