ETSI TR 101 537 V1.1.1 (2011-02)

Electromagnetic compatibility and radio spectrum matters (ERM); Second co-existence test between ER-GSM with RFID

DTR/ERM-TG34-011

General Information

• Status: Published
• Publication Date: 07-Feb-2011
• Technical Committee: ERM TG34 - ERM RF Identification Devices
• Current Stage: 12 - Completion
• Due Date: 07-Feb-2011
• Completion Date: 08-Feb-2011

Standards Content (Sample)

Technical Report
Electromagnetic compatibility and
Radio spectrum Matters (ERM);
Second co-existence test between ER-GSM with RFID

2 ETSI TR 101 537 V1.1.1 (2011-02)

Reference
DTR/ERM-TG34-011
Keywords
ER-GSM, radio, RFID, testing
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3 ETSI TR 101 537 V1.1.1 (2011-02)
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 . 5
3.1 Definitions . 5
3.2 Symbols . 6
3.3 Abbreviations . 6
4 Participants . 7
5 Background Information . 7
6 Equipment under Test . 7
7 Tests with R-GSM as a victim . 8
7.1 Measurement setup . 8
7.2 General Measurement procedure . 9
7.3 Measurement results . 9
7.3.1 Measurement results with different Rx level at the Cab Radio . 9
8 Tests concerning IM3 of RFID . 12
8.1 Measurement setup . 12
8.2 General Measurement procedure . 12
8.3 Measurement results . 13
9 Test with RFID as a victim of R-GSM terminal . 14
9.1 Measurement setup . 14
9.2 General Measurement procedure . 14
9.3 Measurement results . 15
10 Measurements with an RFID near-field antenna . 15
10.1 Measurement setup . 15
10.2 Measurement results . 16
11 Observations and conclusions . 17
Annex A: Measurement values for R-GSM as a victim . 19
Annex B: Screen shot of power levels of IM3 test . 21
Annex C: Measurements values for RFID as a victim . 22
Annex D: Picture gallery . 23
Annex E: Bibliography . 28
History . 29

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4 ETSI TR 101 537 V1.1.1 (2011-02)
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).
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5 ETSI TR 101 537 V1.1.1 (2011-02)
1 Scope
The present document describes a series of tests that were undertaken to determine the parameters necessary to permit
RFID to share the band 918 MHz to 921 MHz with ER-GSM. The tests were undertaken at the BNetzA Test Laboratory
at Kolberg. The main purpose of these tests was to find answers to a number of important questions that had been raised
during some earlier tests and to gather additional information.
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
reference 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] ETSI EN 302 208 (V1.2.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM);
Radio Frequency Identification Equipment operating in the band 865 MHz to 868 MHz with
power levels up to 2 W".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
Cognitive Radio System (CRS): Radio system (optionally including multiple entities and network elements), which
has the following capabilities:
• to obtain the knowledge of radio operational environment and established policies and to monitor usage
patterns and users' needs;
• to dynamically, autonomously and whenever possible adjust its operational parameters and protocols
according to this knowledge in order to achieve predefined objectives, e.g. minimize a loss in performance or
increase spectrum efficiency;
and to learn from the results of its actions in order to further improve its performance.
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6 ETSI TR 101 537 V1.1.1 (2011-02)
Detect And Avoid: (DAA): technology used to protect radio communication services by avoiding co-channel operation
NOTE: Before transmitting, a system should sense the channel within its operative bandwidth in order to detect
the possible presence of other systems. If another system is detected, the first system should avoid
transmission until the detected system disappears.
DownLink (DL): direction from a hierarchic higher network element to the one below, in the case of a typical RFID
system direction from the interrogator to tag or from the (E)R-GSM Base Transceive Station (BTS) to the terminal
Dynamic Frequency Allocation (DFA): protocol that allows for changing transmit frequency during operation
Dynamic Power Control (DPC): capability that enables the transmitter output power of a device to be adjusted during
operation in accordance with its link budget requirements or other conditions
fixed: physically fixed, non- moving device; includes temporary event installations as well
link adaptation: result of applying all of the control mechanisms used in Radio Resource Management to optimize the
performance of the radio link
Listen before Talk (LBT): spectrum access protocol requiring a cognitive radio to perform spectrum sensing before
transmitting
location awareness: capability that allows a device to determine its location to a defined level of precision
master: controls the radio resource changing actions
mobile: physically moving device
Radio Environment Map (REM): integrated multi-domain database that characterises the radio environment in which
a cognitive radio system finds itself
NOTE: It may contain geographical information, available radio communication services, spectral regulations and
policies, and the positions and activities of co-located radios.
Service Level Agreement (SLA): defined level of service agreed between the contractor and the service provider
slave: responds to the commands from the Master
UpLink (UL): Direction from Slave to Master
white space: label indicating a part of the spectrum, which is available for a radio communication application at a given
time in a given geographical area on a non-interfering/non-protected basis with regard to other services with a higher
priority on a national basis
3.2 Symbols
For the purposes of the present document, the following symbols apply:
α Pathloss Exponent in the Friis Equation
dB decibel
d distance
f frequency measured under normal test conditions
fc centre frequency of carrier transmitted by interrogator
λ wavelength
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
BCCH Broadcast Control CHannel
BP BandPass
BTS Base Transceive Station
C/I Carrier to Interference ratio
CMU Central Management Unit
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7 ETSI TR 101 537 V1.1.1 (2011-02)
DAA Detect And Avoid
DFA Dynamic Frequency Allocation
DL DownLink
DPC Dynamic Power Control
ER-GSM Extended R-GSM system
FFT Fast Fourier Transform
GSM Global System for Mobile communication
IM3 third order intermodulation
LBT Listen before Talk
POS Point Of Sale
R&S Rohde&Schwarz
REM Radio Environment Map
RF Radio Frequency
RFID Radio Frequency IDentification
R-GSM Railway Global System for Mobile communications
Rx Receiver
SLA Service Level Agreement
Tx Transmitter
UHF Ultra High Frequency
UL UpLink
4 Participants
Frank Siebert Bundesnetzagentur
Friedbert Berens FBConsulting Sarl, Luxembourg
Georg Ramsch Checkpoint
Dirk Schattschneider Deutsche Bahn AG
Daniel Büth FEIG ELECTRONIC GmbH
Markus Desch FEIG ELECTRONIC GmbH
5 Background Information
In summer 2009 a first feasibility test between R-GSM and RFID was carried out. The results of this test showed that it
is feasible for RFID Systems to co-exist in the band 918 MHz to 921 MHz with ER-GSM (i.e. ER-GSM BS transmit
band) without causing unacceptable levels of interference.
ETSI ERM set up STF 397 to develop procedures, techniques and solutions to achieve co-existence of UHF RFID
devices with the victim radio service ER-GSM.
In order to achieve more information on the parameters necessary to optimise co-existence, STF 397 performed a
second test where they made some more detailed measurements. The results of the measurements should be used to
define suitable mitigation strategies to ensure acceptable protection of ER-GSM. Furthermore the measurements should
verify the initial assumptions of STF 397 and should form a basis for the definition of suitable test parameters for a test
procedure for an RFID interrogator. This document describes the test methods and results of the second co-existence
test performed at Kolberg, which should help the STF to define DAA or similar techniques, test procedures and test
parameters.
6 Equipment under Test
In order to perform the tests the following equipment was used:
• R-GSM:
- 1 × R-GSM base unit (R&S CMU 200 BS); ®
- 1 × R-GSM terminal (Cab Radio, Funkwerke Hörmann with Sagem radio module MRM R2); ®
- 1 × R-GSM terminal (GPH, Sagem ).
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8 ETSI TR 101 537 V1.1.1 (2011-02)
• RFID:
- 2 × RFID interrogators from FEIG (ID-ISC.LRU3500),
- 1 × CISC RFID Tag Emulator R1.1.
The RFID interrogator was operated in accordance with the four channel plan described in EN 302 208 (V1.2.1) [i.1].
For the purpose of the tests the frequency range of the interrogator was shifted to the existing R-GSM frequencies
918 MHz to 924 MHz (3 MHz overlap with R-GSM). In some of the tests the channel width of the transmissions from
the interrogator was increased to 400 kHz.
7 Tests with R-GSM as a victim
The purpose of these tests was to determine the conditions under which RFID can cause interference to the R-GSM
receiver in a mobile unit. To verify the worst interference conditions for the R-GSM receiver in this part of the test
session, the R-GSM receiver was tested with the interrogator operating in different modes. In this first set of
measurements the behaviour of the R-GSM receiver was tested in its various operating modes and at different simulated
distances from the Base station. This was done by increasing the attenuation that can be inserted until the Rx-Qual value
reported by the mobile unit changed from 1 to 2. In the second part of the test session the behaviour of the R-GSM
receiver was tested with different RFID bandwidths and modulation scenarios. It should be noted that some of the RFID
modulation scenarios were not typical of those found in most RFID communication systems. These unusual modulation
scenarios were tested in order to determine the worst case conditions for an R-GSM receiver. Conducted measurements
were also performed to obtain protection distances for the various scenarios.
7.1 Measurement setup
The equipment was configured as shown in figure 1. This measurement setup was the same as that used in the first
co-existence tests between ER-GSM and RFID.

Figure 1: Setup for R-GSM as a victim
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9 ETSI TR 101 537 V1.1.1 (2011-02)
7.2 General Measurement procedure
The CMU behaved like a R-GSM Base Station transmitting the BCCH, i.e. all time slots on air with a constant Tx-level.
The Tx-level of the CMU was adjusted to give different input levels at the Cab Radio. The Tx-levels were specified in
the test sections below. The Rx-level of the R-GSM signal and the levels generated by the RFID interrogators were
measured with a spectrum analyser. The downlink bandpass filter protected the analysers from the high uplink level of
the Cab Radio.
During testing the interrogator was set to the nominal frequency of 921,4 MHz and shifted in 100 kHz steps towards
925 MHz. The output signal level from the interrogator was adjusted by its attenuator to give the specified conditions
on the display of the cab receiver.
The CMU was initially set to transmit at a frequency of 921,4 MHz.
7.3 Measurement results
7.3.1 Measurement results with different Rx level at the Cab Radio
Figure 2 shows a comparison of the measurements made in 2009 and 2010. The figure shows the C/I for one RFID
interrogator experienced by the Cab Radio, with the RFID Interrogator transmitting within a 400 kHz channel width.
This comparison shows that the measurement setup in 2010 was the same as the setup in 2009. There were two minor
differences. Firstly the slopes of the two C/I curves are not exactly the same. This may be due to the fact that the Cab
Radios were not the same, so the filters in the Cab Radios may have slightly different characteristics. Secondly the
frequency offset of 0 kHz was not tested in 2009. From the measurement of 2010 it can be seen that there is a 9 dB
lower C/I between the point of 0 kHz offset and the point of 100 kHz offset. This means an offset of 100 kHz between
the ER-GSM centre frequencies and the RFID centre frequencies improves the protection for ER-GSM terminals by
9 dB.
Figure 2: Comparison measurement 2009 / 2010 (R-GSM as a victim)
A further test was made to determine which of either the idle mode or active voice call needs the most protection
against interference from RFID. The result of this measurement is shown in figure 3. In the frequency offset range from
0 kHz to 600 kHz, the R-GSM terminal needs about 10 dB less protection in idle mode than in an active voice call. This
means that voice call is the worst case situation and therefore should be used for all further measurements of protection
range. Since voice call is the worst case situation, no additional allowance in protection range is necessary for a terminal
when in idle mode.
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10 ETSI TR 101 537 V1.1.1 (2011-02)

Figure 3: Comparison of protection distances
for R-GSM terminal in idle mode and voice call
Figure 4 shows the absolute RF Power at the input of the Cab Radio at which its RxQual level drops to a value of 2. The
three curves were measured at different R-GSM Rx power levels at the Cab Radio input. The power levels are
representative of different communication scenarios of the R-GSM system and are specified below.
• Cab low power -96 dBm.
• Cell edge -86 dBm.
• Good link -76 dBm.
From the measurement it can be seen that a Cab Radio receiving a higher Rx signal from the R-GSM base station can
operate with a higher interfering signal from an RFID Interrogator. This characteristic of the R-GSM terminal is true
until the interfering RF power exceeds the in-band blocking level of -23 dBm. So when the interfering RF power at the
receiver input of the Cab Radio exceeds about -23 dBm, it does not matter whether or not it is receiving a good R-GSM
signal. The receiver of the Cab Radio is blocked.

Figure 4: Protection Cab Radio in different RF link situations
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11 ETSI TR 101 537 V1.1.1 (2011-02)
Figure 5 shows a comparison of the protection ratio of R-GSM as a function of the RFID channel width. The
measurement shows that it does not matter what chan
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