6.2.2 Inter-RAT Cell Selection

38.523-13GPP5GSPart 1: ProtocolRelease 17TSUser Equipment (UE) conformance specification

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

6.2.2.1 Inter-RAT cell selection / From NR RRC_IDLE to EUTRA_Idle / Serving cell becomes non-suitable

6.2.2.1.1 Test Purpose (TP)

(1)

with { UE in NR RRC_IDLE state }

ensure that {

when { the serving cell becomes non-suitable and there is a suitable E-UTRA neighbour cell }

then { UE selects the suitable E-UTRA neighbour cell }

}

(2)

with { UE in NR RRC_IDLE state }

ensure that {

when { the serving cell becomes barred and there is a suitable E-UTRA neighbour cell }

then { UE selects the suitable E-UTRA neighbour cell }

}

6.2.2.1.2 Conformance requirements

References: The conformance requirements covered in the present TC are specified in: 3GPP TS 38.304, clause 5.2.1, 5.2.3.1, 5.2.3.2 and TS 36.304, clause 5.2.1, 5.2.3.1, 5.2.3.2. Unless otherwise stated these are Rel-15 requirements.

[TS 38.304, clause 5.2.1]

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).

[TS 38.304, clause 5.2.3.1]

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.

[TS 38.304, clause 5.2.3.2]

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, Qrxlevmin 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 Qrxlevmin 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.
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.

[TS 36.304, clause 5.2.1]

UE shall perform measurements for cell selection and reselection purposes as specified in TS 36.133 [10].

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 idle mode measurements and cell selection criteria.

In order to speed up the cell selection process, stored information for several RATs may be available in 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, or if the current and selected cell are both E-UTRA cells, a change of the CN type. Details on performance requirements for cell reselection can be found in TS 36.133 [10].

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

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

– Receive system information from the PLMN; and

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

– receive other AS and NAS Information; and

– if registered:

– receive paging and notification messages from the PLMN; and

– initiate transfer to connected mode.

[TS 36.304, clause 5.2.3.1]

The UE shall use one of the following two cell selection procedures:

a) Initial Cell Selection

This procedure requires no prior knowledge of which RF channels are E-UTRA or NB-IoT carriers. The UE shall scan all RF channels in the E-UTRA bands according to its capabilities to find a suitable cell. On each carrier frequency, the UE need only search for the strongest cell. Once a suitable cell is found this cell shall be selected.

b) Stored Information Cell Selection

This procedure requires stored information of carrier frequencies and optionally also information on cell parameters, from previously received measurement control information elements or from previously detected cells. Once the UE has found a suitable cell the UE shall select it. If no suitable cell is found the Initial Cell Selection procedure shall be started.

NOTE 1: Priorities between different frequencies or RATs provided to the UE by system information or dedicated signalling are not used in the cell selection process.

NOTE 2: If BL UE, UE in enhanced coverage or NB-IoT UE has been provisioned with EARFCN, the UE may use this information during Initial Cell Selection and Stored Information Cell Selection to find a suitable cell.

[TS 36.304, clause 5.2.3.2]

For NB-IoT the cell selection criterion is defined in clause 5.2.3.2a.

The cell selection criterion S in normal coverage is fulfilled when:

Srxlev > 0 AND Squal > 0

where:

Srxlev = Q_rxlevmeas – (Q_rxlevmin + Q_{rxlevminoffset}) – Pcompensation – 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 36.331 [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)
Q_qualmin	Minimum required quality level in the cell (dB)
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 TS 23.122 [5]
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 TS 23.122 [5]
Pcompensation	If the UE supports the additionalPmax in the NS-PmaxList, if present, in SIB1, SIB3 and SIB5: max(P_EMAX1 –P_PowerClass, 0) – (min(P_EMAX2, P_PowerClass) – min(P_EMAX1, P_PowerClass)) (dB); else: if P_PowerClass is 14 dBm: max(P_EMAX1–(P_PowerClass – Poffset), 0) (dB); else: max(P_EMAX1 –P_PowerClass, 0) (dB)
P_EMAX1, P_EMAX2	Maximum TX power level an UE may use when transmitting on the uplink in the cell (dBm) defined as P_EMAXin TS 36.101 [33]. P_EMAX1 and P_EMAX2 are obtained from the p-Max and the NS-PmaxList respectively in SIB1, SIB3 and SIB5 as specified in TS 36.331 [3].
P_PowerClass	Maximum RF output power of the UE (dBm) according to the UE power class as defined in TS 36.101 [33]

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 [5]. 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.

If cell selection criterion S in normal coverage is not fulfilled for a cell, UE shall consider itself to be in enhanced coverage if the cell selection criterion S for enhanced coverage is fulfilled, where:

Q_rxlevmin	UE applies coverage specific value Q_{rxlevmin_CE} (dBm)
Q_qualmin	UE applies coverage specific value Q_{qualmin_CE} (dB)

If cell selection criteria S in normal coverage is fulfilled for a cell, UE [may] consider itself to be in enhanced coverage if SystemInformationBlockType1 cannot be acquired but UE is able to acquire MasterInformationBlock, SystemInformationBlockType1-BR and SystemInformationBlockType2.

If cell selection criterion S in normal coverage is not fulfilled for a cell and UE does not consider itself in enhanced coverage based on coverage specific values Q_{rxlevmin_CE} and Q_{qualmin_CE}, UE shall consider itself to be in enhanced coverage if UE supports CE Mode B and CE mode B is not restricted by upper layers and the cell selection criterion S for enhanced coverage is fulfilled, where:

Q_rxlevmin	UE applies coverage specific value Q_{rxlevmin_CE1} (dBm)
Q_qualmin	UE applies coverage specific value Q_{qualmin_CE1} (dB)

For the UE in enhanced coverage, coverage specific values Q_{rxlevmin_CE}and Q_{qualmin_CE}(orQ_{rxlevmin_CE1}and Q_{qualmin_CE1})are only applied for the suitability check in enhanced coverage (i.e. not used for measurement and reselection thresholds).

6.2.2.1.3 Test description

6.2.2.1.3.1 Pre-test conditions

System Simulator:

– E-UTRA Cell 1, NR Cell 1.

– NR Cell 1 is configured to operate in FR1 bands as defined in TS 38.508-1 [4] clause 6.2.3.

– System information combination 31 as defined in TS 36.508-1 [7] clause 4.4.3.1 is used in E-UTRA Cell.

– System information combination NR-6 as defined in TS 38.508-1 [4] clause 4.4.3.1.3 is used in NR Cell.

UE:

– None.

Preamble:

– With E-UTRA Cell 1 "Serving cell" and NR Cell 1 "Non-suitable "Off" cell" in accordance with TS 38.508-1 [4], Table 6.2.2.1-3, the UE is brought to state RRC_IDLE using generic procedure parameters Connectivity (E-UTRA/EPC) and Unrestricted nr PDN (On) in accordance with the procedure described in TS 38.508-1 [4], clause 4.5.2. 4G GUTI and eKSI are assigned and security context established.

– the UE is switched-off.

– With E-UTRA Cell 1 "Non-suitable "Off" cell" and NR Cell 1 "Serving cell" in accordance with TS 38.508-1 [4], Table 6.2.2.1-3, the UE is brought to state 1N-A, RRC_IDLE Connectivity (NR), in accordance with the procedure described in TS 38.508-1 [4], Table 4.5.2.2-2. 5G-GUTI and ngKSI are assigned and security context established.

6.2.2.1.3.2 Test procedure sequence

Table 6.2.2.1.3.2-1 illustrates the downlink power levels and other changing parameters to be applied for the cell at various time instants of the test execution. The exact instants on which these values shall be applied are described in the texts in this clause. Row marked "T0" denotes the conditions in the preamble. Configurations marked "T1", "T2" and "T3" are applied at the points indicated in the Main behaviour description in Table 6.2.2.1.3.2-3.

Table 6.2.2.1.3.2-1: Time instances of cell power level and parameter changes for E-UTRA Cell 1 and NR Cell 1 in conducted test environment

	Parameter	Unit	E-UTRA Cell 1	NR Cell 1	Remark
T0	Cell-specific RS EPRE	dBm/15kHz	Off	–	The power level values are assigned to ensure UE registered on NR cell 1
T0	SS/PBCH SSS EPRE	dBm/SCS	–	-85
T1	Cell-specific RS EPRE	dBm/15kHz	-85	–	The power level value is such to satisfy Srxlev_{NR cell 1} < 0 and ensure UE registered on E-UTRA cell 1
T1	SS/PBCH SSS EPRE	dBm/SCS	–	-115
T2	Cell-specific RS EPRE	dBm/15kHz	Off	–	The power level values are assigned to ensure UE registered on NR cell 1
T2	SS/PBCH SSS EPRE	dBm/SCS	–	-85
T3	Cell-specific RS EPRE	dBm/15kHz	-85	–	The power level values are assigned to ensure UE registered on E-UTRA cell 1
T3	SS/PBCH SSS EPRE	dBm/SCS	–	-85
Note1: Power level “Off” is defined in TS 38.508-1 [4] Table 6.2.2.1-3.

Table 6.2.2.1.3.2-2: Void

Table 6.2.2.1.3.2-3: Main behaviour

St	Procedure	Message Sequence		TP	Verdict
		U – S	Message
1	The SS adjusts the E-UTRA and NR Cells power levels according to row "T1" in table 6.2.2.1.3.2-1.	–	–	–	–
2	Check: Does the test result of generic test procedure in TS 38.508-1 [4] Table 4.9.7.2.2-1 indicate that the UE is camped on E-UTRA Cell 1?	–	–	1	P
3	The SS adjusts the E-UTRA and NR Cells power levels according to row "T2" in table 6.2.2.1.3.2-1.	–	–	–	–
4	The test result of generic test procedure in TS 38.508-1 [4] Table 4.9.9.2.2-1 indicate that the UE is camped on NR Cell 1. (NOTE 1)	–	–	–	–
5	The SS changes SIB1 of NR Cell 1 according to table 6.2.2.1.3.3-3 and notifies the UE of change of System Information on NR Cell 1 by sending Short Message on PDCCH using P-RNTI.	<–	PDCCH (DCI 1_0): Short Message	–	–
6	Wait for 2.1* modification period to allow the new system information to take effect.	–	–	–	–
7	The SS adjusts the NR and E-UTRAN Cell power levels according to row "T3" in table 6.2.2.1.3.2-1.	–	–	–	–
8	Check: Does the test result of generic test procedure in TS 38.508-1 [4] Table 4.9.7.2.2-1 indicate that the UE is camped on E-UTRA Cell 1?	–	–	2	P
Note 1: This is the first time in this test case that the UE moves from S1 to N1.

6.2.2.1.3.3 Specific message contents

Table 6.2.2.1.3.3-1: SIB5 of NR Cell 1(preamble and all steps, Table 6.2.2.1.3.2-3)

Derivation Path: TS 38.508-1 [4], Table 4.6.2-4
Information Element	Value/remark	Comment	Condition
SIB5 ::= SEQUENCE {
carrierFreqListEUTRA SEQUENCE (SIZE (1..maxEUTRA-Carrier)) OF CarrierFreqEUTRA {	1 entry
CarrierFreqEUTRA[1] SEQUENCE {		entry 1
carrierFreq	Downlink EUTRA ARFCN as E-UTRA Cell 1 used
}
}
}

Table 6.2.2.1.3.3-2: SystemInformationBlockType24 of EUTRA Cell 1 (preamble and all steps, Table 6.2.2.1.3.2-3)

Derivation path: TS 36.508 [7], Table 4.4.3.3-20
Information Element	Value/Remark	Comment	Condition
SystemInformationBlockType24-r15 ::= SEQUENCE {
carrierFreqListNR-r15 SEQUENCE (SIZE (1..maxFreq)) OF CarrierFreqNR-r15 {	1 entry
CarrierFreqNR-r15[1] SEQUENCE {		entry 1
carrierFreq-r15	Same downlink SSB ARFCN as used for NR Cell 1
}
}
}

Table 6.2.2.1.3.3-3: SIB1 for NR Cell 1 (step 5, Table 6.2.2.1.3.2-3)

Derivation Path: TS 38.508-1 [4], Table 4.6.1-28
Information Element	Value/remark	Comment	Condition
SIB1 ::= SEQUENCE {
cellAccessRelatedInfo SEQUENCE {
cellReservedForOtherUse	true	The UE shall treat this cell as if cell status is "barred"
}
}

Table 6.2.2.1.3.3-4: REGISTRATION REQUEST (step 4, Table 6.2.2.1.3.2-3)

Derivation Path: TS 38.508-1 [4], Table 4.9.9.2.3-1.
Information Element	Value/remark	Comment	Condition
EPS NAS message container	TRACKING AREA UPDATE REQUEST message	See Table 6.2.2.1.3.3-5

Table 6.2.2.1.3.3-5: TRACKING AREA UPDATE REQUEST (Table 6.2.2.1.3.3-4)

Derivation Path: TS 38.508-1 [4], Table 4.9.9.2.3-2 with condition Mapped EPS security context.

6.2.2.2 Inter-RAT cell selection / From E-UTRA_Idle to NR RRC_IDLE / Serving cell becomes non-suitable

6.2.2.2.1 Test Purpose (TP)

(1)

with { UE in E-UTRA RRC_IDLE state }

ensure that {

when { the serving cell becomes non-suitable and there is a suitable NR neighbour cell }

then { UE selects the suitable NR neighbour cell }

}

(2)

with { UE in E-UTRA RRC_IDLE state }

ensure that {

when { the serving cell becomes barred and there is a suitable NR neighbour cell }

then { UE selects the suitable NR neighbour cell }

}

6.2.2.2.2 Conformance requirements

[TS 38.304, clause 5.2.1]

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

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

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.

– 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:

[TS 38.304, clause 5.2.3.1]

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:

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.

[TS 38.304, clause 5.2.3.2]

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, Qrxlevmin 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 Qrxlevmin 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.
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].

[TS 36.304, clause 5.2.1]

UE shall perform measurements for cell selection and reselection purposes as specified in TS 36.133 [10].

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 idle mode measurements and cell selection criteria.

In order to speed up the cell selection process, stored information for several RATs may be available in 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, or if the current and selected cell are both E-UTRA cells, a change of the CN type. Details on performance requirements for cell reselection can be found in TS 36.133 [10].

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

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

– Receive system information from the PLMN; and

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

– receive other AS and NAS Information; and

– if registered:

– receive paging and notification messages from the PLMN; and

– initiate transfer to connected mode.

[TS 36.304, clause 5.2.3.1]

The UE shall use one of the following two cell selection procedures:

a) Initial Cell Selection

b) Stored Information Cell Selection

NOTE 1: Priorities between different frequencies or RATs provided to the UE by system information or dedicated signalling are not used in the cell selection process.

[TS 36.304, clause 5.2.3.2]

For NB-IoT the cell selection criterion is defined in clause 5.2.3.2a.

The cell selection criterion S in normal coverage is fulfilled when:

Srxlev > 0 AND Squal > 0

where:

Srxlev = Q_rxlevmeas – (Q_rxlevmin + Q_{rxlevminoffset}) – Pcompensation – 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 36.331 [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)
Q_qualmin	Minimum required quality level in the cell (dB)
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 TS 23.122 [5]
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 TS 23.122 [5]
Pcompensation	If the UE supports the additionalPmax in the NS-PmaxList, if present, in SIB1, SIB3 and SIB5: max(P_EMAX1 –P_PowerClass, 0) – (min(P_EMAX2, P_PowerClass) – min(P_EMAX1, P_PowerClass)) (dB); else: if P_PowerClass is 14 dBm: max(P_EMAX1–(P_PowerClass – Poffset), 0) (dB); else: max(P_EMAX1 –P_PowerClass, 0) (dB)
P_EMAX1, P_EMAX2	Maximum TX power level an UE may use when transmitting on the uplink in the cell (dBm) defined as P_EMAXin TS 36.101 [33]. P_EMAX1 and P_EMAX2 are obtained from the p-Max and the NS-PmaxList respectively in SIB1, SIB3 and SIB5 as specified in TS 36.331 [3].
P_PowerClass	Maximum RF output power of the UE (dBm) according to the UE power class as defined in TS 36.101 [33]

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 [5]. 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.

Q_rxlevmin	UE applies coverage specific value Q_{rxlevmin_CE} (dBm)
Q_qualmin	UE applies coverage specific value Q_{qualmin_CE} (dB)

Q_rxlevmin	UE applies coverage specific value Q_{rxlevmin_CE1} (dBm)
Q_qualmin	UE applies coverage specific value Q_{qualmin_CE1} (dB)

6.2.2.2.3 Test description

6.2.2.2.3.1 Pre-test conditions

System Simulator:

– E-UTRA Cell 1, NR Cell 1.

– NR Cell 1 is configured to operate in FR1 bands as defined in TS 38.508-1 [4] clause 6.2.3.

– System information combination 31 as defined in TS 36.508-1 [7] clause 4.4.3.1 is used in E-UTRA Cell.

– System information combination NR-6 as defined in TS 38.508-1 [4] clause 4.4.3.1.3 is used in NR Cell.

UE:

– None.

Preamble:

– With E-UTRA Cell 1 "Non-suitable "Off" cell" and NR Cell 1 "Serving cell" in accordance with TS 38.508-1 [4], Table 6.2.2.2-3, the UE is brought to state 1N-A, RRC_IDLE Connectivity (NR), in accordance with the procedure described in TS 38.508-1 [4], Table 4.5.2.2-2. 5G-GUTI and ngKSI are assigned and security context established.

– The UE is switched-off

– With E-UTRA Cell 1 "Serving cell" and NR Cell 1 "Non-suitable "Off" cell" in accordance with TS 38.508-1 [4], Table 6.2.2.2-3, the UE is brought to state RRC_IDLE using generic procedure parameters Connectivity (E-UTRA/EPC) and Unrestricted nr PDN (On) in accordance with the procedure described in TS 38.508-1 [4], clause 4.5.2. 4G GUTI and eKSI are assigned and security context established.

6.2.2.2.3.2 Test procedure sequence

Table 6.2.2.2.3.2-1 illustrates the downlink power levels and other changing parameters to be applied for the cell at various time instants of the test execution. The exact instants on which these values shall be applied are described in the texts in this clause. Row marked "T0" denotes the conditions in the preamble. Configurations marked "T1", "T2" and "T3" are applied at the points indicated in the Main behaviour description in Table 6.2.2.2.3.2-3.

Table 6.2.2.2.3.2-1: Time instances of cell power level and parameter changes for E-UTRA Cell 1 and NR Cell 1 in conducted test environment

	Parameter	Unit	E-UTRA Cell 1	NR Cell 1	Remark
T0	Cell-specific RS EPRE	dBm/15kHz	-85	–	The power level values are assigned to ensure UE registered on E-UTRA cell 1
T0	SS/PBCH SSS EPRE	dBm/SCS	–	Off
T1	Cell-specific RS EPRE	dBm/15kHz	-115	–	The power level value is such to satisfy Srxlev_{E-UTRA cell 1} < 0 and ensure UE registered on NR cell 1
T1	SS/PBCH SSS EPRE	dBm/SCS	–	-85
T2	Cell-specific RS EPRE	dBm/15kHz	-85	–	The power level values are assigned to ensure UE registered on E-UTRA cell 1
T2	SS/PBCH SSS EPRE	dBm/SCS	–	Off
T3	Cell-specific RS EPRE	dBm/15kHz	-85	–	The power level values are assigned to ensure UE registered on NR cell 1
T3	SS/PBCH SSS EPRE	dBm/SCS	–	-85
Note1: Power level “Off” is defined in TS 38.508-1 [4] Table 6.2.2.1-3.

Table 6.2.2.2.3.2-2: Void

Table 6.2.2.2.3.2-3: Main behaviour

St	Procedure	Message Sequence		TP	Verdict
		U – S	Message
1	The SS adjusts the E-UTRA and NR Cells power levels according to row "T1" in table 6.2.2.2.3.2-1.	–	–	–	–
2	Check: Does the test result of generic test procedure in TS 38.508-1 [4] Table 4.9.9.2.2-1 indicate that the UE is camped on NR Cell 1?. (NOTE 1)	–	–	1	P
3	The SS adjusts the E-UTRA and NR Cells power levels according to row "T2" in table 6.2.2.2.3.2-1.	–	–	–	–
4	The test result of generic test procedure in TS 38.508-1 [4] Table 4.9.7.2.2-1 indicate that the UE is camped on E-UTRA Cell 1.	–	–	–	–
5	The SS changes SystemInformationBlockType1 of E-UTRA Cell 1 according to table 6.2.2.2.3.3-3 and notifies the UE of change of System Information on E-UTRA Cell 1.	<–	Paging	–	–
6	The SS adjusts the E-UTRA and NR Cells power levels according to row "T3" in table 6.2.2.2.3.2-1.	–	–	–	–
7	Check: Does the test result of generic test procedure in TS 38.508-1 [4] Table 4.9.9.2.2-1 indicate that the UE is camped on NR Cell 1?	–	–	2	P
Note 1: This is the first time in this test case that the UE moves from S1 to N1.

6.2.2.2.3.3 Specific message contents

Table 6.2.2.2.3.3-1: SIB5 of NR Cell 1(preamble and all steps, Table 6.2.2.2.3.2-3)

Derivation Path: TS 38.508-1 [4], Table 4.6.2-4
Information Element	Value/remark	Comment	Condition
SIB5 ::= SEQUENCE {
carrierFreqListEUTRA SEQUENCE (SIZE (1..maxEUTRA-Carrier)) OF CarrierFreqEUTRA {
CarrierFreqEUTRA[1] SEQUENCE {		entry 1
carrierFreq	Downlink EUTRA ARFCN as E-UTRA Cell 1 used
}
}
}

Table 6.2.2.2.3.3-2: SystemInformationBlockType24 of EUTRA Cell 1 (preamble and all steps, Table 6.2.2.2.3.2-3)

Derivation path: TS 36.508 [7], Table 4.4.3.3-20
Information Element	Value/Remark	Comment	Condition
SystemInformationBlockType24-r15 ::= SEQUENCE {
carrierFreqListNR-r15 SEQUENCE (SIZE (1..maxFreq)) OF CarrierFreqNR-r15 {	1 entry
CarrierFreqNR-r15[1] SEQUENCE {		entry 1
carrierFreq-r15	Same downlink SSB ARFCN as used for NR Cell 1
}
}
}

Table 6.2.2.2.3.3-3: SystemInformationBlockType1 for E-UTRA Cell 1 (step 5, Table 6.2.2.2.3.2-3)

Derivation Path: TS 36.508-1 [7], Table 4.4.3.2-3
Information Element	Value/remark	Comment	Condition
SystemInformationBlockType1 ::= SEQUENCE {
cellAccessRelatedInfo SEQUENCE {
cellBarred	barred
}
}

Table 6.2.2.2.3.3-4: REGISTRATION REQUEST (step 4, Table 6.2.2.2.3.2-3)

Derivation Path: TS 38.508-1 [4], Table 4.9.9.2.3-1.
Information Element	Value/remark	Comment	Condition
EPS NAS message container	TRACKING AREA UPDATE REQUEST message	See Table 6.2.2.2.3.3-5

Table 6.2.2.2.3.3-5: TRACKING AREA UPDATE REQUEST (Table 6.2.2.2.3.3-4)

Derivation Path: TS 38.508-1 [4], Table 4.9.9.2.3-2 with condition Mapped EPS security context.