P.4 Architecture model and reference points

23.2033GPPPolicy and charging control architectureRelease 17TS

P.4.1 Reference points

P.4.1.1 S9a Reference point

The S9a reference point resides between:

– the PCRF in the PLMN and the BPCF in the Fixed Broadband Access Network (BPCF);

– the PCRF in the VPLMN (V PCRF) and the BPCF in the Fixed Broadband Access Network (BPCF).

The S9a reference point enables transfer of dynamic QoS control policies from the (V-)PCRF to the BPCF for the purpose of allocation of QoS resources in the Fixed Broadband Access Network for non-seamless WLAN offloaded traffic and for EPC-routed traffic.

For scenarios where the traffic is non-seamless WLAN offloaded in the Fixed Broadband Access Network, based on Rx authorizations and event subscriptions, or equivalent information, received by the BPCF from an AF in the Fixed Broadband Access Network, the S9a reference point enables the BPCF to send Rx authorizations and event subscriptions to the PCRF.

NOTE: The AF in the Fixed Broadband Access Network and the reference point between the AF in the Fixed Broadband Access Network and the BPCF are out of scope for this specification.

P.4.1.2 S15 Reference Point

The S15 reference point between the HNB GW and the PCRF and between the HNB GW and the V-PCRF. It enables the transfer of dynamic QoS control policies from the (V-)PCRF to the BPCF for the purpose of allocation of QoS resources in the Fixed Broadband Access Network for HNB CS calls.

P.4.1.3 Gxx reference point

When this reference point corresponds to the Gxb*, it transports access information for WLAN UEs such as the UE local IP address and the UDP port number. It is used scenarios in which the ePDG provides the access information via Gxb* to trigger the PCRF to initiate the S9a session i.e. S2b-PMIP and untrusted S2c.

For the case of H(e)NB with S5/S8 PMIP, this reference point corresponds to Gxc and the requirements in clause 5.2.7 applies. In addition for the purpose of fixed broadband access interworking, Gxc transports the H(e)NB Local IP address and the UDP source port, if available, in the fixed broadband access network where the H(e)NB connects to.

P.4.1.4 S9 reference point

In addition to the specification of the S9 reference point defined in clause 5.2.6, this reference point is used to trigger the V-PCRF to initiate the Gateway Control Session establishment over S9a. The S9 interface is enhanced to carry from the H-PCRF to the V-PCRF the UE local IP address, the UDP port number, if available, the H(e)NB local IP address and UDP port, if available, and the ePDG IP address (for S2b and untrusted S2c access) or the PDN GW IP address (for trusted S2c access), if available.

P.4.1.5 Gx reference point

In addition to the specification of the Gx reference point defined in clause 5.2.2, this reference point is enhanced as described in the following. The IP-CAN establishment/modification request message, send from PCEF to PCRF, should include:

– the UE local IP address and the UDP port number, if available, when WLAN access and GTP is used.

– the UE local IP address and the UDP port number, if available, when trusted S2c is used.

– the H(e)NB local IP address and the UDP port number, if available, when UE accesses from H(e)NB and GTP S5/S8 is used.

P.4.2 Reference architecture

P.4.2.0 General

The reference architecture described in clause 5.1 is:

– extended to include S9a reference point to support fixed broadband access interworking to EPC for the following scenarios:

– S9a reference point between PCRF and BPCF in the non-roaming case for traffic that is routed via EPC and for traffic that is non-seamless WLAN offloaded in the fixed broadband access network; and

– S9a reference point between the V-PCRF and BPCF for roaming cases with visited access and home routed for traffic that is routed via EPC; and for traffic that is non-seamless WLAN offloaded in the fixed broadband access network;

– extended to include the S15 reference point as defined in clause P.4.1.2;

– PCEF resides in the PDN GW;

– for WLAN access: BBERF resides in the ePDG. The BBERF only applies for cases 2b (i.e. S2b-PMIP, S2c-untrusted);

– for H(e)NB access with S5/S8 PMIP: BBERF resides in the Serving GW.

The UE may or may not be behind a NAT. The NAT may reside in the BBF access network or in the customer premises network. Policy interworking via S9a for non-seamless WLAN offloaded traffic in this release is supported for scenarios without NAT in the BBF domain.

P.4.2.1 Reference architecture – Non-Roaming

Figure P.4.2.1-1: PCC Reference architecture for Fixed Broadband Access Interworking

P.4.2.2 Reference architecture – Home Routed

Figure P.4.2.2-1: PCC Reference architecture for Fixed Broadband Access Interworking (home routed)

P.4.2.3 Reference architecture – Visited Access

Figure P.4.2.3-1: PCC Reference architecture for Fixed Broadband Access Interworking (visited access)

P.4.2.4 Reference architecture – Non-Roaming with non-seamless WLAN offload in Fixed Broadband Access Network; scenario with AF

Figure P.4.2.4-1: PCC Reference architecture for Fixed Broadband Access Interworking (non-roaming with non-seamless WLAN offload in Fixed Broadband Access Network)

NOTE 1: The architecture also supports scenarios where there is an Application Function in the Fixed Broadband Access Network. The AF in the Fixed Broadband Access Network and the reference point between the AF in the Fixed Broadband Access Network and the BPCF are out of scope for this specification.

NOTE 2: The AF in this architecture is used with traffic that is non-seamless WLAN offloaded in the Fixed Broadband Access Network.

P.4.2.5 Reference architecture – Roaming with non-seamless WLAN offload in Fixed Broadband Access Network: scenario with AF

Figure P.4.2.5-1: PCC Reference architecture for Fixed Broadband Access Interworking (roaming with non-seamless WLAN offload in Fixed Broadband Access Network)

NOTE 1: The architecture also supports scenarios where there is an Application Function in the Fixed Broadband Access Network. The AF in the Fixed Broadband Access Network and the reference point between the AF in the Fixed Broadband Access Network and the BPCF are out of scope for this specification.

NOTE 2: The AF in this architecture is used with traffic that is non-seamless WLAN offloaded in the Fixed Broadband Access Network.

P.4.2.6 Reference architecture – Non-Roaming with non-seamless WLAN offload in Fixed Broadband Access Network: scenario with TDF

Figure P.4.2.6-1: PCC Reference architecture for Fixed Broadband Access Interworking (non-roaming with non-seamless WLAN offload in Fixed Broadband Access Network)

NOTE 1: The TDF in this architecture is used with traffic that is non-seamless WLAN offloaded in the Fixed Broadband Access Network.

NOTE 2: Sd is an intra-operator interface. Scenarios where non-seamless WLAN offloaded traffic is routed via the TDF are therefore limited to the case where the Fixed Broadband Access Network and the PLMN are owned by the same operator.

P.4.2.7 Reference architecture – Roaming with non-seamless WLAN offload in Fixed Broadband Access Network: scenario with TDF

Figure P.4.2.7-1: PCC Reference architecture for Fixed Broadband Access Interworking (roaming with non-seamless WLAN offload in Fixed Broadband Access Network)

NOTE 1: The TDF in this architecture is used with traffic that is non-seamless WLAN offloaded in the Fixed Broadband Access Network.

NOTE 2: Sd is an intra-operator interface. Scenarios where non-seamless WLAN offloaded traffic is routed via the TDF are therefore limited to the case where the Fixed Broadband Access Network and the VPLMN are owned by the same operator.