ETSI TR 101 538 V1.1.1 (2012-10)

Technical Report
Electromagnetic compatibility
and Radio spectrum Matters (ERM);
Short Range Devices (SRD);
UWB location tracking devices in the railroad environment

2 ETSI TR 101 538 V1.1.1 (2012-10)

Reference
DTR/ERM-TGUWB-020
Keywords
SRD, UWB
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3 ETSI TR 101 538 V1.1.1 (2012-10)
Contents
Intellectual Property Rights . 4
Foreword . 4
Introduction . 4
1 Scope . 6
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definitions, symbols and abbreviations . 8
3.1 Definitions . 8
3.2 Symbols . 8
3.3 Abbreviations . 8
4 Presentation of the system or technology . 9
4.1 Subway and underground . 11
4.2 Depot . 12
4.3 Ground Station or railway station . 12
4.4 Railway signals or POI along railroad . 14
5 Radio spectrum regulations and compliance . 14
5.1 Technical justification for spectrum . 14
5.1.1 Technical justification for power levels . 14
5.1.2 Technical justification for bandwidth . 16
5.2 Compliance to current regulations . 16
5.3 Additional compliance to ECC recommendation . 16
5.4 Summary UWB regulation for specific railway application . 17
Annex A: Detailed market information . 18
Annex B: Detailed technical, density and activity information . 21
B.1 Detailed technical description . 21
B.2 Density and activity . 24
B.2.1 Density of UWB transmitters . 24
B.2.2 Activity Factor . 28
B.3 Technical parameters and implications on spectrum . 30
B.3.1 Transmitter parameters . 30
B.3.1.1 Transmitter Output Power / Radiated Power . 30
B.3.1.1a Antenna Characteristics . 30
B.3.1.2 Operating Frequency. 30
B.3.1.3 Bandwidth . 31
B.3.2 Receiver parameters . 31
B.3.3 Channel access parameters . 33
History . 34

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4 ETSI TR 101 538 V1.1.1 (2012-10)
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
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Electromagnetic compatibility and Radio
spectrum Matters (ERM).
The present document includes necessary information to support the co-operation under the MoU between ETSI and the
Electronic Communications Committee (ECC) of the European Conference of Postal and Telecommunications
Administrations (CEPT).
Introduction
The present document describes devices using Ultra Wide Band (UWB) sensor technology for location tracking
applications in railway environment.
The intended railway scenarios target both indoor and outdoor environments. For example, a subway station is located
under the ground and therefore is essentially indoors, whereas a signal placed at the side of a railway line in open
country is most definitely outdoor. Regulation for indoor UWB, and for some mobile and fixed outdoor UWB devices
in certain circumstances is already included in the Electronic Communications Committee (ECC) decisions and
recommendations issued in the recent years [i.1], [i.2], [i.3], [i.9], [i.10] and [i.11]. Nevertheless, no specific regulation
is pointed for UWB applications having fixed outdoor installed devices or infrastructure belonging to rail or tram
networks. There is evidence that location tracking application with good range resolution is needed in railways.
Therefore, the present document describes a solution for location tracking in railway environment where fixed outdoor
installation of UWB equipment is needed and may be operated according the current ECC regulations.
In UWB location tracking in railways, a transmitter (TX) or a receiver (RX), or both are installed in a moving rail
vehicle. The vehicle is tracked by using fixed wayside network which can be implemented by using UWB TX, UWB
RX or both. A network of fixed wayside equipment around an area to be covered, called as Area-Of-Interest (AOI),
communicate with a UWB equipment installed in a rail vehicle. The 3D position of a rail vehicle can be found by
analysing, e.g. time-of-arrival and/or angle-of-arrival of the radio signal relative to the known reference stations.
The presented system is tracking a rail vehicle within an area around a certain Point-Of-Interest (POI). Position
information are applied to stop a rail vehicle in POI with sub-meter accuracy. When a rail vehicle is stopped,
transmission is turned off.
A tracking system of presented application can be realized in three different ways:
• Transmitter installed into a rail vehicle and receiving fixed wayside equipment (option 1, see Figure B.1).
The UWB signals emitted by a transmitter installed in a moving rail vehicle are detected by a wayside network
of receiving fixed equipment placed at known, fixed points around the area to be covered. By centralized
computational means the location of a rail vehicle can be determined. This is a typical application.
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5 ETSI TR 101 538 V1.1.1 (2012-10)
• Receiver installed into a rail vehicle and transmitting fixed wayside equipment (option 2, see Figure B.2).
The UWB signals emitted by a wayside network of transmitting fixed equipment placed at known, fixed points
around the area to be covered are detected by receiving equipment installed in a moving rail vehicle detecting
their own position.
• Transmitter/receiver installed into a rail vehicle and transmitting/receiving fixed wayside equipment (option 3,
see Figure B.3).
A combination of options 1 and 2; both units installed in a rail vehicle and the fixed wayside equipment can
receive and transmit UWB-signals.
In railways, high precision in range measurement is required. The ranging signals necessarily have to have a very large
bandwidth to attain a good range resolution. Detailed technical description is given in annex B.
There is evidence that this system is needed in railway industry, and the proposed system will lead to greater
addressable markets. Detailed market information are discussed in annex A.
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6 ETSI TR 101 538 V1.1.1 (2012-10)
1 Scope
The present document describes a railway application utilizing ultra wideband technology operating in the preferred
frequency ranges from 3,1 GHz to 4,8 GHz and from 6 GHz to 8,5 GHz. Operation is foreseen for indoor and outdoor
applications, including either mobile devices installed onboard the train cars and fixed devices installed on ground, as
reference stations. These stations, belonging to the fixed infrastructure, will be allowed to operate as UWB emitters
only in the lower frequency band, from 3,1 GHz to 4,8 GHz, in compliance with the compatibility studies and with the
latest recommendation [i.9] proposed by ECC/CEPT, as this provision would allow the deployment of such fixed UWB
devices in the railway environment according to the "registration and coordination" process recently proposed by
ECC/CEPT 167 [i.10].
In railway applications, location tracking is performed within specified areas, called as an Area-Of-Interests (AOIs),
which are areas around Point-Of-Interests (POIs). The POIs are listed below:
• Point in passenger platform
• Railway signal
• Railway crossing
• Generic POI
The UWB radio technology is required to track with sub-meter accuracy any rail vehicle to the purpose of stopping it in
the appropriate POI. The length of AOI is defined by the braking distance of a rail vehicle, and it is typically hundreds
of meters.
The generic regulation on UWB technology for use in rail and road vehicles onboard applications, such as - for instance
- in subway underground stations, within the frequency ranges of 3,1 GHz to 4,8 GHz and 6 GHz to 8,5 GHz has been
recently updated in the last Electronic Communication Committee (ECC) amended ECC/DEC(06)04 [i.1] including the
suitable reference to mitigation techniques. According to [i.2], underground station should be considered as an indoor
environment because surrounding structures shields any emitted radio signal, providing the necessary attenuation to
protect primary radio communication services against harmful interference.
However, in railway stations and trackside signalling installations there may not be structures blocking the propagation
of emitted signals, and therefore the outdoor environment regulation should apply. The outdoor usage of UWB devices
in location and tracking applications such as person and object tracking in industrial, automotive and transportation
environments are described in [i.4] and [i.5]. Nevertheless, these applications do not include the location / tracking
specific application in railway environments, which may occur at many points across a public rail or tram network.
Actually, the latest generic ECC regulation [i.11] for the deployment of UWB devices in vehicles and the
ECC/REC(11)09 [i.9] on provisions relevant to fixed UWB infrastructures do not deal with specific railway application
issues, but are actually permitting the deployment of such UWB, respectively, onboard the trains and along the wayside
of railway infrastructures. Therefore, the present document describes the railway application of UWB devices and
collects specific information, including:
• Market information (annex A).
• Technical information (annex B).
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7 ETSI TR 101 538 V1.1.1 (2012-10)
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ECC/DEC/(06)04 of 24 March 2006 amended 6 July 2007 at Constanta on the harmonised
conditions for devices using Ultra-Wideband (UWB) technology in bands below 10.6 GHz
(2007/131/EC) amended 6 July 2007.
[i.2] Commission Decision 2007/131/EC of 21 February 2007on allowing the use of the radio spectrum
for equipment using ultra-wideband technology in a harmonised manner in the Community.
[i.3] ECC/DEC/(06)12 of 1 December 2006 amended Cordoba, 31 October 2008 on supplementary
regulatory provisions to Decision ECC/DEC/(06)04 for UWB devices using mitigation techniques
amended 31 October 2008.
[i.4] ETSI TR 102 495-5: "Electromagnetic compatibility and Radio spectrum Matters (ERM); System
Reference Document; Short Range Devices (SRD); Technical characteristics for SRD equipment
using Ultra Wide Band Sensor technology (UWB); Part 5: Location tracking applications type 2
operating in the frequency bands from 3,4 GHz to 4,8 GHz and from 6 GHz to 8,5 GHz for person
and object tracking and industrial applications".
[i.5] ETSI TR 102 495-7: "Electromagnetic compatibility and Radio spectrum Matters (ERM); System
Reference Document; Short Range Devices (SRD); Technical characteristics for SRD equipment
using Ultra Wide Band Sensor technology (UWB); Part 7: Location tracking and sensor
applications for automotive and transportation environments operating in the frequency bands
from 3,1 GHz to 4,8 GHz and 6 GHz to 8,5 GHz".
[i.6] The Association of the European Rail Industry (UNIFE).
NOTE: Website: http://www.unife.org/.
[i.7] CEPT/ECC Report 64: "The protection requirements of radiocommunications systems below
10,6 GHz from generic UWB applications", Helsinki, February 2005.
[i.8] IEEE 802.15.4a: "Standard for Information Technology - Telecommunications and information
exchange between systems - Local and metropolitan area networks - specific requirement Part
15.4: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for
Low-Rate Wireless Personal Area Networks (LR-WPANs)".
[i.9] ECC/REC(11)09: "UWB Location Tracking Systems Type 2 (LT2)".
[i.10] ECC Report 167: "The Practical Implementation of registration/coordination mechanism for UWB
LT2 systems".
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[i.11] ECC/DEC (06)04: " The harmonised conditions for devices using UWB technology in bands
below 10.6 GHz ".
[i.12] ECC Report 170: "Specific UWB applications in the bands 3.4 - 4.8 GHz and 6 - 8.5 GHz
Location Tracking Applications for Emergency Services (LAES), location tracking applications
type 2 (LT2) and location tracking and sensor applications for automotive and transportation
environments (LTA)".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
activity factor: effective transmission time ratio, actual on-the-air time divided by active session time or actual on-the-
air emission time within a given time window
distance: Euclidean distance between two objects, i.e. real distance
duty cycle: defined as the ratio, expressed as a percentage, of the transmitter "on" relative to a given time period as
specified in the technical requirements
fixed equipment: UWB location tracking device on a fixed position
mobile equipment: UWB location tracking device to be used while in motion or during halts at specified points
range: measured distance between two objects, i.e. erroneous distance
range resolution: ability to resolve two targets at different range
3.2 Symbols
For the purposes of the present document, the following symbols apply:
AF activity factor
BW bandwidth
c velocity of light in a vacuum
dBm decibel relative to 1 mW
∆h Transmission interval
∆t Transmission on
D data rate
data
δR range resolution or multipath rejection resolution
r Range of UWB device
R ranging packet length
data
T pulse width
p
U Update rate
r
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
3D Three Dimensional
AF Activity Factor
AFR Activity Factor Restriction
AOI Area-Of-Interest
BSS Board SubSystem
CBT Communication-Based Train Control
CBTC Communication-Based Train Control
CEPT European Conference of Post and Telecommunications Administrations
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9 ETSI TR 101 538 V1.1.1 (2012-10)
CIS Commonwealth of Independent States
CO Carbon Dioxide
DAA Detect-And-Avoid
DCR Duty Cycle Reduction
e.i.r.p. Equivalent Isotropic Radiated Power
ECC Electronic Communications Committee
ETCS European Train Control System
FS Fixed Service
GSM-R Global System for Mobile Communications-Railways
GSS Ground SubSystem
LDC Low Duty Cycle
LOS Line-Of-Sight
MAC Medium Access
NAFTA North American Free Trade Agreement
NLOS Non-line-of-sight
OBU OnBoard Unit
PHY Physical
POI Point-Of-Interest
PSD Power Spectral Density
QoS Quality-of-Service
RX Receiver
TDD Time Division Duplex
TPC Transmission Power Control
TX Transmitter
UWB Ultra WideBand
4 Presentation of the system or technology
In a railway network, there are two important functions that rely on knowing the position and speed of the train. The
first, and the oldest, is signalling and the control of the track. The second function is train control, which was once
performed by the train driver alone.
One important part of the train control function in urban railways is stopping the train in the right place at a platform,
and if the platform has gates this requires centimetric accuracy and is always done automatically.
This system can be used by other train-borne systems to sense the train's position along the railway. Using this system
the onboard equipment will stop the train precisely. In fact these functions are real innovations because very often there
are stringent requirements by customers in subways where good efficiency in difficult radio propagation environments
(e.g. tunnels) has to be guaranteed.
Currently the state-of-the-art to perform the train positioning includes inductive cables or railroad circuit to detect
which is the block to be taken by the train and it is easy to understand that using these systems only low position
accuracy is achievable. The conventional line signalling and illustration of braking train when approaching railway
crossing are depicted in Figure 1. In here, the train is receiving information to stop from a wayside device, and the train
is stopped by using, e.g. inductive cables as illustrated Figure 2. The OnBoard Unit (OBU) is a device installed in a
train which takes care on communication between a train and wayside network.
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Figure 11: Conventional line side signalling

Figure 22: Conventional stopping of a train
The heart of this proposed system is the ultrtraa-wideband radio that will introduce high-level performana ces and benefits,
reaching good results for all the requiremennttss listed above. In fact, basically high accuracy positionniingn combined with
high velocity of the train can be considered as as the main challenge. It raises a concern on the ability of of the current
wireless technologies to respond to these chhalallenges. Based on this consideration, UWB is the technnoology that currently
offers the best guarantees.
Specialities for positioning application in railwlway environment are:
• Cost-efficient
• High velocity
• The information of the train's physsiiccs (acceleration.)
• Track discrimination
• High accuracy
• Interference tolerant
• Energy saving
Railway environment can be divided in the f foollowing environments:
1) Subway and underground
2) Depot
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11 ETSI TR 101 538 V1.1.1 (2012-10)
3) Ground Station or Railway station
4) Railway signal or Point-of-Interest (POI) along railroad
Apart from some urban or local transit systems, a "railway" is a part of a very much large network, even on a national
scale. And large cities may have multiple inter-working railways (notably in London). Even a new self-contained
railway system is likely to include parts with different characteristics - for example some underground and some on the
surface, station spacings varying greatly, or some on roads (for trams or light rail) and some on segregated tracks. While
it is obviously an advantage to use one sensor type throughout, other considerations may determine that one (e.g. UWB)
is only used in a part of the network. Also, different parts of the network may be different environments as far as radio
regulations are concerned. The clearest case of this is where part of the network is underground or enclosed (hence
"indoors", though this word might seem a little odd for a large railway station) and part is in the open.
4.1 Subway and underground
The subway represents a classic indoor use scenario for railway applications of UWB. Typically, subway trains are
operating under the ground and stations are located also under the ground as presented in Figure 3. Installation of
devices in the subway environment is illustrated in Figure 4 where UWB transmitter (BSS, Board SubSystem) is
installed in a train and UWB receivers (GSS, Ground SubSystem) are mounted in the ceiling.
In the subway environment, there are structures that block or attenuate an emitted signal, and thus does not interfere
other radio systems. The operating time varies from 20 h to 24 h per day in large and congested subway stations, and
operating frequency is handling 20 to 60 trains per hour.

Figure 3: Typical subway station
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12 ETSI TR 101 538 53 V1.1.1 (2012-10)

Figurre e 4: Installation of UWB devices
4.2 Depot
The railway depot is an area for maintenance ce and storage of trains in, for example, an indoor environonment such as a
wide and open shed where the walls of the s shhed attenuate an emitted signal.
4.3 Ground Station o orr railway station
An uncovered railway station represents a ggoood exo ample of an outdoor railway scenario as illustratedted in Figure 5, as
does the ground tram station shown in Figurre 6e . In these scenarios, there are not always shielding strstruuctures providing
necessary attenuation of an emitted signal toto p protect other radio systems such as Fixed Service (FS)) o or satellite
communications, and there may be many suucchh installations across a public rail network covering (ffoor exr ample) a city or
country. Therefore, mitigation techniques to go give enough protection for other radio systems are needeeded to be carefully
studied.
In typical railway station, the operating freqquueency is 10 to 20 trains per hour 24 hours per day.
The railway waysides are authorized areas an and are restricted from unauthorized persons' presence.
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13 ETSI TR 101 538 V1.1.1 (2012-10)

Figure 5: Typical railway station

Figure 6: Typical ground tram station
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14 ETSI TR 101 538 V1.1.1 (2012-10)
4.4 Railway signals or POI along railroad
A railway signal (see Figure 7) is an electrical device installed along a track to pass information relating the state of the
line ahead to a train. A generic Point-of-Interest can be a stopping point in a loading platform for instance. It is
important to stop a train accurately so that there is no need to relocate a train for loading. Again, these situations
represent largely outdoor use of UWB, and there may be significant numbers of signals across a public rail or tram
network.
Figure 7: Typical railway signal
5 Radio spectrum regulations and compliance
5.1 Technical justification for spectrum
5.1.1 Technical justification for power levels
UWB positioning can only make use of a fraction of the energy emitted by a UWB transmitter: that portion which
reaches a receiver via the direct path. Only the signal travelling along this path conveys information about the location
of the transmitter relative to the receiver. This is in contrast to communications systems, which may utilize signals
travelling along any or all paths between the transmitter and receiver (e.g. systems involving rake receivers).
The UWB system under consideration operates (depending on target scenario) either in the 3,1 GHz to 4,8 GHz or in
the 6 GHz to 8,5 GHz frequency region and is mainly operating under the Line-Of-Sight (LOS) conditions, and thus a
maximum PSD limit of -41,3 dBm/MHz, as defined in ECC/DEC(06)04 [i.1] recently amended in [i.11], is enough for
the applications described in the present document.
It is worth to distinguish between very short range (<10 meters) applications and short range ones (up to 50 m).
Indeed, after the definition of "exterior limit" [i.11], several UWB emitters maybe installed "on board" the train cars,
provided that the proposed "PSD exterior limits" (-53,3 dBm/MHz) are satisfied by each of these mobile UWB emitters,
operating either in the frequency band from 3,1 GHz to 4,8 GHz and in the higher band from 6 GHz to 8,5 GHz.
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15 ETSI TR 101 538 V1.1.1 (2012-10)
This deployment of multiple UWB emitters on-board, transmitting outwards the train cars, is free of limitations (with
the duly exception of the said "PSD exterior limits" [i.11] and activity factor LDC <5 %) as, in other words, devices
registration is not required and they may be coupled with a suitable number of "ground-based" wayside receiving
devices, deployed in the frame of a purely "passive" fixed infrastructure, in such a way that tracking accuracy is
enhanced, together with availability and reliability. Graceful increase of railway signalling system availability/reliability
maybe proportioned to the actual multiplicity of such "mobile" UWB emitters and of the corresponding "ground-based"
receivers installed at fixed reference points belonging to the wayside infrastructure.
Dealing with tracking operation at increased ranges, up to ≈50 meters, the system operation should cope with several
critical factors which may impair the tracking availability and accuracy wayside, unless provision of appropriate
countermeasure is adopted in terms of power level and of other design provisions. As experienced in real installation,
the following list of critical factors is provided as an exemplary, but not limitative, description of main technical
challenges, associated with the operation of short-range low-power UWB tracking systems in railway environment.
Technical descriptions are provided in annex B, including system architectures and corresponding link budgets, shown
in the following clause B.3.
Table 1: Critical factors limiting the performance of UWB systems in railway environment
Frequency (GHz) Area of Operation Critical factors Countermeasures
impairing system compatible with limits
performance and ECC regulations
3,11 < f < 4,8 very short range Multipath Multiple UWB emitters
PSD <-53,3 (<10 meters) Broadband interferers onboard the train cars
dBm/MHz for (e.g. automotive UWB) real-time processing
unregistered UWB  Multiple "ground-based"
unlicensed mobile  fixed receivers
devices with 5 % short range Multipath + path loss Multiple UWB emitters at
activity LDC (<50 meters) Broadband interferers 3,1 GHz to 4,8 GHz
PSD <-41,3 deployed as "ground-
dBm/MHz for based" fixed references
registered devices for real-time processing
6 < f ≤ 8,5 very short range Multipath Multiple UWB emitters
PSD <-53,3 (<10 meters) onboard the train cars
dBm/MHz for real-time processing
unregistered UWB Narrow-beam antenna
mobile devices with
5 % LDC
NOTE: At highest frequencies (6 < f ≤ 8,5 GHz) very short-range (<10 meters) applications only
are affordable, due to the fact that fixed infrastructures made of UWB emitters are not
allowed by ECC.
It is easy to demonstrate that, either onboard and in the fixed infrastructures, the adoption of multiple UWB emitters
improves the system performance and maximises its availability for tracking ranges extending up to 50 meters and over.
On the other hand, the most recent ECC recommendation [i.9], aiming the protection of existing services, dictates that
each UWB emitter belonging to fixed infrastructure is limited to an average PSD of -41,3 dBm/MHz e.i.r.p. in the lower
frequency band only, that is from 3,4 GHz to 4,2 GHz, and maybe extended from 4,2 GHz to 4,8 GHz, when complying
with tighter limit of -47,3 dBm/MHz in the higher portion of this lower band. Moreover, a registration/coordination
process should be undertaken, in charge of national authorities, according to the proposed guidelines given by ECC
Report 167 [i.10] and ECC Report 170 [i.12].
Therefore, the perspective of using UWB devices in railway tracking applications, extending up to 50 meters and over,
appears less favourable and much less affordable than tracking for just shortest ranges (<10 meters), due to the
combined effect of four critical factors: multipath, path loss, PSD/band limitations and registration/coordination
mechanism.
It is clear that UWB devices afford advantages over other wireless technologies particularly in the very short-range
applications, where they maybe suited for widespread "unregistered" use, provided that each UWB emitter installed
onboard the train cars complies with the tightest PSD "exterior limit" of -53,3 dBm/MHz, as ECC recently stated [i.11].
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16 ETSI TR 101 538 V1.1.1 (2012-10)
5.1.2 Technical justification for bandwidth
The accuracy of radio ranging location devices is determined by the occupied bandwidth of the signal, provided it is
processed coherently. For example, in a pulse-based system, if the device has to reliably measure different transmitter-
receiver ranges when the transmitter is moved from one point to another, the difference in the travel time of the signal
from the transmitter to the receiver at the two different positions should be greater than the pulse width. Similarly, a
direct path signal and a reflected multipath signal can be separated if the extra time interval required for the signal to
travel the reflected path rather than the direct path is greater than the pulse width.
The bandwidth required to provide the same resolution as a pulse of width T is approximately 1/T .
P P
Therefore, for a range resolution or multipath rejection resolution of δR, the bandwidth requirement for the UWB
location tracking devices is given by:
�
�� = ,
(��)
where c is the velocity of light in a vacuum.
For a range resolution of 10 cm, this gives a bandwidth requirement of around 3 GHz. For a measurement accuracy of
10 cm, the resolution can be somewhat larger, so that a bandwidth of 1 GHz to 1,5 GHz can be enough.
5.2 Compliance to current regulations
The radio regulations for indoor environments, i.e. subway, underground, and depot as discussed in clauses 4.1 and 4.2
are included in amended ECC/DEC(06)04 [i.11] excluding fixed outdoor location tracking installations as shown in
Table 2.
Table 2: Current regulations (excluding fixed outdoor installations) for UWB systems
Frequency (GHz) Area of Operation Maximum value of mean power spectral density
[dBm/MHz]
3.1 < f < 4.8 generic usage in train < -41.3 (exterior limit -53.3)
6 < f ≤ 8.5 vehicles (assuming implementation of LDC mitigation as
stated in ECC/DEC/(06)04 [i.11])
o
3.1 < f < 4.8 train vehicles in < -41.3 (exterior limit of -53.3 over 0 not necessary,
6 < f ≤ 8.5 underground and see ECC report 170 [i.12])
indoor environment
NOTE: No active UWB outdoor transmitter; Base stations outdoor are passive, all active UWB
transmitters are onboard train vehicles.

5.3 Additional compliance to ECC recommendation
A railway network will usually have some parts that qualify as "indoor" for UWB regulations, and some that are
"outdoor". However, the same UWB terminals may need to operate in both. Not only will terminals on trains move
between such environments, but fixed terminals throughout the network will need to operate with low activity factor,
just in case these mobile terminals come around. In addition, within the network there will be a few places with many
trains and lines, most of the network will have a much lower density.
The ECC recommendation [i.9] has proposed limits for type 2 location tracking UWB fixed emitters applications in the
frequency range 3,4 GHz to 4,8 GHz as shown in Table 3.
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17 ETSI TR 101 538 V1.1.1 (2012-10)
Table 3: Current ECC recommendation [i.9] for LT2 applications
Frequency Maximum value of mean power spectral
GHz density [dBm/MHz]
3,4 < f < 4,8 ≤ -41,3 dBm/MHz fixed outdoor subject to
implementation of DCR and subject to some
coordination/registration [i.10] for licensing.
the maximum mean e.i.r.p. spectral density in the
band 4,2 GHz to 4,4 GHz for emissions that
appear 30° or greater above the horizontal plane
should be less than -47,3 dBm/MHz.

It is worth to underline that coordination/registration process [i.10] allows UWB devices deployment at fixed outdoor
locations (with PSD limit of -41,3 dBm/MHz or -47,3 dBm/MHz), according to [i.9] as LT2 tracking network
"registered" infrastructure, only in the lower band from 3,4 GHz to 4,8 GHz.
The main benefit of such deployment of UWB emitters at fixed outdoor locations would be to make more appealing and
more affordable LT2 railway applications also for tracking range up to 50 meters and over.
5.4 Summary UWB regulation for specific railway application
Table 4: Summary / Interpretation of existing UWB regulation for this specific
UWB railway applications
Frequency Area of Operation System license type Maximum value of mean power spectral
(GHz) density [dBm/MHz]
3,1 ≤ f ≤ 4,8 generic usage in train Unregistered system, licence ≤ -41,3 (exterior limit -53,3)
6 ≤ f ≤ 8,5 vehicles exempt usage (assuming implementation of LDC mitigation as
(Note 1) stated in ECC/DEC/(06)04 [i.11])

3,1 ≤ f ≤ 4,8 train vehicles in Unregistered system, licence ≤ -41,3 (exterior limit of -53,3 over 0º not
(Note 2) underground and exempt usage necessary, see ECC report 170 [i.12]
indoor environment, (assuming implementation of LDC mitigation as
(Note 3) stated in ECC/DEC/(06)04 [i.11])

6 ≤ f ≤ 8,5 train vehicles in ≤ -41,3 (exterior limit of -53,3 over 0º not
Unregistered system, licence
(Note 2) underground and exempt usage necessary, see ECC report 170 [i.12]
indoor environment,
(Note 3)
3,4 ≤ f ≤ 4,8 train vehicles Registered systems [i.10] ≤ -41,3
(Note 4)
3,4 ≤ f ≤ 4,8 outdoor fixed UWB Registered systems [i.10] ≤ -41,3 dBm/MHz fixed outdoor subject to
transmitters implementation of DCR and subject to some
coordination/registration [i.10] for licensing
(Note 5)
NOTE 1: No active UWB outdoor transmitter; Base stations outdoor are passive, all active UWB transmitters are
onboard train vehicles.
NOTE 2: UWB transmitters in the indoor environment can be seen as an device under the Generic UWB rules [i.11],
chapter 1.
NOTE 3: For more details clauses 4.1 and 4.2.
NOTE 4: A maximum duty cycle of 5 % per transmitter per second and a maximum Ton = 25 ms apply. The duty cycle
should also be limited to 1,5 % per minute or equipment should implement an alternative mitigation technique
that provides at least equivalent protection [i.9].
NOTE 5: The maximum mean e.i.r.p. spectral density in the band 4,2 GHz to 4,4 GHz for emissions that appear 30° or
greater above the horizontal plane should be less than -47,3 dBm/MHz [i.9].

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18 ETSI TR 101 538 V1.1.1 (2012-10)
Annex A:
Detailed market information
The proposed specific application using the UWB technology in railway application will play an important rule into the
worldwide railway market. This clause shows how this wireless technology matches the requirements defined for this
growing market. The following considerations were given by [i.6].
The worldwide rail market has grown tremendously in the past few years and the expectations for the next ten years is
to have several new railway projects around the world for upgrading and expanding existing railway lines.
The railway market environment changes in the short time frame and the rail suppliers should adapt their products and
services developing new technologies. In this way, they are able to support passenger's mobility needs and cargo
transport. In this scenario, innovations make rail transport more attractive adding high technological value.
The market rail could be divided into:
• Rail Control
• Infrastructure
• Rolling Stock
• Services
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Figure A.1: Average annual market volumes in the last few years
Figure A.1 shows the annual average market volumes and how it is distributed, moreover it describes which is the
"accessible market" opened to external suppliers.
In the last years this market has grown and this trend will be maintained with an expected annual growth till 2,5 % in
the seven years reaching a volume of EUR 160 billion of which EUR 115 billion will be accessible (71,8 %).
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19 ETSI TR 101 538 V1.1.1 (2012-10)

Figure A.2: World segmentation
Reading Table A.1, the most important markets are: Europe, NAFTA and ASIA/Pacific region but with the expected
dynamic growth, Asia/Pacific will surpass NAFTA in the next six years. On the other hand, the marketing forecast
shows also that the growth in NAFTA will continue but below the world average. The estimated rail market for the last
years listed in Table A.1 has focused on 50 countries that include 95 % of the whole global rail market.
Table A.1: Distribution of Accessible market in the world in the last years
Rail Market
% (EUR bn)
W. Europe 33
E. Europe 5
CIS
NAFTA
Rest of America 3
Asia / Pacific 25
Africa / Mid. East 2
Rail suppliers are companies that manufacture rail infrastructure, rolling stocks and rail signals. Besides these are
multinational companies that spread over thousands of suppliers and sub-suppliers. The telecommunications systems
are key part of these complex systems and the introduction of new technologies in this field pulls the railway products
making these more attractive.
In the medium and long term period, the rail industry follows new trends reported below:
• Ecological awareness
• Resources scarcity
• Urbanization
• Competition with other modes of transport
• Standardization
The companies answer to these treats developing new products where (for example):
1) emissions are reduced (CO emissions limits, noise control, electromagnetic pollution reduction);
2) transport capacity is increased;
3) efficient rolling stocks are developed;
4) standardization activates are included.
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