Content for  TS 23.256  Word version:  18.2.0

In addition to the 5GS functional entities defined in TS 23.501 and the EPS functional entities defined in TS 23.401, the following functional entities are defined for UAS.

The UAS Network Function is supported by the NEF or SCEF+NEF and used for external exposure of services to the USS. The UAS-NF makes use of existing NEF/SCEF exposure services for UAV authentication/authorization, for UAV flight authorization, for UAV-UAVC pairing authorization, and related re-authentication/re-authorization and revocation; for location reporting, presence monitoring, obtaining list of Aerial UEs in a geographic area and control of QoS/traffic filtering for C2 communication. The UAS NF may coordinate with the USS to assist CAA-Level UAV ID assignment. A dedicated NEF may be deployed to provide only the UAS NF functionality, i.e. to support the UAS specific features/APIs and the NEF features/APIs that are specified for capability exposure towards the USS. For external exposure of services related to specific UAV(s), the UAS NF resides in the VPLMN, in order to interface with country specific USS(es). When CAPIF is supported by the UAS NF, the UAS NF supports the CAPIF API provider domain functions as specified in TS 23.222. To support re-authentication/re-authorization and revocation request by USS, the UAS NF stores information as to whether the re-authentication/re-authorization and revocation is towards an AMF or SMF/SMF+PGW-C and the address of the serving AMF or SMF/SMF+PGW-C. UAS NF stores the result of UUAA-MM procedures and the result of UUAA-SM procedures.

The UAV is a 3GPP UE supporting the UE functionality defined in TS 23.401 and in TS 23.501. In addition:

• a UAV that is configured for UAS services is provisioned with a single CAA-Level UAV ID;
• a UAV that is configured for UAS services (i.e. is provisioned with a CAA-Level UAV ID) registers to the 3GPP system for UAS services (i.e. to take advantage of aerial features, connectivity with USS and for C2 connectivity) and provides the CAA-Level UAV ID and a UUAA Aviation Payload to 5GS or EPS. A UAV that has not performed a registration with aviation authorities shall not attempt to request for UAS services.
• a UAV that is configured for UAS services may support the following functions:
  • reports the A2X Capability and PC5 Capability for A2X (i.e. LTE PC5 and/or NR PC5) to 5GC over N1 reference point.
  • indicates A2X Policy Provisioning Request in UE Policy Container for UE triggered A2X Policy provisioning.
  • receives the A2X parameters from 5GC over N1 reference point.
  • supports procedures for A2X communication over PC5 reference point.
  • Configuration of parameters for A2X communication. These parameters can be pre-configured in the UE, or, if in coverage, provisioned or updated by signalling over the N1 reference point from the PCF in the HPLMN or over A2X1 reference point from the A2X Application Server.
  • Provided with the following for receiving Broadcast Remote ID via MBS:
    • Announcement via existing announcement mechanisms specified in TS 23.247, TS 26.502 and TS 26.517; or
    • MBS session announcement provisioned as specified in clause 6.2.1.3.1.
  • Provisioned with MBS session announcement for receiving A2X Application Server information via MBS as specified in clause 6.2.1.3.1.

In addition to the functionality defined in TS 23.501, the AMF:

• may trigger the UUAA-MM procedure for a UE requiring UAV authentication and authorization by a USS when registering with 5GS when the UE has Aerial UE subscription information and based on local operator policy, or when the USS that authenticated the UAV triggers a re-authentication, or when AMF itself determines to re-authentication the UAV after the initial registration.

An AMF supporting A2X additionally performs the following functions:

• Obtain from UDM the subscription information related to A2X and store them as part of the UE context data.
• Select a PCF supporting A2X Policy/Parameter provisioning and report the PC5 Capability for A2X to the selected PCF.
• Obtain from PCF the PC5 QoS information related to A2X and store it as part of the UE context data.
• Provision the NG-RAN with indication about the UE authorization status about A2X communication over PC5 reference point.
• Provision the NG-RAN with PC5 QoS parameters related to A2X communication.

In addition to the functionality defined in TS 23.501, the SMF:

• triggers the UUAA-SM procedure for a UE requiring UAV authentication and authorization by a USS when requesting user plane resources for UAV operation, or when the USS/UTM that authenticated the UAV triggers a re-authentication;
• may trigger the authorization of pairing between a UAV and a networked UAVC or a UAVC that connects to the UAV via Internet connectivity during the establishment/modification of the PDN connection/PDU session for C2 communication.

The SMF+PGW-C implements the functions of the SMF described in clause 4.3.5.

In addition to the functions defined in TS 23.501, the PCF includes the functions described in 23.287 [11] to provision the UE and AMF with necessary parameters in order to use A2X communication.

In addition to the functions defined in TS 23.501, the UDM performs subscription management for A2X communication over PC5 reference point.

The A2X Application Server implements a subset of the V2X AS functionality specified in clause 4.4.3 of TS 23.287:

• includes AF functionality, and may support at least the following capabilities:
• For A2X service parameters provisioning, the A2X AS provides the 5GC and the UAV UE (possibly via the UAVC) with parameters for A2X communications over PC5 reference point and parameters for A2X communications over MBS.
• Act as an AF/AS in clause 5.1 and Annex A of TS 23.247 e.g. request NEF/MBSF for allocation/de-allocation of a set of TMGIs, initiate broadcast service from the 5GC by providing service information including QoS requirement to 5GC.
• Perform MBS service area mapping as specified in clause 5.5.2.4.

In addition to the functions defined in TS 23.501, the UDR stores A2X service parameters.

In addition to the functions defined in TS 23.501, the NRF performs PCF discovery by considering A2X capability.