3GPP 24.501 v20.0.0 — the document's own text

5.1.3.2.1 5GMM sublayer states in the UE

Taught in 5. Finding your way around TS 24.501 (CT1 — the group that writes what your phone says, in depth), 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).

5.1.3.2.1.1 General

In the following clauses, the possible 5GMM sublayer states of the UE are described and shown in figure 5.1.3.2.1.1.1.

Figure 5.1.3.2.1.1.1: 5GMM main states in the UE

NOTE: Not all possible transitions are shown in this figure.

5.1.3.2.1.2 Main states

5.1.3.2.1.2.1 5GMM-NULL

5GS services are disabled in the UE. No 5GS mobility management function shall be performed in this state.

5.1.3.2.1.2.2 5GMM-DEREGISTERED

In the state 5GMM-DEREGISTERED, no 5GMM context has been established and the UE location is unknown to the network and hence it is unreachable by a network. In order to establish a 5GMM context, the UE shall start the initial registration procedure.

5.1.3.2.1.2.3 5GMM-REGISTERED-INITIATED

A UE enters the state 5GMM-REGISTERED-INITIATED after it has started the initial registration procedure or the registration procedure for mobility and periodic registration update, and is waiting for a response from the network.

5.1.3.2.1.2.4 5GMM-REGISTERED

In the state 5GMM-REGISTERED, a 5GMM context has been established. Additionally, one or more PDU session(s) may be established at the UE. The UE may initiate the non-initial registration procedure for mobility and periodic registration update and the service request procedure. The UE in the state 5GMM-REGISTERED over non-3GPP access shall not initiate the periodic registration update procedure.

5.1.3.2.1.2.5 5GMM-DEREGISTERED-INITIATED

A UE enters the state 5GMM-DEREGISTERED-INITIATED after it has requested release of the 5GMM context by starting the de-registration procedure and is waiting for a response from the network.

5.1.3.2.1.2.6 5GMM-SERVICE-REQUEST-INITIATED

A UE enters the state 5GMM-SERVICE-REQUEST-INITIATED after it has started the service request procedure and is waiting for a response from the network.

5.1.3.2.1.3 Substates of state 5GMM-DEREGISTERED

5.1.3.2.1.3.1 General

The state 5GMM-DEREGISTERED is subdivided into a number of substates as described in this clause. The following substates are not applicable to non-3GPP access:

5GMM-DEREGISTERED.PLMN-SEARCH:
5GMM-DEREGISTERED.NO-CELL-AVAILABLE; and
5GMM-DEREGISTERED.eCALL-INACTIVE.

Valid subscriber data are available for the UE before it enters the substates, except for the substate 5GMM-DEREGISTERED.NO-SUPI.

5.1.3.2.1.3.2 5GMM-DEREGISTERED.NORMAL-SERVICE

The substate 5GMM-DEREGISTERED.NORMAL-SERVICE is chosen in the UE when a suitable cell has been found and the PLMN, SNPN, or tracking area is not in the forbidden list.

5.1.3.2.1.3.3 5GMM-DEREGISTERED.LIMITED-SERVICE

The substate 5GMM-DEREGISTERED.LIMITED-SERVICE is chosen in the UE, when it is known that a selected cell for 3GPP access or TA for non-3GPP access is unable to provide normal service (e.g. the selected cell over 3GPP access is in a forbidden PLMN or SNPN or is in a forbidden tracking area or TA for non-3GPP access is forbidden) or the selected cell is a CAG cell for which none of CAG-ID(s) is authorized based on the "Allowed CAG list" in the entry of the "CAG information list" for the PLMN, or the selected cell is a non-CAG cell in a PLMN for which there exists an "indication that the UE is only allowed to access 5GS via CAG cells" in the entry of the "CAG information list" for the PLMN, or the selected cell is a CAG cell belonging to a PLMN and the "CAG information list" does not contain an entry for the PLMN.

5.1.3.2.1.3.4 5GMM-DEREGISTERED.ATTEMPTING-REGISTRATION

The substate 5GMM-DEREGISTERED.ATTEMPTING-REGISTRATION is chosen in the UE if the initial registration procedure failed due to a missing response from the network or due to the circumstances described in clauses 5.2.2.3.7, 5.5.1.2.4, 5.5.1.2.5, 5.5.1.2.7, 5.5.1.3.4, 5.5.2.3.2 and 5.5.2.3.4.

5.1.3.2.1.3.5 5GMM-DEREGISTERED.PLMN-SEARCH

The substate 5GMM-DEREGISTERED.PLMN-SEARCH is chosen in the UE, if the UE is searching for PLMNs or SNPNs. This substate is left either when a cell has been selected (the new substate is NORMAL-SERVICE or LIMITED-SERVICE) or when it has been concluded that no cell is available at the moment (the new substate is NO-CELL-AVAILABLE).

This substate is not applicable to non-3GPP access.

5.1.3.2.1.3.6 5GMM-DEREGISTERED.NO-SUPI

The substate 5GMM-DEREGISTERED.NO-SUPI is chosen in the UE, if the N1 mode is enabled and the UE has no valid subscriber data available (USIM not available, the USIM is considered invalid by the UE or an entry of the "list of subscriber data" with the SNPN identity of the SNPN is considered invalid by the UE).

5.1.3.2.1.3.7 5GMM-DEREGISTERED.NO-CELL-AVAILABLE

No 5G cell can be selected. This substate is entered either after a first intensive search failed when in substate 5GMM-DEREGISTERED.PLMN-SEARCH or unavailability period is activated for 3GPP access. Cells are searched for at a low rhythm. No 5GS services are offered.

This substate is not applicable to non-3GPP access.

5.1.3.2.1.3.8 5GMM-DEREGISTERED.eCALL-INACTIVE

The substate 5GMM-DEREGISTERED.eCALL-INACTIVE is chosen in the UE when:

the UE is configured for eCall only mode as specified in 3GPP TS 31.102 [22];
timer T3444 and timer T3445 have expired or are not running;
a PLMN has been selected as specified in 3GPP TS 23.122 [5];
the UE does not need to perform an eCall over IMS; and
the UE does not need to perform a call to a non-emergency MSISDN or URI for test or terminal reconfiguration service.

In this substate, the UE shall not initiate any signalling towards the network, except to originate an eCall over IMS, or a call to a non-emergency MSISDN or URI for test or terminal reconfiguration service.

This substate is not applicable to non-3GPP access.

5.1.3.2.1.3.9 5GMM-DEREGISTERED.INITIAL-REGISTRATION-NEEDED

Valid subscriber data are available for the UE and for some reason a registration procedure for initial registration has to be performed as soon as possible. This substate can be entered if the access is barred due to unified access control, (see clause 4.5.4) or if the network rejects the N1 NAS signalling connection establishment.

5.1.3.2.1.4 Substates of state 5GMM-REGISTERED

5.1.3.2.1.4.1 General

The state 5GMM-REGISTERED is subdivided into a number of substates as described in this clause. The following substates are not applicable to non-3GPP access:

5GMM-REGISTERED.PLMN-SEARCH:
5GMM-REGISTERED.NON-ALLOWED-SERVICE; and
5GMM-REGISTERED.NO-CELL-AVAILABLE.

5.1.3.2.1.4.2 5GMM-REGISTERED.NORMAL-SERVICE

The substate 5GMM-REGISTERED.NORMAL-SERVICE is chosen by the UE as the primary substate when the UE enters the state 5GMM-REGISTERED, and:

for 3GPP access, the cell the UE selected is known to be in an allowed area (see clause 5.3.5.2); or
for wireline access, the wireline access service area restrictions are not enforced.

5.1.3.2.1.4.3 5GMM-REGISTERED.NON-ALLOWED-SERVICE

The substate 5GMM-REGISTERED.NON-ALLOWED-SERVICE is chosen in the UE, if:

for 3GPP access, the cell the UE selected is known to be in a non-allowed area (see clause 5.3.5.2); or
for wireline access, the wireline access service area restrictions are enforced.

This substate is applicable only to 3GPP access and to wireline access.

5.1.3.2.1.4.4 5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE

The substate 5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE is chosen by the UE if the registration procedure for mobility and periodic registration update failed due to a missing response from the network, or due to the circumstances described in clauses 5.3.9, 5.5.1.3.5 and 5.5.1.3.7. No 5GMM procedure except registration procedure for mobility and periodic registration update (i.e. the 5GS registration type IE set to "mobility registration updating" or "periodic registration updating" in the REGISTRATION REQUEST message) and de-registration procedure, shall be initiated by the UE in this substate. No data shall be sent or received.

NOTE 1: The registration procedure for mobility and periodic registration update over non-3GPP access can be triggered by, e.g. the change of S1 UE network capability or renegotiating some parameters.

NOTE 2: This substate is entered irrespective whether:

the UE is camped on a cell which is in the registration area, and the current TAI is not in the list of "allowed tracking areas"; or
the current TAI is in the list of "non-allowed tracking areas".

5.1.3.2.1.4.5 5GMM-REGISTERED.LIMITED-SERVICE

The substate 5GMM-REGISTERED.LIMITED-SERVICE is chosen in the UE, if the cell the UE selected is known not to be able to provide normal service.

NOTE: When the UE is registered to the network via CAG cell and none of the CAG-ID(s) supported by the current CAG cell is authorized based on the "Allowed CAG list" of the entry for the registered PLMN in the received "CAG information list", then the cell the UE selected is not able to provide normal service.

5.1.3.2.1.4.6 5GMM-REGISTERED.PLMN-SEARCH

The substate 5GMM-REGISTERED.PLMN-SEARCH is chosen in the UE, while the UE is searching for PLMNs or SNPNs.

This substate is not applicable to non-3GPP access.

5.1.3.2.1.4.7 5GMM-REGISTERED.NO-CELL-AVAILABLE

5G coverage has been lost, MICO mode is active in the UE or unavailability period is activated for 3GPP access. If MICO mode is active, the UE can deactivate MICO mode at any time by activating the AS layer when the UE needs to send mobile originated signalling or user data. Otherwise, the UE shall not initiate any 5GMM procedure except for cell and PLMN reselection.

This substate is not applicable to non-3GPP access.

5.1.3.2.1.4.8 5GMM-REGISTERED.UPDATE-NEEDED

This state can be entered if the UE has to perform a registration procedure for mobility and periodic registration update but:

the access is barred due to unified access control when in 3GPP access;
the network rejects the N1 NAS signalling connection establishment when in 3GPP access or in non-3GPP access; or
the UE in 5GMM-CONNECTED mode with RRC inactive indication receives an indication from the lower layers that the resumption of the RRC connection has failed and for access is barred for all categories except categories '0' and '2' as specified in clause 5.3.1.4.

No 5GMM procedure except:

registration procedure for mobility and periodic registration update;
service request procedure as a response to paging or notification; and
de-registration procedure

shall be initiated by the UE in this substate.

NOTE: This substate is entered irrespective whether:

the UE is camped on a cell which is in the registration area, and the current TAI is not in the list of "allowed tracking areas"; or
the current TAI is in the list of "non-allowed tracking areas".