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TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
GSM/EDGE Radio link management in hierarchical networks
(3GPP TS 45.022 version 15.0.0 Release 15)
R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
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3GPP TS 45.022 version 15.0.0 Release 15 1 ETSI TS 145 022 V15.0.0 (2018-07)
Reference
RTS/TSGR-0645022vf00
Keywords
GSM
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3GPP TS 45.022 version 15.0.0 Release 15 2 ETSI TS 145 022 V15.0.0 (2018-07)
Intellectual Property Rights
Essential patents
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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
.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
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3GPP TS 45.022 version 15.0.0 Release 15 3 ETSI TS 145 022 V15.0.0 (2018-07)
Contents
Intellectual Property Rights . 2
Foreword . 2
Modal verbs terminology . 2
Foreword . 6
1 Scope . 7
2 References . 7
3 Abbreviations . 7
4 General . 7
5 Hierarchical networks. 8
5.1 General . 8
5.2 Cell types . 8
5.2.1 Large cells . 8
5.2.2 Small cells . 8
5.2.3 Microcells . 8
6 Idle mode procedures . 9
7 Examples of handover and RF power control algorithms. . 9
7.1 General . 9
Annex A (informative): Example 1 (Siemens AG) . 10
A.1 Introduction . 10
A.2 Functional requirements . 10
A.3 BSS pre-processing and threshold comparisons. 11
A.3.1 Measurement averaging process . 11
A.3.2 Handover threshold comparison process . 11
A.4 BSS decision algorithm . 12
A.5 Additional O&M parameters stored for handover purposes in hierarchical networks . 12
A.6 Bibliography . 13
Annex B (informative): Example 2 (DeTeMobil) . 14
B.1 Introduction . 14
B.2 Definitions . 14
B.2.1 Categories of cells . 14
B.2.2 Classification of MS in connected mode . 15
B.2.2.1 Classification in the lower layer . 15
B.2.2.2 Classification in the middle layer or the upper layer . 15
B.2.2.3 Loss of the "slow MS" or "quasi-stationary MS" status . 16
B.3 Power Control Algorithm . 16
B.3.1 MS connected over a cell of the lower layer . 16
B.3.2 MS connected over a cell of the middle layer or the upper layer . 16
B.4 Handover algorithm in a hierarchical cell structure . 16
B.4.1 MS connected over a cell of the lower layer . 16
B.4.2 MS connected over a cell of the middle layer or the upper layer . 17
B.4.3 Handover at borders of different cell structures . 17
B.5 O&M-Parameter . 17
B.6 State diagrams . 18
ETSI
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3GPP TS 45.022 version 15.0.0 Release 15 4 ETSI TS 145 022 V15.0.0 (2018-07)
Annex C (informative): Example 3 (Alcatel) . 20
C.1 General description. 20
C.1.1 Speed discrimination . 20
C.2 Handover causes . 21
C.2.1 Emergency causes . 21
C.2.2 Better cell causes . 21
C.3 Dwell time in lower layer cells: . 21
C.3.1 Serving cell = lower layer cell . 21
C.3.2 Serving cell = upper layer cell . 21
C.3.3 Mechanism of increasing / decreasing tdwell . 21
C.4 Speed discrimination process: . 22
C.4.1 Serving cell = upperlayer cell . 22
C.4.2 Serving cell = lower layer cell . 22
C.5 Representation of handovers . 23
C.5.1 Ideal behaviour: target cells are available . 23
C.5.2 Real behaviour: target cells may not be available . 23
C.6 Emergency handover . 24
C.6.1 Target cell = upper layer cell . 24
C.7 Upper layer to lower layer cells handover . 25
C.7.1 General principles. 25
C.7.2 Homogeneity of speed discrimination in lower layer and upper layer cells . 25
C.8 Minicells . 25
C.8.1 Handover diagrams. 25
C.9 O&M parameters . 26
Annex D (informative): Example 4 (France Telecom/CNET) . 27
D.1 Introduction . 27
D.2 Descriptions of the algorithm . 28
D.3 Handover causes . 28
D.3.1 emergency handover causes . 28
D.3.2 mobile speeds estimation causes . 28
D.4 Mobile speeds estimations. 29
D.4.1 Estimation of the field strength variations . 29
D.5 BSS decision algorithm . 30
D.6 O&M parameters . 30
D.7 Examples . 31
D.8 State diagrams . 34
D.8.1 Case of a three layers hierarchical network . 34
D.8.2 Case of a two layers hierarchical network . 35
Annex E (informative): Simulation Model for Handover Performance Evaluation in
Hierarchical Cell Structures . 36
E.1 Introduction . 36
E.2 Mobile Environment. 36
E.3 Radio Network Model . . 36
E.3.1 Scenario 1: Hot Spot. 36
E.3.2 Scenario 2: Line of Cells . 36
E.3.3 Scenario 3: Manhattan Coverage . 37
E.4 Propagation Model . 37
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3GPP TS 45.022 version 15.0.0 Release 15 5 ETSI TS 145 022 V15.0.0 (2018-07)
E.4.1 Upper Layer Path Loss . 37
E.4.1.1 Macrocells. 37
E.4.1.2 Small cells . 38
E.4.2 Lower Layer Path Loss . 39
E.4.2.1 Line-of-sight Case . 39
E.4.2.2 Non Line-of-sight Case . 39
E.4.2.3 Shape of the level with the proposed path loss model . 40
E.4.3 Fading . 41
E.5 Motion Model . 41
E.6 Handover Algorithms . 41
E.7 Measurement Reporting . 42
E.8 Performance Criteria . 42
E.9 Open Issues . 42
Annex F (informative): Change history . 43
History . 44
ETSI
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3GPP TS 45.022 version 15.0.0 Release 15 6 ETSI TS 145 022 V15.0.0 (2018-07)
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
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3GPP TS 45.022 version 15.0.0 Release 15 7 ETSI TS 145 022 V15.0.0 (2018-07)
1 Scope
The present document gives examples for the Radio sub-system link control to be implemented in the Base Station
System (BSS) and Mobile Switching Centre (MSC) of the GSM and DCS 1 800 systems in case hierarchical cell
structures are employed.
Unless otherwise specified, references to GSM also include DCS 1 800, and multiband systems if operated by a single
operator.
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 03.22 (ETS 300 930): "Functions related to Mobile Station (MS) in idle mode and group
receive mode".
[2] 3GPP TR 03.30 (ETR 364): "Radio network planning aspects".
[3] 3GPP TS 45.008: "Radio subsystem link control".
[4] 3GPP TR 01.04 (ETR 350): "Abbreviations and acronyms".
3 Abbreviations
Abbreviations used in the present document are listed in 3GPP TR 01.04 [4].
4 General
ETS 300 911 (GSM 05.08 [3]) 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 European
digital cellular telecommunications system (Phase 2).
The present document gives several examples of how the basic handover and RF power control algorithm as contained
in (informative) annex A to ETS 300 911 [3] can be enhanced to cope with the requirements on the radio subsystem link
control in hierarchical networks.
A hierarchical network is a network consisting of multiple layers of cells, allowing for an increased traffic capacity and
performance compared to a single layer network.
ETSI
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3GPP TS 45.022 version 15.0.0 Release 15 8 ETSI TS 145 022 V15.0.0 (2018-07)
The radio sub-system link control aspects that are addressed are as follows:
- Handover;
- RF Power control.
5 Hierarchical networks
5.1 General
In a hierarchical, or microcellular network, traffic is supported on multiple layers of cells. Typically, a network operator
could implement a layer consisting of microcells as a second layer in his existing network consisting of large or small
cells. The addition of this second layer would improve the capacity and coverage of his network.
In the present document the following naming convention is used for the different layers. For a network consisting of
three layers the layer using the biggest cells is the "upper layer", followed by the "middle layer", and then the "lower
layer" which has the smallest cells. For a network consisting of two layers, only "upper layer" and "lower layer" are
used.
The intention in a hierarchical network is to use the radio link control procedures to handle the majority of the traffic in
the lower layer, i.e. the smallest cells, as this will limit interference and therefore improve the frequency reuse.
However, a part of the traffic cannot always efficiently be handled in the lower layer. Examples are cases where the MS
is moving fast (relative to the cell range), or where the coverage is insufficient, or where a cell to make a handover to on
the same level may not be available fast enough (going around corners, entering/leaving buildings).
5.2 Cell types
GSM 03.30 [2] distinguishes between three kinds of cells: large cells, small cells and micro cells. The main difference
between these kinds lies in the cell range, the antenna installation site, and the propagation model applying:
5.2.1 Large cells
In large cells the base station antenna is installed above the maximum height of the surrounding roof tops; the path loss
is determined mainly by diffraction and scattering at roof tops in the vicinity of the mobile i.e. the main rays propagate
above the roof tops; the cell radius is minimally 1 km and normally exceeds 3 km. Hata's model and its extension up to
2 000 MHz (COST 231-Hata model) can be used to calculate the path loss in such cells (GSM 03.30 [2] annex B).
5.2.2 Small cells
For small cell coverage the antenna is sited above the median but below the maximum height of the surrounding roof
tops and so therefore the path loss is determined by the same mechanisms as stated in subclause 5.1.1. However large
and small cells differ in terms of maximum range and for small cells the maximum range is typically less than 1-3 km.
In the case of small cells with a radius of less than 1 km the Hata model cannot be used.
The COST 231-Walfish-Ikegami model (see GSM 03.30 [2] annex B) gives the best approximation to the path loss
experienced when small cells with a radius of less than 5 km are implemented in urban environments. It can therefore
be used to estimate the BTS ERP required in order to provide a particular cell radius (typically in the range 200 m -
3 km).
5.2.3 Microcells
COST 231 defines a microcell as being a cell in which the base station antenna is mounted generally below roof top
level. Wave propagation is determined by diffraction and scattering around buildings i.e. the main rays propagate in
street canyons. COST 231 proposes an experimental model for microcell propagation when a free line of sight exists in
a street canyon (see GSM 03.30 [2]).
The propagation loss in microcells increases sharply as the receiver moves out of line of sight, for example, around a
street corner. This can be taken into account by adding 20 dB to the propagation loss per corner, up to two or three
corners (the propagation being more of a guided type in this case). Beyond, the complete COST231-Walfish-Ikegami
model as presented in annex B of GSM 03.30 [2] should be used.
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3GPP TS 45.022 version 15.0.0 Release 15 9 ETSI TS 145 022 V15.0.0 (2018-07)
Microcells have a radius in the region of 200 to 300 metres and therefore exhibit different usage patterns from large and
small cells.
6 Idle mode procedures
GSM 03.22 [1] outlines how idle mode operation shall be implemented. Further details are given in Technical
Specifications GSM 04.08 and GSM 05.08 [3].
A useful feature for hierarchical networks is that cell prioritization, for Phase 2 MS, can be achieved during cell
reselection by the use of the reselection parameters optionally broadcast on the BCCH. 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
(CELL_RESELECT_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.
The parameters used to calculate C2 are as follows:
a) CELL_RESELECT_OFFSET;
b) PENALTY_TIME
...