SIST ETS 300 930 E2:2003

Digital cellular telecommunications system (Phase 2+) (GSM); Functions related to Mobile Station (MS) in idle mode and group receive mode (GSM 03.22 version 5.1.1)

This European Telecommunication Standard (ETS) gives an overview of the tasks undertaken by a GSM mobile station (MS) when in idle mode, that is, switched on but not having a dedicated channel allocated, e.g. not making or receiving a call. It also describes the corresponding network functions. NOTE: The term GSM MS is used for any type of MS supporting one, or combinations, of the frequency bands specified in GSM 05.05 (e.g. GSM 900 and DCS 1800).  This ETS outlines how the requirements of the GSM 02 series Technical Specifications (especially GSM 02.11) on idle mode operation shall be implemented. Further details are given in GSM 04.08 and GSM 05.08. Clause 2 of this ETS gives a general description of the idle mode process. Clause 3 outlines the main requirements and technical solutions of those requirements. Clause 4 describes the processes used in idle mode. There is inevitably some overlap between these clauses.

Digitalni celični telekomunikacijski sistem (faza 2+) – Funkcije v zvezi z mobilno postajo (MS) v stanju mirovanja in sprejemanja (GSM 03.22, različica 5.1.1)

General Information

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.070.50 - Global System for Mobile Communication (GSM)
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI ETS 300 930 ed.2 (1997-09) - Digital cellular telecommunications system (Phase 2+) (GSM); Functions related to Mobile Station (MS) in idle mode and group receive mode (GSM 03.22 version 5.1.1)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST ETS 300 930 E2:2003
01-december-2003
'LJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHPID]D±)XQNFLMHY]YH]L]PRELOQR
SRVWDMR06YVWDQMXPLURYDQMDLQVSUHMHPDQMD*60UD]OLþLFD
Digital cellular telecommunications system (Phase 2+) (GSM); Functions related to
Mobile Station (MS) in idle mode and group receive mode (GSM 03.22 version 5.1.1)
Ta slovenski standard je istoveten z: ETS 300 930 Edition 2
ICS:
33.070.50 Globalni sistem za mobilno Global System for Mobile
telekomunikacijo (GSM) Communication (GSM)
SIST ETS 300 930 E2:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 930 E2:2003

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SIST ETS 300 930 E2:2003
EUROPEAN ETS 300 930
TELECOMMUNICATION September 1997
STANDARD Second Edition
Source: ETSI SMG Reference: RE/SMG-030322QR
ICS: 33.020
Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM)
R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
Digital cellular telecommunications system (Phase 2+);
Functions related to Mobile Station (MS)
in idle mode and group receive mode
(GSM 03.22 version 5.1.1)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [e-mail]
Tel.: [phone] - Fax: [phone]
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997. All rights reserved.

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Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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Contents
Foreword .5
1 Scope .7
1.1 Normative references .7
1.2 Definitions and abbreviations.8
2 General description of idle mode .10
3 Requirements and technical solutions .11
3.1 PLMN selection and roaming.11
3.2 Camping on a cell .11
3.2.1 Normal camping .11
3.2.2 "Camp on any cell" .12
3.3 Regional provision of service.12
3.4 Borders between location areas .12
3.5 Barred cells and access control.12
3.5.1 Barred cells .12
3.5.2 Prioritizing cells.13
3.5.2.1 For cell selection.13
3.5.2.2 For cell reselection.13
3.5.3 Access control.13
3.5.4 Forbidden LA for regional provision of service.13
3.6 Radio constraints .13
3.7 No suitable cell (limited service state) .14
4 Overall process structure .15
4.1 Process goal .15
4.2 States description .15
4.3 List of states.15
4.3.1 List of states for the PLMN selection process.15
4.3.1.1 List of states for automatic mode (figure 2a).15
4.3.1.2 List of states for manual mode (figure 2b).15
4.3.2 List of States for the cell selection process (figure 3).16
4.3.3 List of states for location updating (figure 4) .16
4.4 PLMN selection process .17
4.4.1 Introduction.17
4.4.2 Registration on a PLMN .17
4.4.3 PLMN selection .17
4.4.3.1 At switch-on or recovery from lack of coverage.17
4.4.3.2 User reselection.18
4.4.3.3 In VPLMN of home country.19
4.4.4 Abnormal cases.19
4.4.5 Roaming not allowed in this LA .19
4.5 Cell selection process.19
4.6 Location updating process.21
4.6.1 General.21
4.6.2 Initiation of Location Updating .21
4.6.3 Periodic Location Updating .22
4.6.4 IMSI attach/detach operation .22
4.7 Service indication.22
4.8 BCCH allocation broadcasting and storage.23
4.9 Pageability of the mobile subscriber .23
5 Group receive mode.30
5.1 General description.30
5.2 Requirements and technical solutions .30
5.2.1 Network provisions.30

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5.2.2 Group receive mode cell monitoring. 30
5.2.3 Group receive mode cell change. 31
5.2.4 Uplink access in group calls . 31
History. 32

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Foreword
This European Telecommunication Standard (ETS) has been produced by the Special Mobile Group
(SMG) of the European Telecommunications Standards Institute (ETSI).
This ETS specifies functions related to Mobile Station (MS) in idle mode and group receive mode within
the digital cellular telecommunications system.
The contents of this ETS is subject to continuing work within SMG and may change following formal SMG
approval. Should SMG modify the contents of this ETS, it will be resubmitted for OAP by ETSI with an
identifying change of release date and an increase in version number as follows:
Version 5.x.y
where:
y the third digit is incremented when editorial only changes have been incorporated in the
specification;
x the second digit is incremented for all other types of changes, i.e. technical enhancements,
corrections, updates, etc.
The specification from which this ETS has been derived was originally based on CEPT documentation,
hence the presentation of this ETS may not be entirely in accordance with the ETSI drafting rules.
Transposition dates
Date of adoption: 5 September 1997
Date of latest announcement of this ETS (doa): 31 December 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 June 1998
Date of withdrawal of any conflicting National Standard (dow): 30 June 1998

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1 Scope
This European Telecommunication Standard (ETS) gives an overview of the tasks undertaken by a GSM
Mobile Station (MS) when in idle mode, that is, switched on but not having a dedicated channel allocated,
e.g. not making or receiving a call, or when in group receive mode, that is, receiving a group call or
broadcast call but not having a dedicated connection. It also describes the corresponding network
functions.
NOTE: The term GSM MS is used for any type of MS supporting one, or combinations, of the
frequency bands specified in GSM 05.05 (e.g. GSM 900 and DCS 1 800).
This ETS outlines how the requirements of the GSM 02 series Technical Specifications (especially
GSM 02.11) on idle mode operation shall be implemented. Further details are given in GSM 04.08 and
GSM 05.08.
Clause 2 of this ETS gives a general description of the idle mode process. Clause 3 outlines the main
requirements and technical solutions of those requirements. Clause 4 describes the processes used in
idle mode. There is inevitably some overlap between these clauses. Clause 5 describes the cell change
procedures for a MS in group receive mode.
1.1 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references, the
latest edition of the publication referred to applies.
[1] GSM 01.04 (ETR 350): "Digital cellular telecommunications system (Phase 2+);
Abbreviations and acronyms".
[2] GSM 02.01: "Digital cellular telecommunications system (Phase 2+); Principles
of telecommunications services supported by a GSM Public Land Mobile
Network (PLMN)".
[3] GSM 02.02 (ETS 300 904): "Digital cellular telecommunications system
(Phase 2+); Bearer Services (BS) supported by a GSM Public Land Mobile
Network (PLMN)".
[4] GSM 02.03 (ETS 300 905): "Digital cellular telecommunications system
(Phase 2+); Teleservices supported by a GSM Public Land Mobile Network
(PLMN)".
[5] GSM 02.04 (ETS 300 918): "Digital cellular telecommunications system
(Phase 2+); General on supplementary services".
[6] GSM 02.06 (ETS 300 919): "Digital cellular telecommunications system
(Phase 2+); Types of Mobile Stations (MS)".
[7] GSM 02.07 (ETS 300 906): "Digital cellular telecommunications system
(Phase 2+); Mobile Station (MS) features".
[8] GSM 02.09 (ETS 300 920): "Digital cellular telecommunications system;
Security aspects".
[9] GSM 02.11 (ETS 300 921): "Digital cellular telecommunications system; Service
accessibility".
[10] GSM 02.16: "Digital cellular telecommunications system; International Mobile
station Equipment Identities (IMEI)".

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[11] GSM 02.17 (ETS 300 922): "Digital cellular telecommunications system;
Subscriber Identity Modules (SIM) Functional characteristics".
[12] GSM 02.24 (ETS 300 923): "Digital cellular telecommunications system;
Description of Charge Advice Information (CAI)".
[13] GSM 02.30 (ETS 300 907): "Digital cellular telecommunications system
(Phase 2+); Man-Machine Interface (MMI) of the Mobile Station (MS)".
[14] GSM 02.40: "Digital cellular telecommunications system; Procedures for call
progress indications".
[15] GSM 02.41: "Digital cellular telecommunications system (Phase 2+); Operator
determined barring".
[16] GSM 02.81: "Digital cellular telecommunications system; Line identification
supplementary services - Stage 1".
[17] GSM 02.82: "Digital cellular telecommunications system (Phase 2+); Call
Forwarding (CF) supplementary services - Stage 1".
[18] GSM 02.83: "Digital cellular telecommunications system; Call Waiting (CW) and
Call Holding (HOLD) supplementary services - Stage 1".
[19] GSM 02.84: "Digital cellular telecommunications system; MultiParty (MPTY)
supplementary services - Stage 1".
[20] GSM 02.85: "Digital cellular telecommunications system; Closed User Group
(CUG) supplementary services - Stage 1".
[21] GSM 02.86: "Digital cellular telecommunications system; Advice of Charge
(AoC) supplementary services - Stage 1".
[22] GSM 02.88: "Digital cellular telecommunications system; Call Barring (CB)
supplementary services - Stage 1".
[23] GSM 04.08 (ETS 300 940): "Digital cellular telecommunications system
(Phase 2+); Mobile radio interface layer 3 specification".
[24] GSM 05.02 (ETS 300 908): "Digital cellular telecommunications system
(Phase 2+); Multiplexing and multiple access on the radio path".
[25] GSM 05.08 (ETS 300 911): "Digital cellular telecommunications system
(Phase 2+); Radio subsystem link control".
1.2 Definitions and abbreviations
For the purposes of this ETS, the following definitions apply:
acceptable cell: This is a cell that the MS may camp on to make emergency calls. It must satisfy criteria
(ii) and (iv) of subclause 3.2.1.
allowable PLMN: This is a PLMN which is not in the list of forbidden PLMNs in the SIM.
available PLMN: This is a PLMN where the MS has found a cell that satisfies conditions (ii) and (iv) of
subclause 3.2.1.
broadcast call: A communication in which several MSs can receive, but only the originator of the call is
allowed to transmit on the radio channel. Examples of the broadcast call are those established for the
voice broadcast service (VBS, see GSM 03.69).

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camped on a cell: The MS (ME if there is no SIM) has completed the cell selection/reselection process
and has chosen a cell from which it plans to receive all available services. Note that the services may be
limited, and that the PLMN may not be aware of the existence of the MS (ME) within the chosen cell.
current serving cell: This is the cell on which the MS is camped.
group call: A communication in which several MSs can receive, but at most one may be allowed to
transmit on a radio channel. Examples of group calls are those established for the voice group call service
(VGCS, see GSM 03.68).
group receive mode: State of the MS when it is engaged in a group or broadcast call as a listener.
home PLMN: This is a PLMN where the MCC and MNC of the PLMN identity are the same as the MCC
and MNC of the IMSI.
registered PLMN (RPLMN): This is the PLMN on which certain LU outcomes have occurred (see
table 1).
registration: This is the process of camping on a cell of the PLMN and doing any necessary LUs.
selected PLMN: This is the PLMN that has been selected according to subclause 3.1, either manually or
automatically.
suitable cell: This is a cell on which an MS may camp. It must satisfy criteria (i) to (iv) of subclause 3.2.1.
For an MS in group receive mode, the suitable cell is determined by the criteria defined in subclause 5.2.3.
visited PLMN of home country: This is a PLMN, different from the home PLMN, where the MCC part of
the PLMN identity is the same as the MCC of the IMSI.
The PLMN to which a cell belongs (PLMN identity) is given in the system information transmitted on the
BCCH (MCC + MNC part of LAI).
Abbreviations used in this ETS are listed in GSM 01.04.

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2 General description of idle mode
When an MS is switched on, it attempts to make contact with a GSM public land mobile network (PLMN).
The particular PLMN to be contacted may be selected either automatically or manually. The MS looks for
a suitable cell of the chosen PLMN and chooses that cell to provide available services, and tunes to its
control channel (BCCH plus CCCH). This choosing is known as "camping on the cell". The MS will then
register its presence in the Location Area (LA) of the chosen cell if necessary, by means of a Location
Updating (LU) or IMSI attach procedure. If the MS loses coverage of a cell, it reselects onto the most
suitable alternative cell of the selected PLMN and camps on that cell. If the new cell is in a different LA, an
LU request is performed. If the MS loses coverage of a PLMN, either a new PLMN is selected
automatically, or an indication of which PLMNs are available is given to the user, so that a manual
selection can be made.
The purpose of camping on a cell in idle mode is threefold:
a) It enables the MS to receive system information from the PLMN.
b) If the MS wishes to initiate a call, it can do this by initially accessing the network on the CCCH of the
cell on which it is camped (with the exceptions defined in subclauses 3.5.3 and 3.5.4).
c) If the PLMN receives a call for the MS, it knows (in most cases) the LA of the cell in which the MS is
camped. It can then send a "paging" message for the MS on CCCHs of all the cells in the LA. The
MS will then receive the paging message because it is tuned to the CCCH of a cell in that LA, and
the MS can respond on that CCCH.
If the MS is unable to find a suitable cell to camp on, or the SIM is not inserted, or if it receives certain
responses to an LU request (e.g. "illegal MS"), 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 3 processes:
- PLMN selection;
- Cell selection and reselection;
- Location updating.
The relationship between these processes is illustrated in figure 1. The states and state transitions within
each process are shown in figures 2 to 4.

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3 Requirements and technical solutions
The following subclauses list the main requirements of idle mode operation and give an outline of the
technical solution.
3.1 PLMN selection and roaming
The MS normally operates on its home PLMN (HPLMN). However a visited PLMN (VPLMN) may be
selected, e.g. if the MS loses coverage. There are two modes for PLMN selection:
i) Automatic mode - This mode utilizes a list of PLMNs in priority order. The highest priority PLMN
which is available and allowable is selected.
ii) Manual mode - Here the MS indicates to the user which PLMNs are available. Only when the user
makes a manual selection does the MS try to obtain normal service on the VPLMN.
There are two cases:
- International Roaming - This is where the MS receives service on a PLMN of a different country
than that of the HPLMN.
- National Roaming - This is where the MS receives service from a PLMN of the same country as
that of the HPLMN, either anywhere or on a regional basis. The MS makes a periodic search for the
HPLMN while national roaming.
To prevent repeated attempts to have roaming service on a not allowed LA, when the MS is informed that
an LA is forbidden, the LA is added to a list of "forbidden LAs for roaming" which is stored in the MS. This
list is deleted when the MS is switched off or when the SIM is removed.
If a "PLMN not allowed" message is received by an MS in response to an LU request from a VPLMN, that
VPLMN is added to a list of "forbidden PLMNs" in the SIM and thereafter that VPLMN will not be accessed
by the MS when in automatic mode. A PLMN is removed from the "forbidden" list if, after a subsequent
manual selection of that PLMN, there is a successful LU. This list is retained when the MS is switched off
or the SIM is removed. The HPLMN shall not be stored on the list of "forbidden PLMNs".
3.2 Camping on a cell
3.2.1 Normal camping
For normal service, the MS has to camp on a suitable cell, tune to that cell's BCCH + CCCH, and possibly
register within the PLMN so that the MS can:
a) Receive system information from the PLMN (on the BCCH), e.g. the cell options.
b) Receive paging messages from the PLMN, e.g. when there is an incoming call for the MS.
c) Initiate call setup for outgoing calls or other actions from the MS (where possible, see
subclauses 3.5.3 and 3.5.4).
The choice of such a suitable cell for the purpose of receiving normal service is referred to as "normal
camping". There are various requirements that a cell must satisfy before an MS can perform normal
camping on it:
i) It should be a cell of the selected PLMN.
ii) It should not be "barred" (see subclause 3.5.1).
iii) It should not be in an LA which is in the list of "forbidden LAs for roaming".
iv) The radio path loss between MS and BTS must be below a threshold set by the PLMN operator.
This is estimated as shown in subclause 3.6.

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Initially, the MS looks for a cell which satisfies these 4 constraints ("suitable cell") by checking cells in
descending order of received signal strength. If a suitable cell is found, the MS camps on it and performs
any registration necessary. Cells can have two levels of priority, suitable cells which are of low priority are
only camped on if there are no other suitable cells of normal priority. (This is called "cell selection").
When camped on a cell the MS regularly looks to see if there is a better cell in terms of a cell re-selection
criterion, and if there is, the better cell is selected. Also if one of the other criteria changes, (e.g. the
current serving cell becomes barred), or there is a downlink signalling failure (see subclause 3.6), a new
cell is selected. (This is called "cell reselection").
In order to speed up these processes, a list of the RF channels containing BCCH carriers of the same
PLMN is broadcast on the BCCH, see subclause 4.8. Also, the MS does not need to search all possible
RF channels to find a suitable cell. If, after searching the number of RF channels, given for each
frequency band below, with the strongest received signal level, a BCCH carrier has been found but no
suitable cell of the selected PLMN has been found, the MS can stop the attempt to find a suitable cell of
the selected PLMN.
The number of channels to be searched are 30 for GSM 900 and 40 for DCS 1 800.
3.2.2 "Camp on any cell"
If the MS cannot find a suitable cell, it attempts to camp on any acceptable cell and enter a "limited service
state", as defined in subclause 3.7.
3.3 Regional provision of service
An MS may have a "regionally restricted service" where it can only obtain service on certain LAs. If such
an MS attempts to camp on a cell of an LA for which it does not have service entitlement, when it does an
LU request, it will receive an "LA not allowed" message. In this case:
- The MS stores the forbidden LA identity (LAI) in a list of "forbidden LAIs for regional provision of
service", to prevent repeated access attempts on a cell of the forbidden LA. This list is deleted when
the MS is switched off or the SIM is removed. If the MS cannot find a suitable cell, the MS performs
the PLMN selection procedure starting at subclause 4.4.3.1 A or B.
3.4 Borders between location areas
If the MS is moving in a border area between LAs, it might repeatedly change between cells of different
LAs. Each change of LA would require an LU, which would cause a heavy signalling load and increase the
risk of a paging message being lost. To prevent this, a "CELL_RESELECT_HYSTERESIS" (CRH)
parameter is used. A cell in a different LA is only selected if it is "better", in terms of the path loss criterion
(see subclause 3.6), than all the cells in the current LA by at least the value of CRH. The CRH parameter
is broadcast on the BCCH. As the value of CRH broadcast may be different on different cells, the CRH
parameter to be used is that broadcast on the current serving cell. There is also a lower limit on the time
interval between reselection of cells on different LAs.
3.5 Barred cells and access control
3.5.1 Barred cells
The PLMN operator may decide not to allow MSs to camp on certain cells. (These cells may, for example,
only be used for hand over traffic, i.e. calls which need to be handed over to other cells). Barred cell
information is broadcast on the BCCH to instruct MSs not to camp on these cells. The barred cell status
may in fact change dynamically; hence the MS needs to regularly check the BCCH system information for
this parameter.
The barred status of a cell depends both on CELL_BAR_ACCESS and on the cell's priority indicated by
CELL_BAR_QUALIFY. The effect of these two parameters is further described in GSM 05.08.
If a cell is barred this applies both for cell selection and reselection.

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3.5.2 Prioritizing cells
In general, cell prioritization is a means of encouraging MSs to select some suitable cells in preference to
others. Since the priority comparison is only between suitable cells, prioritization does not affect coverage.
Operators may prefer a certain type of cell not to be selected unless it is the only suitable type. For
example, umbrella cells due to their large frequency reuse distance, or microcells because the MS could
be travelling too fast for them.
3.5.2.1 For cell selection
During cell selection (see subclause 3.2.1), a cell with low priority indication will only be selected if a
suitable cell of normal priority cannot be found.
3.5.2.2 For cell reselection
Cell prioritization can also be achieved during cell reselection by the use of the reselection parameters
optionally broadcast. Cells are reselected on the basis of a parameter called C2 and the C2 value for each
cell is given a positive or negative offset to encourage or discourage MSs to reselect that cell. A full range
of positive and negative offsets is provided to allow the incorporation of this feature into already
operational networks.
3.5.3 Access control
Due to problems in certain areas, Network Operators may decide to restrict access from some MSs (e.g.
in case of congestion on the AGCH), and for this reason the access control mechanism is provided.
At subscription one or more access control classes are allocated to the subscriber and stored in the SIM.
The information providing all authorized classes is broadcast on the BCCH (together with a bit indicating
whether emergency calls may be made). This information is modified dynamically and therefore the MS
has to check the BCCH before each attempt to access.
The MS ignores the Access Control information when selecting a cell to camp on, i.e. it shall not reject a
cell for camping on because access on that cell is not allowed.
3.5.4 Forbidden
...