CG-GSM-R(14)007
Source: Bouygues Telecom
ECC Report <No>
Guidance for improving coexistence between GSM-R and
MFCN
Approved DD Month YYYY (Arial 9pt bold)
[last updated: DD Month YYYY) (Arial 9pt) [date of the latest update]]
ECC REPORT <No>- Page 2
0
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EXECUTIVE SUMMARY
ECC REPORT <No>- Page 3
TABLE OF CONTENTS
0
EXECUTIVE SUMMARY ............................................................................................................................ 2
1
INTRODUCTION ......................................................................................................................................... 5
2
RAILWAY GENERAL PRINCIPLES .......................................................................................................... 6
2.1 Railway interoperability ..................................................................................................................... 6
2.2 Critical zones and cases for GSM-R ................................................................................................. 6
2.3 Way forward for a European wide implementation of the improved receivers .................................. 6
3
GSM-R VS. MFCN TESTS RESULTS ....................................................................................................... 7
3.1 Lab tests in Munich ........................................................................................................................... 7
3.1.1 Results for the standard receiver Rx2 ..................................................................................... 8
3.1.2 Results for the improved receiver Rx1 .................................................................................... 8
3.2 Field tests in the UK .......................................................................................................................... 9
3.3 Discussion on MFCN unwanted emissions ....................................................................................... 9
3.3.1 Acceptable MFCN OOB emission level above the rail tracks ................................................. 9
3.3.2 Impact study of MFCN OOB emission .................................................................................. 10
3.3.3 Conclusion ............................................................................................................................. 10
3.4 Synthesis of the results ................................................................................................................... 10
4
GENERIC PROCESSES .......................................................................................................................... 11
4.1 Site planning .................................................................................................................................... 11
4.2 Site coordination .............................................................................................................................. 11
4.3 Harmful interference resolution ....................................................................................................... 12
5
CONCLUSIONS ........................................................................................................................................ 13
ANNEX 1: HEADING ...................................................................................................................................... 14
ANNEX 2: LIST OF REFERENCE .................................................................................................................. 15
ECC REPORT <No>- Page 4
LIST OF ABBREVIATIONS
Abbreviation
Explanation
CEPT
ECC
3GPP
BS
EDGE
E-GSM
EIRP
European Conference of Postal and Telecommunications Administrations
Electronic Communications Committee
3rd Generation Partner Project
Base Station
Enhanced Data rates for Global Evolution
Extended GSM band
Equivalent Isotropically Radiated Power
ETSI
E-UTRA
GSM
GSMA
GSM-R
IM
European Telecommunications Standards Institute
Evolved Universal Terrestrial Radio Access
Global System for Mobile communications
GSM Association
GSM for Railway
Intermodulation
LTE
MFCN
NDA
OOB
TR
TS
Long Term Evolution
Mobile/Fixed Communications Networks
Non-Disclosure Agreement
Out-Of-Band
Technical Report
Technical Specification
UE
UIC
UMTS
UTRA
User Equipment
Union Internationale des Chemins de fer
Universal Mobile Telecommunications System
Universal Terrestrial Radio Access
ECC REPORT <No>- Page 5
1
INTRODUCTION
This ECC Report provides the results of the measurements campaign held in Munich in 2013 to understand
the behaviour of GSM-R terminals in front of GSM, UMTS and LTE adjacent signals, and some guidance to
GSM-R licensees and public mobile licensees at 900 MHz, as well as to administrations, who wish to rely on
a more systematic approach in their dialog. Its aim is ensuring a better coexistence between GSM-R and
public mobile networks.
The purpose of this ECC Report is not to list the possible technical solutions, but rather to define options for
a generic and open framework for the discussions between GSM-R and public mobile licensees. This ECC
Report complements ECC Report 162.
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ECC REPORT <No>- Page 6
2
2.1
RAILWAY GENERAL PRINCIPLES
RAILWAY INTEROPERABILITY
Constraints and needs of the infrastructure managers and railway undertakings.
tbc
2.2
CRITICAL ZONES AND CASES FOR GSM-R
This section deals with locations and cases where and when special attention may be given, if agreed by all
stakeholders at national level.
Where trains may stop:
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Railway stations
Light signals (often close to switches)
Long bridges and tunnels (where a new GSM-R BS cannot be installed)
Shunting yards within metropolitan areas
When trains encounter a dangerous situation:
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

They cannot leave or keep on running
They go through an interference zone over a too long distance or over a too long period
ETCS communication is interrupted
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2.3
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WAY FORWARD FOR A EUROPEAN WIDE IMPLEMENTATION OF THE IMPROVED RECEIVERS
ECC REPORT <No>- Page 7
3
3.1
GSM-R VS. MFCN TESTS RESULTS
LAB TESTS IN MUNICH
Two test campaigns were performed in the laboratories of the Monitoring Station Munich of the Federal
Network Agency, Germany (BNetzA): the first one between 19 and 23 August 2013, the second one on 31st
October 2013. Both UIC and GSM Association participated. The two reports are referenced
CG-GSM-R(13)24 and CG-GSM-R(13)24-Annex6.
The interfering effects from MFCN transmitters (unwanted emissions inside the GSM-R band) as well as
from GSM-R receivers (blocking and receiver intermodulation) were measured separately. The results allow
determination of the transition between transmitter and receiver effects to a certain extend which may help to
develop solutions in order to improve the situation, especially when UMTS and LTE are introduced in the
band above 925 MHz in the future.
To assess the possible improvements enabled by internal filtering, a GSM-R receiver with a built-in filter,
called hereafter improved receiver Rx1, was measured in addition to a receiver currently used by the railway
operators, called hereafter standard receiver Rx2, which fulfils the requirements of ETSI EN 301 515. The
two receivers were from two different vendors.
These two GSM-R receivers were tested in front of GSM, UMTS and LTE signals, both standard and
realistic. Standard signals are based on 3GPP/ETSI spectrum emission masks; realistic signals are based on
spectrum emission masks from products currently rolled out. The latter has lower unwanted emissions than
the former.
25,0
15,0
dBm/30kHz
5,0
-5,0
-15,0
-25,0
-35,0
-45,0
-15 000
-10 000
-5 000
standard
0
5 000
10 000
15 000
realistic
Figure 1: UMTS/LTE emission masks, at antenna connector
The main results of these measurement campaigns can be summarized as follows:
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

The standard GSM-R receiver Rx2 generates intermodulation products. It is UMTS/LTE intra-signal
intermodulation and inter-signal intermodulation with also GSM.
When interfered, the whole GSM-R frequency range is affected.
UMTS, LTE/5MHz and LTE/10MHz have the same interference potential.
GSM-R improved receiver Rx1 is mainly affected by unwanted emissions.
Both receivers show a co-channel C/I of 6 dB.
ECC REPORT <No>- Page 8
3.1.1
Results for the standard receiver Rx2
The standard receiver Rx2 is affected by intermodulation:
Carrier frequency
separation
Intermodulation threshold
for the standard receiver Rx2
2,8 MHz
-40 dBm
6,4 MHz and further
-33 dBm
and then increase of 1 dB/2,5MHz of
additional carrier frequency separation
Table 1: Intermodulation thresholds for the standard receiver Rx2,
given for a GSM-R signal level of -98 dBm
Intermodulation threshold in front of 2 GSM carriers: -41 dBm.
The intermodulation threshold increases by 1 dB when the wanted GSM-R signal level increases by 3 dB
(typical of IM3).
3.1.2
Results for the improved receiver Rx1
The improved receiver Rx1 (with built-in filter) may be affected by a UMTS/LTE signal located in the first 5
MHz of the E-GSM band:
WB frequency
block
GSM-R signal level
Effect on the improved
receiver Rx1
1st 5 MHz block
(925-930 MHz)
CGSM-R < -83 dBm
Unwanted emissions: C/I = 6 dB
CGSM-R ≥ -83 dBm
Intermodulation: -24 dBm
any
Unwanted emissions: C/I = 6 dB
2nd 5 MHz block
and beyond
Note 1
Note 1: The tolerable wideband signal level is at least 10 dB higher than for the standard receiver Rx2
Table 2: Effect on the improved receiver Rx1 facing a realistic UMTS/LTE signal
It has to be noted that a 3GPP/ETSI UMTS/LTE emission mask affects much more the improved receiver
Rx1.
The intermodulation threshold increases by 1 dB when the wanted GSM-R signal level increases by 3 dB
(typical of IM3).
ECC REPORT <No>- Page 9
Rx selectivity
0 dB
-10 dB
Rx1 (improved) at 924.8 MHz
-20 dB
Rx2 (standard) at 924.8 MHz
-30 dB
-40 dB
-50 dB
-60 dB
-70 dB
-80 dB
-90 dB
-100 dB
-110 dB
-4000 kHz
-3000 kHz
-2000 kHz
-1000 kHz
0 kHz
1000 kHz
2000 kHz
3000 kHz
4000 kHz
Figure 2: Improved receiver’s filtering capability of the public 900 MHz band
Wanted signal level (dBm)
Protection ratio (dB)
-110
-35
-100
-90
-80
-70
-60
-50
-40
-30
-40
-45
-50
-55
-60
-65
UMTS
LTE
GSM-R at 924,8 MHz – UMTS and LTE at 927,6 MHz
Figure 3: Improved receiver’s behaviour, comparison between UMTS and LTE
3.2
FIELD TESTS IN THE UK
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3.3
3.3.1
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DISCUSSION ON MFCN UNWANTED EMISSIONS
Acceptable MFCN OOB emission level above the rail tracks
ECC REPORT <No>- Page 10
3.3.2
Impact study of MFCN OOB emission
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3.3.3
Conclusion
UIC’s view: tbc
MFCN operators’ view: tbc
3.4
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SYNTHESIS OF THE RESULTS
ECC REPORT <No>- Page 11
4
GENERIC PROCESSES
Each MFCN licensee should provide a point of contact to the GSM-R licensee and vice-versa. The following
sub-sections describe typical processes that can be adapted to each national situation.
When a formal cooperation procedure is desired, the national implementation of the proposed processes
should be discussed between GSM-R and MFCN mobile licensees. In case of no agreement is reached
between the stakeholders when defining the process or when applying it, the national spectrum regulator
may act as an arbitrator.
4.1
SITE PLANNING
When planning a new site, the GSM-R operator should take into account the surrounding existing sites of the
MFCN operators. To do so, the characteristics of these MFCN sites should be provided:
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exact location
antenna height
azimuths
frequencies of the carriers
EIRP per carrier
Several possibilities exist to get this information. For instance, the GSM-R operator may request it to the
MFCN operators when planning a new area; or the GSM-R operator may get it from the national spectrum
regulator who consolidates this information when each MFCN operator registers a new base station.
In order to preserve the confidentiality of the rollout of each MFCN operator, some NDA between the
involved parties may be necessary.
When planning a new site or the rollout of a new technology, the MFCN operator may as well take into
account the surrounding existing sites of the GSM-R operator and of the other MFCN operators.
4.2
SITE COORDINATION
The GSM-R operator may be notified when a new MFCN site is planned or when a new technology such as
UMTS or LTE is about to be switched on close to the rail tracks. A set of criteria that triggers this notification
should be agreed between GSM-R and MFCN operators. Here are some possible criteria among others:
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Distance from rail tracks
UMTS900/LTE900 antenna in line-of-sight of the tracks
Tracks located in a critical zone for GSM-R
etc.
The volume of MFCN BS to be coordinated must remain low, otherwise the ability to rollout could be
jeopardized. So the criteria and their values must be selected very carefully.
The GSM-R operator is the best placed to take into account the density of MFCN sites close to the rail tracks
(and potentially belonging to different operators) and then to assess the risk on its own network. As an
alternative, the national spectrum regulator could perform this analysis. How to evaluate the interference
likelihood should also be agreed by all involved parties.
If a risk is identified, the GSM-R operator may request the MFCN operator(s) to discuss possible technical
and/or operational solutions that could be applied on both sides 1. In case no conclusion can be found, the
national spectrum regulator may have the possibility to apply an appropriate measure.
1
In some cases, the GSM-R operator may prefer to act alone without involving the MFCN operator(s).
ECC REPORT <No>- Page 12
A timeline should also be agreed between all stakeholders, e.g.:
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4.3
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the notification should be sent X days prior the switch on;
the GSM-R operator has Y days to identify a risk;
discussions between GSM-R and MFCN operators should start Z1 days after a risk is notified to the
MFCN operator(s) and should end Z2 days after;
etc.
HARMFUL INTERFERENCE RESOLUTION
ECC REPORT <No>- Page 13
5
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CONCLUSIONS
ECC REPORT <No>- Page 14
ANNEX 1: HEADING
Body text
A1.1 HEADING 2
ECC REPORT <No>- Page 15
ANNEX 2: LIST OF REFERENCE
[1]
[2]
[3]
[4]
[5]
[6]
[7]
ECC Report 162: Practical mechanism to improve the compatibility between GSM-R and public mobile
networks and guidance on practical coordination; version of May 2011
CG-GSM-R(13)24: GSM-R Measurement Report
CG-GSM-R(13)24-Annex6: GSM-R Measurement Report – Additional Measurements
UIC O-8736: UIC Assessment report on GSM-R current and future radio environment; version of March
2014
ETSI TS 145 005: GSM/EDGE; Radio transmission and reception
3GPP TR 43.030: GSM/EDGE; Radio network planning aspects
3GPP TR 45.050: GSM/EDGE; Background for Radio Frequency (RF) requirements