ETSI TR 102 654 V1.1.1 (2009-01)

Electromagnetic compatibility and Radio spectrum Matters (ERM); Road Transport and Traffic Telematics (RTTT); Co-location and Co-existence Considerations regarding Dedicated Short Range Communication (DSRC) transmission equipment and Intelligent Transport Systems (ITS) operating in the 5 GHz frequency range and other potential sources of interference

DTR/ERM-TG37-265

General Information

• Status: Published
• Publication Date: 22-Jan-2009
• Technical Committee: ERM TG37 - ERM Intelligent Transport Systems
• Current Stage: 12 - Completion
• Due Date: 19-Dec-2008
• Completion Date: 23-Jan-2009

Standards Content (Sample)

ETSI TR 102 654 V1.1.1 (2009-01)
Technical Report
Electromagnetic compatibility
and Radio spectrum Matters (ERM);
Road Transport and Traffic Telematics (RTTT);
Co-location and Co-existence Considerations regarding
Dedicated Short Range Communication (DSRC)
transmission equipment
and Intelligent Transport Systems (ITS)
operating in the 5 GHz frequency range
and other potential sources of interference

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2 ETSI TR 102 654 V1.1.1 (2009-01)



Reference
DTR/ERM-TG37-265
Keywords
DSRC, ITS, RTTT
ETSI
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3 ETSI TR 102 654 V1.1.1 (2009-01)
Contents
Intellectual Property Rights . 4
Foreword . 4
1 Scope . 5
2 References . 5
2.1 Normative references . 5
2.2 Informative references . 5
3 Definitions, symbols and abbreviations . 6
3.1 Definitions . 6
3.2 Symbols . 7
3.3 Abbreviations . 8
4 Summary . 9
4.1 Overview . 9
4.2 Interference scenarios . 9
5 Interference Limits . 12
5.1 DSRC frequency table . 12
5.2 Typical RF parameters of DSRC equipment . 13
5.3 Interference to DSRC . 14
5.3.1 Categorization of interference types . 14
5.3.2 Interferer at UL frequency located in RSU active angle . 14
5.3.3 Interferer at UL frequency located outside RSU active angle. 14
5.3.4 Interference to OBU receiver . 15
5.3.5 Disturbance of OBU power save mode. 15
5.4 Interference limit parameters . 16
Annex A: Solutions to improve co-existence . 17
A.1 Interference mitigation techniques applicable to interfering transmitters . 17
A.1.1 Recommended minimum distance . 17
A.1.2 Recommended maximum output power level . 17
A.1.3 Distance dependent dynamic output power level . 18
A.2 Recommended improvements to DSRC devices . 18
A.3 System level measures to provide coexistence . 18
Annex B: Examples of coexistence scenario calculations . 19
B.1 Example for interferers at UL frequency located within RSU active angle . 19
B.2 Example for interferers at UL frequency located outside RSU active angle . 20
B.3 Example of interference to OBU receivers . 20
B.4 Example of disturbance of OBU power save mode . . 28
History . 29

ETSI

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4 ETSI TR 102 654 V1.1.1 (2009-01)
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://webapp.etsi.org/IPR/home.asp).
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).
ETSI

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5 ETSI TR 102 654 V1.1.1 (2009-01)
1 Scope
European CEN Dedicated Short Range Communication (DSRC) equipment operating in the frequency range from
5 795 MHz to 5 815 MHz can suffer from interference caused by Intelligent Transport System (ITS) transmitters and
other users of the same and adjacent frequency bands. The present document provides guidance on how to achieve
co-existence between existing DSRC equipment and other users such as ITS equipment.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
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 indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
Not applicable.
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] CEN EN 12253: "Road transport and traffic telematics - Dedicated short-range communication -
Physical layer using microwave at 5,8 GHz".
[i.2] CEPT ECC Report 101: "Compatibility studies in the band 5 855 - 5 925 MHz between Intelligent
Transport Systems (ITS) and other systems".
[i.3] ETSI EN 302 571: "Intelligent Transport Systems (ITS); Radiocommunications equipment
operating in the 5 855 MHz to 5 925 MHz frequency band; Harmonized EN covering the essential
requirements of article 3.2 of the R&TTE Directive".
[i.4] CEPT ECC Report 127: "The impact of receiver parameters on spectrum management".
[i.5] ETSI EN 300 674 (all parts): "Electromagnetic compatibility and Radio spectrum Matters (ERM);
Road Transport and Traffic Telematics (RTTT); Dedicated Short Range Communication (DSRC)
transmission equipment (500 kbit/s / 250 kbit/s) operating in the 5,8 GHz Industrial, Scientific and
Medical (ISM) band".
ETSI

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6 ETSI TR 102 654 V1.1.1 (2009-01)
[i.6] ISO 21218:"Intelligent Transport Systems - Communications access for land mobiles (CALM) -
Medium Service Access Points".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
adjacent band: part of the radio-frequency spectrum that is close to the DSRC spectrum defined by [i.7] and [i.8]
amplitude envelope: magnitude of the complex analytic representation of the modulated signal.
NOTE: It describes the amplitude variation of a modulated sinusoidal signal as a function of time.
boresight: direction of maximum radiation of a directional antenna
NOTE: If boresight cannot be determined unambiguously, then boresight is declared by the provider.
broadband interferer: noise like interfering signal that covers more than one of the DSRC channels in the frequency
domain
carrier frequency: frequency to which the RSU transmitter is tuned
NOTE: In DSRC, the carrier frequency is in the centre of a channel.
channel: continuous part of the radio-frequency spectrum to be used for a specified emission or transmission
NOTE: A radio-frequency channel may be defined by two specified limits, or by its centre frequency and its
bandwidth, or any equivalent indication. It is often designated by a sequential number. A radio-frequency
channel may be time-shared in order to allow radio communication in both directions by simplex
operation. The term "channel" is sometimes used to denote two associated radio-frequency channels, each
of which is used for one of two directions of transmission, i.e. in fact a telecommunication circuit.
communication zone: spatial region within which the OBU is situated such that its transmissions are received by the
RSU with a bit error ratio of less than a specified value
rd rd rd
cross-polar discrimination, ellipticity of polarization: ratio P /P of power level P of the left hand circular
polarized wave to the power level P of the right hand circular wave when the total power of the transmitted wave
RHCP
rd rd
is P + P
NOTE: Antennas designed to transmit left hand circular waves may transmit some right hand circular waves in
addition.
cross polarization: See cross-polar discrimination.
down link: signal transmitted from the RSU to the OBU
equivalent isotropically radiated power: signal power fed into an ideal loss-less antenna radiating equally well in all
directions that generates the same power flux at a reference distance as the one generated by a signal fed into the
antenna under consideration in a predefined direction within its far field region
narrowband interferer: interfering signal with a bandwidth much smaller than the DSRC sub-channel bandwidth
OBU sleep mode: optional mode for battery powered OBUs that allows to save battery power
NOTE 1: In this mode, the OBU can only detect the presence of a DSRC down-link signal which under certain
defined conditions, see CEN EN 12253 [i.1], will lead to wake-up, i.e. a transition to the transmit mode.
NOTE 2: An OBU may be either in sleep mode, the stand-by mode, or the transmit mode.
polarization: locus of the tip of the electrical field strength vector in a plane perpendicular to the transmission vector
ETSI

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7 ETSI TR 102 654 V1.1.1 (2009-01)
power envelope: describes the power variation of a modulated sinusoidal signal as a function of time
RSU active angle: defines a cone where it is allowed to transmit maximum EIRP (parameter D4 in EN 12253 [i.1])
NOTE: Ranges from 0° to Θ = 70° relative to a vector perpendicular to the road surface pointing downwards
(parameter D4a in EN 12253 [i.1]) (see figure 1). The RSU provider may declare a smaller value for Θ.

Figure 1: RSU active angle
sub-channel: part of a channel to be used for a specified purpose
NOTE: For DSRC the purpose can be up link or down link.
ˆ
total peak power level: maximum time domain instantaneous power level defined by the peak voltage V at a resistive
rd
load R
2
ˆ
V
ˆ
P =
R
l
 (1)
NOTE: For a sinusoidal signal, the total peak power level is twice the average power level measured with a power
meter. For a modulated signal the peak power level is given by the power envelope maximum.
up link: signal transmitted from the OBU to the RSU
3.2 Symbols
For the purposes of the present document, the following symbols apply:
ˆ
P Instantaneous peak power level
ˆ
V Instantaneous peak Voltage
Θ Angle relative to a vector perpendicular to the road surface
σ Standard deviation
a Noise amplitude
N
Att Free space attenuation
BER Bit error rate with interference signal
i
d Distance between phase centres of transmitting and receiving antenna
f Frequency
I3a Average interference power limit
rms
N Noise power level
0
p Noise amplitude density
AN
P Discriminator value
d
P Maximum possible OFDM peak power level
emax
P Mean envelope power level (average of RF peak power levels)
env
p (t) Power envelope
env
ETSI

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8 ETSI TR 102 654 V1.1.1 (2009-01)
P Power envelope value
ev
P Power level of left hand circular polarized wave
LHCP
p Superposition of noise and interferer amplitude density
ni
P OBU sensitivity limit
OBUsens
p Probability of power envelope value
pe
P Power level of right hand circular polarized wave
RHCP
P Mean RMS power level
RMS
R Resistive load
l
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
2-PSK Binary Phase-Shift Keying
AM Amplitude Modulation
BER Bit Error Ratio
C/I Carrier to Interference Ratio
CEN Comité Européen de Normalization
DFT Discrete Fourier Transformation
DL Down Link
DSRC Dedicated Short Range Communication
EIRP Equivalent Isotropically Radiated Power also called e.i.r.p., eirp, E.I.R.P.
EN European Standard
ERM Electromagnetic compatibility and Radio spectrum Matters
ETSI European Telecommunication Standard Institute
IPR Intellectual Property Rights
ISM Industrial, Scientific, Medical
ITS Intelligent Transport System
LHCP Left Hand Circular Polarized
LP Linear Polarized
OBU On Board Unit
OFDM Orthogonal Frequency-Division Multiplexing
RF Radio Frequency
RHCP Right Hand Circular Polarized
RMS Root Mean Square
RSU Road Side Unit
RTTT Road Transport and Traffic Telematics
RX Receiver
S/I Signal to Interference Ratio
SNR Signal to Noise Ratio
TR Technical Report
TX Transmitter
UL Up Link
UWB Ultra WideBand
EN 12253 [i.1] list of down-link parameter abbreviations:
D1 Carrier frequencies
D4 Maximum EIRP
D4a Angular EIRP mask
D5 Polarization
D5a Cross polarization
D8 DL bit rate
D9 DL bit error ratio
U1-0 Sub-carrier frequency 1,5 MHz
U1-1 Sub-carrier frequency 2 MHz
U5 Polarization
U5a Cross polarization
U8 UL bit rate
ETSI

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Communicating Link
Distance between interferer and RSU
UL frequency
 9 ETSI TR 102 654 V1.1.1 (2009-01)
4 Summary
4.1 Overview
The following elementary interference scenarios to CEN DSRC by other users of the same and adjacent frequency
bands have been identified:
a) Interferer located within RSU active angle at UL frequency.
b) Interferer located outside RSU active angle at UL frequency.
c) Interference to OBU receiver.
d) Disturbance of OBU power save mode.
These interference scenarios are elementary. Most practical cases are represented by one or more of those elementary
interference scenarios.
While scenarios a) and b) can be handled by means of frequency regulation - e.g. output power or unwanted emission
restrictions for interferers, scenarios c) and d) address also the OBU manufacturers to amend their design to reduce the
susceptibility to interference presently caused by the enormous receiver bandwidth as compared with the transmitter
signal bandwidth. This aspect is also recognized in ECC Report 127 [i.4].
Since in Europe more than 10 million OBUs are in the market at the time of creation of the present document, such
improvements for new OBUs will not have an instantaneous effect. However, these necessary improvements will only
reduce the impact of the interference but can not avoid it. Strong interferers will need to implement an additional
mitigation technique on their own. Furthermore, it is expected that ITS systems will commence to be placed on the
market in 3 to 5 years from the time of creation of the present document.
Annex A of the present documents introduces possible solutions to improve coexistence situations.
4.2 Interference scenarios
Scenarios a) and b) shown in figure 2 apply to interferers that use the UL frequencies shown in figures 7 and 8.
RSU
Interferer
OBU
TX

Figure 2: Schematic of interference scenarios a) and b)
From the definition of the active angle of a typical RSU mounted at 5,5 meters height above ground follows that:
Scenario a) applies to interferers within a distance of less than 16 m from this RSU. The interference is typically caused
by devices mounted in cars driving through the communication zone.
Scenario b) applies to interferers outside the 16 m range. The interference is typically caused by fixed or mobile
interferers located outside the communication zone of the RSU.
ETSI

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Communicating Link
Interference to OBU receiver
 10 ETSI TR 102 654 V1.1.1 (2009-01)
Figure 3 shows, under these assumptions, the recommended maximum transmit power spectral density for different
polarized interference signals.
The result in figure 3 is in line with the result of ECC report 101 [i.2] which specifies unwanted ITS emission levels of
less than -55 dBm/MHz below 5 850 MHz and -65 dBm/MHz below 5 815 MHz. The ITS harmonized European
standard EN 302 571 [i.3] includes these limits as a technical requirement.
20
0
-20
-40
-60 LHCP
LP
RHCP
-80
1 10 100 1000 10000
Distance between interferer and RSU [m]

Figure 3: Recommended maximum power spectral density for interference signals
Figure 3 summarizes the results derived from using formulae B.1 and parameters I1b, I1c, I1d, and I2b.
Scenario c) as shown in figure 4 describes data reception interference to OBUs located within the communication zone
of an RSU. This interference is caused by fixed or mobile interferers located inside or outside the RSU communication
zone.
The RF frontend of the OBU is a broadband design to cope with typical tolling scenarios on highways (multilane free
flow), where it is essential that all DSRC channels are processed simultaneously. Therefore the significant parameter
that defines an interference limit to this design is the total incident RF peak power level at the OBU (within the DSRC
and its adjacent bands). Therefore, a relation between distance to the OBU and total interference peak power level can
be defined to protect DSRC.
RSU
Interferer
OBU
TX
Distance between interferer and OBU

Figure 4: Schematic of interference scenario c)
ETSI
Max. spectral power density of interferer
at UL frequency [dBm/MHz]

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Interference to OBU receiver
 11 ETSI TR 102 654 V1.1.1 (2009-01)
Figure 5 shows the relation between recommended maximum total peak output power level for interferers with different
kinds of polarization and the distance to the OBU, under the worst case assumption of free space propagation and 3 dB
windscreen attenuation.
Figure 5 summarizes the results derived from using formulae B.1 and parameters I3a, I3b, and I3c.
NOTE: The peak power level of a sinusoidal signal is 3 dB higher than the average power level measured with a
power meter or a spectrum analyzer for constant envelope modulations. For non sinusoidal signals,
e.g. pulsed signals, the ratio between peak and average power can be much larger than 3 dB.
50
40
30
20
10
LHCP
0
LP
RHCP
-10
1 10 100 1000
Distance between interferer and OBU [m]

Figure 5: Recommended maximum total peak power level to avoid interference
to an OBU mounted behind a windscreen
Scenario d) as shown in figure 6, applies to a battery powered OBU with power save mode. This interference occurs
outside the communication zone of an RSU and is caused by a fixed or mobile interferer.
An interference signal can trigger the OBU to switch from power save mode to operational mode. This causes a
reduction of battery lifetime. The relation between the recommended maximum total peak power level and interferer
distance is similar to scenario c).
Interferer
OBU
TX
Distance between interferer and OBU

Figure 6: Schematic of interference scenario d)
ETSI
Max. total peak power level of OBU RX interferer [dBm]

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12 ETSI TR 102 654 V1.1.1 (2009-01)
5 Interference Limits
5.1 DSRC frequency table
Table 1 summarizes the carrier frequencies and channels specified for DSRC byEN 12253 [i.1] and EN 300 674 [i.5]
(parameter D1).
Figure 7 shows which UL and DL sub-channels are utilized when a 1,5 MHz UL sub-carrier is used (parameter U1-0 in
EN 12253 [i.1] and EN 300 674 [i.5]).
Figure 8 shows which UL and DL sub-channels are utilized when a 2 MHz UL sub-carrier is used (parameter U1-1 in
EN 12253 [i.1] and EN 300 674 [i.5]).
The nominal bandwidth of the UL sub-channel is 250 kHz for each side band. The nominal bandwidth of the DL sub-
channel is 500 kHz for each side band.
NOTE: The bandwidth values result from the bit rates defined in EN 12253 [i.1] and EN 300 674 [i.5] (parameter
U8, D8).
Table 1: DSRC channels defined by EN 12253 [i.1] and EN 300 674 [i.5]
Pan European Service Frequencies Channel Start Channel End Carrier (D1)
Channel 1 5 795 MHz 5 800 MHz 5 797,5 MHz
Channel 2 5 800 MHz 5 805 MHz 5 802,5 MHz
National Service Frequencies Channel Start Channel End Carrier
Channel 3 5 805 MHz 5 810 MHz 5 807,5 MHz
Channel 4 5 810 MHz 5 815 MHz 5 812,5 MHz

Channel 1 Channel 2 Channel 3 Channel 4

Figure 7: DSRC frequency utilization for 1,5 MHz sub-carrier frequency (U1-0)
ETSI
5.7950 GHz
UL 5.7960 GHz
DL 5.7970 GHz
Carrier 5.7975 GHz
DL 5.7980 GHz
UL 5.7990 GHz
5.8000 GHz
UL 5.8010 GHz
DL 5.8020 GHz
Carrier 5.8025 GHz
DL 5.8030 GHz
UL 5.8040 GHz
5.8050 GHz
UL 5.8060 GHz
DL 5.8070 GHz
Carrier 5.8075 GHz
DL 5.8080 GHz
UL 5.8090 GHz
5.8100 GHz
UL 5.8110 GHz
DL 5.8120 GHz
Carrier 5.8125 GHz
DL 5.8130 GHz
UL 5.8140 GHz
5.8150 GHz

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13 ETSI TR 102 654 V1.1.1 (2009-01)
Channel 1 Channel 2 Channel 3 Channel 4

Figure 8: DSRC frequency utilization for 2 MHz sub-carrier frequency (U1-1)
5.2 Typical RF parameters of DSRC equipment
The RF parameters of a typical RSU are provided in table 2 and are also indicated in ECC Report 101 [i.2].
Table 2: Parameters of a typical RSU
DSRC Road Side Unit (RSU) Value Units
Receiver bandwidth 500 kHz
Receiver sensitivity -104 dBm
Antenna gain bore sight 13 dBi
Antenna gain outside RSU active angle
-2 dBi
(worst case as in [i.1])
Antenna polarization LHCP
cross-polar discrimination,
10 dB
ellipticity of polarization
TX output power level, EIRP 33 dBm
RSU mounting height above ground 2,5 to 7 m
Protection criterion (S/I) 6 dB
TX Frequency / Bandwidth see clause 5.1

The RF parameters of a typical OBU are provided in table 3 and are also indicated in ECC Report 101 [i.2].
Table 3: Parameters of a typical OBU
DSRC On Board Unit (OBU) Value Units
OBU sensitivity (typical) -60 to -50 dBm
Wakeup sensitivity -60 to -43 dBm
Antenna polarization LHCP
cross-polar discrimination,
6 dB
ellipticity of polarization
Car windscreen loss 3 dB
OBU mounting height above ground 1 to 2,2 m
Protection criterion (S/I) 10 dB
TX Frequency / Bandwidth see clause 5.1

NOTE: The OBU maximum usable sensitivity value of -60 dBm is defined as cut-off power level in [i.1].
However, considering measurement uncertainty in testing, the value of -60 dBm is unlikely to be
implemented. The lowest reasonable value does exceed the value of -60 dBm by the measurement
uncertainty.
ETSI
5.7950 GHz
UL 5.7955 GHz
DL 5.7970 GHz
Carrier 5.7975 GHz
DL 5.7980 GHz
UL 5.7995 GHz
5.8000 GHz
UL 5.8005 GHz
DL 5.8020 GHz
Carrier 5.8025 GHz
DL 5.8030 GHz
UL 5.8045 GHz
5.8050 GHz
UL 5.8055 GHz
DL 5.8070 GHz
Carrier 5.8075 GHz
DL 5.8080 GHz
UL 5.8095 GHz
5.8100 GHz
UL 5.8105 GHz
DL 5.8120 GHz
Carrier 5.8125 GHz
DL 5.8130 GHz
UL 5.8145 GHz
5.8150 GHz

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14 ETSI TR 102 654 V1.1.1 (2009-01)
5.3 Interference to DSRC
5.3.1 Categorization of interference types
Depending on location and frequency, different types of interferers can be categorized:
• Interferer located within RSU active angle at UL frequency.
• Interferer located outside RSU active angle at UL frequency.
• Interference to OBU receiver.
• Disturbance of OBU power save mode.
The RF parameter limits I1a to I4a necessary to allow coexistence under these conditions are listed in
table 4 in clause 5.4.
5.3.2 Interferer at UL frequency located in RSU active angle
The power level of a narrowband LHCP interference signal in one of the UL sub-channels, radiated in direction of the
RSU receiver antenna, from an interferer which is located within the RSU active angle, should not exceed a value of
I1a at the RSU referred to a loss-less isotropic LHCP antenna.
NOTE: It is assumed that RSU receiver and RSU transmitter antennas are similar. Hence, the maximum RSU
receiver sensitivity is expected to be within the RSU active angle.
For a broadband interferer (e.g. wideband noise-like or carrierless UWB unwanted emissions) covering the whole
DSRC channel, a receiver bandwidth of 500 kHz should be considered (250 kHz upper and lower side band). Hence,
the broadband LHCP interferer power spe
...