5 Process and procedure descriptions

38.3043GPPNRRelease 17TSUser Equipment (UE) procedures in idle mode and in RRC Inactive state

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

5.1 PLMN selection and SNPN selection

In the UE not operating in SNPN access mode, the AS shall report available PLMNs and any associated CAG-IDs to the NAS on request from the NAS or autonomously. In the UE operating in SNPN access mode, the AS shall report available SNPNs to the NAS on request from the NAS or autonomously.

During PLMN selection, based on the list of PLMN identities in priority order, the particular PLMN may be selected either automatically or manually. Each PLMN in the list of PLMN identities is identified by a ‘PLMN identity’. In the system information on the broadcast channel, the UE can receive one or multiple ‘PLMN identity’ in a given cell. The result of the PLMN selection performed by NAS (see TS 23.122 [9]) is an identifier of the selected PLMN.

During SNPN selection, based on the list of SNPN identities, the particular SNPN may be selected either automatically or manually. Each SNPN in the list of SNPN identities is identified by a ‘SNPN identity’. In the system information on the broadcast channel, the UE can receive one or multiple ‘SNPN identity’ in a given cell and optionally may receive associated HRNNs; the UE may also optionally receive indicators for whether an SNPN allows access using credentials from a Credentials Holder, whether an SNPN allows registration attempts from UEs that are not explicitly configured to select this SNPN, and whether an SNPN allows onboarding; the UE may also optionally receive a list of supported Group IDs for Network selection (see TS 38.331 [3]). The result of the SNPN selection performed by NAS (see TS 23.122 [9]) is an identifier of the selected SNPN.

5.1.1 Support for PLMN selection

5.1.1.1 General

On request of the NAS, the AS shall perform a search for available PLMNs and report them to NAS.

5.1.1.2 NR case

The UE shall scan all RF channels in the NR bands according to its capabilities to find available PLMNs and available CAGs. On each carrier, the UE shall search for the strongest cell and read its system information, in order to find out which PLMN(s) the cell belongs to and any associated CAG(s). For operation with shared spectrum channel access, the UE may also read the system information of multiple strongest cell(s). If the UE can read one or several PLMN identities in the strongest cell or the multiple strongest cell(s) in case of operation with shared spectrum channel access, each found PLMN (see the PLMN reading in TS 38.331 [3]) shall be reported to the NAS as a high quality PLMN (but without the RSRP value) and any associated CAG-ID, provided that the following high-quality criterion is fulfilled:

1. For an NR cell, the measured RSRP value shall be greater than or equal to -110 dBm.

Found PLMNs that do not satisfy the high-quality criterion but for which the UE has been able to read the PLMN identities are reported to the NAS together with their corresponding RSRP values and any associated CAG-ID. The quality measure reported by the UE to NAS shall be the same for each PLMN found in one cell.

The search for PLMNs may be stopped on request from the NAS. The UE may optimise PLMN search by using stored information e.g. frequencies and optionally also information on cell parameters from previously received measurement control information elements.

Once the UE has selected a PLMN, the cell selection procedure shall be performed in order to select a suitable cell of that PLMN to camp on.

To support manual CAG selection, the UE shall upon request by NAS report available CAG-ID(s) together with their manual CAG selection allowed indicator (if broadcast), HRNN (if broadcast) and PLMN(s) to the NAS. If NAS has selected a CAG and provided this selection to AS, the UE shall search for an acceptable or suitable cell belonging to the selected CAG to camp on.

5.1.1.3 E-UTRA case

Support for PLMN selection in E-UTRA is described in TS 36.304 [7].

5.1.2 Support for SNPN selection

5.1.2.1 General

On request of the NAS, the AS shall perform a search for available SNPNs on only NR cells and report them to NAS.

5.1.2.2 NR case

The UE shall scan all RF channels in the NR bands according to its capabilities to find available SNPNs. On each carrier, the UE shall search for the strongest cell and read its system information, in order to find out which SNPN(s) the cell belongs to. For operation with shared spectrum channel access, the UE may also read the system information of multiple strongest cell(s). If the UE can read one or several SNPN identities in the strongest cell, each found SNPN (see the SNPN reading in TS 38.331 [3]) shall be reported to the NAS. For manual selection, UE shall upon request by NAS report available SNPN identifiers together with their HRNN (if broadcast) to the NAS and the search for available SNPNs may be stopped on request of the NAS.

The search for SNPNs may be stopped on request from the NAS. The UE may optimise SNPN search by using stored information e.g. frequencies and optionally also information on cell parameters from previously received measurement control information elements.

Once the UE has selected a SNPN, the cell selection procedure shall be performed in order to select a suitable cell of that SNPN to camp on.

5.2 Cell selection and reselection

5.2.1 Introduction

UE shall perform measurements for cell selection and reselection purposes as specified in TS 38.133 [8].

When evaluating Srxlev and Squal of non-serving cells for reselection evaluation purposes, the UE shall use parameters provided by the serving cell and for the final check on cell selection criterion, the UE shall use parameters provided by the target cell for cell reselection.

The NAS can control the RAT(s) in which the cell selection should be performed, for instance by indicating RAT(s) associated with the selected PLMN, and by maintaining a list of forbidden registration area(s) and a list of equivalent PLMNs. The UE shall select a suitable cell based on RRC_IDLE or RRC_INACTIVE state measurements and cell selection criteria.

In order to expedite the cell selection process, stored information for several RATs, if available, may be used by the UE.

When camped on a cell, the UE shall regularly search for a better cell according to the cell reselection criteria. If a better cell is found, that cell is selected. The change of cell may imply a change of RAT. Details on performance requirements for cell reselection can be found in TS 38.133 [8].

The NAS is informed if the cell selection and reselection result in changes in the received system information relevant for NAS.

For normal service, the UE shall camp on a suitable cell, monitor control channel(s) of that cell so that the UE can:

– receive system information from the PLMN or SNPN; and

– receive registration area information from the PLMN or SNPN, e.g., tracking area information; and

– receive other AS and NAS Information; and

– if registered:

– receive paging and notification messages from the PLMN or SNPN; and

– initiate transfer to Connected mode.

For cell selection in multi-beam operations, measurement quantity of a cell is up to UE implementation.

For cell reselection in multi-beam operations, including inter-RAT reselection from E-UTRA to NR, the measurement quantity of this cell is derived amongst the beams corresponding to the same cell based on SS/PBCH block as follows:

– if nrofSS-BlocksToAverage (maxRS-IndexCellQual in E-UTRA) is not configured in SIB2/SIB4 (SIB24 in E-UTRA); or

– if absThreshSS-BlocksConsolidation (threshRS-Index in E-UTRA) is not configured in SIB2/SIB4 (SIB24 in E-UTRA); or

– if the highest beam measurement quantity value is below or equal to absThreshSS-BlocksConsolidation (threshRS-Index in E-UTRA):

– derive a cell measurement quantity as the highest beam measurement quantity value, where each beam measurement quantity is described in TS 38.215 [11].

– else:

– derive a cell measurement quantity as the linear average of the power values of up to nrofSS-BlocksToAverage (maxRS-IndexCellQual in E-UTRA) of highest beam measurement quantity values above absThreshSS-BlocksConsolidation (threshRS-Index in E-UTRA).

5.2.2 States and state transitions in RRC_IDLE state and RRC_INACTIVE state

Figure 5.2.2-1 shows the states and state transitions and procedures in RRC_IDLE and RRC_INACTIVE. Whenever a new PLMN selection or new SNPN selection is performed, it causes an exit to number 1.

Figure 5.2.2-1: RRC_IDLE and RRC_INACTIVE Cell Selection and Reselection

5.2.3 Cell Selection process

5.2.3.1 Description

Cell selection is performed by one of the following two procedures:

a) Initial cell selection (no prior knowledge of which RF channels are NR frequencies):

1. The UE shall scan all RF channels in the NR bands according to its capabilities to find a suitable cell.

2. On each frequency, the UE need only search for the strongest cell, except for operation with shared spectrum channel access where the UE may search for the next strongest cell(s).

3. Once a suitable cell is found, this cell shall be selected.

b) Cell selection by leveraging stored information:

1. This procedure requires stored information of frequencies and optionally also information on cell parameters from previously received measurement control information elements or from previously detected cells.

2. Once the UE has found a suitable cell, the UE shall select it.

3. If no suitable cell is found, the initial cell selection procedure in a) shall be started.

NOTE: Priorities between different frequencies or RATs provided to the UE by system information or dedicated signalling are not used in the cell selection process.

5.2.3.2 Cell Selection Criterion

The cell selection criterion S is fulfilled when:

Srxlev > 0 AND Squal > 0

where:

Srxlev = Q_rxlevmeas – (Q_rxlevmin + Q_{rxlevminoffset} )– P_compensation– Qoffset_temp

Squal = Q_qualmeas – (Q_qualmin + Q_{qualminoffset}) – Qoffset_temp

where:

Srxlev	Cell selection RX level value (dB)
Squal	Cell selection quality value (dB)
Qoffset_temp	Offset temporarily applied to a cell as specified in TS 38.331 [3] (dB)
Q_rxlevmeas	Measured cell RX level value (RSRP)
Q_qualmeas	Measured cell quality value (RSRQ)
Q_rxlevmin	Minimum required RX level in the cell (dBm). If the UE supports SUL frequency for this cell, Q_rxlevmin is obtained from q-RxLevMinSUL, if present, in SIB1, SIB2 and SIB4, additionally, if Q_{rxlevminoffsetcellSUL} is present in SIB3 and SIB4 for the concerned cell, this cell specific offset is added to the corresponding Qrxlevmin to achieve the required minimum RX level in the concerned cell; else Q_rxlevmin is obtained from q-RxLevMin in SIB1, SIB2 and SIB4, additionally, if Q_{rxlevminoffsetcell} is present in SIB3 and SIB4 for the concerned cell, this cell specific offset is added to the corresponding Qrxlevmin to achieve the required minimum RX level in the concerned cell.
Q_qualmin	Minimum required quality level in the cell (dB). Additionally, if Q_{qualminoffsetcell} is signalled for the concerned cell, this cell specific offset is added to achieve the required minimum quality level in the concerned cell.
Q_{rxlevminoffset}	Offset to the signalled Q_rxlevmin taken into account in the Srxlev evaluation as a result of a periodic search for a higher priority PLMN while camped normally in a VPLMN, as specified in TS 23.122 [9].
Q_{qualminoffset}	Offset to the signalled Q_qualmin taken into account in the Squal evaluation as a result of a periodic search for a higher priority PLMN while camped normally in a VPLMN, as specified in TS 23.122 [9].
P_compensation	For FR1, if the UE supports the additionalPmax in the NR-NS-PmaxList, if present, in SIB1, SIB2 and SIB4: max(P_EMAX1 –P_PowerClass, 0) – (min(P_EMAX2, P_PowerClass) – min(P_EMAX1, P_PowerClass)) (dB); else: max(P_EMAX1 –P_PowerClass, 0) (dB) For FR2, P_compensation is set to 0. For IAB-MT, P_compensation is set to 0.
P_EMAX1, P_EMAX2	Maximum TX power level of a UE may use when transmitting on the uplink in the cell (dBm) defined as P_EMAX in TS 38.101 [15]. If UE supports SUL frequency for this cell, P_EMAX1 and P_EMAX2are obtained from the p-Max for SUL in SIB1 and NR-NS-PmaxList for SUL respectively in SIB1, SIB2 and SIB4 as specified in TS 38.331 [3], else P_EMAX1 and P_EMAX2 are obtained from the p-Max and NR-NS-PmaxList respectively in SIB1, SIB2 and SIB4 for normal UL as specified in TS 38.331 [3].
P_PowerClass	Maximum RF output power of the UE (dBm) according to the UE power class as defined in TS 38.101-1 [15].

The signalled values Q_{rxlevminoffset} and Q_{qualminoffset} are only applied when a cell is evaluated for cell selection as a result of a periodic search for a higher priority PLMN while camped normally in a VPLMN (TS 23.122 [9]). During this periodic search for higher priority PLMN, the UE may check the S criteria of a cell using parameter values stored from a different cell of this higher priority PLMN.

5.2.3.3 E-UTRAN case in Cell Selection

The cell selection criteria and procedures in E-UTRAN are specified in TS 36.304 [7].

5.2.4 Cell Reselection evaluation process

5.2.4.1 Reselection priorities handling

Absolute priorities of different NR frequencies or inter-RAT frequencies may be provided to the UE in the system information, in the RRCRelease message, or by inheriting from another RAT at inter-RAT cell (re)selection. In the case of system information, an NR frequency or inter-RAT frequency may be listed without providing a priority (i.e. the field cellReselectionPriority is absent for that frequency). If any fields with cellReselectionPriority or nsag-CellReselectionPriority are provided in dedicated signalling, the UE shall ignore any fields with cellReselectionPriority and nsag-CellReselectionPriority provided in system information.

When UE is in camped normally state, if it supports slice-based cell reselection and has received NSAG(s) and their priorities from NAS, UE shall derive re-selection priorities according to clause 5.2.4.11.

If UE is in camped on any cell state, UE shall only apply the priorities provided by system information from current cell, and the UE preserves priorities provided by dedicated signalling and deprioritisationReq received in RRCRelease unless specified otherwise. When the UE in camped normally state, has only dedicated priorities other than for the current frequency, the UE shall consider the current frequency to be the lowest priority frequency (i.e. lower than any of the network configured values). When the HSDN capable UE is in High-mobility state, the UE shall always consider the HSDN cells to be the highest priority (i.e., higher than any other network configured priorities). When the HSDN capable UE is not in High-mobility state, the UE shall always consider HSDN cells to be the lowest priority (i.e., lower than any other network configured priorities). If the UE is configured to perform both NR sidelink communication and V2X sidelink communication, the UE may consider the frequency providing both NR sidelink communication configuration and V2X sidelink communication configuration to be the highest priority. If the UE is configured to perform NR sidelink communication and not perform V2X communication, the UE may consider the frequency providing NR sidelink communication configuration to be the highest priority. If the UE is configured to perform V2X sidelink communication and not perform NR sidelink communication, the UE may consider the frequency providing V2X sidelink communication configuration to be the highest priority.

NOTE 0a: The frequency only providing the anchor frequency configuration should not be prioritized for V2X service during cell reselection, as specified in TS 38.331[3].

NOTE 0b: When UE is configured to perform NR sidelink communication or V2X sidelink communication performs cell reselection, it may consider the frequencies providing the intra-carrier and inter-carrier configuration have equal priority in cell reselection.

NOTE 0c: The prioritization among the frequencies which UE considers to be the highest priority frequency is left to UE implementation.

NOTE 0d: The UE is configured to perform V2X sidelink communication or NR sidelink communication, if it has the capability and is authorized for the corresponding sidelink operation.

NOTE 0e: When UE is configured to perform both NR sidelink communication and V2X sidelink communication, but cannot find a frequency which can provide both NR sidelink communication configuration and V2X sidelink communication configuration, UE may consider the frequency providing either NR sidelink communication configuration or V2X sidelink communication configuration to be the highest priority.

NOTE 0f: Void.

The UE shall only perform cell reselection evaluation for NR frequencies and inter-RAT frequencies that are given in system information and for which the UE has a priority provided.

If the MBS broadcast capable UE is receiving or interested to receive an MBS broadcast service(s) and can only receive this MBS broadcast service(s) by camping on a frequency on which it is provided, the UE may consider that frequency to be the highest priority during the MBS broadcast session as specified in TS 38.300 [2] as long as the two following conditions are fulfilled:

1) SIB1 scheduling information of the cell reselected by the UE due to frequency prioritization for MBS contains SIB20;

2) Either:

– One or more MBS FSAI(s) of that frequency is indicated in SIB21 of the serving cell and the same MBS FSAI(s) is also indicated for this MBS broadcast service in MBS User Service Description (USD) as specified in TS 26.346 [20], or

– SIB21 is not provided in the serving cell and that frequency is included in the USD of this service, or

– SIB21 is provided in the serving cell but does not provide the frequency mapping for the concerned service, and that frequency is included in the USD of this service.

NOTE 0g: It is up to UE implementation which frequency to select, when the USD provides multiple frequencies for the service the UE is interested in.

If the MBS broadcast capable UE is receiving or interested to receive an MBS broadcast service, the UE may consider cell reselection candidate frequencies at which it cannot receive the MBS broadcast service to be of the lowest priority during the MBS broadcast session as specified in TS 38.300 [2], as long as the SIB20 is provided by the cell on the MBS frequency which the UE monitors and as long as the condition 2) above is fulfilled for the serving cell.

NOTE 0h: Example scenarios in which such down-prioritisation may be needed include the cases where camping is not possible for the UE on the MBS broadcast frequency (e.g. the MBS broadcast frequency belongs to a PLMN different from UE’s registered PLMN) while the UE can receive the MBS broadcast service when camped on another frequency than the MBS broadcast frequency or current frequency.

In case UE receives RRCRelease with deprioritisationReq, UE shall consider current frequency and stored frequencies due to the previously received RRCRelease with deprioritisationReq or all the frequencies of NR to be the lowest priority frequency (i.e. lower than any of the network configured values) while T325 is running irrespective of camped RAT. The UE shall delete the stored deprioritisation request(s) when a PLMN selection or SNPN selection is performed on request by NAS (TS 23.122 [9]).

NOTE 1: UE should search for a higher priority layer for cell reselection as soon as possible after the change of priority. The minimum related performance requirements specified in TS 38.133 [8] are still applicable.

The UE shall delete priorities provided by dedicated signalling when:

– the UE enters a different RRC state; or

– the optional validity time of dedicated priorities (T320) expires; or

– the UE receives an RRCRelease message with the field cellReselectionPriorities absent; or

– a PLMN selection or SNPN selection is performed on request by NAS (TS 23.122 [9]).

NOTE 2: Equal priorities between RATs are not supported.

The UE shall not consider any exclude-listed cells as candidate for cell reselection.

The UE shall consider only the allow-listed cells, if configured, as candidates for cell reselection.

The UE in RRC_IDLE state shall inherit the priorities provided by dedicated signalling and the remaining validity time (i.e. T320 in NR and E-UTRA), if configured, at inter-RAT cell (re)selection.

NOTE 3: The network may assign dedicated cell reselection priorities for frequencies not configured by system information.

5.2.4.2 Measurement rules for cell re-selection

Following rules are used by the UE to limit needed measurements:

– If the serving cell fulfils Srxlev> S_IntraSearchP and Squal > S_IntraSearchQ:

– If distanceThresh and referenceLocation are broadcasted in SIB19, and if UE supports location-based measurement initiation and has obtained its location information:

– If the distance between UE and the serving cell reference location referenceLocation is shorter than distanceThresh, the UE may not perform intra-frequency measurements;

– Else, the UE shall perform intra-frequency measurements;

– Else, the UE may not perform intra-frequency measurements;

– Else, the UE shall perform intra-frequency measurements.

– The UE shall apply the following rules for NR inter-frequencies and inter-RAT frequencies which are indicated in system information and for which the UE has priority provided as defined in 5.2.4.1:

– For a NR inter-frequency or inter-RAT frequency with a reselection priority higher than the reselection priority of the current NR frequency, the UE shall perform measurements of higher priority NR inter-frequency or inter-RAT frequencies according to TS 38.133 [8].

– For a NR inter-frequency with an equal or lower reselection priority than the reselection priority of the current NR frequency and for inter-RAT frequency with lower reselection priority than the reselection priority of the current NR frequency:

– If the serving cell fulfils Srxlev > S_{nonIntraSearchP} and Squal > S_{nonIntraSearchQ}:

– If distanceThresh and referenceLocation are broadcasted in SIB19, and if UE supports location-based measurement initiation and has obtained its UE location information:

– If the distance between UE and the serving cell reference location referenceLocation is shorter than distanceThresh, the UE may choose not to perform measurements of NR inter-frequency cells of equal or lower priority, or inter-RAT frequency cells of lower priority;

– Else, the UE shall perform measurements of NR inter-frequency cells of equal or lower priority, or inter-RAT frequency cells of lower priority according to TS 38.133 [8];

– Else, the UE may choose not to perform measurements of NR inter-frequency cells of equal or lower priority, or inter-RAT frequency cells of lower priority;

– Else, the UE shall perform measurements of NR inter-frequency cells of equal or lower priority, or inter-RAT frequency cells of lower priority according to TS 38.133 [8].

– If the UE supports relaxed measurement and relaxedMeasurement is present in SIB2, the UE may further relax the needed measurements, as specified in clause 5.2.4.9.

If the t-Service of the serving cell is present in SIB19, and if UE supports time-based measurement initiation, the UE shall perform intra-frequency, inter-frequency or inter-RAT measurements before the t-Service, regardless of the distance between UE and the serving cell reference location or whether the serving cell fulfils Srxlev > SIntraSearchP and Squal > SIntraSearchQ, or Srxlev > SnonIntraSearchP and Squal > SnonIntraSearchQ, The exact time to start measurement before t-Service is up to UE implementation. UE shall perform measurements of higher priority NR inter-frequency or inter-RAT frequencies according to TS 38.133 [8] regardless of the remaining service time of the serving cell (i.e. time remaining until t-Service).

NOTE: When evaluating the distance between UE and the serving cell reference location, it’s up to UE implementation to obtain UE location information.

5.2.4.3 Mobility states of a UE

5.2.4.3.0 Introduction

The UE mobility state is determined if the parameters (T_CRmax, N_{CR_H}, N_{CR_M}, T_CRmaxHyst and cellEquivalentSize) are broadcasted in system information for the serving cell.

State detection criteria:

Normal-mobility state criteria:

– If number of cell reselections during time period T_CRmax is less than N_{CR_M}.

Medium-mobility state criteria:

– If number of cell reselections during time period T_CRmax is greater than or equal to N_{CR_M} but less than or equal to N_{CR_H}.

High-mobility state criteria:

– If number of cell reselections during time period T_CRmax is greater than N_{CR_H}.

The UE shall not consider consecutive reselections where a cell is reselected again right after one reselection for mobility state detection criteria. If the UE is capable of HSDN and the cellEquivalentSize is configured, the UE counts the number of cell reselections for this cell as cellEquivalentSize configured for this cell.

State transitions:

The UE shall:

– if the criteria for High-mobility state is detected:

– enter High-mobility state.

– else if the criteria for Medium-mobility state is detected:

– enter Medium-mobility state.

– else if criteria for either Medium- or High-mobility state is not detected during time period T_CRmaxHys_t:

– enter Normal-mobility state.

If the UE is in High- or Medium-mobility state, the UE shall apply the speed dependent scaling rules as defined in clause 5.2.4.3.1.

5.2.4.3.1 Scaling rules

UE shall apply the following scaling rules:

– If neither Medium- nor High-mobility state is detected:

– no scaling is applied.

– If High-mobility state is detected:

– Add the sf-High of "Speed dependent ScalingFactor for Q_hyst" to Q_hyst if broadcasted in system information;

– For NR cells, multiply Treselection_NR by the sf-High of "Speed dependent ScalingFactor for Treselection_NR" if broadcasted in system information;

– For EUTRA cells, multiply Treselection_EUTRA by the sf-High of "Speed dependent ScalingFactor for Treselection_EUTRA" if broadcasted in system information.

– If Medium-mobility state is detected:

– Add the sf-Medium of "Speed dependent ScalingFactor for Q_hyst" to Q_hyst if broadcasted in system information;

– For NR cells, multiply Treselection_NR by the sf-Medium of "Speed dependent ScalingFactor for Treselection_NR" if broadcasted in system information;

– For EUTRA cells, multiply Treselection_EUTRA by the sf-Medium of "Speed dependent ScalingFactor for Treselection_EUTRA" if broadcasted in system information.

In case scaling is applied to any Treselection_RAT parameter, the UE shall round up the result after all scalings to the nearest second.

5.2.4.4 Cells with cell reservations, access restrictions or unsuitable for normal camping

For the highest ranked cell (including serving cell) according to cell reselection criteria specified in clause 5.2.4.6, for the best cell according to absolute priority reselection criteria specified in clause 5.2.4.5, the UE shall check if the access is restricted according to the rules in clause 5.3.1.

If that cell and other cells have to be excluded from the candidate list, as stated in clause 5.3.1, the UE shall not consider these as candidates for cell reselection. This limitation shall be removed when the highest ranked cell changes.

If the highest ranked cell or best cell according to absolute priority reselection rules is an intra-frequency or inter-frequency cell which is not suitable due to one or more of the following reasons:

– this cell belongs to a PLMN which is not indicated as being equivalent to the registered PLMN, or

– this cell is a CAG cell that belongs to a PLMN which is equivalent to the registered PLMN but with no CAG-ID that is present in the UE’s allowed CAG list being broadcasted, or

– this cell is not a CAG cell and the CAG-only indication in the UE is set, or

– this cell does not belong to a SNPN that is equal to the registered or selected SNPN of the UE in SNPN access mode,

the UE shall not consider this cell and, for operation in licensed spectrum, other cells on the same frequency as candidates for reselection for a maximum of 300 seconds.

For operation with shared spectrum channel access, when the highest ranked cell or best cell is not a candidate for reselection per the previous paragraph, the UE should continue to consider other cells on the same frequency for cell reselection, however if the second highest ranked cell on this frequency is also not suitable due to one or more of the above reasons, the UE may consider this frequency to be the lowest priority for a maximum of 300 seconds.

If the highest ranked cell or best cell according to absolute priority reselection rules is an intra-frequency or inter-frequency cell which is not suitable due to being part of the "list of 5GS forbidden TAs for roaming", the UE shall not consider this cell and other cells on the same frequency as candidates for reselection for a maximum of 300 seconds.

If the highest ranked cell or best cell according to absolute priority reselection rules is an inter-RAT cell which is not suitable due to being part of the "list of forbidden TAs for roaming" or belonging to a PLMN which is not indicated as being equivalent to the registered PLMN, the UE shall not consider this cell and other cells on the same frequency, as candidates for reselection for a maximum of 300 seconds.

If the UE enters into state any cell selection, any limitation shall be removed. If the UE is redirected under NR control to a frequency for which the timer is running, the limitation(s) on that frequency shall be removed.

5.2.4.5 NR Inter-frequency and inter-RAT Cell Reselection criteria

If threshServingLowQ is broadcast in system information and more than 1 second has elapsed since the UE camped on the current serving cell, cell reselection to a cell on a higher priority NR frequency or inter-RAT frequency than the serving frequency shall be performed if:

– A cell of a higher priority NR or EUTRAN RAT/frequency fulfils Squal > Thresh_{X, HighQ} during a time interval Treselection_RAT

Otherwise, cell reselection to a cell on a higher priority NR frequency or inter-RAT frequency than the serving frequency shall be performed if:

– A cell of a higher priority RAT/ frequency fulfils Srxlev > Thresh_{X, HighP} during a time interval Treselection_RAT; and

– More than 1 second has elapsed since the UE camped on the current serving cell.

Cell reselection to a cell on an equal priority NR frequency shall be based on ranking for intra-frequency cell reselection as defined in clause 5.2.4.6.

If threshServingLowQ is broadcast in system information and more than 1 second has elapsed since the UE camped on the current serving cell, cell reselection to a cell on a lower priority NR frequency or inter-RAT frequency than the serving frequency shall be performed if:

– The serving cell fulfils Squal < Thresh_{Serving, LowQ} and a cell of a lower priority NR or E-UTRAN RAT/ frequency fulfils Squal > Thresh_{X, LowQ} during a time interval Treselection_RAT.

Otherwise, cell reselection to a cell on a lower priority NR frequency or inter-RAT frequency than the serving frequency shall be performed if:

– The serving cell fulfils Srxlev < Thresh_{Serving, LowP} and a cell of a lower priority RAT/ frequency fulfils Srxlev > Thresh_{X, LowP} during a time interval Treselection_RAT; and

– More than 1 second has elapsed since the UE camped on the current serving cell.

Cell reselection to a higher priority RAT/frequency shall take precedence over a lower priority RAT/frequency if multiple cells of different priorities fulfil the cell reselection criteria.

If more than one cell meets the above criteria, the UE shall reselect a cell as follows:

– If the highest-priority frequency is an NR frequency, the highest ranked cell among the cells on the highest priority frequency(ies) meeting the criteria according to clause 5.2.4.6;

– If the highest-priority frequency is from another RAT, the strongest cell among the cells on the highest priority frequency(ies) meeting the criteria of that RAT.

5.2.4.6 Intra-frequency and equal priority inter-frequency Cell Reselection criteria

The cell-ranking criterion R_s for serving cell and R_n for neighbouring cells is defined by:

R_s = Q_meas,s +Q_hyst – Qoffset_temp

R_n = Q_meas,n -Qoffset – Qoffset_temp

where:

Q_meas

RSRP measurement quantity used in cell reselections.

Qoffset

For intra-frequency: Equals to Qoffset_s,n, if Qoffset_s,n is valid, otherwise this equals to zero.

For inter-frequency: Equals to Qoffset_s,n plus Qoffset_frequency, if Qoffset_s,n is valid, otherwise this equals to Qoffset_frequency.

Qoffset_temp

Offset temporarily applied to a cell as specified in TS 38.331 [3].

The UE shall perform ranking of all cells that fulfil the cell selection criterion S, which is defined in 5.2.3.2.

The cells shall be ranked according to the R criteria specified above by deriving Q_meas,nand Q_meas,sand calculating the R values using averaged RSRP results.

If rangeToBestCell is not configured, the UE shall perform cell reselection to the highest ranked cell. If this cell is found to be not-suitable, the UE shall behave according to clause 5.2.4.4.

If rangeToBestCell is configured, then the UE shall perform cell reselection to the cell with the highest number of beams above the threshold (i.e. absThreshSS-BlocksConsolidation) among the cells whose R value is within rangeToBestCell of the R value of the highest ranked cell. If there are multiple such cells, the UE shall perform cell reselection to the highest ranked cell among them. If this cell is found to be not-suitable, the UE shall behave according to clause 5.2.4.4.

In all cases, the UE shall reselect the new cell, only if the following conditions are met:

– the new cell is better than the serving cell according to the cell reselection criteria specified above during a time interval Treselection_RAT;

– more than 1 second has elapsed since the UE camped on the current serving cell.

NOTE: If rangeToBestCell is configured but absThreshSS-BlocksConsolidation is not configured on an NR frequency, the UE considers that there is one beam above the threshold for each cell on that frequency.

5.2.4.7 Cell reselection parameters in system information broadcasts

5.2.4.7.0 General reselection parameters

Editor’s Note: Slice specific cell reselection parameters to be added here and aligned with TS 38.331.

Cell reselection parameters are broadcast in system information and are read from the serving cell as follows:

absThreshSS-BlocksConsolidation

This specifies the minimum threshold for beams which can be used for selection of the highest ranked cells, if rangeToBestCell is configured, and for beams used for derivation of cell measurement quantity. The parameter in SIB2 applies to the current serving frequency and the parameter in SIB4 applies to the corresponding inter-frequency.

cellReselectionPriority

This specifies the absolute priority for NR frequency or E-UTRAN frequency.

cellReselectionSubPriority

This specifies the fractional priority value added to cellReselectionPriority for NR frequency or E-UTRAN frequency.

combineRelaxedMeasCondition

This indicates when the UE needs to fulfil both low mobility criterion and not-at-cell-edge criterion to determine whether to relax measurement requirements.

combineRelaxedMeasCondition2

This indicates when a RedCap UE needs to fulfil both stationary criterion and not-at-cell-edge criterion to determine whether to relax measurement requirements.

nrofSS-BlocksToAverage

This specifies the number of beams which can be used for selection of the highest ranked cell, if rangeToBestCell is configured, and the number of beams used for derivation of cell measurement quantity. The parameter in SIB2 applies to the current serving frequency and the parameter in SIB4 applies to the corresponding inter-frequency.

Qoffset_s,n

This specifies the offsetbetween the two cells.

Qoffset_frequency

Frequency specific offset for equal priority NR frequencies.

Q_hyst

This specifies the hysteresis value for ranking criteria.

Qoffset_temp

This specifies the additional offset to be used for cell selection and re-selection. It is temporarily used in case the RRC Connection Establishment fails on the cell as specified in TS 38.331 [3].

Q_qualmin

This specifies the minimum required quality level in the cell in dB.

Q_rxlevmin

This specifies the minimum required Rx level in the cell in dBm.

Q_{rxlevminoffsetcell}

This specifies the cell specific Rx level offset in dB to Qrxlevmin.

Q_{qualminoffsetcell}

This specifies the cell specific quality level offset in dB to Qqualmin.

rangeToBestCell

This specifies the R value range which the cells whose R value is within the range can be a candidate for the highest ranked cell. It is configured in SIB2 and used for intra-frequency and equal priority inter-frequency cell reselection and among the cells on the highest priority frequency(ies) for inter-frequency cell reselection within NR.

S_IntraSearchP

This specifies the Srxlev threshold (in dB) for intra-frequency measurements.

S_IntraSearchQ

This specifies the Squal threshold (in dB) for intra-frequency measurements.

S_{nonIntraSearchP}

This specifies the Srxlev threshold (in dB) for NR inter-frequency and inter-RAT measurements.

S_{nonIntraSearchQ}

This specifies the Squal threshold (in dB) for NR inter-frequency and inter-RAT measurements.

S_SearchDeltaP

This specifies the threshold (in dB) on Srxlev variation for relaxed measurement.

S_{SearchDeltaP-Stationary}

This specifies the threshold (in dB) on Srxlev variation to evaluate stationary criterion for relaxed measurement.

S_{SearchThresholdP}

This specifies the Srxlev threshold (in dB) for relaxed measurement.

S_{SearchThresholdP2}

This specifies the Srxlev threshold (in dB) to evaluate not-at-cell-edge-criterion for relaxed measurement.

S_{SearchThresholdQ}

This specifies the Squal threshold (in dB) for relaxed measurement.

S_{SearchThresholdQ2}

This specifies the Squal threshold (in dB) to evaluate not-at-cell-edge-criterion for relaxed measurement.

Treselection_RAT

This specifies the cell reselection timer value. For each target NR frequency and for each RAT other than NR, a specific value for the cell reselection timer is defined, which is applicable when evaluating reselection within NR or towards other RAT (i.e. Treselection_RAT for NR is Treselection_NR, for E-UTRAN Treselection_EUTRA).

NOTE: Treselection_RATis not broadcast in system information but used in reselection rules by the UE for each RAT.

Treselection_NR

This specifies the cell reselection timer value Treselection_RAT for NR. The parameter can be set per NR frequency as specified in TS 38.331 [3].

Treselection_EUTRA

This specifies the cell reselection timer value Treselection_RAT for E-UTRAN.

Thresh_{X, HighP}

This specifies the Srxlev threshold (in dB) used by the UE when reselecting towards a higher priority RAT/ frequency than the current serving frequency. Each frequency of NR and E-UTRAN might have a specific threshold.

Thresh_{X, HighQ}

This specifies the Squal threshold (in dB) used by the UE when reselecting towards a higher priority RAT/ frequency than the current serving frequency. Each frequency of NR and E-UTRAN might have a specific threshold.

Thresh_{X, LowP}

This specifies the Srxlev threshold (in dB) used by the UE when reselecting towards a lower priority RAT/ frequency than the current serving frequency. Each frequency of NR and E-UTRAN might have a specific threshold.

Thresh_{X, LowQ}

This specifies the Squal threshold (in dB) used by the UE when reselecting towards a lower priority RAT/ frequency than the current serving frequency. Each frequency of NR and E-UTRAN might have a specific threshold.

Thresh_{Serving, LowP}

This specifies the Srxlev threshold (in dB) used by the UE on the serving cell when reselecting towards a lower priority RAT/ frequency.

Thresh_{Serving, LowQ}

This specifies the Squal threshold (in dB) used by the UE on the serving cell when reselecting towards a lower priority RAT/ frequency.

T_SearchDeltaP

This specifies the time period over which the Srxlev variation is evaluated for relaxed measurement.

T_{SearchDeltaP-Stationary}

This specifies the time period over which the Srxlev variation is evaluated for stationary criterion for relaxed measurement.

5.2.4.7.1 Speed dependent reselection parameters

Speed dependent reselection parameters are broadcast in system information and are read from the serving cell as follows:

T_CRmax

This specifies the duration for evaluating allowed amount of cell reselection(s).

N_{CR_M}

This specifies the maximum number of cell reselections to enter Medium-mobility state.

N_{CR_H}

This specifies the maximum number of cell reselections to enter High-mobility state.

T_CRmaxHyst

This specifies the additional time period before the UE can enter Normal-mobility state.

Speed dependent ScalingFactor for Qhyst

This specifies scaling factor for Qhyst in sf-High for High-mobility state and sf-Medium for Medium-mobility state.

Speed dependent ScalingFactor for Treselection_NR

This specifies scaling factor for Treselection_NRin sf-High for High-mobility state and sf-Medium for Medium-mobility state.

Speed dependent ScalingFactor for Treselection_EUTRA

This specifies scaling factor for Treselection_EUTRA in sf-High for High-mobility state and sf-Medium for Medium-mobility state.

5.2.4.8 Inter-RAT Cell reselection in RRC_INACTIVE state

For UE in the RRC_INACTIVE state, upon cell reselection to another RAT, UE transitions from RRC_INACTIVE to RRC_IDLE and performs actions as specified in TS 38.331 [3].

5.2.4.9 Relaxed measurement

5.2.4.9.0 Relaxed measurement rules

When the UE is required to perform measurements of intra-frequency cells or NR inter-frequency cells or inter-RAT frequency cells according to the measurement rules in clause 5.2.4.2:

– if lowMobilityEvaluation is configured and cellEdgeEvaluation is not configured; and

– if the UE has performed normal intra-frequency, NR inter-frequency, or inter-RAT frequency measurements for at least T_SearchDeltaP after (re-)selecting a new cell; and

– if the relaxed measurement criterion in clause 5.2.4.9.1 is fulfilled for a period of T_SearchDeltaP:

– the UE may choose to perform relaxed measurements for intra-frequency cells, NR inter-frequency cells or inter-RAT frequency cells according to relaxation methods in clauses 4.2.2.9, 4.2.2.10, and 4.2.2.11 in TS 38.133 [8];

– if cellEdgeEvaluation is configured and lowMobilityEvaluation is not configured; and

– if the relaxed measurement criterion in clause 5.2.4.9.2 is fulfilled:

– the UE may choose to perform relaxed measurements for intra-frequency cells according to relaxation methods in clauses 4.2.2.9 in TS 38.133 [8];

– if the serving cell fulfils Srxlev ≤ S_{nonIntraSearchP} or Squal ≤ S_{nonIntraSearchQ}:

– the UE may choose to perform relaxed measurements for NR inter-frequency cells or inter-RAT frequency cells according to relaxation methods in clauses 4.2.2.10, and 4.2.2.11 in TS 38.133 [8];

– if both lowMobilityEvaluation and cellEdgeEvaluation are configured:

– if the UE has performed normal intra-frequency, NR inter-frequency, or inter-RAT frequency measurements for at least T_SearchDeltaP after (re-)selecting a new cell; and

– if the relaxed measurement criterion in clause 5.2.4.9.1 is fulfilled for a period of T_SearchDeltaP; and

– if the relaxed measurement criterion in clause 5.2.4.9.2 is fulfilled:

– the UE may choose to perform relaxed measurements for NR intra-frequency cells, inter-frequency cells or inter-RAT frequency cells according to relaxation methods in clauses 4.2.2.9, 4.2.2.10, and 4.2.2.11 in TS 38.133 [8];

– else:

– if the UE has performed normal intra-frequency, NR inter-frequency, or inter-RAT frequency measurements for at least T_SearchDeltaP after (re-)selecting a new cell, and the relaxed measurement criterion in clause 5.2.4.9.1 is fulfilled for a period of T_SearchDeltaP; or,

– if the relaxed measurement criterion in clause 5.2.4.9.2 is fulfilled:

– if combineRelaxedMeasCondition is not configured:

– the UE may choose to perform relaxed measurements for intra-frequency cells, NR inter-frequency cells of equal or lower priority, or inter-RAT frequency cells of lower priority according to relaxation methods in clauses 4.2.2.9, 4.2.2.10, and 4.2.2.11 in TS 38.133 [8];

– if the serving cell fulfils Srxlev ≤ S_{nonIntraSearchP} or Squal ≤ S_{nonIntraSearchQ}:

– the UE may choose to perform relaxed measurement for NR inter-frequency cells of higher priority, or inter-RAT frequency cells of higher priority according to relaxation methods in clauses 4.2.2.10, and 4.2.2.11 in TS 38.133 [8];

– if the UE is a RedCap UE; and

– if stationaryMobilityEvaluation is configured and cellEdgeEvaluationWhileStationary is not configured; and

– if the UE has performed normal intra-frequency, NR inter-frequency, or inter-RAT frequency measurements for at least T_{SearchDeltaP-Stationary} after (re-)selecting a new cell; and

– if the relaxed measurement criterion in clause 5.2.4.9.3 is fulfilled for a period of T_{SearchDeltaP-Stationary}:

– the UE may choose to perform relaxed measurements for intra-frequency cells, NR inter-frequency cells, or inter-RAT frequency cells according to relaxation methods in clauses 4.2B.2.9, 4.2B.2.10, and 4.2B.2.11 in TS 38.133 [8];

– if the UE is a RedCap UE; and

– if both stationaryMobilityEvaluation and cellEdgeEvaluationWhileStationary are configured:

– if the UE has performed normal intra-frequency, NR inter-frequency, or inter-RAT frequency measurements for at least T_{SearchDeltaP-Stationary} after (re-)selecting a new cell; and

– if the relaxed measurement criterion in clause 5.2.4.9.4 is fulfilled:

– else:

– if combineRelaxedMeasCondition2 is not configured:

– if the UE has performed normal intra-frequency, NR inter-frequency, or inter-RAT frequency measurements for at least T_{SearchDeltaP-Stationary} after (re-)selecting a new cell; and

– if the relaxed measurement criterion in clause 5.2.4.9.3 is fulfilled for a period of T_{SearchDeltaP-Stationary}:

NOTE 1: It is up to UE implementation when to start performing relaxed measurements in RRC Idle/Inactive if multiple methods are configured.

NOTE 2: It is up to UE implementation which relaxation method to perform based on the "allowed" cases as specified in TS 38.133 [8] for RRC Idle/Inactive if multiple methods are configured.

The above relaxed measurements and no measurement are not applicable for frequencies that are included in VarMeasIdleConfig, if configured and for which the UE supports dual connectivity or carrier aggregation between those frequencies and the frequency of the current serving cell.

5.2.4.9.1 Relaxed measurement criterion for UE with low mobility

The relaxed measurement criterion for UE with low mobility is fulfilled when:

– (Srxlev_Ref – Srxlev) < S_SearchDeltaP,

Where:

– Srxlev = current Srxlev value of the serving cell (dB).

– Srxlev_Ref = reference Srxlev value of the serving cell (dB), set as follows:

– After selecting or reselecting a new cell, or

– If (Srxlev – Srxlev_Ref) > 0, or

– If the relaxed measurement criterion has not been met for T_SearchDeltaP:

– The UE shall set the value of Srxlev_Ref to the current Srxlev value of the serving cell.

5.2.4.9.2 Relaxed measurement criterion for UE not at cell edge

The relaxed measurement criterion for UE not at cell edge is fulfilled when:

– Srxlev > S_{SearchThresholdP}, and,

– Squal > S_{SearchThresholdQ}, if S_{SearchThresholdQ} is configured,

Where:

– Srxlev = current Srxlev value of the serving cell (dB).

– Squal = current Squal value of the serving cell (dB).

5.2.4.9.3 Relaxed measurement criterion for a stationary RedCap UE

The relaxed measurement criterion for a stationary RedCap UE is fulfilled when:

– (Srxlev_{RefStationary} – Srxlev) < S_{SearchDeltaP-Stationary},

Where:

– Srxlev = current Srxlev value of the serving cell (dB).

– Srxlev_{RefStationary} = reference Srxlev value of the serving cell (dB), set as follows:

– After selecting or reselecting a new cell, or

– If (Srxlev – Srxlev_{RefStationary}) > 0, or

– If the relaxed measurement criterion has not been met for T_{SearchDeltaP-Stationary}:

– The UE shall set the value of Srxlev_{RefStationary} to the current Srxlev value of the serving cell.

5.2.4.9.4 Relaxed measurement criterion for a stationary RedCap UE not at cell edge

The relaxed measurement criterion for a stationary RedCap UE not at cell edge is fulfilled when:

– the relaxed measurement criterion in clause 5.2.4.9.3 is fulfilled for a period of T_{SearchDeltaP-Stationary},

– Srxlev > S_{SearchThresholdP2}, and,

– Squal > S_{SearchThresholdQ2}, if S_{SearchThresholdQ2} is configured.

Where:

– Srxlev = current Srxlev value of the serving cell (dB).

– Squal = current Squal value of the serving cell (dB).

5.2.4.10 Cell reselection with CAG cells

In addition to normal cell reselection, a UE may optionally use an autonomous search function to detect CAG cells on serving and non-serving frequencies. However UE shall follow the cell reselection criteria based on dedicated frequency priorities and only follow the autonomous cell search result if the result fulfils also the existing cell reselection criteria based on dedicated frequency priorities.

5.2.4.11 Reselection priorities for slice-based cell reselection

The UE derives reselection priorities for slice-based cell reselection by using:

– NSAGs and their priorities provided by NAS,

– sliceInfoList and or sliceInfoListDedicated per frequency with nsag-CellReselectionPriority per NSAG, if provided in system information and/or dedicated signalling,

– cellReselectionPriority per frequency provided in system information and/or dedicated signalling.

The UE considers an NR frequency to support all slices of an NSAG if

– the nsag-ID and TA of the NSAG as provided by NAS are indicated for the NR frequency (see TS 38.331).

The UE considers a cell on an NR frequency to support all slices of an NSAG if

– the nsag-ID and TA of the NSAG as provided by NAS are indicated for the NR frequency (see TS 38.331); and

– the cell is either listed in the sliceAllowedCellListNR (if provided in the used slice-based cell reselection information) or the cell is not listed in the sliceExcludedCellListNR (if provided in the used slice-based cell reselection information); or

– Neither sliceAllowedCellListNR nor sliceExcludedCellListNR is configured in the used slice-based cell reselection information

The UE shall derive reselection priorities for slice-based cell reselection according to the following rules:

– Frequencies that support at least one prioritized NSAG received from NAS have higher reselection priority than frequencies that support none of the NSAG(s) received from NAS.

– Frequencies that support at least one NSAG provided by NAS are prioritised in the order of the NAS-provided priority for the NSAG with highest priority supported on the frequency.

– Among the frequencies (one or multiple) that support the highest prioritised NSAG(s) with the same NAS-provided priorities, the frequencies are prioritized in the order of their highest nsag-CellReselectionPriority given for these NSAG(s). If no nsag-CellReselectionPriority is given for a NSAG at a frequency, the lowest priority value is used (i.e, lower than any of the network configured values for these frequencies).

– Frequencies that support none of the NSAG(s) provided by NAS are prioritized in the order of their cellReselectionPriority;

For a UE performing slice-based cell reselection, if the highest ranked cell or best cell in a frequency fulfils the inter- freqeuency cell reselection criteria (see clause 5.2.4.5) based on reselection priority for the frequency and NSAG derived according to this clause or fulfils intra-frequency and equal priority inter-frequency cell reselection criteria (see clause 5.2.4.6), but this cell does not support the NSAG according to this clause,

– if this cell supports any other NSAG(s) according to this clause, the UE shall re-derive a reselection priority for the frequency by considering the NSAG(s) supported by this cell (rather than those of the corresponding NR frequency);

– Otherwise, the UE shall re-derive a reselection priority for the frequency as if none of the NSAG(s) provided by NAS is supported.

This re-derived reselection priority is used for a maximum of 300 seconds, or until new information of NSAG(s) and their priorities are received from NAS. UE shall ensure the cell reselection criteria above are fulfilled based on the newly derived priorities.

5.2.5 Camped Normally state

This state is applicable for RRC_IDLE and RRC_INACTIVE state.

When camped normally, the UE shall perform the following tasks:

– monitor the paging channel of the cell as specified in clause 7 according to information broadcast in SIB1;

– monitor Short Messages transmitted with P-RNTI over DCI as specified in clause 6.5 in TS 38.331 [3];

– monitor relevant System Information as specified in TS 38.331 [3];

– perform necessary measurements for the cell reselection evaluation procedure;

– execute the cell reselection evaluation process on the following occasions/triggers:

1) UE internal triggers, so as to meet performance as specified in TS 38.133 [8];

2) When information on the BCCH used for the cell reselection evaluation procedure has been modified.

3) When information on NSAG(s) and their priorities received from NAS changes.

5.2.6 Selection of cell at transition to RRC_IDLE or RRC_INACTIVE state

At reception of RRCRelease message to transition the UE to RRC_IDLE or RRC_INACTIVE, UE shall attempt to camp on a suitable cell according to redirectedCarrierInfo if included in the RRCRelease message. If the UE cannot find a suitable cell, the UE is allowed to camp on any suitable cell of the indicated RAT. If the RRCRelease message does not contain the redirectedCarrierInfo, UE shall attempt to select a suitable cell on an NR carrier. If no suitable cell is found according to the above, the UE shall perform cell selection using stored information in order to find a suitable cell to camp on.

When returning to RRC_IDLE state after UE moved to RRC_CONNECTED state from camped on any cell state, UE shall attempt to camp on an acceptable cell according to redirectedCarrierInfo, if included in the RRCRelease message. If the UE cannot find an acceptable cell, the UE is allowed to camp on any acceptable cell of the indicated RAT. If the RRCRelease message does not contain redirectedCarrierInfo UE shall attempt to select an acceptable cell on an NR frequency. If no acceptable cell is found according to the above, the UE not in SNPN Access Mode shall continue to search for an acceptable cell of any PLMN in state any cell selection. If no acceptable cell is found according to the above, the UE in SNPN access mode shall continue to search for an acceptable cell of any SNPN in state any cell selection.

5.2.7 Any Cell Selection state

This state is applicable for RRC_IDLE and RRC_INACTIVE state. In this state, the UE shall perform cell selection process to find a suitable cell. If the cell selection process fails to find a suitable cell after a complete scan of all RATs and all frequency bands supported by the UE, the UE not in SNPN Access Mode shall attempt to find an acceptable cell of any PLMN to camp on, trying all RATs that are supported by the UE and searching first for a high-quality cell, as defined in clause 5.1.1.2. If the cell selection process fails to find a suitable cell after a complete scan of all frequency bands supported by the UE, the UE in SNPN access mode shall attempt to find an acceptable cell of any SNPN to camp on.

The UE, which is not camped on any cell, shall stay in this state.

5.2.8 Camped on Any Cell state

This state is only applicable for RRC_IDLE state. In this state, the UE shall perform the following tasks:

– monitor Short Messages transmitted with P-RNTI over DCI as specified in clause 6.5 in TS 38.331 [3];

– monitor relevant System Information as specified in TS 38.331 [3];

– perform necessary measurements for the cell reselection evaluation procedure;

– execute the cell reselection evaluation process on the following occasions/triggers:

1) UE internal triggers, so as to meet performance as specified in TS 38.133 [8];

2) When information on the BCCH used for the cell reselection evaluation procedure has been modified.

– regularly attempt to find a suitable cell trying all frequencies of all RATs that are supported by the UE. If a suitable cell is found, UE shall move to camped normally state.

– if the UE supports voice services, the UE is not in SNPN access mode, and the current cell does not support IMS emergency calls as indicated by the field ims-EmergencySupport in SIB1 as specified in TS 38.331 [3], the UE shall perform cell selection/reselection to an acceptable cell that supports emergency calls in any supported RAT regardless of priorities provided in system information from current cell, if no suitable cell is found.

– if the UE supports voice services, the UE is in SNPN access mode, and the current cell does not support IMS emergency calls for any SNPN(s) as indicated by the field imsEmergencySupportForSNPN in SIB1 as specified in TS 38.331 [3], the UE shall perform cell selection/reselection to an acceptable cell of any available SNPN that supports emergency calls, if no suitable cell is found.

5.3 Cell Reservations and Access Restrictions

5.3.0 Introduction

There are two mechanisms which allow an operator to impose cell reservations or access restrictions. The first mechanism uses indication of cell status and special reservations for control of cell selection and reselection procedures. The second mechanism, referred to as Unified Access Control as specified in TS 38.331 [3], shall allow preventing selected access categories or access identities from sending initial access messages for load control reasons.

Unified Access Control does not apply to IAB-MTs.

5.3.1 Cell status and cell reservations

Cell status and cell reservations are indicated in the MIB or SIB1 message as specified in TS 38.331 [3] by means of following fields:

– cellBarred (IE type: "barred" or "not barred")
Indicated in MIB message. In case of multiple PLMNs or NPNs indicated in SIB1, this field is common for all PLMNs and NPNs. This field is ignored by UEs supporting NTN while cellBarredNTN is included in SIB1.

– cellBarredNTN (IE type: "barred" or "not barred")
Indicated in SIB1 message. In case of multiple PLMNs indicated in SIB1, this field is common for all PLMNs. This field is ignored if the UE does not support NTN connectivity.

– cellBarredRedCap1Rx (IE type: "barred" or "not barred")
Indicated in SIB1 message. In case of multiple PLMNs or NPNs indicated in SIB1, this field is common for all PLMNs and NPNs. This field is only applicable to RedCap UEs.

– cellBarredRedCap2Rx (IE type: "barred" or "not barred")
Indicated in SIB1 message. In case of multiple PLMNs or NPNs indicated in SIB1, this field is common for all PLMNs and NPNs. This field is only applicable to RedCap UEs.

– cellReservedForOperatorUse (IE type: "reserved" or "not reserved")
Indicated in SIB1 message. In case of multiple PLMNs or NPNs indicated in SIB1, this field is specified per PLMN or per SNPN.

– cellReservedForOtherUse (IE type: "true")
Indicated in SIB1 message. In case of multiple PLMNs indicated in SIB1, this field is common for all PLMNs.

– cellReservedForFutureUse (IE type: "true")
Indicated in SIB1 message. In case of multiple PLMNs or NPNs indicated in SIB1, this field is common for all PLMNs and NPNs.

NOTE 0: IAB-MT ignores the cellBarred, cellReservedForOperatorUse, cellReservedForFutureUse, and intraFreqReselection (i.e. treats intraFreqReselection as if it was set to allowed) as defined in TS 38.331 [3]. IAB-MT also ignores cellReservedForOtherUse for cell barring determination (i.e. NPN capable IAB-MT considers cellReservedForOtherUse for determination of an NPN-only cell) as defined in TS 38.331 [3].

– iab-Support (IE type: "true")
Indicated in SIB1 message. In case of multiple PLMNs or NPNs indicated in SIB1, this field is specified per PLMN or per SNPN.

When cell status is indicated as "not barred" and "not reserved" for operator use and not "true" for other use and not "true" for future use,

– UEs shall treat this cell as candidate during the cell selection and cell reselection procedures.

When cell broadcasts any CAG-IDs or NIDs and the cell status is indicated as "not barred" and "not reserved" for operator use and "true" for other use, and not "true" for future use:

– All NPN-capable UEs shall treat this cell as candidate during the cell selection and cell reselection procedures, other UEs shall treat this cell as if cell status is "barred".

When cell status is indicated as "true" for other use, and either cell does not broadcast any CAG-IDs or NIDs or does not broadcast any CAG-IDs and the UE is not operating in SNPN Access Mode,

– The UE shall treat this cell as if cell status is "barred".

When cell status is indicated as "true" for future use,

– The UE shall treat this cell as if cell status is "barred".

When cellBarredNTN is not broadcast in this cell,

– For NTN access, the UE shall treat this cell as if cell status is "barred".

When cell status is indicated as "not barred" and "reserved" for operator use for any PLMN/SNPN and not "true" for other use and not "true" for future use,

– UEs assigned to Access Identity 11 or 15 operating in their HPLMN/EHPLMN shall treat this cell as candidate during the cell selection and reselection procedures if the field cellReservedForOperatorUse for that PLMN set to "reserved".

– UEs assigned to Access Identity 11 or 15 shall treat this cell as candidate during the cell selection and reselection procedures if the field cellReservedForOperatorUse for selected/registered SNPN is set to "reserved".

– UEs assigned to an Access Identity 0, 1, 2 and 12 to 14 shall behave as if the cell status is "barred" in case the cell is "reserved for operator use" for the registered PLMN/SNPN or the selected PLMN/SNPN.

– UEs assigned to Access Identity 3 shall behave as if the cell status is "barred" in case the cell is "reserved for operator use" for the registered PLMN or the selected PLMN.

NOTE 1: Access Identities 11, 15 are only valid for use in the HPLMN/ EHPLMN; Access Identities 12, 13, 14 are only valid for use in the home country as specified in TS 22.261 [12].

NOTE 1a: Access Identity 3 is only valid for PLMNs that indicate to potential Disaster Inbound Roamers that the UEs can access the PLMN as specified in TS 22.261 [12].

When cell status "barred" is indicated or to be treated as if the cell status is "barred",

– The UE is not permitted to select/reselect this cell, not even for emergency calls.

– The UE shall select another cell according to the following rule:

– If the cell is to be treated as if the cell status is "barred" due to being unable to acquire the MIB:

– the UE may exclude the barred cell as a candidate for cell selection/reselection for up to 300 seconds.

– the UE may select another cell on the same frequency if the selection criteria are fulfilled.

– else:

– If the UE is a RedCap UE, the UE shall acquire SIB1 and, in the remainder of this procedure, consider ‘intraFreqReselection in MIB’ to be ‘intraFreqReselectionRedCap in SIB1′, if available.

– If the UE is not a RedCap UE, or if the UE is a RedCap UE and intraFreqReselectionRedCap in SIB1 is available:

– If the field intraFreqReselection in MIB message is set to "allowed":

– the UE may select another cell on the same frequency if re-selection criteria are fulfilled;

– If the cell is to be treated as if the cell status is "barred" due to being unable to acquire the SIB1:

– the UE may exclude the barred cell as a candidate for cell selection/reselection for up to 300 seconds;

– else:

– the UE shall exclude the barred cell as a candidate for cell selection/reselection for 300 seconds.

– If the field intraFreqReselection in MIB message is set to "not allowed":

– If the cell is to be treated as if the cell status is "barred" due to being unable to acquire the SIB1:

– the UE may exclude the barred cell as a candidate for cell selection/reselection for up to 300 seconds;

– If the cell operates in licensed spectrum:

– the UE shall not re-select to another cell on the same frequency as the barred cell and exclude such cell(s) as candidate(s) for cell selection/reselection for 300 seconds;

– else:

– the UE may select to another cell on the same frequency if the reselection criteria are fulfilled.

– else:

– If the cell operates in licensed spectrum, or if this cell belongs to a PLMN which is indicated as being equivalent to the registered PLMN or the selected PLMN of the UE, or if this cell belongs to the registered SNPN or the selected SNPN of the UE:

– the UE shall not re-select to another cell on the same frequency as the barred cell and exclude such cell(s) as candidate(s) for cell selection/reselection for 300 seconds;

– else:

– the UE may select to another cell on the same frequency if the reselection criteria are fulfilled.

– the UE shall exclude the barred cell as a candidate for cell selection/reselection for 300 seconds.

For RedCap UEs with 1Rx/2Rx; when cell status "barred" is indicated or to be treated as if the cell status is "barred",

– The UE shall select another cell according to the following rule:

– If the cell is to be treated as if the cell status is "barred" due to being unable to acquire the SIB1:

– the UE may exclude the barred cell as a candidate for cell selection/reselection for up to 300 seconds.

– the UE may select another cell on the same frequency if the selection criteria are fulfilled.

– else:

– If the cell is to be treated as if the cell status is "barred" due to not supporting RedCap UEs:

– the UE shall exclude the barred cell as a candidate for cell selection/reselection for 300 seconds.

– the UE may select another cell on the same frequency if re-selection criteria are fulfilled.

The cell selection of another cell may also include a change of RAT.

NOTE 2: If barring of a cell is triggered by the condition of trackingAreaCode and trackingAreaList not being provided, as specified in TS 38.331 [3], the barring only applies to this PLMN and the UE can re-evaluate the barring condition again due to selection of another PLMN.

5.3.2 Unified access control

The information on cell access restrictions associated with Access Categories and Identities is broadcast in SIB1 as part of Unified Access Control as specified in TS 38.331 [3].

The UE shall ignore Access Category and Identity related cell access restrictions for cell reselection. A change of the indicated access restriction shall not trigger cell reselection by the UE.

The UE shall consider Access Category and Identity related cell access restrictions for NAS initiated access attempts and RNAU as specified in TS 38.331 [3].

A L2 U2N Relay UE does not need to perform the Unified Access Control as specified in TS 38.331 [3], due to the U2N Remote UE access attempt.

5.4 Tracking Area registration

In the UE, the AS shall report tracking area information to the NAS.

If the UE reads more than one PLMN identity in the current cell, the UE shall report the found PLMN identities that make the cell suitable in the tracking area information to NAS.

If the UE operating in SNPN access mode reads more than one SNPN identity in the current cell, the UE shall report the found SNPN identities that make the cell suitable in the tracking area information to NAS.

The NAS part of the location registration process is specified in TS 23.122 [9].

5.5 RAN Area registration

The UE performs a RAN-based notification area update (RNAU) periodically or when the UE selects a cell that does not belong to the configured RNA.

A L2 U2N Remote UE, while in RRC_INACTIVE performs RNAU periodically or when the serving cell of the L2 U2N Relay UE changes (e.g., due to reconfiguration with sync, when a different L2 U2N Relay UE is reselected, or when the L2 U2N Relay UE reselects a new cell) and this new serving cell does not belong to the configured RNA of L2 U2N Remote UE.