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Content for  TS 24.501  Word version:  17.7.1

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4.15  Time synchronization and time sensitive communication |R16|Word‑p. 122

4.15.1  GeneralWord‑p. 122

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.

4.15.2Void

4.15.3  Time synchronization |R17|Word‑p. 122

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.
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4.15.4  User plane node management |R17|Word‑p. 122

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.
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4.16  UE radio capability signalling optimisation |R16|Word‑p. 123

UE radio capability signalling optimisation (RACS) is a feature that is optional at both the UE and the network and which aims to optimise the transmission of UE radio capability over the radio interface (see TS 23.501). RACS works by assigning an identifier to represent a set of UE radio capabilities. This identifier is called the UE radio capability ID. A UE radio capability ID can be either manufacturer-assigned or network-assigned. The UE radio capability ID is an alternative to the signalling of the radio capabilities container over the radio interface.
In this release of the specification, RACS is applicable to neither NB-N1 mode nor non-3GPP access.
If the UE supports RACS:
  1. the UE shall indicate support for RACS by setting the RACS bit to "RACS supported" in the 5GMM capability IE of the REGISTRATION REQUEST message;
  2. if the UE performs a registration procedure for initial registration and the UE has an applicable UE radio capability ID for the current UE radio configuration in the selected network, the UE shall include the UE radio capability ID in the UE radio capability ID IE as a non-cleartext IE in the REGISTRATION REQUEST message. If both a network-assigned UE radio capability ID and a manufacturer-assigned UE Radio Capability ID are applicable, the UE shall include the network-assigned UE radio capability ID in the REGISTRATION REQUEST message;
  3. if the radio configuration at the UE changes (for instance because the UE has disabled a specific radio capability) then:
    1. if the UE has an applicable UE radio capability ID for the new UE radio configuration, the UE shall initiate a registration procedure for mobility and periodic registration update. The UE shall include the applicable UE radio capability ID in the UE radio capability ID IE of the REGISTRATION REQUEST message and shall include the 5GS update type IE in the REGISTRATION REQUEST message with the NG-RAN-RCU bit set to "UE radio capability update needed". If both a network-assigned UE radio capability ID and a manufacturer-assigned UE Radio Capability ID are applicable, the UE shall include the network-assigned UE radio capability ID in the REGISTRATION REQUEST message; and
    2. if the UE does not have an applicable UE radio capability ID for the new UE radio configuration, the UE shall initiate a registration procedure for mobility and periodic registration update and include the 5GS update type IE in the REGISTRATION REQUEST message with the NG-RAN-RCU bit set to "UE radio capability update needed";
  4. upon receiving a network-assigned UE radio capability ID in the REGISTRATION ACCEPT message or the CONFIGURATION UPDATE COMMAND message, the UE shall store the network-assigned UE radio capability ID and the PLMN ID or SNPN identity of the serving network and, if the UE supports access to an SNPN using credentials from a credentials holder, the selected entry of the "list of subscriber data" or the selected PLMN subscription along with a mapping to the current UE radio configuration in its non-volatile memory as specified in Annex C. The UE shall be able to store at least the last 16 received network-assigned UE radio capability IDs with the associated PLMN ID or SNPN identity and, if the UE supports access to an SNPN using credentials from a credentials holder, the selected entry of the "list of subscriber data" or the selected PLMN subscription and the mapping to the corresponding UE radio configuration;
  5. the UE shall not use a network-assigned UE radio capability ID assigned by a PLMN in PLMNs equivalent to the PLMN which assigned it;
  6. upon receiving a UE radio capability ID deletion indication IE set to "Network-assigned UE radio capability IDs deletion requested" in the REGISTRATION ACCEPT message or the CONFIGURATION UPDATE COMMAND message, the UE shall delete all network-assigned UE radio capability IDs stored at the UE for the serving network, initiate a registration procedure for mobility and periodic registration update and include an applicable manufacturer-assigned UE radio capability ID for the current UE radio configuration, if available at the UE, in the UE radio capability ID IE of the REGISTRATION REQUEST message; and
  7. if the UE performs a registration procedure for mobility and periodic registration update due to entering a tracking area that is not in the list of tracking areas that the UE previously registered in the AMF and the UE has an applicable UE radio capability ID for the current UE radio configuration in the selected network, the UE shall include the UE radio capability ID in the UE radio capability ID IE as a non-cleartext IE in the REGISTRATION REQUEST message. If both a network-assigned UE radio capability ID and a manufacturer-assigned UE Radio Capability ID are applicable, the UE shall include the network-assigned UE radio capability ID in the REGISTRATION REQUEST message.
If the network supports RACS:
  1. the network may assign a network-assigned UE radio capability ID to a UE which supports RACS by including a UE radio capability ID IE in the REGISTRATION ACCEPT message or in the CONFIGURATION UPDATE COMMAND message;
  2. the network may trigger the UE to delete all network-assigned UE radio capability IDs stored at the UE for the serving network by including a UE radio capability ID deletion indication IE set to "Network-assigned UE radio capability IDs deletion requested" in the REGISTRATION ACCEPT message or in the CONFIGURATION UPDATE COMMAND message; and
  3. the network may send an IDENTITY REQUEST message to the UE that supports RACS to retrieve the PEI, if not available in the network.
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4.17  5GS mobility management in NB-N1 mode |R16|Word‑p. 124

A UE in NB-N1 mode (see TS 36.331) shall calculate the value of the applicable NAS timer indicated in Table 10.2.1 plus 240s.
The timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure and shall not re-calculate the use of the NAS timer value until the NAS procedure is completed, restarted or aborted.
When an AMF that supports NB-N1 mode performs NAS signalling with a UE, which is using NB-N1 mode, the AMF shall calculate the value of the applicable NAS timer indicated in Table 10.2.2 plus 240s.
The timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure and shall not re-calculate the use of the NAS timer value until the NAS procedure is completed, restarted or aborted.
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4.18  5GS session management in NB-N1 mode |R16|Word‑p. 124

A UE in NB-N1 mode (see TS 36.331) shall calculate the value of the applicable NAS timer indicated in Table 10.3.1 plus 180s.
The timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure and shall not re-calculate the use of the NAS timer value until the NAS procedure is completed, restarted or aborted.
When an SMF that supports NB-N1 mode performs NAS signalling with a UE, which is using NB-N1 mode, the SMF shall calculate the value of the applicable NAS timer indicated in Table 10.3.2 plus 180s.
The timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure and shall not re-calculate the use of the NAS timer value until the NAS procedure is completed, restarted or aborted.
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4.19  5GS mobility management in WB-N1 mode for IoT |R16|Word‑p. 124

In WB-N1 mode, a UE operating in category CE can operate in either CE mode A or CE mode B (see TS 36.306). If a UE that supports CE mode B and operates in WB-N1 mode, the UE's usage setting is not set to "voice centric" (see TS 23.501), and:
  1. the use of enhanced coverage is not restricted by the network; or
  2. CE mode B is not restricted by the network (see TS 23.501);
the UE shall apply the value of the applicable NAS timer indicated in Table 10.2.1 for WB-N1/CE mode.
A UE that supports CE mode B and operates in WB-N1 mode shall not apply the value of the applicable NAS timer indicated in Table 10.2.1 for WB-N1/CE mode before receiving an indication from the network that the use of enhanced coverage is not restricted, or CE mode B is not restricted, as described in this subclause.
The NAS timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure, and shall not be re-calculated until the NAS procedure is completed, restarted or aborted.
The support of CE mode B by a UE is indicated to the AMF by lower layers and shall be stored by the AMF. When an AMF that supports WB-N1 mode performs NAS signalling with a UE, which supports CE mode B and operates in WB-N1 mode, the UE's usage setting is not set to "voice centric" (see TS 23.501) and the AMF determines that:
  1. the use of enhanced coverage is not restricted for the UE; or
  2. CE mode B is not restricted for the UE (see TS 23.501);
the AMF shall calculate the value of the applicable NAS timer indicated in Table 10.2.2 for WB-N1/CE mode.
The NAS timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure and shall not be re-calculated until the NAS procedure is completed, restarted or aborted.
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4.20  5GS session management in WB-N1 mode for IoT |R16|Word‑p. 125

In WB-N1 mode, a UE operating in category CE can operate in either CE mode A or CE mode B (see TS 36.306). If a UE that supports CE mode B and operates in WB-N1 mode and the UE's usage setting is not set to "voice centric" (see TS 23.501), and:
  1. the use of enhanced coverage is not restricted by the network; or
  2. CE mode B is not restricted by the network (see TS 23.501);
the UE shall apply the value of the applicable NAS timer indicated in Table 10.3.1 for WB-N1/CE mode.
A UE that supports CE mode B and operates in WB-N1 mode shall not apply the value of the applicable NAS timer indicated in Table 10.3.1 for WB-N1/CE mode before receiving an indication from the network that the use of enhanced coverage is not restricted, or CE mode B is not restricted, as described in this subclause.
The NAS timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure, and shall not be re-calculated until the NAS procedure is completed, restarted or aborted.
If the use of extended NAS timer is indicated by the AMF (see TS 23.501 and TS 23.502), the SMF shall calculate the value of the applicable NAS timer indicated in Table 10.3.2 for WB-N1/CE mode.
The NAS timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure and shall not be re-calculated until the NAS procedure is completed, restarted or aborted.
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4.21  Authentication and Key Management for Applications (AKMA) |R17|Word‑p. 125

The UE may support AKMA.
The purpose of AKMA is to provide authentication and key management to applications based on 3GPP credentials used for 5GS access as specified in TS 33.535, which allows the UE to securely exchange data with an AKMA application function.
Upon receiving a request from the upper layers to obtain AKMA Anchor Key (KAKMA) and AKMA Key Identifier (A-KID), the UE supporting AKMA shall derive the KAKMA and the AKMA Temporary Identifier (A-TID) from the valid KAUSF if available as specified in TS 33.535, shall further derive the A-KID from the A-TID as specified in TS 33.535 and shall provide KAKMA and A-KID to the upper layers.
The UE supporting AKMA shall notify the upper layers whenever there is a change of the KAUSF upon reception of an EAP-success message in subclauses 5.4.1.2.2.8, 5.4.1.2.3.1 and 5.4.1.2.3A.1 or upon reception of SECURITY MODE COMMAND message in subclauses 5.4.2.3.
During an ongoing primary authentication and key agreement procedure (see subclause 5.4.1), if the UE receives a request from upper layers to obtain KAKMA and A-KID, the UE shall derive the KAKMA and A-TID after the completion of the ongoing primary authentication and key agreement procedure, shall further derive the A-KID from the A-TID as specified in TS 33.535 and shall provide KAKMA and A-KID to the upper layers.
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4.22  Uncrewed aerial vehicle identification, authentication, and authorization |R17|Word‑p. 126

4.22.1  GeneralWord‑p. 126

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, authorization and C2 communication 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.
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4.22.2  Authentication and authorization of UAVWord‑p. 126

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 5.5.1.2 or the UUAA-SM procedure can be performed by the UE and the SMF at a PDU session establishment procedure as specified in subclause 6.4.1.2. 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 the registration procedure as described in subclause 5.5.1.2, the UE supporting UAS services provides CAA-level UAV ID to the AMF, 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-MM at registration procedure, the AMF may accept the registration request and shall mark in the UE's 5GMM context that the UE is not allowed to request UAS services. If the UE wants to use the UAS services by providing the CAA-Level UAV ID later on, the UE shall perform the registration procedure for mobility and periodic registration update.
When a UE supporting UAS services requests to establish a PDU session as described in subclause 6.4.1.2 for USS communication, the UE provides CAA-level UAV ID to the network, and the SMF may trigger the UUAA-SM procedure. If the UE does not provide CAA-level UAV ID and the SM subscription data for the UE requires the UUAA-SM, the network rejects the UE-requested PDU session establishment procedure for the 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.
If provided by the upper layers, the UE supporting UAS services provides to the network the USS address during the registration procedure or PDU session establishment procedure so that the network uses 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, the AMF shall request the SMF to perform the release of these PDU sessions and may trigger a network-initiated de-registration procedure based on operator 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 the 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.
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4.22.3  Authorization of C2 communicationWord‑p. 127

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. For C2 authorization procedure, the UE supporting UAS services provides to the network with CAA-level UAV ID and if provided by upper layers, an application layer payload containing information for UAV-C pairing and information for UAV flight authorization.
If a UE supporting UAS services uses a common PDU session for both USS communication and C2 communication, the C2 comunication 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, the C2 communication 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.
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4.22.4  Authorization of UAV flightWord‑p. 127

The 5GS supports USS authorization of UAV flight.

4.23  NAS over Non-Terrestrial Network |R17|Word‑p. 127

4.23.1  GeneralWord‑p. 127

A 5GS can support 3GPP satellite NG-RAN access technology (see TS 23.501). This clause describes NAS-specific aspects of the 5GS features to support 3GPP satellite NG-RAN access technology.

4.23.2  List of "PLMNs not allowed to operate at the present UE location"Word‑p. 128

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; and
  2. the geographical location, if known by the UE, where 5GMM cause value #78 was received on satellite NG-RAN access technology; and
  3. if the geographical location exists, a UE implementation specific distance value.
Before storing a new entry in the list, the UE shall delete any existing entry with the same PLMN identity. Upon storing a new entry, the UE starts a timer instance associated with the entry with an implementation specific value that shall not be set to a value smaller than the timer value indicated by the network in the Lower bound timer value IE, if any. If the Lower bound timer value IE was not provided by the network, the value of the timer shall be set based on the UE implementation.
The UE is allowed to 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" only 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 larger than a UE implementation specific value.
  2. the timer associated with the entry of this PLMN has expired; or
  3. the access is for emergency services (see TS 23.122 for further details).
The list shall accommodate three or more entries. The maximum number of entries is an implementation decision. 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 via satellite NG-RAN access technology to the PLMN stored in the entry; or
  2. the timer instance associated with the entry expires.
The UE may delete the entry in the list, if 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 larger than a UE implementation specific value.
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.
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4.23.3  5GS mobility management via a satellite NG-RAN cellWord‑p. 128

For 5GS mobility management via a satellite NG-RAN cell the UE shall apply the value of the applicable NAS timer indicated in Table 10.2.1 for access via a satellite NG-RAN cell.
The NAS timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure, and shall not be re-calculated until the NAS procedure is completed, restarted or aborted.
The access via a satellite NG-RAN cell by a UE is indicated to the AMF by lower layers and shall be stored by the AMF. When an AMF that supports access via satellite NG-RAN cells performs NAS signalling with a UE via satellite NG-RAN cells, the AMF shall calculate the value of the applicable NAS timer indicated in Table 10.2.2 for access via a satellite NG-RAN cell.
The NAS timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure and shall not be re-calculated until the NAS procedure is completed, restarted or aborted.
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4.23.4  5GS session management via a satellite NG-RAN cellWord‑p. 129

For 5GS session management via a satellite NG-RAN cell the UE shall apply the value of the applicable NAS timer indicated in Table 10.2.1 for access via a satellite NG-RAN cell.
The NAS timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure, and shall not be re-calculated until the NAS procedure is completed, restarted or aborted.
If the use of extended NAS timer for access via a satellite NG-RAN cell is indicated by the AMF (see TS 23.501 and TS 23.502), the SMF shall calculate the value of the applicable NAS timer indicated in Table 10.3.2 for access via a satellite NG-RAN cell.
The NAS timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure and shall not be re-calculated until the NAS procedure is completed, restarted or aborted.
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4.23.5  Handling multiple tracking area codes from the lower layersWord‑p. 129

When a UE camps on a satellite NG-RAN cell, the UE may receive multiple TACs from the lower layers. The UE shall construct TAIs from the multiple TACs (i.e. concatenate the identity of the current PLMN and each of the TACs) and select a TAI as follows:
  1. if at least one TAI belongs to the current registration area of the UE, the UE shall select a TAI which belongs to the current registration area of the UE according to the followings.
    If there are multiple TAIs which belong to the current registration area of the UE, the UE shall select a TAI as follows:
    1. if there is a TAI which belongs to the list of "allowed tracking area" (if any) and does not belong to the list of "non-allowed tracking areas" (if any), the UE shall select a TAI which belongs to the list of "allowed tracking area" (if any) and does not belong to the list of "non-allowed tracking areas" (if any). In this case, if there are multiple TAIs which belong to the list of "allowed tracking area" (if any) and does not belong to the list of "non-allowed tracking areas" (if any), then the UE shall consider each of these TAIs equal and select a TAI in an implementation-specific way (e.g. taking into account LADN service area information).
    2. if there is no TAI which belongs to the list of "allowed tracking area" (if any) and does not belong to the list of "non-allowed tracking areas" (if any) or neither the list of "allowed tracking area" nor the list of "non-allowed tracking areas" is available, then the UE shall consider each of these TAIs equal and select a TAI in an implementation-specific way (e.g. taking into account LADN service area information).
  2. if no TAI belongs to the current registration area of the UE and:
    1. there is a TAI which belongs to neither the list of "5GS forbidden tracking areas for roaming" nor the list of "5GS forbidden tracking areas for regional provision of service", the UE shall select a TAI which belongs to neither the list of "5GS forbidden tracking areas for roaming" nor the list of "5GS forbidden tracking areas for regional provision of service". In this case, if there are multiple TAIs which belong to neither the list of "5GS forbidden tracking areas for roaming" nor the list of "5GS forbidden tracking areas for regional provision of service", then the UE shall select a TAI according to a)-1) and a)-2) above.
    2. all TAIs belong to the list of "5GS forbidden tracking areas for roaming" or the list of "5GS forbidden tracking areas for regional provision of service", then the UE shall consider each of these TAIs equal and select a TAI in an implementation-specific way.
The UE shall consider the selected TAI as the current TAI. The UE shall select a TAI when:
  1. the UE receives multiple TACs from the lower layers; or
  2. the UE has received multiple TACs from the lower layers upon starting to camping on the current cell and the registration area, the list of "allowed tracking areas", the list of "non-allowed tracking areas", the list of "5GS forbidden tracking areas for roaming", or the list of "5GS forbidden tracking areas for regional provision of service" is updated.
Handling of the list of "5GS forbidden tracking areas for roaming" and the list of "5GS forbidden tracking areas for regional provision of service" is specified in clause 5.3.13.
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4.24  Minimization of service interruption |R17|Word‑p. 130

The UE and the network may support Minimization of service interruption (MINT). MINT aims to enable a UE to obtain service from a PLMN offering disaster roaming service when a disaster condition applies to the UE's determined PLMN with disaster condition.
If the UE supports MINT, the indication of whether disaster roaming is enabled in the UE, the indication of 'applicability of "lists of PLMN(s) to be used in disaster condition" provided by a VPLMN', the one or more "list of PLMN(s) to be used in disaster condition", disaster roaming wait range and disaster return wait range provisioned by the network, if available, are stored in the non-volatile memory in the ME as specified in Annex C and are kept when the UE enters 5GMM-DEREGISTERED state. Annex C specifies condition under which the indication of whether disaster roaming is enabled in the UE, the indication of 'applicability of "lists of PLMN(s) to be used in disaster condition" provided by a VPLMN', the one or more "lists of PLMN(s) to be used in disaster condition", disaster roaming wait range and disaster return wait range stored in the ME are deleted.
Upon selecting a PLMN for disaster roaming as specified in TS 23.122:
  1. if the UE does not have a stored disaster roaming wait range, the UE shall perform a registration procedure for disaster roaming services on the selected PLMN as described in clause 5.5.1; and
  2. if the UE has a stored disaster roaming wait range, the UE shall generate a random number within the disaster roaming wait range and start a timer with the generated random number. While the timer is running, the UE shall not initiate registration on the selected PLMN except if the UE needs to request an emergency PDU session, in which case the UE shall initiate the registration procedure, set the 5GS registration type IE to "emergency registration" in the REGISTRATION REQUEST message and keep the timer running. Upon expiration of the timer, if the UE does not have an emergency PDU session, the UE shall perform a registration procedure for disaster roaming services as described in clause 5.5.1 if still camped on the selected PLMN. If the UE has an emergency PDU session when the timer expires, the registration procedure for disaster roaming services as described in clause 5.5.1 shall be performed after the release of the emergency PDU session, if the UE is still camped on the selected PLMN.
The timer started with a generated random number within the disaster roaming wait range is stopped and the UE shall perform a PLMN selection as described in TS 23.122, if:
  1. the UE has successfully registered over non-3GPP access on another PLMN;
  2. the UE has successfully registered with an allowable PLMN; or
  3. an NG-RAN cell selected for camping of the selected PLMN broadcasts neither the disaster related indication nor a "list of one or more PLMN(s) with disaster condition for which disaster roaming is offered by the available PLMN" including the determined PLMN with Disaster Condition (see TS 23.122).
Upon determining that a disaster condition has ended and that the UE shall perform PLMN selection as specified in TS 23.122:
  1. if the UE does not have a stored disaster return wait range, the UE shall perform a registration procedure on the selected PLMN; and
  2. if the UE has a stored disaster return wait range, the UE shall generate a random number within the disaster return wait range and start a timer with the generated random number value. While the timer is running, the UE shall not initiate registration on the selected PLMN. Upon expiration of the timer, the UE shall perform a registration procedure if still camped on the selected PLMN.
When the AMF assigns a registration area to the UE registered for disaster roaming services, the AMF shall only include TAIs covering the area with the disaster condition.
When the AMF determines that the disaster condition has ended and the UE which is registered for disaster roaming services has an emergency PDU session, the AMF shall initiate the generic UE configuration update procedure to indicate that the UE is registered for emergency services as described in subclause 5.4.4.2.
Interworking with EPS is not supported for UEs that are registered for disaster roaming services. When registering for disaster roaming services, the UE indicates to the network that S1 mode is not supported as described in subclause 5.5.1.2.2. While registered for disaster roaming service and upon a need to establish an emergency PDU session or perform emergency services fallback, the UE initiates the registration procedure for mobility and periodic registration update and indicates that S1 mode is supported as described in subclause 5.5.1.3.2.
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4.25  Support of MUSIM features |R17|Word‑p. 131

A network and a MUSIM UE may support one or more of the MUSIM features (i.e. the N1 NAS signalling connection release, the paging indication for voice services, the reject paging request, the paging restriction and the paging timing collision control).
If MUSIM UE supports one or more MUSIM features, the UE indicates support of one or more MUSIM features (except for the paging timing collision control) during the registration procedure. If the UE has indicated support of the N1 NAS signalling connection release or the reject paging request or both and the UE supports the paging restriction, the UE indicates support of the paging restriction.
If the UE indicates support of one or more MUSIM features and the network decides to accept one or more MUSIM features, the network indicates the support of one or more MUSIM features during the registration procedure. The network only indicates the support of the paging restriction together with the support of either N1 NAS signalling connection release or the reject paging request.
The network does not indicate support for any MUSIM feature to the UE during the registration for emergency services.
If a UE stops fulfilling the condition to be considered a MUSIM UE as defined in subclause 3.1, and the UE has negotiated support of one or more MUSIM features, then the UE shall initiate a registration procedure for mobility and periodic registration update to indicate that all the MUSIM features are not supported (except for the paging timing collision control) as specified in subclause 5.5.1.3.
A MUSIM UE operating in NB-N1 mode or in WB-N1 mode CE mode B does not indicate the support for paging indication for voice services during the registration procedure towards the network.
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