Content for  TS 23.304  Word version:  19.1.0

In order to support PC5 radio resource control in NG-RAN, ProSe service Authorisation information and PC5 QoS parameters for ProSe need to be made available in NG-RAN. This clause describes the corresponding procedures and aspects.

The Registration procedure for UE is performed as defined in clause 4.2.2.2 of TS 23.502 with the following additions:

• The UE includes the 5G ProSe Capability as part of the "5GMM capability" in the Registration Request message. The AMF stores the 5G ProSe Capability for 5G ProSe operation.
  • The 5G ProSe Capability indicates whether the UE supports one or more of the following ProSe capabilities:
    • 5G ProSe Direct Discovery;
    • 5G ProSe Direct Communication;
    • 5G ProSe Layer-2 UE-to-Network Relay;
    • 5G ProSe Layer-3 UE-to-Network Relay;
    • 5G ProSe Layer-2 Remote UE;
    • 5G ProSe Layer-3 Remote UE;
    • 5G ProSe Layer-2 UE-to-UE Relay;
    • 5G ProSe Layer-3 UE-to-UE Relay;
    • 5G ProSe Layer-2 End UE; and
    • 5G ProSe Layer-2 End UE;
    • 5G ProSe Layer-3 End UE;
    • 5G ProSe Layer-3 UE-to-Network Relay supporting 5G ProSe Layer-3 multi-hop UE-to-Network Relay;
    • 5G ProSe Layer-3 Remote UE supporting 5G ProSe Layer-3 multi-hop UE-to-Network Relay;
    • 5G ProSe Layer-3 Intermediate UE-to-Network Relay;
    • 5G ProSe Layer-3 UE-to-UE Relay supporting 5G ProSe Layer-3 multi-hop UE-to-UE Relay;
    • 5G ProSe Layer-3 End UE supporting 5G ProSe Layer-3 multi-hop UE-to-UE Relay.
• The AMF obtains the 5G ProSe subscription data as part of the user subscription data from UDM during UE Registration procedure using Nudm_SDM service as defined in clause 4.2.2.2.2 of TS 23.502.
• The AMF determines whether the UE is authorised to use 5G ProSe services based on UE's 5G ProSe Capability and the ProSe Service Authorisation included in the subscription data received from UDM as specified in clause 5.7. ProSe NR UE-PC5-AMBR is also provided to the AMF as part of the subscription data for 5G ProSe services. The AMF stores the authorized 5G ProSe Capability.
• The AMF sends the authorized 5G ProSe Capability for 5G ProSe operation to PCF. Based on the received 5G ProSe Capability from the AMF, the PCF provides the PC5 QoS parameters for 5G ProSe to AMF. The AMF stores such information as part of the UE context.
• If the UE is authorised to use 5G ProSe services, then the AMF shall include in a NGAP message sent to NG-RAN:
  • "5G ProSe authorised" information, including one or more of the following:
    • whether the UE is authorized to use 5G ProSe Direct Discovery;
    • whether the UE is authorized to use 5G ProSe Direct Communication;
    • whether the UE is authorized to act as a 5G ProSe Layer-2 UE-to-Network Relay;
    • whether the UE is authorized to act as a 5G ProSe Layer-3 UE-to-Network Relay;
    • whether the UE is authorized to act as a 5G ProSe Layer-2 Remote UE;
    • whether the UE is authorized to use multi-path communication via direct Uu path and via 5G ProSe Layer-2 UE-to-Network Relay as a 5G ProSe Layer-2 Remote UE;
    • whether the UE is authorized to act as a 5G ProSe Layer-2 UE-to-UE Relay;
    • whether the UE is authorized to act as a 5G ProSe Layer-2 End UE;
    • whether the UE is authorized to act as a 5G ProSe Layer-3 UE-to-Network Relay supporting 5G ProSe Layer-3 multi-hop UE-to-Network Relay;
  • ProSe NR UE-PC5-AMBR, used by NG-RAN for the resource management of UE's PC5 transmission for 5G ProSe services in network scheduled mode.
  • the PC5 QoS parameters for 5G ProSe used by the NG-RAN for the resource management of UE's PC5 transmission for ProSe services in network scheduled mode.
• If the UE is authorised to use 5G ProSe services, then the AMF should not initiate the release of the signalling connection after the completion of the Registration procedure. The release of the signalling connection relies on the decision of NG-RAN, as specified in TS 23.502.

The Service Request procedures for UE in CM-IDLE state are performed as defined in clause 4.2.3.2 and clause 4.2.3.3 of TS 23.502 with the following additions:

• If the UE is authorised to use ProSe services, then the AMF shall include "ProSe authorised" information in the NGAP message, indicating which of the ProSe services the UE is authorised to use as described in clause 6.6.2.
• The AMF includes the ProSe NR UE-PC5-AMBR in the NGAP message to the NG-RAN as part of the UE context and NG-RAN may use in resource management of UE's PC5 transmission for ProSe services in network scheduled mode.
• The AMF sends the PC5 QoS parameters for ProSe to NG-RAN via N2 signalling. The PC5 QoS parameters for ProSe may be stored in the UE context after the registration procedure. If the UE is authorised to use ProSe services but AMF does not have PC5 QoS parameters for ProSe available, the AMF fetches the PC5 QoS parameters for ProSe from the PCF.

The N2 based handover procedures for UE are performed as defined in clause 4.9.1.3 of TS 23.502 with the following additions:

• If the UE is authorised to use ProSe services, then the target AMF shall send the "ProSe authorised" information, ProSe NR UE-PC5-AMBR and PC5 QoS parameters for ProSe to the target NG-RAN in the NGAP Handover Request message.

The Xn based handover procedures for UE are performed as defined in clause 4.9.1.2 of TS 23.502 with the following additions:

• If the "ProSe authorised" information is included in the UE context, then the source NG-RAN shall include a "ProSe authorised" information, ProSe NR UE-PC5-AMBR and PC5 QoS parameters for ProSe in the XnAP Handover Request message to the target NG-RAN.
• If the "ProSe authorised" information is included in the UE context, then the AMF shall send the "ProSe authorised" information, the ProSe NR UE-PC5-AMBR and PC5 QoS parameters for ProSe to the target NG-RAN in the Path Switch Request Acknowledge message.

The procedure of Subscriber Data Update Notification to AMF is performed as defined in clause 4.5.1 of TS 23.502 with the following additions:

• The Nudm_SDM_Notification service operation may contain the ProSe Service Authorisation or the ProSe NR UE-PC5-AMBR or any combination.
• The AMF updates the UE Context with the above new ProSe subscription data.
• When the AMF updates UE context stored at NG-RAN, the UE context contains the ProSe subscription data.

The UE Policy Association Establishment procedure and UE Policy Association Modification procedure, as defined in TS 23.502, is used to provide the AMF with PC5 QoS parameters used by NG-RAN. When receiving the 5G ProSe Capability in Npcf_UEPolicyControl_Create Request from the AMF or when receiving the updated subscription data from UDR, the PCF generates the PC5 QoS parameters used by NG-RAN corresponding to a UE as defined in clause 5.4.2 of TS 23.287. The (V-)PCF provides the information to the AMF as follows:

• In the roaming case, the H-PCF includes the PC5 QoS parameters used by NG-RAN in the Npcf_UEPolicyControl_Create Response message or Npcf_UEPolicyControl UpdateNotify Request message sent to V-PCF in an N2 PC5 policy container and V-PCF relays this N2 PC5 policy container as the N2 container in the Namf_Communication_N1N2MessageTransfer message sent to AMF.
• In the non-roaming case, the PCF includes the PC5 QoS parameters used by NG-RAN in an N2 container in Namf_Communication_N1N2MessageTransfer message sent to AMF.

When the AMF receives the N2 PC5 policy container from (V-)PCF, the AMF stores such information as part of the UE context. In the UE Configuration Update procedure triggered by UE Policy Association Establishment or UE Policy Association Modification:

• The AMF forwards the PC5 QoS parameters in the NGAP message to the NG-RAN if a N2 PC5 policy container is received in the Namf_Communication_N1N2MessageTransfer message.