Section: 5.17.8 URSP Provisioning in EPS
Content: When the UE registers in 5GS, the UE includes the Indication of URSP Provisioning Support in EPS in the UE Policy Container carried in Registration Request. On receiving this indication in the UE Policy Container, the PCF will provision the URSP to UE in EPS. The UE may include the indication of URSP Provisioning Support in EPS in PCO or ePCO to the SMF+PGW-C during: - Initial Attach with default PDN connection establishment (according to clause 5.3.2.1 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [26]). - Any UE requested PDN connectivity request to an additional PDN (according to clause 5.10.2 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [26]. If the SMF+PGW-C supports URSP provisioning in EPS, it provides the Indication of URSP Provisioning Support in EPS in ePCO in the Create Session Response message. The UE ensures that there is only one PDN connection used for URSP rule delivery in EPS. When the UE receives an indication of URSP provisioning support in EPS in the PDN Connectivity Accept message and this PDN connection is not released, then for any subsequent PDN connectivity requests the UE does not include an indication of URSP Provisioning Support in EPS. When the UE receives the Indication of URSP Provisioning Support in EPS included in ePCO in the PDN Connectivity Accept message, then the UE initiates the UE requested bearer resource modification without QoS update procedure and includes the UE Policy Container ePCO in the Request Bearer Resource Modification message, the UE Policy Container in ePCO will be further forwarded by MME to SMF+PGW-C. When the UE Policy Container ePCO is received by SMF+PGW-C, it forwards transparently the UE Policy Container to PCF for the PDU Session, then the PCF for the PDU Session establishes the UE Policy Association with PCF for the UE. The PCF for the UE generates the corresponding URSP rules in a similar way as it is done in 5GS and sends the URSP rules to UE in the UE Policy Container as described in clause 4.11.0a.5 of TS 23.502[ Procedures for the 5G System (5GS) ]  [3]. NOTE 1: The UE includes the Indication of URSP Provisioning Support in EPS in PCO or ePCO in the PDN connectivity request according to clause 6.6.1.1 of TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [13]. NOTE 2: The MME and Serving-GW can be configured to prioritize the selection of a SMF+PGW-C that support URSP Rule provisioning in EPS. If the UE does not receive the Indication of URSP Provisioning Support in EPS in ePCO in the PDN Connectivity Accept message, then the UE does not initiate the UE requested bearer resource modification procedure to send the UE Policy Container. The PDN Connection used by UE and SMF+PGW-C to convey UE Policy Container PCO shall be kept when the UE is in the CONNECTED mode. When the UE is attached to EPS, the PCF for the PDU Session retrieves the PCRTs for UE Policy from PCF for the UE and subscribes to the applicable PCRTs to SMF+PGW-C. The PCF for the PDU Session sends the UE Policy Container in the same PDN connection/PDU session in which the UE Policy Container was received. During EPS to 5GS mobility with N26, the UE Policy Association is terminated by PCF for PDU Session when it receives the indication of RAT type change from the SMF+PGW-C. During 5GS to EPS mobility with N26, the PCF for the PDU Session determines whether the UE supports URSP delivery in EPS by checking UE context policy control subscription information in UDR. The PCF for the PDU Session discovers the address of PCF for the UE serving the UE by querying BSF. The PCF for the UE recovers the information about the PSI list in the UE and the subscribed PCRTs in 5GS from former UE Policy Association for the UE after receiving the UE Policy Association Establishment request including a UE Policy Container only including an indication about the trigger for the UE Policy Association Establishment ("5GS to EPS mobility"). After the 5GS to EPS mobility, if PCF for the UE needs to provision the URSP to UE, the PCF for the UE sends the UE Policy Container in Npcf_UEPolicyControl_UpdateNotify Request to the PCF for the PDU Session as described in clause 4.11.0a.2a.10 of TS 23.502[ Procedures for the 5G System (5GS) ]  [3]. In case there are more than one PDN connections for the UE, then the PCF for the PDU Session selects any of the ongoing PDN Connections via a SMF+PGW-C supporting URSP delivery in EPS for the UE. Then via the selected PDN Connection, the SMF+PGW-C sends the UE Policy Container via ePCO to UE by initiating the PDN GW initiated bearer modification without QoS update procedure as defined in clause 5.4.3 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [26]. NOTE 3: At 5GS to EPS mobility with N26, the guard timer in the AMF (as specified in clauses 4.11.1.2.1 and 4.11.1.3.2 of TS 23.502[ Procedures for the 5G System (5GS) ]  [3]) ensures that the UE Policy Association remains until the PCF for the UE detects that a UE Policy Association establishment is received from a PCF for the PDU Session indicating 5GS to EPS mobility. NOTE 4: In the case that the UE is still registered and reachable over non-3GPP access, the PCF for UE can have two UE policy associations for one UE, and based on local configuration the PCF can decide to use one of the UE policy associations to update URSP rule to the UE. The UE can receive URSP Rules over any of these two accesses. When the PCF for the UE decides to update the URSPs in the UE via EPS, the PCF for the UE sends the updated URSP rules in UE Policy Container to the PCF for the PDU Session, then the PCF for the PDU Session forwards it to the SMF+PGW-C. The SMF+PGW-C transfers the received UE Policy Container via ePCO to the UE by triggering PDN-GW initiated Bearer without QoS Modification procedure as described in clause 5.4.3 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [26]. After update the UE policy provided by the PCF, the UE response about the delivery result via ePCO to the network. The SMF+PGW-C transparently forwards the UE response to the PCF for the PDU Session via Update Bearer Response message, and then the PCF for the PDU Session forwards it to the PCF for the UE via Npcf_UEPolicyControl_Update Request. If the SMF+PGW-C receives a rejection for Update Bearer Request message (e.g. due to paging failure), the delivery failure result is sent to PCF for the PDU Session and the PCF for the UE. To request to forward the result of delivery of UE policies, "Result of UE Policy Container delivery via EPS" PCRT is applied to the PCF for the PDU Session and the SMF+PGW-C as described in clause 4.11.0a.2a.10 of TS 23.502[ Procedures for the 5G System (5GS) ]  [3].