ETSI TS 125 304 V7.8.0 (2009-09)

Universal Mobile Telecommunications System (UMTS); User Equipment (UE) procedures in idle mode and procedures for cell reselection in connected mode (3GPP TS 25.304 version 7.8.0 Release 7)

RTS/TSGR-0225304v780

General Information

• Status: Published
• Publication Date: 01-Oct-2009
• Technical Committee: 3GPP RAN 2 - Radio layer 2 specification and Radio layer 3 RR specification
• Current Stage: 12 - Completion
• Due Date: 12-Oct-2009
• Completion Date: 02-Oct-2009

Standards Content (Sample)

Technical Specification
Universal Mobile Telecommunications System (UMTS);
User Equipment (UE) procedures in idle mode and procedures
for cell reselection in connected mode
(3GPP TS 25.304 version 7.8.0 Release 7)

3GPP TS 25.304 version 7.8.0 Release 7 1 ETSI TS 125 304 V7.8.0 (2009-09)

Reference
RTS/TSGR-0225304v780
Keywords
UMTS
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ETSI
3GPP TS 25.304 version 7.8.0 Release 7 2 ETSI TS 125 304 V7.8.0 (2009-09)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
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Foreword
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or
GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.
The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under
http://webapp.etsi.org/key/queryform.asp.
ETSI
3GPP TS 25.304 version 7.8.0 Release 7 3 ETSI TS 125 304 V7.8.0 (2009-09)
Contents
Intellectual Property Rights . 2
Foreword . 2
Foreword . 5
1 Scope . 6
2 References . 6
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 8
4 General description of Idle mode . 10
4.1 Overview . 10
4.2 Functional division between AS and NAS in Idle mode . 11
4.3 Service type in Idle and Connected Mode . 13
5 Process and procedure descriptions . 14
5.1 PLMN selection . 14
5.1.1 General . 14
5.1.2 Support for PLMN Selection . 14
5.1.2.1 General . 14
5.1.2.2 UTRA case . 15
5.1.2.3 GSM case . 15
5.2 Cell selection and reselection in idle mode . 15
5.2.1 Introduction. 15
5.2.2 States and state transitions in Idle Mode . 16
5.2.2.1 Cell Selection process overview . 16
5.2.2.2 Camped normally state overview . 17
5.2.2.3 Connected mode State overview . 17
5.2.2.4 Any cell selection State overview . 17
5.2.2.5 Camped on any cell State overview . 17
5.2.3 Cell Selection Process . 18
5.2.3.1 UTRA case . 18
5.2.3.1.1 Description . 18
5.2.3.1.2 Criteria . 18
5.2.3.2 GSM case . 19
5.2.4 Void . 19
5.2.5 Camped Normally State . 19
5.2.5.1 UTRA case . 19
5.2.5.2 GSM case . 19
5.2.6 Cell Reselection Evaluation Process . 19
5.2.6.1 UTRA case . 19
5.2.6.1.0 Use of MBMS PL . 20
5.2.6.1.1 Measurement rules for cell re-selection when HCS is not used . 20
5.2.6.1.1a High mobility state when HCS is not used . 20
5.2.6.1.2 Measurement rules for cell re-selection when HCS is used . 21
5.2.6.1.3 Highest ranked cells with cell reservations, access restrictions or unsuitable for normal
camping . 23
5.2.6.1.4 Cell Reselection Criteria . 23
5.2.6.1.5 Cell reselection parameters in system information broadcasts . 27
5.2.6.2 GSM case . 30
5.2.7 Cell Selection when leaving connected mode . 30
5.2.7.1 UTRA case . 30
5.2.7.2 GSM case . 30
5.2.8 Any Cell Selection state . 30
5.2.9 Camped on Any Cell State . 30
5.2.9.1 UTRA case . 30
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3GPP TS 25.304 version 7.8.0 Release 7 4 ETSI TS 125 304 V7.8.0 (2009-09)
5.2.9.2 GSM case . 30
5.3 Cell Reservations and Access Restrictions (cells not operating in MBSFN mode) . 31
5.3.1 UTRA cells . 31
5.3.1.1 Cell status and cell reservations . 31
5.3.1.2 Access Control . 32
5.3.1.3 Emergency Call . 32
5.3.2 GSM cells . 32
5.3a Cell Reservations and Access Restrictions (MBSFN cells only for FDD and 3.84/7.68 Mcps TDD) . 32
5.4 Cell Selection and Reselection Processes in RRC Connected Mode . 33
5.4.1 Void . 33
5.4.2 Void . 33
5.4.3 Cell Reselection Process in RRC connected mode . 33
5.4.4 Cell Selection Process in RRC connected mode . 33
5.5 Location Registration . 33
6 Broadcast information receiving . 33
6.1 Reception of System Information . 33
6.2 Cell Broadcast in Idle Mode, CELL_PCH and URA_PCH . 33
6.3 MBMS Services . 34
6.3.1 MBSFN cluster selection and reselection . 34
6.3.1.1 MBSFN cluster selection . 34
6.3.1.2 Camped on MBSFN cluster . 34
6.3.1.3 MBSFN inter frequency neighbour information . 35
7 Void . 35
8 Paging and SCCPCH selection and in FDD the H-RNTI selection . 35
8.1 Paging Channel selection . 35
8.2 SCCPCH selection when entering Connected mode . 35
8.2b H-RNTI selection when entering Connected mode (FDD only) . 36
8.3 Discontinuous Reception for Paging . 37
8.4 Discontinuous Reception for MBMS . 38
8.4.1 Discontinuous Reception for MCCH . 38
8.4.1.1 Discontinuous Reception via MICH . 38
8.4.1.2 Discontinuous Reception via MODIFIED SERVICES INFORMATION . 39
8.4.2 Discontinuous Reception for MTCH . 39
8a MBMS Notification . 39
9 Void . 39
10 Void . 40
Annex A (informative): Change history . 41
History . 43

ETSI
3GPP TS 25.304 version 7.8.0 Release 7 5 ETSI TS 125 304 V7.8.0 (2009-09)
Foreword
rd
This Technical Specification has been produced by the 3 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.
ETSI
3GPP TS 25.304 version 7.8.0 Release 7 6 ETSI TS 125 304 V7.8.0 (2009-09)
1 Scope
The present document specifies the Access Stratum (AS) part of the Idle Mode procedures applicable to a UE. The non-
access stratum (NAS) part of Idle mode procedures and processes is specified in [5].
The present document also specifies cell selection and reselection processes applicable to UEs in connected mode.
Invocation of these processes is described in [4].
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 UTRA, including multi-RAT UEs as described in 3GPP
specifications, in the following cases:
- When the UE is camped on a UTRA cell;
- When the UE is searching for a cell to camp on;
NOTE: The details for those cases are described in the specifications of the other RAT.
The present document presents also examples of inter-layer procedures related to the idle mode processes and describes
idle mode functionality of a dual RAT UTRA/GSM UE.
The present document also specifies how idle-mode and reselection procedures are affected by the provision of MBMS
services.
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 TS 43.022: "Functions related to Mobile Station in idle mode and group receive mode".
[2] 3GPP TS 25.301: "Radio Interface Protocol Architecture".
[3] 3GPP TS 25.303: "Interlayer Procedures in Connected Mode".
[4] 3GPP TS 25.331: "Radio Resource Control (RRC); protocol specification".
[5] 3GPP TS 23.122: "NAS functions related to Mobile Station (MS) in idle mode ".
[6] 3GPP TR 25.922: "Radio Resource Management Strategies".
[7] 3GPP TS 25.211: "Physical channels and mapping of transport channels onto physical channels
(FDD)".
[8] 3GPP TS 25.221: "Physical channels and mapping of transport channels onto physical channels
(TDD)".
[9] 3GPP TS 22.011: "Service accessibility".
[10] 3GPP TS 25.133: "Requirements for Support of Radio Resource Management (FDD)".
[11] 3GPP TS 25.123: "Requirements for Support of Radio Resource Management (TDD)".
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3GPP TS 25.304 version 7.8.0 Release 7 7 ETSI TS 125 304 V7.8.0 (2009-09)
[12] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[13] 3GPP TS 45.008: "Radio subsystem link control".
[14] 3GPP TS 25.214: "Physical layer procedures (FDD)".
[15] 3GPP TS 25.224: "Physical Layer Procedures (TDD)".
[16] 3GPP TS 24.008: "Mobile radio interface layer 3 specification, Core Network Protocols - Stage 3".
[17] 3GPP TS 25.346: "Introduction of the Multimedia Broadcast Multicast Service (MBMS) in the
Radio Access Network (Stage-2)".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following definitions and the definitions in [12] apply.
Acceptable Cell: A cell that satisfies certain conditions as specified in 4.3. A UE can always attempt emergency calls
on an acceptable cell.
Available PLMN: A PLMN for which the UE has found at least one cell and read its PLMN identity.
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.
Camped on MBSFN cluster: UE has completed the MBSFN Cluster selection/reselection process and has chosen a
MBSFN Cluster. The UE monitors system information and receives notifications for MBMS services and possibly
receives a MBMS service.
DRX cycle: Individual time interval between monitoring Paging Occasion for a specific UE.
EHPLMN: Any of the PLMN entries contained in the Equivalent HPLMN list stored on the USIM [5].
Equivalent PLMN list: List of PLMNs considered as equivalent by the UE for cell selection, cell reselection , MBSFN
Cluster selection MBSFN Cluster 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.
Location Registration (LR): UE registers its presence in a registration area, for instance regularly or when entering a
new registration area.
Maximum DRX cycle: Time interval for the longest possible DRX cycle in a cell.
MBMS Activated Service: An MBMS service that the UE has joined (multicast) or is interested in (broadcast).
MBMS Preferred Layer (PL): A frequency layer that is indicated by the UTRAN to be preferred for camping for
MBMS purposes.
MBSFN cluster: Set of cells operating in MBSFN mode providing only MBMS service in PtM mode and seen as one
cell by a UE.
MBSFN mode: In order to achieve higher spectral efficiency synchronized cells operate in MBSFN mode which
implies that they transmit exactly the same content over an area that is seen as one MBSFN cell by the UE.
Paging Block Periodicity (PBP): Period of the occurrence of Paging Blocks. (For FDD, PBP = 1).
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3GPP TS 25.304 version 7.8.0 Release 7 8 ETSI TS 125 304 V7.8.0 (2009-09)
Paging Message Receiving Occasion (TDD only): The frame where the UE receives actual paging message.
Paging occasion:
(FDD) The SFN of the PICH frame where the UE monitors its paging indicator (i.e. the SFN of the PCCPCH frame in
which the PICH frame begins).
(TDD) The paging block, which consists of several frames. The value of Paging Occasion is equal to the first frame of
the Paging Block.
Process: A local action in the UE invoked by a RRC procedure or an Idle Mode procedure.
Radio Access Mode: Radio access mode of the cell, FDD or TDD.
Radio Access Technology: Type of technology used for radio access, for instance UTRA or GSM.
Registered PLMN: This is the PLMN on which certain Location Registration outcomes have occurred [5].
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.
Reserved Cell: A cell on which camping is not allowed, except for particular UEs, if so indicated in the system
information.
Restricted Cell: A cell on which camping is allowed, but access attempts are disallowed for UEs whose access classes
are indicated as barred.
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 carrier that is considered strongest according to the layer 1 cell search procedure
[14][15]. As the details of the layer 1 cell search are implementation dependent, the precise definition of 'strongest cell'
is also implementation dependent.
Suitable Cell: This is a cell on which an UE may camp. For a UTRA cell, the criteria are defined in subclause 4.3, and
for a GSM cell the criteria are defined in [1].
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AS Access Stratum
BCCH Broadcast Control Channel
CM Connection Management
CN Core Network
DRX Discontinuous Reception
DSCH Downlink Shared Channel
FDD Frequency Division Duplex
GC General Control (SAP)
GPRS General Packet Radio Service
GSM Global System for Mobile Communications
HCS Hierarchical Cell Structure
IMSI International Mobile Subscriber Identity
MBMS Multimedia Broadcast-Multicast Service
MBSFN MBMS over a Single Frequency Network
MCC Mobile Country Code
MCCH MBMS point-to-multipoint Control Channel
MICH MBMS notification Indicator Channel
MM Mobility Management
MNC Mobile Network Code
MSCH MBMS point-to-multipoint Scheduling Channel
MTCH MBMS point-to-multipoint Traffic Channel
NAS Non-Access Stratum
NI (MBMS) Notification Indicator
PCH Paging Channel
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3GPP TS 25.304 version 7.8.0 Release 7 9 ETSI TS 125 304 V7.8.0 (2009-09)
PI Page Indicator
PICH Page Indication Channel
PLMN Public Land Mobile Network
RAT Radio Access Technology
RRC Radio Resource Control
SAP Service Access Point
TDD Time Division Duplex
TMGI Temporary Mobile Group Identity
UE User Equipment
UMTS Universal Mobile Telecommunications System
UTRA UMTS Terrestrial Radio Access
UTRAN UMTS Terrestrial Radio Access Network
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3GPP TS 25.304 version 7.8.0 Release 7 10 ETSI TS 125 304 V7.8.0 (2009-09)
4 General description of Idle mode
4.1 Overview
When a UE is switched on, a public land mobile network (PLMN) is selected and the UE searches for a suitable cell of
this PLMN to camp on. Criteria for cell selection and cell re-selection between radio access technologies (RATs)
described in this document only consider radio criteria. In addition to RAT, the PLMN type may differ as well. In this
specification, the term PLMN is used as a generic term covering both GSM MAP and ANSI-41 type of PLMNs.
According to the type of PLMN, the way to identify it can be different. If the PLMN type is GSM, the PLMN is
identified by 'PLMN identity' and if the PLMN type is ANSI-41, the PLMN is identified by 'SID'
The NAS shall provide a list of equivalent PLMNs, if available, that the AS shall use for cell selection and cell
reselection.
The UE searches for a suitable cell of the selected PLMN and chooses that cell to provide available services, and tunes
to its control channel. This choosing is known as "camping on the cell". The UE will, if necessary, then register its
presence, by means of a NAS registration procedure, in the registration area of the chosen cell and as outcome of a
successful Location Registration the selected PLMN becomes the registered PLMN [5].
If the UE finds a more suitable cell, it reselects onto that cell and camps on it. If the new cell is in a different registration
area, location registration is performed.
If necessary, the UE shall search for higher priority PLMNs at regular time intervals as described in [9] and search for a
suitable cell if another PLMN has been selected by NAS.
NOTE: For RRC connected mode the requirements for the search for higher priority PLMNs are defined in [4].
If the UE loses coverage of the registered PLMN, either a new PLMN is selected automatically (automatic mode), or an
indication of which PLMNs are available is given to the user, so that a manual selection can be made (manual mode).
Registration is not performed by UEs only capable of services that need no registration.
The purpose of camping on a cell in idle mode is fourfold:
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, it can do this by initially accessing the
network on the control channel of the cell on which it is camped.
c) If the PLMN receives a call for the registered UE, it knows (in most cases) the registration area of the cell in
which the UE is camped. It can then send a "paging" message for the UE on control channels of all the cells in
the registration area. The UE will then receive the paging message because it is tuned to the control channel of a
cell in that registration area and the UE can respond on that control channel.
d) It enables the UE to receive cell broadcast services.
If the UE is unable to find a suitable cell to camp on, or the USIM is not inserted, or if the location registration failed
(except for LR rejected with cause #12, cause #14 or cause #15, see [5] and [16]), it attempts to camp on a cell
irrespective of the PLMN identity, and enters a "limited service" state in which it can only attempt to make emergency
calls.
The idle mode tasks can be subdivided into three processes:
- PLMN selection;
- Cell selection and reselection;
- Location registration.
The relationship between these processes is illustrated in Figure 1.
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3GPP TS 25.304 version 7.8.0 Release 7 11 ETSI TS 125 304 V7.8.0 (2009-09)

Automatic mode
Manual Mode
PLMN Selection
Indication
to user
Locat ion PLMNs
Registration
available
response
PLMN
selected
NAS Control
Cell Selection
and Reselection
Radio measurements
Registration
Area
changes
CM requests
Location
Registration
Figure 1: Overall Idle Mode process
4.2 Functional division between AS and NAS in Idle mode
Table 1 presents the functional division between UE non-access stratum (NAS) and UE access stratum (AS) in idle
mode. The NAS part is specified in [5] and the AS part in the present document. Examples of different idle mode
procedures are presented in Clause 10.
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3GPP TS 25.304 version 7.8.0 Release 7 12 ETSI TS 125 304 V7.8.0 (2009-09)
Table 1: Functional division between AS and NAS in idle mode
Idle Mode UE Non-Access Stratum UE Access Stratum
Process
PLMN Selection Maintain the list of allowed PLMN types. It can be Search for available PLMNs.
GSM-MAP only, ANSI-41 only or both.
If associated RAT(s) is (are) set for the
Maintain a list of PLMNs in priority order according PLMN, search in this (these) RAT(s) and
to [5]. Select a PLMN using automatic or manual other RAT(s) for that PLMN as specified in
mode as specified in [5] and request AS to select [5].
a cell belonging to this PLMN. For each PLMN,
associated RAT(s) may be set. Perform measurements to support PLMN
selection.
Evaluate reports of available PLMNs from AS for
PLMN selection. Synchronise to a broadcast channel to
identify found PLMNs.
Maintain a list of equivalent PLMN identities.
Report available PLMNs with associated
PLMN type and RAT to NAS on request
from NAS or autonomously.
It shall respect allowed PLMN types
indications from NAS.
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. NAS is also maintaining lists of Detect and synchronise to a broadcast
forbidden registration areas. channel. Receive and handle broadcast
information. Forward NAS system
information to NAS.
Search for a suitable cell. The cells
broadcast their 'PLMN identity' (GSM-MAP)
or 'SID' 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 [5].
If such a cell is found, the cell is selected to
camp on.
Cell Control cell reselection by for example, Perform measurements needed to support
Reselection maintaining lists of forbidden registration areas. cell reselection.

Maintain a list of equivalent PLMN identities and Detect and synchronise to a broadcast
provide the list to AS. channel. Receive and handle broadcast
information. Forward NAS system
Maintain a list of forbidden LAs and provide the list information to NAS.
to AS
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
registration area.
Maintain lists of forbidden LAs.

Deregister UE when shutting down.
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Idle Mode UE Non-Access Stratum UE Access Stratum
Process
MBMS Maintain priority information for various services Maintain a list of TMGIs of activated
and participate in service selection. services.

Indicate to AS if an offered session has previously Notify NAS of service availability and
been received. request NAS to prioritise in case of service
conflicts.
Report to NAS when an activated service
requires action.
Receive and handle the MCCH and MTCH,
and, if applicable, the MSCH and MICH.

4.3 Service type in Idle and Connected Mode
This clause defines the level of service that may be provided by the network to a UE in Idle mode and Connected Mode.
The action of camping on a cell is necessary to get access to some services. Three levels of services are defined for UE:
- Limited service (emergency calls on an acceptable cell)
- Normal service (for public use on a suitable cell)
- Operator service (for operators only on a reserved cell)
Furthermore, 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). Such a
cell shall fulfil the following requirements, which is the minimum set of requirements to initiate an emergency call in a
UTRAN network:
- The cell is not barred, see subclause 5.3.1.1;
- The cell selection criteria are fulfilled, see subclause 5.2.3.1.2;
suitable cell:
A "suitable cell" is a cell on which the UE may camp on to obtain normal service. Such a cell shall fulfil all the
following requirements.
- The cell shall be part of either:
the selected PLMN, or:
the registered PLMN, or:
a PLMN of the Equivalent PLMN list
according to the latest information provided by the NAS.
- The cell is not barred, see subclause 5.3.1.1;
- The cell is part of at least one LA that is not part of the list of "forbidden LAs for roaming" [9], which belongs to
a PLMN that fulfills the first bullet above;
- The cell selection criteria are fulfilled, see subclause 5.2.3.1.2.
If the IE 'Multiple PLMN List' [4] is broadcast in the cell, the cell is considered to be part of all LAs with LAIs
constructed from the PLMN identities in the 'Multiple PLMN List' and the LAC broadcast in the cell.
barred cell:
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A cell is barred if it is so indicated in the system information [4].
reserved cell:
A cell is reserved if it is so indicated in system information [4].
Exceptions to these definitions are applicable for UEs camped on a cell that belongs to a LA that is forbidden for
regional provision of service, and during emergency calls.
A cell that belongs to a LA that is forbidden for regional provision service ([5], [16]) is suitable but provides only
limited service.
If a UE has an ongoing emergency call, all acceptable cells of that PLMN are treated as suitable for cell reselection for
the duration of the emergency call.
suitable MBSFN cluster:
A cell is part of an MBSFN cluster if it is indicated in system information [4]. An MBSFN cluster provides exclusively
MBMS services. A suitable MBSFN cluster shall fulfil all the following requirements:
- For FDD and 3.84/7.68 Mcps TDD the MBSFN cluster shall be part of either:
the registered PLMN, or:
a PLMN of the Equivalent PLMN list
The MBSFN cluster shall be indicated as:
- providing MBSFN only service
For FDD and 3.84/7.68 Mcps TDD MBSFN cluster selection/reselection process for MBSFN clusters operating on the
same frequency shall be based on reception quality. Details of the process are not specified.
5 Process and procedure descriptions
5.1 PLMN selection
5.1.1 General
In the UE, the AS shall report available PLMNs to the NAS on request from the NAS or autonomously.
UE shall maintain a list of allowed PLMN types. The allowed PLMN type can be GSM-MAP only, ANSI-41 only or
both. During PLMN selection, based on the list of allowed PLMN types and a 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 can
be identified by either 'PLMN identity' (GSM-MAP) or 'SID'. In the system information on the broadcast channel, the
UE can receive a 'PLMN identity' (GSM-MAP) or a 'SID' or a 'PLMN identity' (GSM-MAP) and a 'SID', in a given cell.
For a given cell, the UE might receive several 'PLMN identities' from the system information on the broadcast channel.
The result of the PLMN selection is an identifier of the selected PLMN, the choice being based on the allowed PLMN
types, UE capability or other factors. This identifier is one of either 'PLMN identity' for GSM-MAP type of PLMNs or
'SID' for ANSI-41 type of PLMNs.
In case that the list of allowed PLMN types includes GSM-MAP, the non-access part of the PLMN selection process is
specified in [5]. In the case that list of allowed PLMN types includes ANSI-41, the non-access stratum part of the
PLMN selection is specified in TIA/EIA/IS-2000.5 and TIA/EIA/IS-707.
5.1.2 Support for PLMN Selection
5.1.2.1 General
On request of the NAS the AS should perform a search for available PLMNs and report them to NAS.
ETSI
3GPP TS 25.304 version 7.8.0 Release 7 15 ETSI TS 125 304 V7.8.0 (2009-09)
5.1.2.2 UTRA case
The UE shall scan all RF channels in the UTRA 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 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 [4]) shall be reported to the NAS as a high quality PLMN (but without the RSCP value), provided
that the following high quality criterion is fulfilled:
1. For an FDD cell, the measured primary CPICH RSCP value shall be greater than or equal to -95 dBm.
2. For a TDD cell, the measured P-CCPCH RSCP shall be greater than or equal to -84 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 the CPICH RSCP value for UTRA FDD cells and P-CCPCH RSCP for
UTRA TDD cells. The quality measure reported by the UE to NAS shall be the same for each PLMN found in one cell.
The search for PLMNs on the rest of the carriers may be stopped on request of the NAS. The UE may optimise this
search by using stored information of carrier frequencies and optionally also information on cell parameters, e.g.
scrambling codes, 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.
5.1.2.3 GSM case
Support for network selection in GSM is described in [1].
5.2 Cell selection and reselection in idle mode
5.2.1 Introduction
As stated in clause 1, the present document applies to UEs that support at least UTRA.
Different types of measurements are used in different RATs and modes for the cell selection and reselection. The
performance requirements for the measurements are specified in [10] and [11].
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 and the radio access mode 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. Details on performance
requirements for cell reselection can be found in [10] and [11].
The NAS is informed if the cell selection and reselection results in changes in the received system information.
For normal service, the UE has to camp on a suitable cell, tune to that cell's control channel(s) so that the UE can:
- Receive system information from the PLMN;
- Receive registration area information from the PLMN, e.g., location area and routing area; and
- Receive other AS and NAS Information;
- If registered:
- receive paging and notification messages from the PLMN; and
- initiate call setup for outgoing calls or other actions from the UE.
ETSI
3GPP TS 25.304 version 7.8.0 Release 7 16 ETSI TS 125 304 V7.8.0 (2009-09)
5.2.2 States and state transitions in Idle Mode
Figure 2 shows the states and procedures in Idle Mode.

go here whenever a
new PLMN is
selected
no cell information
cell information
stored for the PLMN
stored for the PLMN
Stored Initial
information no suitable cell found
Cell Selection
Cell Selection
no suitable
suitable cell found suitable cell found
cell found
no suitable
cell found
Cell Selection
NAS indicates that
when leaving suitable
registration on selected
Camped
connected PLMN is rejected
cell found
normally
(except w ith cause
mode
#12, #14 or #15
[5][16])
r
...