Content for  TS 24.501  Word version:  17.5.0

A 5GS can support time synchronization and TSC (see TS 23.501, TS 23.502, and TS 23.503). The clause describes NAS-specific aspects of the 5GS features to support time synchronization and TSC. Interworking with EPS is not supported for a PDU session for time synchronization or TSC.

Two types of synchronization processes are supported by the 5GS: 5GS synchronization and (g)PTP domain synchronization (see TS 23.501). For 5GS synchronization, the lower layers provide the 5G internal system clock signalled via the NG-RAN (see TS 38.331) and the UE forwards the 5G internal system clock to the DS-TT(s). For (g)PTP domain synchronization, the UE supports forwarding (g)PTP messages (see TS 23.501, TS 23.502, and TS 24.535). For all (g)PTP domains associated with a PDU session:

1. if the UE receives (g)PTP message via the PDU session, the UE forwards the (g)PTP messages to the DS-TT associated with the PDU session; or
2. if the UE receives (g)PTP messages from the DS-TT associated with the PDU session, the UE forwards the (g)PTP messages via the PDU session.

A 5G system (5GS) can act as a user plane node of an external network (e.g. IEEE TSN bridge) or a 5GS can be independently used to enable TSC. For these purposes, information available at a UE is provided to the network and port management information containers are exchanged between a DS-TT and a TSN AF or a TSCTSF (see TS 24.539). During a UE-requested PDU session establishment procedure, if the UE supports transfer of port management information containers, then the UE indicates that transfer of port management information container is supported and the UE provides a DS-TT Ethernet port MAC address (if the PDU session type is Ethernet), port management information container, and a UE-DS-TT residence time (if available) to the network (see subclause 6.4.1.2). Once the UE has successfully established a PDU session and the UE has indicated that transfer of port management information container is supported during the UE-requested PDU session establishment procedure (see subclause 6.4.1.2), then port management information containers are exchanged via a UE-requested PDU session modification procedure and a network-requested PDU session modification procedure (see subclauses 6.3.2 and 6.4.2). The UE receiving a port management information container from the network shall forward the port management information container to the DS-TT. The SMF receiving a port management information container from the UE shall operate as described in TS 23.502.

A 5GS can support UAV identification, authentication, and authorization (see TS 23.256). This subclause describes NAS-specific aspects of the 5GS features to support UAV identification, authentication, and authorization. Before accessing 5GS for UAS services, the UE supporting UAS services must have an assigned CAA-level UAV ID. The UE can be registered to 5GS for UAS services if there is a valid aerial subscription in the UE's subscription.

The 5GS supports the USS UAV Authorization and Authentication (UUAA) procedure for a UE supporting UAS services. Depending on operator policy or regulatory requirements, the UUAA-MM procedure can be performed by the UE and the AMF at a registration procedure as specified in subclause 5.5.1 or the UUAA-SM procedure can be performed by the UE and the SMF at a PDU session establishment procedure as specified in subclause 6.4.1. The UE shall support UUAA-MM and UUAA-SM, and the network shall support UUAA-SM and may optionally support UUAA-MM. The UUAA procedure needs to be performed by 5GS with USS successfully before the connectivity for UAS services is established. During a registration procedure, the UE supporting UAS services provides CAA-level UAV ID to the AMF (see subclause 5.5.1.2), and the AMF may trigger the UUAA-MM procedure. If the UE supporting UAS services does not provide CAA-level UAV ID to the AMF and the network is configured to perform UUAA at registration, the AMF may accept the registration and shall reject PDU session establishment requests for UAS services. If the UE wants to use the UAS services by providing the CAA Level UAV ID later on, then the UE shall first perform UE-initiated de-registration procedure followed by an initial registration to the 5GS including the CAA Level UAV ID in the registration request. When a UE supporting UAS services requests to establish a PDU session for USS communication, the UAV provides CAA-level UAV ID to the network (see subclause 6.4.1.2), and the SMF may trigger the UUAA-SM procedure. If the UE does not provide CAA-Level UAV ID and the SM subscription for the UE requires the UUAA-SM, the network rejects the UE-requested PDU session establishment procedure for UAS services. The UE supporting UAS services shall not provide CAA-level UAV ID to the network over non-3gpp access, and the network shall not perform UUAA procedure for non-3gpp access and shall ensure that the UE is not allowed to access any aerial services in non-3GPP access. A UE supporting UAS services may provide to the network the USS address or USS FQDN during the registration procedure or PDU session establishment procedure so that the network may use the information to discover the USS. After successful UUAA procedure, either the AMF or the SMF may initiate re-authentication of the UAV when required by the USS. If UUAA-MM fails during a re-authentication and there are PDU sessions established using UAS services, AMF shall release these PDU sessions and may trigger a network-initiated de-registration procedure based on network policy. If UUAA-SM fails during a re-authentication, the SMF shall release the PDU session related to re-authentication. If the UUAA is revoked, the PDU session related to UAS services shall be released by the SMF. Based on operator policy, the AMF may decide to keep the UE registered or trigger a de-registration procedure.

The 5GS supports USS authorization of C2 communication for pairing of UAV and UAV-C. The pairing of UAV and UAV-C needs to be authorized by USS successfully before the user plane connectivity for C2 communication is enabled. The UE supporting UAS services may provide the SMF with an identification information of UAV-C to pair with, if available. If a UE supporting UAS services uses a common PDU session for both USS communication and C2 communication with a UAV-C, the C2 comunication with the UAV-C can be authorized using UUAA-SM procedure during the PDU session establishment procedure or during the PDU session modification procedure. If the pairing of UAV and UAV-C is revoked, the network shall disable C2 communication for the PDU session. If a UE supporting UAS services uses separate PDU sessions for, respectively, USS communication and C2 communication with a UAV-C, the C2 communication with the UAV-C is authorized using UUAA-SM during the PDU session establishment procedure. If the pairing of UAV and UAV-C is revoked, the PDU session for C2 communication shall be released by the SMF.

The 5GS supports USS authorization of UAV flight. The authorization of UAV flight for the UE supporting UAS services can be performed using UUAA-SM procedure during the PDU session establishment procedure or during PDU session modification procedure. The UE may provide flight authorization information to the SMF if the authorization information is already available in the UAV.

Void

For 3GPP satellite NG-RAN the UE shall store a list of "PLMNs not allowed to operate at the present UE location". Each entry consists of:

1. the PLMN identity of the PLMN which sent a message including 5GMM cause value #78 "PLMN not allowed to operate at the present UE location" via satellite NG-RAN access technology;
2. the geographical location, if known by the UE, where 5GMM cause value #78 was received on satellite NG-RAN access technology; and
3. a UE implementation specific timer value which shall not be set to a value smaller than the value indicated by the network, if any.

Before storing a new entry in the list, the UE shall delete any existing entry with the same PLMN identity. The UE shall not attempt to access a PLMN via satellite NG-RAN access technology which is part of the list of "PLMNs not allowed to operate at the present UE location" if:

1. the current UE location is known, a geographical location is stored for the entry of this PLMN, and the distance to the current UE location is smaller than a UE implementation specific value. This UE implementation specific value shall not be set to a value smaller than the value indicated by the network, if any; or
2. the timer associated with the entry of this PLMN is running.

The list shall accommodate three or more entries. When the list is full and a new entry has to be inserted, the oldest entry shall be deleted. Each entry shall be removed if for the entry:

1. the UE successfully registers to the PLMN stored in the entry; or
2. the timer instance associated with the entry expires.

When the UE is switched off, the UE shall keep the list of "PLMNs not allowed to operate at the present UE location" in its non-volatile memory. The UE shall delete the list of "PLMNs not allowed to operate at the present UE location" if the USIM is removed.