ETSI TS 102 903 V1.1.1 (2011-08)

Electromagnetic compatibility and Radio spectrum Matters (ERM); Compliance tests for cognitive interference mitigation for use by UHF RFID using Detect-And-Avoid (DAA) or other similar techniques

DTS/ERM-TG34-012

General Information

• Status: Published
• Publication Date: 10-Aug-2011
• Technical Committee: ERM TG34 - ERM RF Identification Devices
• Current Stage: 12 - Completion
• Due Date: 12-Aug-2011
• Completion Date: 11-Aug-2011

Standards Content (Sample)

Technical Specification
Electromagnetic compatibility
and Radio spectrum Matters (ERM);
Compliance tests for cognitive interference mitigation
for use by UHF RFID using Detect-And-Avoid (DAA)
or other similar techniques
2 ETSI TS 102 903 V1.1.1 (2011-08)

Reference
DTS/ERM-TG34-012
Keywords
ER-GSM, radio, RFID
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ETSI
3 ETSI TS 102 903 V1.1.1 (2011-08)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definitions, symbols and abbreviations . 7
3.1 Definitions . 7
3.2 Symbols . 8
3.3 Abbreviations . 8
4 Demonstration of principle . 8
4.1 Introduction . 8
4.2 Methods of measurement . 9
4.2.1 Unmodulated Signal in the ER-GSM UL and DL band. 9
4.3 Results of the demonstration . 10
4.3.1 Unmodulated Signal in the ER-GSM DL band. 10
5.3.2 Unmodulated Signal in the ER-GSM UL band. 13
5 Test procedures . 16
5.1 Introduction . 16
5.2 Technical requirement specifications . 16
5.2.1 General requirements . 16
5.2.1.1 Class A: Interrogators without detection capabilities . 17
5.2.1.2 Class B: Interrogators with ER-GSM Downlink detection capability . 17
5.2.1.3 Class C: Interrogators with ER-GSM Uplink and Downlink detection capability . 18
5.2.1.3.1 Class C1: Slow Uplink detection . 18
5.2.1.3.2 Class C2: Fast Uplink detection . 18
5.2.2.2 Operational frequency ranges. 19
5.2.2.2.1 Choice of frequencies . 19
5.2.2.2.2 Channel range . 19
5.2.2.2.3 Testing of operational frequencies. 19
5.3 Methods of measurement and limits for transmitter parameters . 20
5.3.1 Frequency error for mains operated equipment . 20
5.3.1.1 Definition . 20
5.3.1.2 Method of measurement of frequency error . 20
5.3.1.3 Limits . 21
5.3.2 Frequency stability under low voltage conditions . 21
5.3.2.1 Definition . 21
5.3.2.2 Method of measurement . 21
5.3.2.3 Limits . 21
5.3.3 Radiated power (e.r.p.) . 21
5.3.3.1 Definition . 21
5.3.3.2 Method of measurement . 22
5.3.3.2.1 Radiated measurement . 22
5.3.3.2.2 Conducted measurement. 23
5.3.3.3 Limits . 23
5.3.4 Transmitter spectrum mask . 23
5.3.4.1 Definition . 23
5.3.4.2 Method of measurement . 23
5.3.4.3 Limits . 24
5.3.5 Unwanted emissions in the spurious domain. 25
5.3.5.1 Definition . 25
5.3.5.2 Method of measurement . 25
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4 ETSI TS 102 903 V1.1.1 (2011-08)
5.3.5.2.1 Method of measuring the power level in a specified load, clause 5.3.5.2, a) i) . 26
5.3.5.2.2 Method of measuring the effective radiated power, clause 5.3.5.2, a) ii). 26
5.3.5.2.3 Method of measuring effective radiated power, clause 5.3.5.2, b) . 28
5.3.5.3 Limits . 28
5.3.6 Downlink detection . 28
5.3.6.1 Definition . 28
5.3.6.2 Downlink detection mode . 28
5.3.6.3 Method of measurement . 29
5.3.6.3.1 Method of measuring radiated signals in the R-GSM band . 29
5.3.6.3.2 Method of measuring radiated signals in the ER-GSM band . 30
5.3.6.3.3 Conducted method of measurement for signals in the R-GSM band . 31
5.3.6.3.4 Conducted method of measurement for signals in the ER-GSM band . 33
5.3.6.4 Limits . 34
5.3.7 Uplink detection . 34
5.3.7.1 Definition . 34
5.3.7.2 Uplink detection mode . 35
5.3.7.3 Method of measurement . 35
5.3.7.3.1 Method of measuring radiated signals . 35
5.3.7.3.2 Conducted method of measurement . 37
5.3.7.4 Limits . 38
5.3.7.4.1 Test sequence . 38
5.3.7.4.2 Threshold levels. 38
5.3.7.4.3 Transmission times for class C1 interrogators . 38
5.3.7.4.4 Uplink detection time . 39
6 Field evaluation test. 39
6.1 Introduction . 39
6.2 Initial field test . 40
6.3 Field test at a shunting area/distribution centre . 42
Annex A (informative): Bibliography . 43
History . 44

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5 ETSI TS 102 903 V1.1.1 (2011-08)
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 Specification (TS) has been produced by ETSI Technical Committee Electromagnetic compatibility and
Radio spectrum Matters (ERM).
Introduction
In order to accommodate the spectrum needs for the increasing number of RFID devices and systems, an extension band
for high power RFID systems in the range between 915 MHz and 921 MHz has been requested. This band is already
used by RFID in several countries worldwide and its designation in Europe would increase its functionality and
simplify the international movement of goods using RFID identification systems. In Europe, part of this new frequency
band will be shared between the primary user ER-GSM and RFID. In order to guarantee an interference-free
coexistence between the two systems, mechanisms have to be implemented by RFID systems to reduce the probability
of interference to an acceptable minimum. These techniques can be either regulatory, or technical mechanisms or
operational restrictions.
This Technical Specification (TS) includes a description of the practical evaluation and the certification test procedure
for the mitigation mechanisms defined in TS 102 902 [3] (Methods, parameters and test procedures for cognitive
interference mitigation towards ER-GSM for use by UHF RFID using Detect-And-Avoid (DAA) or other similar
techniques). The focus in the present document will be on the sensing of the environment and estimation of the isolation
between a RFID high power interrogator and a potential victim ER-GSM terminal. The location based mechanisms
presented in [2] are not part of the present TS. The interference evaluations performed in [2] have shown that RFID
devices will not cause any harmful interference towards the potential ER-GSM victim terminals if the power is below
0 dBm (1mW) and the protection distance is larger than 20 m. Since the maximum TX power of RFID tags in the band
915 MHz to 921 Mhz is below -10 dBm, they do not require any additional mitigation.
The present document follows on from the recommendations contained in TS 102 902 [2]. It begins by describing the
results of a demonstration of principle which was performed by members of STF 397 (Specialist Task Force 397). The
knowledge gained from this work was central to the development of the specifications for the tests. Finally the
document outlines a set of practical tests which are considered necessary in order to finalise the values of certain critical
parameters and to validate that the mitigation techniques function as predicted in an operational environment.
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6 ETSI TS 102 903 V1.1.1 (2011-08)
1 Scope
The present document reports on the practical evaluation, demonstrations and certification procedures for the mitigation
mechanisms for RFID systems operating in the band between 915 MHz to 921 MHz as described in [2]. The active
mechanisms covered in this Technical Specification are intended to mitigate against any harmful interference generated
by RFID interrogators towards ER-GSM terminals operated in the band between 918 MHz to 921 MHz.
The report does not cover the location based methods presented in [2] nor does it include RFID tags operating in the
band with a power levels up to -10 dBm.
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.
[1] ETSI EN 302 208 (all parts) (V1.3.1): "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".
[2] ETSI TS 102 902 (V1.1.1): "Electromagnetic compatibility and radio spectrum matters (ERM);
Methods, parameters and test procedures for cognitive interference mitigation towards ER-GSM
for use by UHF RFID using Detect-And-Avoid (DAA) or other similar techniques".
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 ERM TG34: ERM-TG34#15-04r1: "ETSI tests at a Distribution Centre", September 2006.
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7 ETSI TS 102 903 V1.1.1 (2011-08)
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:
• obtains knowledge of the radio operational environment and established policies and monitors usage patterns
and users' needs;
• adjusts dynamically and autonomously 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
• learns from the results of its actions in order to further improve its performance.
Detect And Avoid: (DAA): technology used to protect radio communication services by avoiding co-channel
operation.
NOTE: Before transmitting, a system senses the channel within its operational bandwidth in order to detect the
possible presence of other systems. If the channel is occupied, the system avoids transmission until the
channel becomes available.
Downlink (DL): direction of communication from master to slave, where in the case of a typical RFID system the
direction flows from the interrogator to tag
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 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: 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: performs the commands transmitted by the Master
Uplink (UL): direction of communication from Slave to Master
white space: term 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
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8 ETSI TS 102 903 V1.1.1 (2011-08)
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
Ω omh
∆f frequency offset
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
BCCH Broadcast Control Channel
BTS Base Transceive Station
DAA Detect and Avoid
DL Downlink
ER-GSM Extended Railways GSM
GSM Global System for Mobile Communication
IM3 third order intermodulation
RBW Resolution Band Width
RF Radio Frequency
RFID Radio Frequency Identification
R-GSM Railways Global System for Mobile communications
RX Receiver
TCH Traffic Channel
TX Transmitter
UHF Ultra High Frequency
UL Uplink
4 Demonstration of principle
4.1 Introduction
The purpose of the initial demonstration of principle was to show the ability of an interrogator to detect the defined
threshold levels for Uplink and Downlink detection. This demonstration of principle was also presented at the ECC
workshop in Mainz in April 2011. The demonstration showed the feasibility of the active mitigation techniques
proposed in [2]. Further information will follow as soon as a more detailed implementation is available.
For demonstrations of UL detection in the future, the effect of possible use of wireless smart metering applications in
the band will have to be taken into account. This is covered in clause 5 of the present document, which describes the
recognition of specific R-GSM and ER-GSM signal patterns.
The detection process of the ER-GSM Uplink and the Downlink is performed during the power up process of the
interrogator. The method of measurement is similar to the test procedure defined in clause 5.3.6. All measurements are
made as conducted.
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9 ETSI TS 102 903 V1.1.1 (2011-08)
4.2 Methods of measurement
The demonstration setup and procedure shows the detection process and the corresponding response of the interrogator.
In the first step, downlink detection of a BCCH is demonstrated. The interrogator, operating in the band between
915 MHz to 921 MHz, monitors the complete R-GSM and ER-GSM bands between 918 MHz to 925 MHz in order to
detect a BCCH. In the initial implementation, due to the non-availability of ER-GSM equipment, the core R-GSM band
between 921 MHz to 925 MHz is monitored. For the initial demonstration of concept an unmodulated signal is used to
show the ability of the interrogator to identify a specific detection threshold.
In the second step the interrogator is configured to detect an unmodulated signal at a specified threshold level in the
ER-GSM uplink band.
4.2.1 Unmodulated Signal in the ER-GSM UL and DL band
This test shows that an interrogator is able to detect a signal in the ER-GSM Uplink and Downlink band down to the
defined threshold levels. The demonstration only needs to be done for the lowest defined threshold level.
Step 1: The measurement receiver is connected to the input of a power splitter. One input of the power
splitter is connected to a signal source A. The other input is connected to a 50 Ω resistor. Signal
source A is adjusted to produce an un-modulated continuous carrier with its frequency tuned to
919,2 MHz. The signal is adjusted to give a level at the input to the measuring receiver that is 3 dB
above the appropriate threshold limit taken from table 3 in clause 5.3.6.4. A diagram of the test
configuration is shown at figure 1.

Figure 1: Calibration for conducted measurement
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10 ETSI TS 102 903 V1.1.1 (2011-08)
Step 2: The measuring receiver is replaced by the interrogator. The 50 Ω resistor is replaced by the
measuring receiver. A diagram of the test configuration is shown at figure 2.

Figure 2: Conducted measurement of signal detection
Step 3: With signal source A switched off the interrogator is powered on.
Step 4: The interrogator should switch automatically to scan mode. The transmission from the interrogator
shall be monitored. The interrogator shall start transmission at a frequency of 920,1 MHz.
Step 5: The power supply to the interrogator is turned off.
Step 6: With signal source A switched on the interrogator is powered up. The interrogator shall switch
automatically to scan mode. The frequency of transmission from the interrogator shall be
monitored.
Step 7: The frequency of transmission of the interrogator should be at 916,5 MHz, which shows that the
interrogator has successfully detected the signal from source A.
In the second demonstration the signal source A is tuned to a frequency of 875 MHz and the threshold level in the
interrogator is set to the value defined in table 5 of clause 5.3.7.4.2. This demonstration should show the capability of an
RFID interrogator to detect signals in the uplink band of the ER-GSM system.
4.3 Results of the demonstration
4.3.1 Unmodulated Signal in the ER-GSM DL band
In the first part of the test the capability of the interrogator to detect a continuous unmodulated signal in ER-GSM
downlink band was shown. Initially the interrogator was powered on while the signal source simulating the ER-GSM
downlink signal was turned off. After power up the interrogator performed the downlink detection. No ER-GSM
downlink signal was detected. In accordance with the specified test method, the interrogator started transmission at
920,1 MHz.
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11 ETSI TS 102 903 V1.1.1 (2011-08)

Figure 3: Reader transmission at 920,1 MHz, no ER-GSM downlink signal
The interrogator was then turned off. The signal source simulating the ER-GSM downlink signal was powered on. The
signal source was adjusted to give a level at the input to the interrogator that is 3 dB above the appropriate threshold
limit taken from table 3 in clause 5.3.6.4.
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12 ETSI TS 102 903 V1.1.1 (2011-08)

Figure 4: Signal source at 919,2 MHz with a power level of -83 dBm
The interrogator was powered on again. After power up the interrogator performed the downlink detection. The
interrogator detected the downlink signal at a frequency of 919,2 MHz. In accordance with the specified test method,
the interrogator started transmission at 916,5 MHz.
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13 ETSI TS 102 903 V1.1.1 (2011-08)

Figure 5: Interrogator transmission at 916,5 MHz and ER-GSM downlink signal at 919,2 MHz
This demonstration successfully showed that the interrogator is able to detect signals in the ER-GSM downlink band
with power levels down to the defined threshold level.
5.3.2 Unmodulated Signal in the ER-GSM UL band
In the second part of the test the capability of the interrogator to detect a continuous unmodulated signal in the ER-GSM
uplink band was shown. Initially the interrogator was powered on while the signal source simulating the ER-GSM
uplink signal was turned off. After power up the interrogator performed the uplink detection. No ER-GSM uplink signal
was detected. In accordance with the specified test method, the interrogator started transmission at 920.1 MHz.
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14 ETSI TS 102 903 V1.1.1 (2011-08)

Figure 6: Reader transmission at 920,1 MHz, no ER-GSM uplink signal
The interrogator was then turned off. The signal source simulating the ER-GSM uplink signal was switched on. The
signal source was adjusted to give a level at the input to the interrogator that is 3 dB above the appropriate threshold
limit taken from table 5 in clause 5.3.7.4.2.
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15 ETSI TS 102 903 V1.1.1 (2011-08)

Figure 7: Signal source at 875 MHz with a power level of -77 dBm
The interrogator was powered up again. After power up the interrogator performed the uplink detection. The
interrogator detected the uplink signal at a frequency of 875 MHz. In accordance with the specified test method, the
interrogator started transmission at 916,5 MHz.
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16 ETSI TS 102 903 V1.1.1 (2011-08)

Figure 8: Interrogator transmission at 916,5 MHz and ER-GSM uplink signal at 875 MHz
This demonstration successfully showed that the interrogator is able to detect signals in the ER-GSM uplink band with
power levels down to the defined threshold level.
5 Test procedures
5.1 Introduction
In this clause the conformance test procedures for the active mitigation techniques proposed in [2] will be presented.
5.2 Technical requirement specifications
5.2.1 General requirements
The present document describes test methods to ensure the co-existence of RFID and ER-GSM Systems in the
frequency range between 915 MHz and 921 MHz. To achieve co-existence an interrogator should comply with the
following requirements:
• The interrogator/interrogator antenna should be at least 20 m away from a railway track.
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17 ETSI TS 102 903 V1.1.1 (2011-08)
• Interrogators shall transmit on any of the high power channels specified in clause 5.2.2.2.1 at power levels up
to the limit specified in clause 5.3.3.3. Interrogators shall transmit preferably on either of the high power
channels with centre frequencies of 916,5 MHz and 917,7 MHz. The channels located at frequencies of,
918,9 MHz and 920,1 MHz shall be used either when the channels at 916,5 MHz and 917,7 MHz are
unavailable or when the use of the channels 918,9 MHz or 920,1 MHz improves the performance of the RFID
system. When interrogators use either of the channels 918,5 MHz or 920,1 MHz they shall use appropriate
mitigation techniques as defined in the present document.
• Interrogators using only the high power channels with the centre frequencies 916,5 MHz and 917,7 MHz do
not need to implement the additional mitigation techniques described below. Thus no tests related to the
mitigation techniques are needed and only the spectrum requirements have to be met.
• In a preferred method of operation tags, which are activated by an interrogator transmitting in a high power
channel, shall respond in the adjacent low power channels. This technique is called the dense interrogator
mode. It has the benefit of separating the frequencies of transmission of the interrogators and tags, allowing
multiple interrogators to share the same channel thereby improving system performance. It also minimizes the
generation of inter-modulation products, which may disrupt the behaviour of tags.
Each interrogator shall be so configured as to ensure that its length of transmission is no greater than is necessary to
perform the intended operation. According to their capabilities, interrogators can be categorized into three different
classes:
• Class A: Interrogators without Detection Capabilities
• Class B: Interrogators with ER-GSM Downlink Detection Capability
• Class C: Interrogators with ER-GSM Uplink and Downlink Detection Capability
To demonstrate compliance with a specific class, the interrogator shall fulfil the requirements defined in table 1.
Table 1: Interrogator classes
Compliance required in
Class Description accordance with specified
clauses
A Interrogators without Detection Capabilities 5.3.1, 5.3.2, 5.3.3, 5.3.4 and 5.3.5
Interrogators with ER-GSM Downlink Detection 5.3.1, 5.3.2, 5.3.3, 5.3.4, 6.3.5 and
B
Capability 5.3.6
Interrogator with ER-GSM Downlink and Slow Uplink 5.3.1, 5.3.2, 5.3.3, 5.3.4, 5.3.5, 5.3.6
C1
Detection Capability and 5.3.7
C
Interrogator with ER-GSM Downlink and Fast Uplink 5.3.1, 5.3.2, 5.3.3, 5.3.4, 5.3.5, 5.3.6
C2
Detection Capability and 5.3.7

5.2.1.1 Class A: Interrogators without detection capabilities
Interrogators according to class A shall only transmit at centre frequencies of 916,5 MHz and 917,7 MHz. Class A
interrogators shall demonstrate this with the tests defined in clauses 5.3.1, 5.3.2, 5.3.3, 5.3.4 and 5.3.5.
5.2.1.2 Class B: Interrogators with ER-GSM Downlink detection capability
An interrogator complying with class B requirements shall perform a scan for the presence of a BCCH within the
complete ER-GSM and R-GSM band across the frequency band 918,2 MHz to 924,8 MHz immediately on power up.
There are 33 potential BCCH channels available located at centre frequencies between 918,2 MHz and 924,8 MHz with
a spacing of 200 kHz. The detection threshold shall be in accordance with the limits defined in clause 5.3.6.4 measured
at the centre frequency of each BCCH channel. To detect the presence of a BCCH, the interrogator shall recognize the
pattern of its signal measured at the centre of a BCCH channel at a constant power level above the threshold for
duration of at least 50 ms.
An interrogator shall not transmit on the RFID channels located at 918,9 MHz and 920,1 MHz while it continues to
detect more than three BCCHs in the R-GSM band. If the number of detected BCCHs in the R-GSM band is three or
less, the interrogator is allowed to transmit on all available RFID channels. If an interrogator detects the presence of a
BCCH in the ER-GSM channel it shall not operate on the RFID channels 918,9 MHz and 920,1 MHz.
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18 ETSI TS 102 903 V1.1.1 (2011-08)
Scanning for BCCH by stationary interrogators shall be repeated at least once every 24 hours. A mobile interrogator
shall repeat scanning at least every 15 minutes.
Class B interrogators shall demonstrate compliance with the tests defined in clauses 5.3.1, 5.3.2, 5.3.3, 5.3.4, 5.3.5,
5.3.6 and 5.3.7.
5.2.1.3 Class C: Interrogators with ER-GSM Uplink and Downlink detection capability
5.2.1.3.1 Class C1: Slow Uplink detection
A class C1 interrogator may transmit a continuous signal on any of the high power channels for a period not exceeding
the limit defined in clause 5.3.7.4.3. At the end of the transmission the interrogator may transmit again for the same
period on the same channel provided that it is still available.
Interrogators complying with class C1 shall be capable of detecting the downlink transmission from a BCCH in
accordance with the specification in clause 5.2.1.2. If a class C1 interrogator detects a downlink transmission from a
BCCH Channel in the ER-GSM or R-GSM band, detection of an ER-GSM uplink is mandatory. The detection of the
uplink shall be performed within ±300 kHz of the uplink frequency corresponding to the RFID transmit channels
located at either 918,9 MHz or 920,1 MHz. The detection threshold shall be in accordance with the limits defined in
clause 6.3.7.4 at the centre frequency of the corresponding ER-GSM uplink channels. For uplink detection the
interrogator shall detect the protocol sequence as defined in clause 5.3.7.4. If no uplink signal is detected
within ±300 kHz of the corresponding ER-GSM uplink channels, the interrogator can transmit on the RFID channel in
the corresponding ER-GSM downlink band. This is 45 MHz above the ER-GSM uplink channel as a consequence of
the duplex spacing between UL and DL. (e.g. if the BCCH of a base station operates at a frequency of 920 MHz, the
Mobile will transmit at a frequency of 875 MHz. The nearest high power RFID channel is located just 100 kHz below
the BCCH of the base station.) Channels within ±300 kHz of the centre frequency of transmission of an interrogator on
which no uplink signal is detected shall be monitored continuously by the interrogator. Any signal above the threshold
level on an uplink channel within ±300 kHz shall be detected by the interrogator within 4 s of its transmission. If an
uplink signal is detected within the specified frequency range, the interrogator shall register as blocked the channel on
which the transmission occurred and shall not use the channel again until it is no longer occupied. A channel can be
considered unoccupied once it is no longer possible to detect the BCCH transmission.
Class C1 interrogators shall demonstrate compliance with the tests defined in clauses 5.3.1, 5.3.2, 5.3.3, 5.3.4, 5.3.5,
6.3.6 and 5.3.7.
5.2.1.3.2 Class C2: Fast Uplink detection
Interrogators complying with class C1 shall be capable of detecting the downlink transmission from a BCCH in
accordance with the specification in clause 5.2.1.2. If a class C1 interrogator detects a downlink transmission from a
BCCH Channel in the ER-GSM or R-GSM band, detection of an ER-GSM uplink is mandatory. The detection of the
uplink shall be performed within ±300 kHz of the uplink frequency corresponding to the RFID transmit channels
located at either 918,9 MHz or 920,1 MHz. The detection threshold shall be in accordance with the limits defined in
clause 5.3.7.4 at the centre frequencies of the corresponding ER-GSM uplink channels. For uplink detection the
interrogator shall detect the protocol sequence as defined in clause 5.3.7.4. If no uplink signal is detected within
±300 kHz of the corresponding ER-GSM uplink channel, the interrogator can use the RFID channel. (This is 45 MHz
above the ER-GSM uplink channel as a consequence of the duplex spacing between UL and DL. e.g. If the BCCH of a
base station is located at a frequency of 920 MHz, the Mobile communicates at a frequency of 875 MHz.) Channels
within ±300 kHz of the centre frequency of transmission of an interrogator on which no uplink signal is detected shall
be monitored continuously by the interrogator. Any signal above the threshold level on an uplink channel within
±300 kHz shall be detected by the interrogator within 50 ms of its initialisation. If an uplink signal is detected within the
specified frequency range, the interrogator shall register the channel in which the transmission occurred as blocked and
shall not use the channel again until it is no longer occupied. A channel can be considered unoccupied if it is not
possible to detect the transmission specified in clause 5.3.8.4.2 in the channel for a continuous period of 1 second.
Class C2 interrogators shall demonstrate compliance with the tests defined in clauses 5.3.1, 5.3.2, 5.3.3, 5.3.4, 5.3.5,
5.3.6 and 5.3.7.
ETSI
19 ETSI TS 102 903 V1.1.1 (2011-08)
5.2.2.2 Operational frequency ranges
5.2.2.2.1 Choice of frequencies
Interrogators shall operate within the band 915 MHz to 921 MHz in any one of the four specified high power channels
as illustrated in figure 9. The band width of each high power channel shall be 400 kHz and the centre frequency of the
lowest channel shall be 916,5 MHz. The remaining three high power channels shall be spaced at equal intervals of
1 200 kHz. Tags should preferably respond in the dense interrogator mode within the adjacent low power channels.
)
)
z
z
H H
k
k
z z 0 z z
z z 0
H H
H H H H
k k
( (
M 0 M M 0 M
z
z
0 0
5 7 9 1
4 H 4 H
, , , ,
K k
6 7 8 0
W 0 W
1 1 1 2 0
B B
9 9 4 9 9 4
W
W
B
B
GSM
R-GSM
mobile ER-GSM base station
band
z z z z z z z
H H H H H H H
M M M M M M M
5 6 7 8 9 0 1
1 1 1 1 1 2 2
9 9 9 9 9 9 9
Figure 9: Diagram of channel plan
5.2.2.2.2 Channel range
When submitting equipment for testing, the provider shall state the frequencies of the channels on which the
interrogator will operate. The provider shall also confirm that the interrogator shall operate on each of the declared
channels without any change to the circuit or trimming of discrete components.
Trimming is an act by which the value (in this case relating to frequency) of a component is changed within the circuit.
This act may include the physical alteration, substitution (by components of similar size and type) or
activation/de-activation (via the setting of soldered bridges) of components.
5.2.2.2.3 Testing of operational frequencies
Figure 9 shows the centre frequencies of the four high power channels permitted for use by interrogators at levels up to
4 W e.r.p. within the band designated for RFID. Full (FT) and Limited (LT) Tests, as defined in clause 3.1 in [1], shall
be carried out in the applicable channels at the frequencies shown in figure 10.
ETSI
20 ETSI TS 102 903 V1.1.1 (2011-08)

Legend: LT: Limited tests, see clause 3.1 in [1].
FT: Full tests, see clause 3.1 in [1].

Figure 10: Tests on a single sample for equipment
within the band 915,0 MHz to 921,0 MHz
5.3 Methods of measurement and limits for transmitter
parameters
Where the interrogator is designed with an adjustable carrier, then all transmitt
...