6.2.3 Inter-RAT Cell Reselection

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

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

6.2.3.1 Inter-RAT cell reselection / From E-UTRA_IDLE to NR RRC_IDLE (lower priority & higher priority, Srxlev based)

6.2.3.1.1 Test Purpose (TP)`

(1)

with { UE in E-UTRA RRC_Idle state }

ensure that {

when { UE detects the cell re-selection criteria are met for the cell which belongs to the lower priority inter-RAT NR cell }

then { UE reselects the cell which belongs to the lower priority inter-RAT NR cell }

}

(2)

with { UE in E-UTRA RRC_Idle state }

ensure that {

when { UE detects the cell re-selection criteria are met for the cell which belongs to the higher priority inter-RAT NR cell }

then { UE reselects the cell which belongs to the higher priority inter-RAT NR cell }

}

6.2.3.1.2 Conformance requirements

References: The conformance requirements covered in the present TC are specified in: 3GPP TS 36.304, clause 5.2.4.1, 5.2.4.2 and 5.2.4.5. Unless otherwise stated these are Rel-15 requirements.

[TS 36.304, clause 5.2.4.1]

Absolute priorities of different E-UTRAN frequencies or inter-RAT frequencies may be provided to the UE in the system information, in the RRCConnectionRelease message, or by inheriting from another RAT at inter-RAT cell (re)selection. In the case of system information, an E-UTRAN frequency or inter-RAT frequency may be listed without providing a priority (i.e. the field cellReselectionPriority is absent for that frequency). If priorities are provided in dedicated signalling, the UE shall ignore all the priorities provided in system information. 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 RRCConnectionReject 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). While the UE is camped on a suitable CSG cell in normal coverage, the UE shall always consider the current frequency to be the highest priority frequency (i.e. higher than any of the network configured values), irrespective of any other priority value allocated to this frequency. 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 network configured priorities). If the UE capable of sidelink communication is configured to perform sidelink communication and can only perform the sidelink communication while camping on a frequency, the UE may consider that frequency to be the highest priority. If the UE capable of V2X sidelink communication is configured to perform V2X sidelink communication and can only perform the V2X sidelink communication while camping on a frequency, the UE may consider that frequency to be the highest priority. If the UE capable of V2X sidelink communication is configured to perform V2X sidelink communication and can only use pre-configuration while not camping on a frequency, the UE may consider the frequency providing inter-carrier V2X sidelink configuration to be the highest priority. If the UE capable of sidelink discovery is configured to perform Public Safety related sidelink discovery and can only perform the Public Safety related sidelink discovery while camping on a frequency, the UE may consider that frequency to be the highest priority.

NOTE 1: The prioritization among the frequencies which UE considers to be the highest priority frequency is left to UE implementation.

If the UE is capable either of MBMS Service Continuity or of SC-PTM reception and is receiving or interested to receive an MBMS service and can only receive this MBMS service while camping on a frequency on which it is provided, the UE may consider that frequency to be the highest priority during the MBMS session TS 36.300 [2] as long as the two following conditions are fulfilled:

1) Either:

– the UE is capable of MBMS service continuity and the reselected cell is broadcasting SIB13; or

– the UE is capable of SC-PTM reception and the reselected cell is broadcasting SIB20;

2) Either:

– SIB15 of the serving cell indicates for that frequency one or more MBMS SAIs included and associated with that frequency in the MBMS User Service Description (USD) TS 26.346 [22] of this service; or

– SIB15 is not broadcast in the serving cell and that frequency is included in the USD of this service.

If the UE is capable either of MBMS Service Continuity or of SC-PTM reception and is receiving or interested to receive an MBMS service provided on a downlink only MBMS frequency, on a frequency used by dedicated MBMS cells, on a frequency used by FeMBMS/Unicast-mixed cells as defined in TS 36.300 [2], or on a frequency belonging to PLMN different from its registered PLMN, the UE may consider cell reselection candidate frequencies at which it can not receive the MBMS service to be of the lowest priority during the MBMS session TS 36.300 [2], as long as the above mentioned condition 1) is fulfilled for the cell on the MBMS frequency which the UE monitors or this cell broadcasts SIB1-MBMS and as long as the above mentioned condition 2) is fulfilled for the serving cell.

NOTE 2: Example scenarios in which the previous down-prioritisation may be needed concerns the cases where camping is not possible, while the UE can only receive this MBMS frequency when camping on a subset of cell reselection candidate frequencies, e.g. the MBMS frequency is a downlink only carrier, the MBMS frequency is used by dedicated MBMS cells, the MBMS frequency is used by FeMBMS/Unicast-mixed cells TS 36.300 [2], or the MBMS frequency belongs to a PLMN different from UE’s registered PLMN.

If the UE is not capable of MBMS Service Continuity but has knowledge on which frequency an MBMS service of interest is provided, it may consider that frequency to be the highest priority during the MBMS session TS 36.300 [2] as long as the reselected cell is broadcasting SIB13.

If the UE is not capable of MBMS Service Continuity but has knowledge on which downlink only frequency, on which frequency used by dedicated MBMS cells, on which frequency used by FeMBMS/Unicast-mixed cells as defined in TS 36.300 [2] or on which frequency belonging to PLMN different from its registered PLMN an MBMS service of interest is provided, it may consider cell reselection candidate frequencies at which it can not receive the MBMS service to be of the lowest priority during the MBMS session TS 36.300 [2] as long as the cell on the MBMS frequency which the UE monitors is broadcasting SIB13 or SIB1-MBMS.

NOTE 3: The UE considers that the MBMS session is ongoing using the session start and end times as provided by upper layers in the USD i.e. the UE does not verify if the session is indicated on MCCH.

In case UE receives RRCConnectionReject with deprioritisationReq, UE shall consider current carrier frequency and stored frequencies due to the previously received RRCConnectionReject with deprioritisationReq or all the frequencies of EUTRA 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 is performed on request by NAS TS 23.122 [5].

NOTE 4: Connecting to CDMA2000 does not imply PLMN selection.

NOTE 5: 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 36.133 [10] 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

– a PLMN selection is performed on request by NAS TS 23.122 [5].

NOTE 6: Equal priorities between RATs are not supported.

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

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

The UE shall inherit the priorities provided by dedicated signalling and the remaining validity time (i.e., T320 in E-UTRA and NR, T322 in UTRA and T3230 in GERAN), if configured, at inter-RAT cell (re)selection.

NOTE 7: The network may assign dedicated cell reselection priorities for frequencies not configured by system information.

While T360 is running, redistribution target is considered to be the highest priority (i.e. higher than any of the network configured values). UE shall continue to consider the serving frequency as the highest priority until completion of E-UTRAN Inter-frequency Redistribution procedure specified in 5.2.4.10 if triggered on T360 expiry/ stop.

[TS 36.304, clause 5.2.4.2]

For NB-IoT measurement rules for cell re-selection is defined in sub-clause 5.2.4.2.a.

When evaluating Srxlev and Squal of non-serving cells for reselection purposes, the UE shall use parameters provided by the serving cell.

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

– If the serving cell fulfils Srxlev> S_IntraSearchP and Squal > S_IntraSearchQ, the UE may choose not to perform intra-frequency measurements.

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

– The UE shall apply the following rules for E-UTRAN 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 an E-UTRAN inter-frequency or inter-RAT frequency with a reselection priority higher than the reselection priority of the current E-UTRA frequency the UE shall perform measurements of higher priority E-UTRAN inter-frequency or inter-RAT frequencies according to TS 36.133 [10].

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

– If the serving cell fulfils Srxlev > S_{nonIntraSearchP} and Squal > S_{nonIntraSearchQ}, the UE may choose not to perform measurements of E-UTRAN inter-frequencies or inter-RAT frequency cells of equal or lower priority unless the UE is triggered to measure an E-UTRAN inter-frequency which is configured with redistributionInterFreqInfo.

– Otherwise, the UE shall perform measurements of E-UTRAN inter-frequencies or inter-RAT frequency cells of equal or lower priority according to TS 36.133 [10].

– If the UE supports relaxed monitoring and s-SearchDeltaP is present in SystemInformationBlockType3, the UE may further limit the needed measurements, as specified in sub-clause 5.2.4.12.

[TS 36.304, clause 5.2.4.5]

For NB-IoT inter-frequency cell reselection shall be based on ranking as defined in sub-clause 5.2.4.6.

If threshServingLowQ is provided in SystemInformationBlockType3 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 E-UTRAN frequency or inter-RAT frequency than the serving frequency shall be performed if:

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

– A cell of a higher priority UTRAN TDD, GERAN or CDMA2000 RAT/ frequency fulfils Srxlev > Thresh_{X, HighP} during a time interval Treselection_RAT.

Otherwise, cell reselection to a cell on a higher priority E-UTRAN 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 E-UTRAN frequency shall be based on ranking for Intra-frequency cell reselection as defined in sub-clause 5.2.4.6.

If threshServingLowQ is provided in SystemInformationBlockType3 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 E-UTRAN 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 EUTRAN, NR or UTRAN FDD RAT/ frequency fulfils Squal > Thresh_{X, LowQ} during a time interval Treselection_RAT; or

– The serving cell fulfils Squal < Thresh_{Serving, LowQ} and a cell of a lower priority UTRAN TDD, GERAN or CDMA2000 RAT/ frequency fulfils Srxlev > Thresh_{X, LowP} during a time interval Treselection_RAT.

Otherwise, cell reselection to a cell on a lower priority E-UTRAN 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.

The UE shall not perform cell reselection to NR or UTRAN FDD cells for which the cell selection criterion S is not fulfilled.

For cdma2000 RATs, Srxlev is equal to -FLOOR(-2 x 10 x log10 Ec/Io) in units of 0.5 dB, as defined in [18], with Ec/Io referring to the value measured from the evaluated cell.

For cdma2000 RATs, Thresh_{X, HighP} and Thresh_{X, LowP} are equal to -1 times the values signalled for the corresponding parameters in the system information.

In all the above criteria the value of Treselection_RAT is scaled when the UE is in the medium or high mobility state as defined in subclause 5.2.4.3.1. If more than one cell meets the above criteria, the UE shall reselect a cell as follows:

– If the highest-priority frequency is an E-UTRAN frequency, a cell ranked as the best 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, a cell ranked as the best cell among the cells on the highest priority frequency(ies) meeting the criteria of that RAT.

Cell reselection to another RAT, for which Squal based cell reselection parameters are broadcast in system information, shall be performed based on the Squal criteria if the UE supports Squal (RSRQ) based cell reselection to E-UTRAN from all the other RATs provided by system information which UE supports. Otherwise, cell reselection to another RAT shall be performed based on Srxlev criteria.

Cell reselection to NR, for which a cell reselection parameter, q-RxLevMinSUL is broadcast in system information and the UE supports SUL, shall be performed based on Srxlev criteria taking the parameter into account.

6.2.3.1.3 Test description

6.2.3.1.3.1 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 "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.

– 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 6.2.2.1-3, 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.

6.2.3.1.3.2 Test procedure sequence

Table 6.2.3.1.3.2-1 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 6.2.3.1.3.2-3.

Table 6.2.3.1.3.2-1: 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	-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	-95	–	The power level values are assigned to satisfy both Srxlev_{NR Cell 1} > Thresh_{x, low} and Srxlev_{E-UTRA Cell 1} < Thresh_{serving, low}
T1	SS/PBCH SSS EPRE	dBm/SCS	–	-80
T2	Cell-specific RS EPRE	dBm/15kHz	-80	–	The power level values are assigned to ensure UE registered on E-UTRA cell 1
T2	SS/PBCH SSS EPRE	dBm/SCS	–	-95	, Srxlev_{E-UTRA Cell 1} > Thresh_{x, high}
T3	Cell-specific RS EPRE	dBm/15kHz	-95	–	The Priority and power level values are assigned to satisfy Srxlev_{NR Cell 1} > Thresh_{x, high}
T3	SS/PBCH SSS EPRE	dBm/SCS	–	-80
Note1: Power level “Off” is defined in TS 38.508-1 [4] Table 6.2.2.1-3.

Table 6.2.3.1.3.2-2: Void

Table 6.2.3.1.3.2-3: Main behaviour

St	Procedure	Message Sequence		TP	Verdict
		U – S	Message
1	The SS adjusts the E-UTRAN and NR Cell power levels according to row "T1" in table 6.2.3.1.3.2-1.	–	–	–	–
2	Wait for 1 second to allow UE to recognise the change.	–	–	–	–
3	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?	–	–	1	P
4	Void.	–	–	–	–
5	The SS adjusts the E-UTRAN and NR Cell power levels according to row "T2" in table 6.2.3.1.3.2-1.	–	–	–	–
6	Wait for 1 second to allow UE to recognise the change.	–	–	–	–
7	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-UTRAN Cell 1.	–	–	–	–
7A	The SS changes Priority of NR cell 1 in SystemInformationBlockType24. And the systemInfoValueTag in the SystemInformationBlockType1 of E-UTRA Cell 1 is increased.	–	–	–	–
8	The SS notifies the UE of change of System Information on E-UTRAN Cell 1.	<–	Paging	–	–
9	Void	–	–	–	–
10	Wait for 6 s for UE to receive system information.	–	–	–	–
11	The SS re-adjusts the E-UTRAN and NR Cell levels according to row "T3" in table 6.2.3.1.3.2-1.	–	–	–	–
12	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
13	Void.	–	–	–	–

6.2.3.1.3.3 Specific message contents

Table 6.2.3.1.3.3-1: SystemInformationBlockType3 of EUTRA Cell 1 (preamble and all steps, Table 6.2.3.1.3.2-3)

Derivation Path: TS 36.508 [7], Table 4.4.3.3-2
Information Element	Value/remark	Comment	Condition
SystemInformationBlockType3 ::= SEQUENCE {
cellReselectionServingFreqInfo SEQUENCE {
threshServingLow	10	20 dB
}
}

Table 6.2.3.1.3.3-2: SystemInformationBlockType24 of EUTRA Cell 1 (preamble, Table 6.2.3.1.3.2-3)

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	Downlink NR ARFCN of SSB for NR Cell 1
cellReselectionPriority-r15	3
threshX-High-r15	20	40 dB
threshX-Low-r15	10	20 dB
}
}
t-ReselectionNR-r15	7
}

Table 6.2.3.1.3.3-3: SIB2 of NR Cell 1(preamble and all steps, Table 6.2.3.1.3.2-3)

Derivation Path: TS 38.508-1 [4], Table 4.6.2-1
Information Element	Value/remark	Comment	Condition
SIB2 ::= SEQUENCE {
cellReselectionServingFreqInfo SEQUENCE {
threshServingLowP	10	20 dB
cellReselectionPriority	3
}
}

Table 6.2.3.1.3.3-4: SIB5 of NR Cell 1(preamble and all steps, Table 6.2.3.1.3.2-3)

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
cellReselectionPriority	5
threshX-High	10	20 dB
threshX-Low	20	40 dB
}
}
t-ReselectionEUTRA	7
}

Table 6.2.3.1.3.3-5: Paging (step 8, Table 6.2.3.1.3.2-3)

Derivation path: TS 36.508 [7], Table 4.6.1-7
Information Element	Value/Remark	Comment	Condition
Paging ::= SEQUENCE {
systemInfoModification	True
}

Table 6.2.3.1.3.3-6: SystemInformationBlockType1 of EUTRA Cell 1 (step 7A, Table 6.2.3.1.3.2-3)

Derivation Path: TS 36.508 [7], Table 4.4.3.2-3
Information Element	Value/remark	Comment	Condition
SystemInformationBlockType1 ::= SEQUENCE {
systemInfoValueTag	1	Previous value is 0
}

Table 6.2.3.1.3.3-7: SystemInformationBlockType24 of EUTRA Cell 1 (step 7A, Table 6.2.3.1.3.2-3)

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
cellReselectionPriority-r15	5
threshX-High-r15	10	20 dB
threshX-Low-r15	20	40 dB
}
}
t-ReselectionNR-r15	7	7 Seconds
}

Table 6.2.3.1.3.3-8: TRACKING AREA UPDATE REQUEST (Step 7, Table 6.2.3.1.3.2-3)

Derivation Path: TS 38.508-1 [4], Table 4.9.7.2.3-1
Information Element	Value/remark	Comment	Condition
EPS update type
EPS update type Value	‘010’B	Combined TA/LA updating	combined_TA_LA
EPS update type Value	‘000’B	TA updating	TA_only
NOTE: The message shall be integrity protected using the 5GS security context available in the UE.

Condition	Explanation
TA_only	This condition applies if the UE is configured to initiate EPS attach or if explicitly specified.
combined_TA_LA	This condition applies if the UE is configured to initiate combined EPS/IMSI attach or if explicitly specified.

Table 6.2.3.1.3.3-9: REGISTRATION REQUEST (Step 12, Table 6.2.3.1.3.2-3)

Derivation Path: TS 38.508-1 [4], Table 4.7.1-6.
Information Element	Value/remark	Comment	Condition
EPS NAS message container	TRACKING AREA UPDATE REQUEST message	See Table 6.2.3.1.3.3-10

Table 6.2.3.1.3.3-10: TRACKING AREA UPDATE REQUEST (Table 6.2.3.1.3.3-9)

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

6.2.3.2 Inter-RAT cell reselection / From E-UTRA_IDLE to NR RRC_IDLE (lower priority & higher priority, Squal based)

6.2.3.2.1 Test Purpose (TP)

(1)

with { UE in E-UTRA RRC_IDLE state }

ensure that {

when { UE detects the cell re-selection criteria are met for the cell which belongs to the lower priority inter-RAT NR cell}

then { UE reselects the cell which belongs to the lower priority inter-RAT NR cell }

}

(2)

with { UE in E-UTRA RRC_IDLE state }

ensure that {

when { UE detects the cell re-selection criteria are met for the cell which belongs to the higher priority inter-RAT NR cell}

then { UE reselects the cell which belongs to the higher priority inter-RAT NR cell }

}

6.2.3.2.2 Conformance requirements

References: The conformance requirements covered in the present TC are specified in: 3GPP TS 36.304, clause 5.2.4.1, 5.2.4.2 and 5.2.4.5. Unless otherwise stated these are Rel-15 requirements.

[TS 36.304, clause 5.2.4.1]

NOTE 1: The prioritization among the frequencies which UE considers to be the highest priority frequency is left to UE implementation.

1) Either:

– the UE is capable of MBMS service continuity and the reselected cell is broadcasting SIB13; or

– the UE is capable of SC-PTM reception and the reselected cell is broadcasting SIB20;

2) Either:

– SIB15 is not broadcast in the serving cell and that frequency is included in the USD of this service.

NOTE 3: The UE considers that the MBMS session is ongoing using the session start and end times as provided by upper layers in the USD i.e. the UE does not verify if the session is indicated on MCCH.

NOTE 4: Connecting to CDMA2000 does not imply PLMN selection.

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

– a PLMN selection is performed on request by NAS TS 23.122 [5].

NOTE 6: Equal priorities between RATs are not supported.

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

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

NOTE 7: The network may assign dedicated cell reselection priorities for frequencies not configured by system information.

[TS 36.304, clause 5.2.4.2]

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

– If the serving cell fulfils Srxlev> S_IntraSearchP and Squal > S_IntraSearchQ, the UE may choose not to perform intra-frequency measurements.

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

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