P.5 Functional description

23.2033GPPPolicy and charging control architectureRelease 17TS

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

P.5.1 Overall description

For EPC based Fixed Broadband Access Interworking with EPC-routed traffic the credit management, reporting, usage monitoring, termination actions, service data flow prioritization and standardized QoS characteristics as defined in clause 6.1 shall apply.

For non-seamless WLAN offloaded traffic service data flow prioritization as defined in clause 6.1 applies. For scenario with TDF, usage monitoring as defined in clause 6.1 applies. For NSWO traffic in other scenarios, without TDF, usage monitoring is out of scope of this specification. For all scenarios, credit management, termination actions and reporting for NSWO traffic are out of scope of this specification.

The purpose of policy interworking via S9a for non-seamless WLAN offloaded traffic (PCC Rules provisioned for the UE local IP address) is to enable policy control in the BBF domain in two different ways:

– Gate enforcement. The BPCF is expected to provide information over R interface to control whether a service data flow, which is subject to policy control, pass through the BNG if and only if the corresponding gate is open.

– QoS enforcement: The BPCF is expected to provide information over R interface to control the authorized QoS of a service data flow according to the QoS information received over S9a interface.

The complete specification of the BPCF is defined in BBF TR-134 [31] and BBF TR-203 [30] and BBF TR-291 [33] and it is out of the scope of 3GPP.

The information contained in a PCC Rule generated by the PCRF for NSWO traffic includes Service Data Flow Detection and Policy Control information elements specified in table 6.3. The PCC rules for NSWO traffic do not include the Charging and Usage Monitoring Control elements specified in table 6.3.

For Fixed Broadband Access the event triggers in table P.5.1-1 shall apply in addition to the ones in table 6.2.

Table P.5.1-1: Fixed Broadband specific event triggers

Event trigger	Description	Reported from	Conditions for reporting
UE local IP address change	Either the UE local IP address or the UDP port number or both assigned by Fixed Broadband Access have changed	PCEF, BBERF	Always set
H(e)NB local IP address change	Either the H(e)NB IP address or the UDP port number or both assigned by Fixed Broadband Access have changed	PCEF, BBERF	PCRF

P.5.1.1 Binding Mechanism

P.5.1.1.1 EPC-routed traffic

For EPC routed traffic, binding mechanisms apply as defined in clause 6.1.1 by PCRF, PCEF and BBERF. In addition, the PCC and QoS Rule generation is performed by PCRF as specified in clause 6.1.1, in addition when:

– Both a Gx and associated Gateway Control Session exist for the same IP-CAN session; the PCRF shall generate QoS Rules for all the authorized PCC rules in this step.

P.5.1.1.2 Non-seamless WLAN offloaded traffic

The binding mechanism includes two steps for the non-seamless WLAN offloaded traffic:

1. Session binding.

2. PCC rule authorization.

For NSWO traffic, session binding of AF session and TDF session (in unsolicited mode) to an IP-CAN session is performed by the PCRF, as defined in clause 6.1.1, for the purpose of policy control in the BBF domain.

The PCRF derives and authorises PCC rules as described in clause 6.1.1.

P.5.1.2 S9a, Gx and S15 Session Linking

For WLAN, PCRF and BPCF both need to support session linking function. Depending on the deployment there may be one or multiple PCRF that have a Gateway Control Session on S9a for a given UE. The PCRF shall be able to perform the linking between IP-CAN sessions on Gx and the Gateway Control Session on S9a for the same UE based on IMSI and UE local IP address.

For H(e)NB scenarios a Gateway Control Session on S9a may be linked to:

– IP-CAN Sessions on Gx for all UEs connected to the H(e)NB;

– Gateway Control Sessions on S9 and/or IP-CAN Sessions on S9 (in roaming cases);

– S15 Session;

NOTE 1: There is a single S15 session per HNB for CS calls for all UEs connected to the HNB in order to improve performance. In addition, for CS calls there are no UE specific policies and therefore a single PCRF can handle CS calls for all UEs.

When the Gateway Control Session on S9a is initiated by PCRF, BPCF is expected to associate the session on R with the Gateway Control Session on S9a.

NOTE 2: How the BPCF performs the association of a Gateway Control Session on S9a and R session is out of the scope of 3GPP.