Content for  TS 37.483  Word version:  17.3.0

The purpose of the Bearer Context Setup procedure is to allow the gNB-CU-CP to establish a bearer context in the gNB-CU-UP. The procedure uses UE-associated signalling.

The gNB-CU-CP initiates the procedure by sending the BEARER CONTEXT SETUP REQUEST message to the gNB-CU-UP. If the gNB-CU-UP succeeds to establish the requested resources, it replies to the gNB-CU-CP with the BEARER CONTEXT SETUP RESPONSE message. The gNB-CU-UP shall report to the gNB-CU-CP, in the BEARER CONTEXT SETUP RESPONSE message, the result for all the requested resources in the following way: When the gNB-CU-UP reports the unsuccessful establishment of a PDU Session Resource, DRB or QoS Flow the cause value should be precise enough to enable the gNB-CU-CP to know the reason for the unsuccessful establishment. If the Existing Allocated NG DL UP Transport Layer Information IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP may re-use the indicated resources already allocated for this bearer context. If the gNB-CU-UP decides to re-use the indicated resources, it shall include the NG DL UP Unchanged IE in the BEARER CONTEXT SETUP RESPONSE message. If the PDU Session Resource DL Aggregate Maximum Bit Rate IE is contained in the PDU Session Resource To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall store and use the information for the down link traffic policing for the Non-GBR QoS flows for the concerned UE as specified in TS 23.501. If the Data Forwarding Information Request IE, PDU Session Data Forwarding Information Request IE or the DRB Data Forwarding Information Request IE are included in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall include the requested forwarding information in the Data Forwarding Information Response IE, PDU Session Data Forwarding Information Response IE or the DRB Data Forwarding Information Response IE in the BEARER CONTEXT SETUP RESPONSE message. If the DL UP Parameters IE is contained in the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall configure the corresponding information. For each PDU session for which the Security Indication IE is included in the PDU Session Resource To Setup List IE of the BEARER CONTEXT SETUP REQUEST message, and the Integrity Protection Indication IE or Confidentiality Protection Indication IE is set to "preferred", then the gNB-CU-UP should, if supported, perform user plane integrity protection or ciphering, respectively, for the concerned PDU session and shall notify whether it performed the user plane integrity protection or ciphering by including the Integrity Protection Result IE or Confidentiality Protection Result IE, respectively, in the PDU Session Resource Setup List IE of the BEARER CONTEXT SETUP RESPONSE message. For each PDU session for which the Security Indication IE is included in the PDU Session Resource To Setup List IE of the BEARER CONTEXT SETUP REQUEST message, and the Integrity Protection Indication IE or Confidentiality Protection Indication IE is set to "required", then the gNB-CU-UP shall perform user plane integrity protection or ciphering, respectively, for the concerned PDU Session. If the gNB-CU-UP cannot perform the user plane integrity protection or ciphering, it shall reject the setup of the PDU Session Resources with an appropriate cause value. For each PDU session for which the Security Indication IE is included in the PDU Session Resource To Setup List IE of the BEARER CONTEXT SETUP REQUEST message:

• if the Integrity Protection Indication IE is set to "not needed", then the gNB-CU-UP shall not perform user plane integrity protection for the concerned PDU session;
• if the Confidentiality Protection Indication IE is set to "not needed", then the gNB-CU-UP shall not perform user plane ciphering for the concerned PDU session.

For E-UTRAN:

• For each DRB for which the Security Indication IE is included in the DRB To Setup List IE of the BEARER CONTEXT SETUP REQUEST message, and the Integrity Protection Indication IE is set to "preferred", then the gNB-CU-UP should, if supported, perform user plane integrity protection for the concerned DRB and notify whether it performed the user plane integrity protection by including the Integrity Protection Result IE, in the DRB Setup List IE of the BEARER CONTEXT SETUP RESPONSE message.
• For each DRB for which the Security Indication IE is included in the DRB To Setup List IE of the BEARER CONTEXT SETUP REQUEST message, and the Integrity Protection Indication IE is set to "required", then the gNB-CU-UP shall, if supported, perform user plane integrity protection for the concerned DRB. If the gNB-CU-UP cannot perform the user plane integrity protection, it shall reject the setup of the DRB with an appropriate cause value.
• For each DRB for which the Security Indication IE is included in the DRB To Setup List IE of the BEARER CONTEXT SETUP REQUEST message, and the Integrity Protection Indication IE is set to "not needed", then the gNB-CU-UP shall not perform user plane integrity protection for the concerned DRB.

For each PDU session, if the Data Forwarding to E-UTRAN Information List IE is included in the PDU Session Resource To Modify List IE in the BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, use it for inter-system data forwarding from 5GS to EPS as specified in TS38.300 [8]. If the UE DL Maximum Integrity Protected Data Rate IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall use this value when enforcing the maximum integrity protected data rate for the UE. If the Bearer Context Status Change IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall consider the UE RRC state and act as specified in TS 38.401. If the Bearer Context Status Change IE is set to "ResumeforSDT", the gNB-CU-UP shall, if supported, consider that DRBs not configured with SDT are suspended after being established. For each requested DRB, if the PDCP Duplication IE is included in the PDCP Configuration IE contained in the BEARER CONTEXT SETUP REQUEST message, then the gNB-CU-UP shall include two UP Transport Layer Information IEs in the BEARER CONTEXT SETUP RESPONSE message to support packet duplication. If only one cell group is included in the Cell Group Information IE for the concerned DRB, then the gNB-CU-UP shall consider that the first UP Transport Layer Information IE of the two UP Transport Layer Information IEs is for the primary path. For each requested DRB, if the Additional PDCP duplication Information IE is included in the PDCP Configuration IE contained in the BEARER CONTEXT SETUP REQUEST message, then the gNB-CU-UP shall, if supported, include the same number of UP Transport Layer Information IEs indicated by the Additional PDCP duplication Information IE in the BEARER CONTEXT SETUP RESPONSE message to support packet duplication. If only one cell group is included in the Cell Group Information IE for the concerned DRB, then the gNB-CU-UP shall consider that the first UP Transport Layer Information IE of these UP Transport Layer Information IEs is for the primary path. If more than one cell group is included in the Cell Group Information IE, then the gNB-CU-UP shall consider that the number of duplication tunnels for each cell group is indicated by the Number of tunnels IE, and that the first UP Transport Layer Information IE for each cell group is for the primary path or the split secondary path. If the PDCP SN Status Information IE is contained within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall take it into account and act as specified in TS 38.401. If the QoS Flow Mapping Indication IE is contained in the QoS Flows Information To Be Setup IE within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP may take it into account that only the uplink or downlink QoS flow is mapped to the DRB. If the QoS Flows Remapping IE is contained within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message for a DRB and set to "update", the gNB-CU-UP shall, if supported, consider that QoS flows mapped for the DRB is updated to the QoS flow(s) included in the QoS Flows Information To Be Setup IE after finishing handling forwarded PDCP SDUs during an intra-system handover procedure. If the QoS Flows Remapping IE is contained within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message for a DRB and set to "source configuration", the gNB-CU-UP shall, if supported, consider that no QoS flow is mapped to the DRB after finishing handling forwarded PDCP SDUs over that DRB during an intra-system handover procedure and ignore the information included in the QoS Flows Information To Be Setup IE for the concerned DRB. For each PDU Session Resource, if the Network Instance IE is included in the PDU Session Resource To Setup List IE in the BEARER CONTEXT SETUP REQUEST message and the Common Network Instance IE is not included, the gNB-CU-UP shall, if supported, use it when selecting transport network resource as specified in TS 23.501. For each PDU session, if the Common Network Instance IE is included in the PDU Session Resource To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, use it when selecting transport network resource as specified in TS 23.501. For each PDU session, if the Redundant NG UL UP Transport Layer Information IE is included in the PDU Session Resource To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, use it as the uplink termination point of the redundant tunnel for the user plane data of those QoS flows in this PDU session which need redundant transmission as described in TS 23.501, and it shall include the Redundant NG DL UP Transport Layer Information IE in the PDU Session Resource Setup List IE in the BEARER CONTEXT SETUP RESPONSE message. For each PDU Session Resource, if the Redundant Common Network Instance IE is included in the PDU Session Resource To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, use it when selecting transport network resource for the redundant transmission as specified in TS 23.501. For each PDU session, if the Redundant QoS Flow Indicator IE is included in the QoS Flow QoS Parameters List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, consider it for the redundant transmission. For each PDU session, if the Redundant PDU Session Information IE is included in the PDU Session Resource To Setup List IE contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, set up the redundant user plane resources, as specified in TS 23.501 and include, if supported, the Used Redundant PDU Session Information IE in the PDU Session Resource Setup List IE in the BEARER CONTEXT SETUP RESPONSE message. If the PDU Session Pair ID IE is included in the Redundant PDU Session Information IE, the gNB-CU-UP may use it to identify the paired PDU Sessions. If UE Inactivity Timer IE or PDU session Inactivity Timer IE or DRB Inactivity Timer IE is contained in BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall take it into account when perform inactivity monitoring. If the DRB QoS IE is contained within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, take it into account as specified in TS 28.552. If the gNB-DU-ID IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall store the information received. If the RAN UE ID IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall store the information received. For each successfully established DRB, the gNB-CU-UP shall provide, in the respective UL UP Parameters IE of the BEARER CONTEXT SETUP RESPONSE, one UL UP Transport Layer Information Item per cell group entry contained in the respective Cell Group Information IE of the BEARER CONTEXT SETUP REQUEST message. If the Trace Activation IE is included in the BEARER CONTEXT SETUP REQUEST message the gNB-CU-UP shall, if supported, initiate the requested trace function as described in TS 32.422. In particular, the gNB-CU-UP shall, if supported:

• if the MDT Activation IE is set to "Immediate MDT Only", initiate the requested MDT session as described in TS 32.422 and the gNB-CU-UP shall ignore Interfaces To Trace IE, and Trace Depth IE;
• if the MDT Activation IE is set to "Immediate MDT and Trace", initiate the requested trace session and MDT session as described in TS 32.422;

If the Management Based MDT PLMN List IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, store the received information, and use this information to allow subsequent selection of the UE for management based MDT defined in TS 32.422. For EN-DC, if the Subscriber Profile ID for RAT/Frequency priority IE is included in the BEARER CONTEXT SETUP REQUEST, the gNB-CU-UP may use it to apply specific RRM policies as specified in TS 36.300. If the Additional RRM Policy Index IE is included in the BEARER CONTEXT SETUP REQUEST, the gNB-CU-UP may use it to apply specific RRM policies as specified in TS 36.300. If the TSC Traffic Characteristics IE is included in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, take into account the corresponding information received in the TSC Traffic Characteristics IE. For each QoS flow whose DRB has been successfully established and the QoS Monitoring Request IE was included in the QoS Flow Level QoS Parameters IE contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall store this information, and, if supported, perform delay measurement and QoS monitoring, as specified in TS 23.501. If the QoS Monitoring Reporting Frequency IE was included in the QoS Flow Level QoS Parameters IE contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall store this information, and, if supported, use it for RAN part delay reporting. If the BEARER CONTEXT SETUP REQUEST message contains the NPN Context Information IE the gNB-CU-UP shall, if supported, take it into account when allocating UP resources for the bearer context. For each requested DRB, if the EHC Parameters IE is included in the PDCP Configuration IE, the gNB-CU-CP shall, if supported, also include ROHC Parameters IE in the PDCP Configuration IE in the BEARER CONTEXT SETUP REQUEST message, to enable the gNB-CU-UP to perform appropriate header compression. If the EHC parameters IE is included in the PDCP Configuration IE contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP may take these parameters into account to perform appropriate header compression for the concerned DRB. If the EHC Downlink IE is included in the EHC parameters IE and the value of drb-ContinueEHC-DL IE is set to 'true', the gNB-CU-UP shall, if supported, configure Ethernet header compression for downlink and continue the downlink EHC header compression protocol as specified in TS 38.331. If the EHC Downlink IE is included in the EHC parameters IE and the value of drb-ContinueEHC-DL IE is set to 'false', the gNB-CU-UP shall, if supported, configure Ethernet header compression for downlink and reset the downlink EHC header compression protocol during PDCP re-establishment as specified in TS 38.331. If the EHC Uplink IE is included in the EHC parameters IE and the value of drb-ContinueEHC-UL IE is set to 'true', the gNB-CU-UP shall, if supported, configure Ethernet header compression for uplink and continue the uplink EHC header compression protocol as specified in TS 38.331. If the EHC Uplink IE is included in the EHC parameters IE and the value of drb-ContinueEHC-UL IE is set to 'false', the gNB-CU-UP shall, if supported, configure Ethernet header compression for uplink and resets the uplink EHC header compression protocol during PDCP re-establishment as specified in TS 38.331. If the DAPS Request Information IE is included for a DRB to be setup in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall consider that the request concerns a DAPS handover for that DRB and, if admitted, act as specified in TS 38.300. If the CHO Initiation IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall consider that the request concerns conditional handover or conditional PSCell change or conditional PSCell addition and act as specified in TS 38.401. If the MCG Offered GBR QoS Flow Information IE is contained in the QoS Flows Information To Be Setup IE within the DRB To Setup List IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP may take it into account when two cell groups are served by the gNB-CU-UP. If the Additional Handover Information IE is included in the BEARER CONTEXT SETUP REQUEST message and set to "Discard PDCP SN", the gNB-CU-UP shall, if supported, remove the forwarded PDCP SNs if received in the forwarded GTP-U packets, and deliver the forwarded PDCP SDUs to the UE, as specified in TS 38.300. If the Ignore Mapping Rule Indication IE is contained within the DRB To Setup List IE for a DRB in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, ignore the QoS flow mapping information indicated by the QoS Flows Information To Be Setup IE for the concerned DRB. If the Direct Forwarding Path Availability IE set to "inter-system direct path available" is included in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, assign the UP Transport Layer Information for inter-system direct data forwarding from the appropriate address space, if applicable. If the Direct Forwarding Path Availability IE set to "intra-system direct path available" is included in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, assign the UP Transport Layer Information for intra-system direct data forwarding from the appropriate address space, if applicable. If the gNB-CU-UP UE E1AP ID IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP may use it to identify the UE context as specified in TS 38.401. If the Data Forwarding Source IP Address IE is included in the DRB To Setup List E-UTRAN IE or in the QoS Flow Level QoS Parameters IE contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, store this information in the UE context and use it as part of its ACL functionality configuration actions, if such ACL functionality is deployed. If the Data Forwarding Source IP Address IE is included in the DRB Setup List E-UTRAN IE or in the Flow Setup List IE within the DRB Setup List IE in the PDU Session Resource Setup List IE of the BEARER CONTEXT SETUP RESPONSE message, the gNB-CU-CP shall, if supported, store this information in the UE context and use it as part of its ACL functionality configuration actions, if such ACL functionality is deployed. If the MDT Polluted Measurement Indicator IE is included in the BEARER CONTEXT SETUP REQUEST, the gNB-CU-UP shall take this information into account as specified in TS 38.401. If the UE Slice Maximum Bit Rate List IE is included in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, store and use the information for the downlink traffic policing for each concerned slice as specified in TS 23.501. If the UDC parameters IE is included in the PDCP Configuration IE in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall, if supported, take these parameters into account to perform appropriate uplink data compression for the concerned DRB. If the SCG Activation Status IE is contained in the BEARER CONTEXT SETUP REQUEST message, the gNB-CU-UP shall take it into account when handling DL data transfer as specified in TS 37.340.

If the gNB-CU-UP cannot establish the requested bearer context, or cannot even establish one bearer, or cannot handle SCG with the indicated activated or deactivated status it shall consider the procedure as failed and respond with a BEARER CONTEXT SETUP FAILURE message and appropriate cause value.

If the gNB-CU-UP receives a BEARER CONTEXT SETUP REQUEST message containing a E-UTRAN QoS IE in the DRB To Setup List IE for a GBR QoS DRB but where the GBR QoS Information IE is not present, the gNB-CU-UP shall report the establishment of the corresponding DRB as failed in the DRB Failed List IE of the BEARER CONTEXT SETUP RESPONSE message with an appropriate cause value. If the gNB-CU-UP receives a BEARER CONTEXT SETUP REQUEST message containing a QoS Flow Level QoS Parameters IE in the PDU Session Resource To Setup List IE for a GBR QoS Flow but where the GBR QoS Flow Information IE is not present, the gNB-CU-UP shall report the establishment of the corresponding QoS Flow as failed in the corresponding Flow Failed List IE of the BEARER CONTEXT SETUP RESPONSE message with an appropriate cause value.