Section: 4.11.1.5.4 Session Management
Content: 4.11.1.5.4.1 PDN Connection Request The UE Requested PDN Connectivity Procedure specified in clause 5.10.2 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] is impacted as shown in in Figure 4.11.1.5.4.1-1 when interworking with 5GS is supported. Figure 4.11.1.5.4.1-1: Impacts to UE Requested PDN Connectivity Procedure 1. UE sends a PDN connectivity Request to the MME as specified in Step 1 in clause 5.10.2 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] with the following modification: - If the UE is 5G NAS capable and the Request type is "initial request", the UE shall allocate a PDU Session ID and include it in the PCO. The PDU Session ID shall be unique across all other PDN connections of the UE. 2. The relevant steps of the procedure as specified in the figure above are executed. In step 4 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13], IP Session Establishment/Modification procedure is replaced by SM Policy Association Establishment/Modification procedure as specified in clauses 4.16.4 and 4.16.5. 3. Step 6 as specified in clause 5.10.2 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] is executed with the following modification: - If the SMF+PGW-C accepts to provide interworking of the PDN connection with 5GC, the SMF+PGW-C shall allocate 5G QoS parameters corresponding to PDN connection, e.g. Session AMBR, QoS rules and QoS Flow level QoS parameters if needed for the QoS Flow(s) associated with the QoS rule(s) and then include them in PCO. - If the SMF+PGW-C accepts to provide interworking of the PDN connection with 5GC, the SMF+PGW-C shall determine the S-NSSAI associated with the PDN connection based on the operator policy and send the S-NSSAI together with the PLMN ID to the UE in the PCO. - If the SMF+PGW-C accepts to provide interworking of the PDN connection with 5GC the SMF+PGW-C, if Small Data Rate Control is used, provides the Small Data Rate Control parameters to the UE in the PCO. 4. The relevant steps of the procedure as specified in the figure above are executed. 5. Step 8 as specified in clause 5.10.2 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] with the following modification: - If 5G QoS parameters are included in the PCO, the UE shall store them. If 5G QoS parameters are not included in the PCO, the UE shall note that session continuity for this PDN connection on mobility to 5G is not provided by the network. - If the S-NSSAI and the PLMN ID associated with the PDN connection are included in the PCO, the UE shall store them. - If the Small Data Rate Control parameters are included in the PCO, the UE shall store them. 6. The relevant steps of the procedure as specified in the figure above are executed. 4.11.1.5.4.2 UE or MME Requested PDN Disconnection The procedure as specified in clause 5.10.3 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] applies with the following modification: Step 8. (RRC Connection Reconfiguration): On receiving the NAS Deactivate EPS Bearer Context Request(LBI) message, if the UE has mapped 5G parameters for the PDU session, the UE deletes the corresponding mapped 5GS PDU session. In addition if the SMF+PGW-C has registered to HSS+UDM for this PDN connection before, the SMF+PGW-C invokes the Nudm_UECM_Deregistration service operation to notify the UDM to remove the association between the SMF+PGW-C identity and the associated DNN and PDU Session Id as described in the step 12 of clause 4.3.4.2. If there is no PDN connection for the associated (DNN, S-NSSAI) handled by the SMF+PGW-C, the SMF+PGW-C unsubscribes from Session Management Subscription data changes notification with the HSS+UDM by means of the Nudm_SDM_Unsubscribe (SUPI, DNN, S-NSSAI) service operation as described in step 12 of clause 4.3.4.2. 4.11.1.5.4.3 Dedicated Bearer Activation, Bearer Modification and Bearer Deactivation The procedures specified in clauses 5.4.1 through 5.4.5 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] apply with the following modifications: - PCRF initiated IP-CAN Modification in TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] is replaced with PCF initiated SM Policy Association Modification as specified in clause 4.16.5.2. PCEF initiated IP-CAN Session Modification/Termination TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] is replaced with SM Policy Association Modification/Termination as specified in clauses 4.16.5 and 4.16.6. - In the step where the PDN-GW sends a Create Bearer Request, i.e.: - Step 2 in clause 5.4.1 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] (Dedicated Bearer Activation). the PCO includes mapped 5GS QoS parameters for the EPS bearer being created. - In the step where the PDN-GW sends an Update Bearer Request, i.e.: - Step 2 in clause 5.4.2.1 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] (PDN GW initiated bearer modification with bearer QoS update). - Step 5 in clause 5.4.2.2 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] (HSS Initiated Subscribed QoS Modification). - Step 2 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 ]  [13] (PDN GW initiated bearer modification without bearer QoS update) if TFT or APN-AMBR is being modified. the PCO includes the modification to the mapped 5GS QoS parameters, if impacted by the modification, corresponding to the EPS bearer being modified. - In the step where the UE receives the NAS Session Management message from the MME which contains the PCO relayed via the MME, i.e.: - Step 5 in clause 5.4.1 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] (Dedicated Bearer Activation). - Step 5 in clause 5.4.2.1 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] (PDN GW initiated bearer modification with bearer QoS update). - Step 5 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 ]  [13] (PDN GW initiated bearer modification without bearer QoS update) if TFT or APN-AMBR is being modified. the UE updates the mapped 5G QoS parameters as included in the PCO from the PDN-GW. - In the step where the UE receives EPS bearer request message, i.e.: - Step 5 in clause 5.4.4.1 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [13] (PDN GW initiated bearer deactivation). the UE also deletes the mapped 5GS QoS flow and its associated parameter.