ETSI TS 138 304 V15.4.0 (2019-07)

5G; NR; User Equipment (UE) procedures in idle mode and in RRC Inactive state (3GPP TS 38.304 version 15.4.0 Release 15)

RTS/TSGR-0238304vf40

General Information

• Status: Published
• Publication Date: 24-Jul-2019
• Technical Committee: 3GPP RAN 2 - Radio layer 2 specification and Radio layer 3 RR specification
• Current Stage: 12 - Completion
• Completion Date: 25-Jul-2019

Standards Content (Sample)

TECHNICAL SPECIFICATION
5G;
NR;
User Equipment (UE) procedures in idle mode and in RRC
Inactive state
(3GPP TS 38.304 version 15.4.0 Release 15)

3GPP TS 38.304 version 15.4.0 Release 15 1 ETSI TS 138 304 V15.4.0 (2019-07)

Reference
RTS/TSGR-0238304vf40
Keywords
5G
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3GPP TS 38.304 version 15.4.0 Release 15 2 ETSI TS 138 304 V15.4.0 (2019-07)
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Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 5
1 Scope . 6
2 References . 6
3 Definitions, symbols and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 7
4 General description of RRC_IDLE state and RRC_INACTIVE state . 8
4.1 Overview . 8
4.2 Functional division between AS and NAS in RRC_IDLE state and RRC_INACTIVE state . 9
4.3 Service types in RRC_IDLE state . 12
4.4 Service types in RRC_INACTIVE state . 12
4.5 Cell Categories . 12
5 Process and procedure descriptions . 13
5.1 PLMN selection . 13
5.1.1 Support for PLMN selection . 13
5.1.1.1 General . 13
5.1.1.2 NR case . 13
5.1.1.3 E-UTRA case . 13
5.2 Cell selection and reselection . 13
5.2.1 Introduction. 13
5.2.2 States and state transitions in RRC_IDLE state and RRC_INACTIVE state . 15
5.2.3 Cell Selection process . 16
5.2.3.1 Description . 16
5.2.3.2 Cell Selection Criterion . 16
5.2.3.3 E-UTRAN case in Cell Selection . 17
5.2.4 Cell Reselection evaluation process . 17
5.2.4.1 Reselection priorities handling . 17
5.2.4.2 Measurement rules for cell re-selection . 18
5.2.4.3 Mobility states of a UE . 18
5.2.4.3.0 Introduction . 18
5.2.4.3.1 Scaling rules . 19
5.2.4.4 Cells with cell reservations, access restrictions or unsuitable for normal camping. 20
5.2.4.5 NR Inter-frequency and inter-RAT Cell Reselection criteria . 20
5.2.4.6 Intra-frequency and equal priority inter-frequency Cell Reselection criteria . 21
5.2.4.7 Cell reselection parameters in system information broadcasts . 21
5.2.4.7.0 General reselection parameters . 21
5.2.4.7.1 Speed dependent reselection parameters . 23
5.2.4.8 Inter-RAT Cell reselection in RRC_INACTIVE state . 24
5.2.5 Camped Normally state . 24
5.2.6 Selection of cell at transition to RRC_IDLE or RRC_INACTIVE state . 24
5.2.7 Any Cell Selection state . 24
5.2.8 Camped on Any Cell state . 24
5.3 Cell Reservations and Access Restrictions . 25
5.3.0 Introduction. 25
5.3.1 Cell status and cell reservations . 25
5.3.2 Unified access control . 26
5.4 Tracking Area registration . 26
5.5 RAN Area registration . 26
6 Reception of broadcast information . 26
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6.1 Reception of system information . 26
7 Paging . 27
7.1 Discontinuous Reception for paging . 27
Annex A (informative): Change history . 29
History . 30

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Foreword
This Technical Specification has been produced by the 3rd Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
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1 Scope
The present document specifies the Access Stratum (AS) part of the UE procedures in RRC_IDLE state (also called Idle
mode) and RRC_INACTIVE state. The non-access stratum (NAS) part of Idle mode procedures and processes is
specified in TS 23.122 [9].
The present document specifies the model for the functional division between the NAS and AS in a UE.
The present document applies to all UEs that support at least NR Radio Access, including multi-RAT UEs as described
in 3GPP specifications, in the following cases:
- When the UE is camped on a NR cell;
- When the UE is searching for a cell to camp on;
NOTE: When the UE is camped on or searching for a cell to camp on belonging to other RATs, the UE behaviour
is described in the specifications of the other RATs.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 38.300: "NR Overall Description; Stage 2".
[3] 3GPP TS 38.331: "NR; Radio Resource Control (RRC) - Protocol Specification".
[4] 3GPP TS 38.213: "NR; Physical layer procedures for control ".
[5] Void
[6] 3GPP TS 36.331: "E-UTRA; Radio Resource Control (RRC) - Protocol Specification".
[7] 3GPP TS 36.304: "E-UTRA; User Equipment (UE) procedures in RRC_IDLE state ".
[8] 3GPP TS 38.133: "NR; Requirements for Support of Radio Resource Management".
[9] 3GPP TS 23.122: "NAS functions related to Mobile Station (MS) in RRC_IDLE state".
[10] 3GPP TS 23.501: "System Architecture for the 5G System; Stage 2".
[11] 3GPP TS 38.215: "NR; Physical layer measurements".
[12] 3GPP TS 22.261: "Service requirements for the 5G system".
[13] 3GPP TS 24.890: "5G System – Phase 1; CT WG1 Aspects".
[14] 3GPP TS 24.501: "Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3".
[15] 3GPP TS 38.101-1: "NR; User Equipment (UE) radio transmission and reception; Part 1: Range 1
Standalone".
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3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
Acceptable Cell: A cell that satisfies certain conditions as specified in 4.5.
Available PLMN(s): One or more PLMN(s) for which the UE has found at least one cell and read its PLMN
identity(ies).
Barred Cell: A cell a UE is not allowed to camp on.
Camped on a cell: UE has completed the cell selection/reselection process and has chosen a cell. The UE monitors
system information and (in most cases) paging information.
Camped on any cell: UE is in idle mode and has completed the cell selection/reselection process and has chosen a cell
irrespective of PLMN identity.
Commercial Mobile Alert System: Public Warning System that delivers Warning Notifications provided by Warning
Notification Providers to CMAS capable UEs.
EHPLMN: Any of the PLMN entries contained in the Equivalent HPLMN list TS 23.122 [9].
Equivalent PLMN list: List of PLMNs considered as equivalent by the UE for cell selection, cell reselection, and
handover according to the information provided by the NAS.
Home PLMN: A PLMN where the Mobile Country Code (MCC) and Mobile Network Code (MNC) of the PLMN
identity are the same as the MCC and MNC of the IMSI.
Process: A local action in the UE invoked by an RRC procedure or an RRC_IDLE or RRC_INACTIVE state
procedure.
Radio Access Technology: Type of technology used for radio access, for instance NR or E-UTRA.
Registration Area: (NAS) registration area is an area in which the UE may roam without a need to perform location
registration, which is a NAS procedure.
Registered PLMN: This is the PLMN on which certain Location Registration outcomes have occurred, as specified in
TS 23.122 [9].
Reserved Cell: A cell on which camping is not allowed, except for particular UEs, if so indicated in the system
information.
Selected PLMN: This is the PLMN that has been selected by the NAS, either manually or automatically.
Serving cell: The cell on which the UE is camped.
Strongest cell: The cell on a particular frequency that is considered strongest according to the layer 1 cell search
procedure (TS 38.213 [4], TS 38.215 [11]).
Suitable Cell: This is a cell on which a UE may camp. For NR cell, the criteria are defined in clause 4.5, for E-UTRA
cell in TS 36.304 [7].
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in TR 21.905 [1] and the following apply. An
abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in
TR 21.905 [1].
AS Access Stratum
CMAS Commercial Mobile Alert System
CN Core Network
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DCI Downlink Control Information
ETWS Earthquake and Tsunami Warning System
E-UTRA Evolved UMTS Terrestrial Radio Access
E-UTRAN Evolved UMTS Terrestrial Radio Access Network
IMSI International Mobile Subscriber Identity
MCC Mobile Country Code
MICO Mobile Initiated Connection Only
NAS Non-Access Stratum
NR NR Radio Access
PLMN Public Land Mobile Network
RAT Radio Access Technology
RNA RAN-based Notification Area
RNAU RAN-based Notification Area Update
RRC Radio Resource Control
UAC Unified Access Control
UE User Equipment
UMTS Universal Mobile Telecommunications System
4 General description of RRC_IDLE state and
RRC_INACTIVE state
4.1 Overview
The RRC_IDLE state and RRC_INACTIVE state tasks can be subdivided into three processes:
- PLMN selection;
- Cell selection and reselection;
- Location registration and RNA update.
PLMN selection, cell reselection procedures, and location registration are common for both RRC_IDLE state and
RRC_INACTIVE state. RNA update is only applicable for RRC_INACTIVE state. When UE selects a new PLMN, UE
transitions from RRC_INACTIVE to RRC_IDLE, as specified in TS 24.501 [14].
When a UE is switched on, a public land mobile network (PLMN) is selected by NAS. For the selected PLMN,
associated RAT(s) may be set, as specified in TS 23.122 [9]. The NAS shall provide a list of equivalent PLMNs, if
available, that the AS shall use for cell selection and cell reselection.
With cell selection, the UE searches for a suitable cell of the selected PLMN, chooses that cell to provide available
services, and monitors its control channel. This procedure is defined as "camping on the cell".
The UE shall, if necessary, then register its presence, by means of a NAS registration procedure, in the tracking area of
the chosen cell. As an outcome of a successful Location Registration, the selected PLMN then becomes the registered
PLMN, as specified in TS 23.122 [9].
If the UE finds a more suitable cell, according to the cell reselection criteria, it reselects onto that cell and camps on it.
If the new cell does not belong to at least one tracking area to which the UE is registered, location registration is
performed. In RRC_INACTIVE state, if the new cell does not belong to the configured RNA, an RNA update
procedure is performed.
If necessary, the UE shall search for higher priority PLMNs at regular time intervals as described in TS 23.122 [9] and
search for a suitable cell if another PLMN has been selected by NAS.
If the UE loses coverage of the registered PLMN, either a new PLMN is selected automatically (automatic mode), or an
indication of available PLMNs is given to the user so that a manual selection can be performed (manual mode).
Registration is not performed by UEs only capable of services that need no registration.
The purpose of camping on a cell in RRC_IDLE state and RRC_INACTIVE state is fourfold:
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a) It enables the UE to receive system information from the PLMN.
b) When registered and if the UE wishes to establish an RRC connection or resume a suspended RRC connection, it
can do this by initially accessing the network on the control channel of the cell on which it is camped.
c) If the network needs to send a message or deliver data to the registered UE, it knows (in most cases) the set of
tracking areas (in RRC_IDLE state) or RNA (in RRC_INACTIVE state) in which the UE is camped. It can then
send a "paging" message for the UE on the control channels of all the cells in the corresponding set of areas. The
UE will then receive the paging message and can respond.
d) It enables the UE to receive ETWS and CMAS notifications.
When the UE is in RRC_IDLE state, upper layers may deactivate AS layer when MICO mode is activated as specified
in TS 24.501 [14]. When MICO mode is activated, the AS configuration (e.g. priorities provided by dedicated
signalling) is kept and all running timers continue to run but the UE need not perform any idle mode tasks. If a timer
expires while MICO mode is activated it is up to the UE implementation whether it performs the corresponding action
immediately or the latest when MICO mode is deactivated. When MICO mode is deactivated, the UE shall perform all
idle mode tasks.
4.2 Functional division between AS and NAS in RRC_IDLE
state and RRC_INACTIVE state
Table 4.2-1 presents the functional division between UE non-access stratum (NAS) and UE access stratum (AS) in
RRC_IDLE state and RRC_INACTIVE states. The NAS part is specified in TS 23.122 [9] and the AS part in the
present document.
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Table 4.2-1: Functional division between AS and NAS in RRC_IDLE state and RRC_INACTIVE state
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RRC_IDLE and UE Non-Access Stratum UE Access Stratum
RRC_INACTIVE
state Process
PLMN Selection Maintain a list of PLMNs in priority order according Search for available PLMNs.
to TS 23.122 [9]. Select a PLMN using automatic
or manual mode as specified in TS 23.122 [9] and If associated RAT(s) is (are) set for the
request AS to select a cell belonging to this PLMN, search in this (these) RAT(s) and
PLMN. For each PLMN, associated RAT(s) may other RAT(s) for that PLMN as specified in
be set. TS 23.122 [9].
Evaluate reports of available PLMNs from AS for Perform measurements to support PLMN
PLMN selection. selection.
Maintain a list of equivalent PLMN identities. Synchronise to a broadcast channel to
identify found PLMNs.
Report available PLMNs with associated
RAT(s) to NAS on request from NAS or
autonomously.
Cell Control cell selection for example by indicating Perform measurements needed to support
Selection RAT(s) associated with the selected PLMN to be cell selection.
used initially in the search of a cell in the cell
selection. Detect and synchronise to a broadcast
channel. Receive and handle broadcast
Maintain a list of "Forbidden Tracking Areas" and information. Forward NAS system
provide the list to AS. information to NAS.

Search for a suitable cell. The cells
broadcast one or more 'PLMN identity' in
the system information. Respond to NAS
whether such cell is found or not.

If associated RATs is (are) set for the
PLMN, perform the search in this (these)
RAT(s) and other RATs for that PLMN as
specified in TS 23.122 [9].
If a cell is found which satisfies cell
selection criteria, camp on that cell.
Cell Maintain a list of equivalent PLMN identities and Perform measurements needed to support
Reselection provide the list to AS. cell reselection.

Maintain a list of "Forbidden Tracking Areas" and Detect and synchronise to a broadcast
provide the list to AS. channel. Receive and handle broadcast
information. Forward NAS system
information to NAS.
Change cell if a more suitable cell is found.
Location Register the UE as active after power on. Report registration area information to
registration NAS.
Register the UE's presence in a registration area,
for instance regularly or when entering a new
tracking area.
Deregister UE when shutting down.

Maintain a list of "Forbidden Tracking Areas".

RAN Notification Not applicable. Register the UE's presence in a RAN-
Area Update based notification area (RNA), periodically
or when entering a new RNA.
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4.3 Service types in RRC_IDLE state
This clause defines the level of service that may be provided by the network to a UE in RRC_IDLE state. The following
three levels of services are provided while a UE is in RRC_IDLE state:
- Limited service (emergency calls, ETWS and CMAS on an acceptable cell);
- Normal service (for public use on a suitable cell);
- Operator service (for operators only on a reserved cell).
4.4 Service types in RRC_INACTIVE state
This clause defines the level of service that may be provided by the network to a UE in RRC_INACTIVE state. The
following two levels of services are provided while a UE is in RRC_INACTIVE state:
- Normal service (for public use on a suitable cell);
- Operator service (for operators only on a reserved cell).
4.5 Cell Categories
The cells are categorised according to which services they offer:
acceptable cell:
An "acceptable cell" is a cell on which the UE may camp to obtain limited service (originate emergency calls and
receive ETWS and CMAS notifications). Such a cell shall fulfil the following requirements, which is the minimum set
of requirements to initiate an emergency call and to receive ETWS and CMAS notification in an NR network:
- The cell is not barred, see clause 5.3.1;
- The cell selection criteria are fulfilled, see clause 5.2.3.2.
suitable cell:
A cell is considered as suitable if the following conditions are fulfilled:
- The cell is part of either the selected PLMN or the registered PLMN or PLMN of the Equivalent PLMN list;
- The cell selection criteria are fulfilled, see clause 5.2.3.2.
According to the latest information provided by NAS:
- The cell is not barred, see clause 5.3.1;
- The cell is part of at least one TA that is not part of the list of "Forbidden Tracking Areas" (TS 22.261 [12]),
which belongs to a PLMN that fulfils the first bullet above.
barred cell:
A cell is barred if it is so indicated in the system information, as specified in TS 38.331 [3].
reserved cell:
A cell is reserved if it is so indicated in system information, as specified in TS 38.331 [3].
Following exception to these definitions are applicable for UEs:
- if a UE has an ongoing emergency call, all acceptable cells of that PLMN are treated as suitable for the duration
of the emergency call.
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- camped on a cell that belongs to a registration area that is forbidden for regional provision of service; a cell that
belongs to a registration area that is forbidden for regional provision service (TS 23.122 [9], TS 24.501 [14]) is
suitable but provides only limited service.
5 Process and procedure descriptions
5.1 PLMN selection
In the UE, the AS shall report available PLMNs 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.
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. 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. If the UE can read one or several PLMN identities in the strongest cell, 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),
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. 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.
5.1.1.3 E-UTRA case
Support for PLMN selection in E-UTRA is described in TS 36.304 [7].
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.
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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; 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.
For cell selection in multi-beam operations, measurement quantity of a cell is up to UE implementation.
For cell reselection in multi-beam operations, 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 is not configured in SIB2/SIB4; or
- if absThreshSS-BlocksConsolidation is not configured in SIB2/SIB4; or
- if the highest beam measurement quantity value is below or equal to absThreshSS-BlocksConsolidation:
- 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 of highest beam measurement quantity values above absThreshSS-BlocksConsolidation.
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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 is performed, it causes an exit to number 1.

go here whenever a
new PLMN is
selected
no cell information
cell information
stored for the PLMN
stored for the PLMN
Stored Initial
no suitable cell found
information Cell Selection
Cell Selection
no suitable
suitable cell found suitable cell found
cell found
no suitable
cell found
Cell selection NAS indicates that
upon leaving suitable
registration on selected
Camped
connected cell found
PLMN is rejected
normally
mode (except with cause
#12, #14 , #15 or #25
[9][14])
return to
trigger
leave
idle/inactive
idle/inactive
suitable
mode
mode cell found
Connected
Cell
mode no suitable
Reselection
cell found
Evaluation
Process
go here
when no
USIM in
the UE
Any Cell
no acceptable cell found Selection
USIM inserted
acceptable cell
found; move to
idle mode
suitable cell
found
Cell Selection
when leaving
acceptable cell suitable
Camped on
connected
found cell found
any cell
mode
return to trigger
leave
idle mode idle mode
acceptable
cell found
Connected
mode
Cell
(Emergency
no acceptable
Reselection
calls only)
cell found
Evaluation
Process
Figure 5.2.2-1 RRC_IDLE and RRC_INACTIVE Cell Selection and Reselection
ETSI
3GPP TS 38.304 version 15.4.0 Release 15 16 ETSI TS 138 304 V15.4.0 (2019-07)
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.
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 – (Q + Q )– P - Qoffset
rxlevmeas rxlevmin rxlevminoffset compensation temp
Squal = Q – (Q + Q ) - Qoffset
qualmeas qualmin qualminoffset temp
where:
ETSI
3GPP TS 38.304 version 15.4.0 Release 15 17 ETSI TS 138 304 V15.4.0 (2019-07)
Srxlev Cell selection RX level value (dB)
Squal Cell selection quality value (dB)
Qoffset Offset temporarily applied to a cell as specified in TS 38.331 [3] (dB)
temp
Qrxlevmeas Measured cell RX level value (RSRP)
Qqualmeas Measured cell quality value (RSRQ)
Qrxlevmin 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 is
rxlevminoffsetcellSUL
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 Qrxlevminoffsetcell 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.
Qqualmin Minimum required quality level in the cell (dB). Additionally, if
Q is signalled for the concerned cell, this cell specific offset
qualminoffsetcell
is added to achieve the required minimum quality level in the
concerned cell.
Qrxlevminoffset Offset to the signalled Qrxlevmin 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 Offset to the signalled Q taken into account in the Squal
qualminoffset qualmin
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].
Pcompensation If the UE supports the additionalPmax in the NR-NS-PmaxList, if
present, in SIB1, SIB2 and SIB4:
max(PEMAX1 –PPowerClass, 0) – (min(PEMAX2, PPowerClass) – min(PEMAX1,
PPowerClass)) (dB);
else:
max(PEMAX1 –PPowerClass, 0) (dB)
PEMAX1, PEMAX2 Maximum TX power level of a UE may use when transmitting on the
uplink in the cell (dBm) defined as PEMAX in TS 38.101 [15]. If UE
supports SUL frequency for this cell, P and P are obtained
EMAX1 EMAX2
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 and P are obtained from the p-Max and NR-NS-
EMAX1 EMAX2
PmaxList respectively in SIB1, SIB2 and SIB4 for normal UL as
specified in TS 38.331 [3].
PPowerClass 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 and Q are only applied when a cell is evaluated for cell selection as a result of
rxlevminoffset qualminoffset
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 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 RRCRelease unless specified otherwise. When the UE in camped
ETSI
3GPP TS 38.304 version 15.4.0 Release 15 18 ETSI TS 138 304 V15.4.0 (2019-07)
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).
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.
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 is performed on request by
NAS (TS 23.122 [9]).
NOTE: 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
- a PLMN 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 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 NR and
E-UTRA), if configured, at inter-RAT cell (re)selection.
NOTE
...