ETSI ETS 300 578 ed.7 (1996-11)

Digital cellular telecommunications system (Phase 2) (GSM); Radio subsystem link control (GSM 05.08)

RE/SMG-020508PR6

Digitalni celični telekomunikacijski sistem (faza 2) – Krmiljenje povezave radijskega podsistema (GSM 05.08)

General Information

• Status: Published
• Publication Date: 12-Nov-1996
• Technical Committee: SMG 2 - Radio
• Current Stage: 12 - Completion
• Due Date: 08-Nov-1996
• Completion Date: 13-Nov-1996
• Ref Project: SIST ETS 300 578 E7:2003 - Digital cellular telecommunications system (Phase 2) (GSM); Radio subsystem link control (GSM 05.08)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST ETS 300 578 E7:2003
01-december-2003
'LJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHPID]D±.UPLOMHQMHSRYH]DYH
UDGLMVNHJDSRGVLVWHPD*60
Digital cellular telecommunications system (Phase 2) (GSM); Radio subsystem link
control (GSM 05.08)
Ta slovenski standard je istoveten z: ETS 300 578 Edition 7
ICS:
33.070.50 Globalni sistem za mobilno Global System for Mobile
telekomunikacijo (GSM) Communication (GSM)
SIST ETS 300 578 E7:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 578 E7:2003

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SIST ETS 300 578 E7:2003
EUROPEAN ETS 300 578
TELECOMMUNICATION November 1996
STANDARD Seventh Edition
Source: ETSI TC-SMG Reference: RE/SMG-020508PR6
ICS: 33.060.50
Key words: Digital telecommunications system, Global System for Mobile communications (GSM)
R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
Digital cellular telecommunications system (Phase 2);
Radio subsystem link control
(GSM 05.08)
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 1996. 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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ETS 300 578: November 1996 (GSM 05.08 version 4.17.0)
Contents
Foreword .5
1 Scope .7
1.1 Normative references .7
1.2 Abbreviations .8
2 General.8
3 Handover.8
3.1 Overall process.8
3.2 MS measurement procedure .9
3.3 BSS measurement procedure .9
3.4 Strategy.9
4 RF power control.9
4.1 Overall process.9
4.2 MS implementation .9
4.3 MS power control range.10
4.4 BSS implementation .10
4.5 BSS power control range.10
4.6 Strategy.10
4.7 Timing .10
5 Radio link failure.10
5.1 Criterion .10
5.2 MS procedure .11
5.3 BSS procedure.11
6 Idle mode tasks .11
6.1 Introduction .11
6.2 Measurements for normal cell selection .12
6.3 Measurements for stored list cell selection.12
6.4 Criteria for cell selection and reselection .13
6.5 Downlink signalling failure.14
6.6 Measurements for Cell Reselection.14
6.6.1 Monitoring of received level and BCCH data .14
6.6.2 Path loss criteria and timings for cell re-selection .15
6.7 Release of TCH and SDCCH .16
6.7.1 Normal case .16
6.7.2 Call re-establishment.16
6.8 Abnormal cases and emergency calls.17
7 Network pre-requisites .17
7.1 BCCH carriers.17
7.2 Identification of surrounding BSS for handover measurements .17
8 Radio link measurements.18
8.1 Signal strength.19
8.1.1 General.19
8.1.2 Physical parameter.19
8.1.3 Statistical parameters.20
8.1.4 Range of parameter .20
8.2 Signal quality.20
8.2.1 General.20
8.2.2 Physical parameter.20
8.2.3 Statistical parameters.20

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8.2.4 Range of parameter. 21
8.3 Aspects of discontinuous transmission (DTX) . 22
8.4 Measurement reporting . 22
8.5 Absolute MS-BTS distance . 25
8.5.1 General . 25
8.5.2 Physical parameter . 25
9 Control parameters. 26
Annex A (informative): Definition of a basic GSM or DCS 1 800 handover and RF power control
algorithm . 29
A.1 Scope. 29
A.2 Functional requirement. 29
A.3 BSS pre-processing and threshold comparisons . 29
A.3.1 Measurement averaging process. 30
A.3.2 Threshold comparison process. 31
A.3.2.1 RF power control process. 31
A.3.2.2 Handover Process . 32
A.4 BSS decision algorithm. 32
A.4.1 Internal intracell handover according to radio criteria: (Interference problems). 33
A.4.2 Internal handover according to other criteria. 33
A.4.3 General considerations .34
A.5 Channel allocation . 34
A.6 Handover decision algorithm in the MSC . 34
History. 37

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Foreword
This European Telecommunication Standard (ETS) has been produced by the Special Mobile Group
(SMG) Technical Committee (TC) of the European Telecommunications Standards Institute (ETSI).
This ETS specifies the Radio sub system link control implemented in the Mobile Station (MS), Base
Station System (BSS) and Mobile Switching Centre (MSC) of the GSM and DCS 1 800 systems of the
Digital cellular telecommunications system (Phase 2). Unless stated, references to GSM also include
DCS 1 800.
This seven edition is a result of further work carried out by TC-SMG and corresponds to GSM technical
specification, GSM 05.08 version 4.17.0.
The specification from which this ETS has been derived was originally based on CEPT documentation,
hence the presentation of this ETS is not in accordance with the ETSI/PNE rules.
Reference is made within this ETS to GSM Technical Specifications (GSM-TS) (See note).
Reference is also made within this ETS to GSM 0x.xx. series. The specifications in the series can be
identified, with their full title, within the normative reference Clause of this ETS by the first two digits of
their GSM reference number e.g. GSM 09.xx series, refers to GSM 09.01, GSM 09.02, etc.
NOTE: TC-SMG has produced documents which give the technical specifications for the
implementation of the Digital cellular telecommunications system. Historically, these
documents have been identified as GSM Technical Specifications (GSM-TSs). These
TSs may have subsequently become I-ETSs (Phase 1), or ETSs (Phase 2), whilst
others may become ETSI Technical Reports (ETRs). GSM-TSs are, for editorial
reasons, still referred to in current GSM ETSs.
Transposition dates
Date of adoption of this ETS: 18 October 1996
Date of latest announcement of this ETS (doa): 28 February 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 31 August 1997
Date of withdrawal of any conflicting National Standard (dow): 31 August 1997

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1 Scope
This European Telecommunication Standard (ETS) specifies the Radio sub-system link control
implemented in the Mobile Station (MS), Base Station System (BSS) and Mobile Switching Centre (MSC)
of the GSM and DCS 1 800 systems.
Unless otherwise specified, references to GSM also include DCS 1 800.
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 100): "Digital cellular telecommunication system (Phase 2);
Abbreviations and acronyms".
[2] GSM 03.03 (ETS 300 523): "Digital cellular telecommunication system
(Phase 2); Numbering, addressing and identification".
[3] GSM 03.09 (ETS 300 527): "Digital cellular telecommunication system
(Phase 2); Handover procedures".
[4] GSM 03.22 (ETS 300 535): "Digital cellular telecommunication system
(Phase 2); Functions related to Mobile Station (MS) in idle mode".
[5] GSM 04.04 (ETS 300 553): "Digital cellular telecommunication system
(Phase 2); Layer 1 General requirements".
[6] GSM 04.06 (ETS 300 555): "Digital cellular telecommunication system
(Phase 2); Mobile Station - Base Station System (MS - BSS) interface Data Link
(DL) layer specification".
[7] GSM 04.08 (ETS 300 557): "Digital cellular telecommunication system
(Phase 2); Mobile radio interface layer 3 specification".
[8] GSM 05.02 (ETS 300 574): "Digital cellular telecommunication system
(Phase 2); Multiplexing and multiple access on the radio path".
[9] GSM 05.05 (ETS 300 577): "Digital cellular telecommunication system
(Phase 2); Radio transmission and reception".
[10] GSM 05.10 (ETS 300 579): "Digital cellular telecommunication system
(Phase 2); Radio subsystem synchronization".
[11] GSM 06.11 (ETS 300 580-3): "Digital cellular telecommunication system
(Phase 2); Substitution and muting of lost frames for full rate speech channels".
[12] GSM 08.08 (ETS 300 590): "Digital cellular telecommunication system
(Phase 2); Mobile Switching Centre - Base Station System (MSC - BSS)
interface Layer 3 specification".
[13] GSM 08.58 (ETS 300 596): "Digital cellular telecommunication system
(Phase 2); Base Station Controller - Base Transceiver Station (BSC - BTS)
interface Layer 3 specification".

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[14] GSM 11.10 (ETS 300 607): "Digital cellular telecommunication system
(Phase 2); Mobile Station (MS) conformity specification".
[15] GSM 11.20 (ETS 300 609): "Digital cellular telecommunication system
(Phase 2); The GSM Base Station System (BSS) equipment specification".
1.2 Abbreviations
Abbreviations used in this ETS are listed in GSM 01.04.
2 General
The radio sub-system link control aspects that are addressed are as follows:
- Handover;
- RF Power control;
- Radio link Failure;
- Cell selection and re-selection in Idle mode.
Handover is required to maintain a call in progress as a MS passes from one cell coverage area to
another and may also be employed to meet network management requirements, e.g. relief of congestion.
Handover may occur during a call from TCH to TCH, it may also occur from DCCH to DCCH or from
DCCH to TCH, e.g. during the initial signalling period at call set-up.
The handover may be either from a channel on one cell to another channel on a surrounding cell, or
between channels on the same cell which are carried on the same frequency band. Examples are given of
handover strategies, however, these will be determined in detail by the network operator.
For a multiband MS, specified in GSM 02.06, the handover described is also allowed between any
channels on different cells which are carried on different frequency bands, e.g. between a GSM 900/TCH
and a DCS 1 800/TCH. Handover between two co-located cells, carried on different frequency bands, is
considered as inter-cell handover irrespective of the handover procedures used.
Adaptive control of the RF transmit power from an MS and optionally from the BSS is implemented in
order to optimize the uplink and downlink performance and minimize the effects of co-channel interference
in the system.
The criteria for determining radio link failure are specified in order to ensure that calls which fail either
from loss of radio coverage or unacceptable interference are satisfactorily handled by the network. Radio
link failure may result in either re-establishment or release of the call in progress.
Procedures for cell selection and re-selection whilst in Idle mode (i.e. not actively processing a call), are
specified in order to ensure that a mobile is camped on a cell with which it can reliably communicate on
both the radio uplink and downlink. The operations of an MS in Idle Mode are specified in GSM 03.22.
Information signalled between the MS and BSS is summarized in tables 1 and 2. A full specification of the
Layer 1 header is given in GSM 04.04, and of the Layer 3 fields in GSM 04.08.
3 Handover
3.1 Overall process
The overall handover process is implemented in the MS, BSS and MSC. Measurement of radio
subsystem downlink performance and signal strengths received from surrounding cells, is made in the
MS. These measurements are signalled to the BSS for assessment. The BSS measures the uplink
performance for the MS being served and also assesses the signal strength of interference on its idle
traffic channels. Initial assessment of the measurements in conjunction with defined thresholds and
handover strategy may be performed in the BSS. Assessment requiring measurement results from other
BTS or other information resident in the MSC, may be performed in the MSC.
GSM 03.09 describes the handover procedures to be used in PLMNs.

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3.2 MS measurement procedure
A procedure shall be implemented in the MS by which it monitors the downlink RX signal level and quality
from its serving cell and the downlink RX signal level and BSIC of surrounding BTS. The method of
identification of surrounding BTS is described in section 7.2. The requirements for the MS measurements
are given in section 8.1.
3.3 BSS measurement procedure
A procedure shall be implemented in the BSS by which it monitors the uplink RX signal level and quality
from each MS being served by the cell. A procedure shall be implemented by which the BSS monitors the
levels of interference on its idle traffic channels.
3.4 Strategy
The handover strategy employed by the network for radio link control determines the handover decision
that will be made based on the measurement results reported by the MS/BSS and various parameters set
for each cell. Network directed handover may also occur for reasons other than radio link control, e.g. to
control traffic distribution between cells. The exact handover strategies will be determined by the network
operator, a detailed example of a basic overall algorithm appears in annex A. Possible types of handover
are as follows:
Inter-cell handover:
Intercell handover from the serving cell to a surrounding cell will normally occur either when the
handover measurements show low RXLEV and/or RXQUAL on the current serving cell and a better
RXLEV available from a surrounding cell, or when a surrounding cell allows communication with a
lower TX power level. This typically indicates that an MS is on the border of the cell area.
Intercell handover may also occur from the DCCH on the serving cell to a TCH on another cell
during call establishment. This may be used as a means of providing successful call establishment
when no TCH resource is available on the current serving cell.
Inter-cell handover between cells using different frequency bands is allowed for a multi band MS.
Intra-cell handover:
Intra-cell handover from one channel/timeslot in the serving cell to another channel/timeslot in the
same cell will normally be performed if the handover measurements show a low RXQUAL, but a
high RXLEV on the serving cell. This indicates a degradation of quality caused by interference even
though the MS is situated within the serving cell. The intra-cell handover should provide a channel
with a lower level of interference. Intra-cell handover can occur either to a timeslot on a new carrier
or to a different timeslot on the same carrier.
GSM 08.08 defines the causes for handover that may be signalled from BSS to MSC.
4 RF power control
4.1 Overall process
RF power control is employed to minimize the transmit power required by MS or BSS whilst maintaining
the quality of the radio links. By minimizing the transmit power levels, interference to co-channel users is
reduced.
4.2 MS implementation
RF power control shall be implemented in the MS.
The power control level to be employed by the MS is indicated by means of the power control information
sent either in the layer 1 header of each downlink SACCH message block (see GSM 04.04), or in a
dedicated signalling block (see GSM 04.08).

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The MS shall employ the most recently commanded power control level appropriate to the channel for all
transmitted bursts on either a TCH (including handover access burst), FACCH, SACCH or SDCCH. If the
commanded power control level is not supported by the MS as defined by its power class in GSM 05.05,
the MS shall act as though the closest supported power control level had been broadcast.
The MS shall confirm the power control level that it is currently employing in the uplink SACCH L1 header.
The indicated value shall be the power control level actually used by the mobile for the last burst of the
previous SACCH period.
When accessing a cell on the RACH (random access) and before receiving the first power command
during a communication on a DCCH or TCH (after an IMMEDIATE ASSIGNMENT), all GSM and class 1
and class 2 DCS 1 800 MS shall use the power level defined by the MS_TXPWR_MAX_CCH parameter
broadcast on the BCCH of the cell, or if MS_TXPWR_MAX_CCH corresponds to a power control level not
supported by the MS as defined by its power class in GSM 05.05, the MS shall act as though the closest
supported power control level had been broadcast. The class 3 DCS 1 800 MS shall use the power level
defined by MS TXPWR MAX CCH plus the value POWER OFFSET also broadcast on the BCCH of the
cell.
4.3 MS power control range
The range over which a MS shall be capable of varying its RF output power shall be from its maximum
output down to its minimum, in steps of nominally 2 dB.
GSM 05.05 gives a detailed definition of the RF power level step size and tolerances.
4.4 BSS implementation
RF power control may optionally be implemented in the BSS.
4.5 BSS power control range
The range over which the BSS shall be capable of reducing its RF output power from its maximum level
shall be nominally 30 dB, in 15 steps of nominally 2 dB.
GSM 05.05 gives a detailed definition of the RF power level step size and tolerances.
4.6 Strategy
The RF power control strategy employed by the network determines the ordered power level that is
signalled to the MS, and the power level that is employed by the BSS.
The power level to be employed in each case will be based on the measurement results reported by the
MS/BTS and various parameters set for each cell. The exact strategies will be determined by the network
operator. A detailed example of a basic algorithm appears in annex A.
4.7 Timing
Upon receipt of a command from the SACCH to change its power level, the MS shall change to the new
level at a rate of one nominal 2 dB power control step every 60 ms (13 TDMA frames), i.e. a range change
of 15 steps should take about 900 ms. The change shall commence at the first TDMA frame belonging to
the next reporting period (as specified in 8.4). The MS shall change the power one nominal 2 dB step at a
time, at a rate of one step every 60 ms following the initial change, irrespective of whether actual
transmission takes place or not.
In case of channel change, the commanded power level shall be applied on the new channel immediately.
5 Radio link failure
5.1 Criterion
The criterion for determining Radio Link Failure in the MS shall be based on the success rate of decoding
messages on the downlink SACCH.

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5.2 MS procedure
The aim of determining radio link failure in the MS is to ensure that calls with unacceptable voice/data
quality, which cannot be improved either by RF power control or handover, are either re-established or
released in a defined manner. In general the parameters that control the forced release should be set
such that the forced release will not normally occur until the call has degraded to a quality below that at
which the majority of subscribers would have manually released. This ensures that, for example, a call on
the edge of a radio coverage area, although of bad quality, can usually be completed if the subscriber
wishes.
The radio link failure criterion is based on the radio link counter S. If the MS is unable to decode a SACCH
message (BFI=1),S is decreased by 1. In the case of a successful reception of a SACCH message
(BFI=0) S is increased by 2. In any case S shall not exceed the value of RADIO_LINK_TIMEOUT. If
S reaches 0 a radio link failure shall be declared. The action to be taken is specified in GSM 04.08. The
RADIO_LINK_TIMEOUT parameter is transmitted by each BSS in the BCCH data (see table 1).
The MS shall continue transmitting as normal on the uplink until S reaches 0.
The algorithm shall start after the assignment of a dedicated channel and S shall be initialized to
RADIO_LINK_TIMEOUT.
The detailed operation shall be as follows:
- The radio link time-out algorithm shall be stopped at the reception of a channel change command.
- (Re-)initialization and start of the algorithm shall be done whenever the MS switches to a new
channel (this includes the old channel in assignment and handover failure cases), at the latest when
the main signalling link (see GSM 04.08) has been established.
- The RADIO_LINK_TIMEOUT value used at (re-)initialization shall be that used on the previous
channel (in the Immediate Assignment case the value received on the BCCH), or the value received
on SACCH if the MS has received a RADIO_LINK_TIMEOUT value on the new channel before the
initialization.
- If the first RADIO_LINK_TIMEOUT value on the SACCH is received on the new channel after the
initialization, the counter shall be re-initialized with the new value.
5.3 BSS procedure
The criteria for determining radio link failure in the BSS should be based upon either the error rate on the
uplink SACCH or on RXLEV/RXQUAL measurements of the MS. The exact criteria to be employed shall
be determined by the network operator.
6 Idle mode tasks
6.1 Introduction
Whilst in idle mode, an MS shall implement the cell selection and re-selection procedures described in
GSM 03.22. These procedures make use of measurements and sub-procedures described in this section.
The procedures ensure that the MS is camped on a cell from which it can reliably decode downlink data
and with which it has a high probability of communications on the uplink. Once the MS is camped on a
cell, access to the network is allowed.
This sectio
...