ETSI TR 103 319 V1.1.1 (2017-08)

ETSI TR 103 319 V1.1.1 (2017-08)






TECHNICAL REPORT
Broadband Radio Access Networks (BRAN);
5 GHz high performance RLAN;
Mitigation techniques to enable sharing between RLANs
and Road Tolling and Intelligent Transport Systems
in the 5 725 MHz to 5 925 MHz band

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2 ETSI TR 103 319 V1.1.1 (2017-08)



Reference
DTR/BRAN-60018
Keywords
broadband, ITS, LAN, radio, transport
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3 ETSI TR 103 319 V1.1.1 (2017-08)
Contents
Intellectual Property Rights . 6
Foreword . 6
Modal verbs terminology . 6
Executive Summary . 6
Introduction . 7
1 Scope . 8
2 References . 8
2.1 Normative references . 8
2.2 Informative references . 8
3 Definitions, symbols and abbreviations . 11
3.1 Definitions . 11
3.2 Symbols . 11
3.3 Abbreviations . 12
4 Overview of services under study . 13
4.1 Existing/Proposed RLAN . 13
4.1.1 Overview . 13
4.1.2 Existing regulations in the 5 150 MHz to 5 350 MHz and 5 470 MHz to 5 725 MHz bands . 13
4.1.3 Proposal for additional spectrum for RLANs . 14
4.1.4 Technical characteristics . 14
4.2 Transport and Traffic Telematics (TTT) . 15
4.2.1 Overview . 15
4.2.2 Road-tolling applications in the band 5 795 MHz to 5 815 MHz . 15
4.2.3 Technical characteristics . 16
4.3 Transport systems (ITS) . 16
4.3.1 Overview . 16
4.3.2 Transport systems (ITS) in the bands 5 875 MHz to 5 905 MHz, 5 905 MHz to 5 925 MHz and
5 855 MHz to 5 875 MHz . 16
4.3.3 Technical characteristics . 18
5 Interference scenarios . 18
5.1 Introduction . 18
5.1.1 Overview . 18
5.1.2 RLAN and Road Tolling (TTT) - description of scenarios . 18
5.1.3 RLAN and ITS - description of scenarios . 19
5.1.4 Proposed evaluation settings . 21
6 Coexistence and mitigation techniques . 22
6.1 Introduction . 22
6.2 Mitigation techniques to enable coexistence of RLAN and road tolling (TTT) . 23
6.3 Detection of road toll stations. 24
6.3.0 Overview . 24
6.3.1 Road toll detector . 24
6.3.2 Detection of road toll stations via ITS-G5 . 24
6.3.3 RLAN beacons . 24
6.3.4 ITS-G5 beacons (coexistence CAMs). 24
6.3.5 Geo-location database . 25
6.4 Mitigation methods to reduce interference to road tolling (TTT). 25
6.4.0 Overview . 25
6.4.1 Vacate/frequency non-use . 25
6.4.2 Transmit power control . 26
6.4.3 Duty cycle limitation . 26
6.4.4 Packet by packet interoperation . 27
6.5 Mitigation techniques to enable coexistence of RLAN and ITS . 27
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4 ETSI TR 103 319 V1.1.1 (2017-08)
6.5.0 Overview . 27
6.5.1 Energy detection . 27
6.5.2 Detect and mitigate proposal . 27
6.5.3 Detect and vacate . 29
7 Mitigation technique evaluation . 32
7.1 Introduction . 32
7.2 Mitigation techniques to enable coexistence of RLAN and road tolling (TTT) . 33
7.3 Detection of road toll stations. 33
7.3.0 Overview . 33
7.3.1 Road toll detector . 33
7.3.2 Detection of road toll stations via ITS-G5 . 33
7.3.3 RLAN beacons . 33
7.3.4 ITS-G5 beacons (coexistence CAMs). 33
7.3.5 Geo-location database . 34
7.4 Mitigation methods to reduce interference to road tolling . 34
7.4.0 Overview . 34
7.4.1 Vacate/frequency non-use . 34
7.4.2 Transmit power control . 35
7.4.3 Duty cycle limitation . 35
7.4.4 Packet by packet interoperation . 35
7.5 Mitigation techniques to enable coexistence of RLAN and ITS . 35
7.5.0 Overview . 35
7.5.1 Energy detection . 35
7.5.2 Summary of Detect and Mitigate and Detect and Vacate Simulations . 36
7.5.3 Detect and vacate . 38
7.6 Summary . 38
7.7 Recommendations for future work . 38
7.7.1 Overview . 38
7.7.2 General . 38
7.7.3 Road tolling . 38
7.7.4 ITS . 39
Annex A: Duty cycle evaluations of road tolling interference . 41
A.1 Introduction to duty cycle evaluations . 41
A.2 Results from previous investigations. 42
A.3 Evaluated scenarios . 42
A.3.1 Typical parameters for different tollgate types . 42
A.3.2 Relevant RLAN parameters . 43
A.4 Duty cycle evaluations . 43
A.4.1 Evaluation method . 43
A.4.1.1 Interference probability as function of the duty cycle. 43
A.4.1.2 Influence of road traffic statistics . 45
A.4.2 Evaluation results . 45
A.4.2.1 MLFF tollgate . 45
A.4.2.2 Open lane tollgate . 46
A.4.2.3 Single lane tollgate with barrier . 47
Annex B: Evaluations of the proposed ITS protection mechanisms . 48
B.1 Introduction to ITS evaluations . 48
B.2 ITS/RLAN performance analysis for a single intersection with varying topologies/device
densities . 48
B.2.1 Introduction . 48
B.2.2 Simulation scenarios. 48
B.2.3 Physical layer abstractions . 50
B.2.4 Examples of transition period behaviour . 52
B.2.5 Summarized simulation results . 54
B.2.6 Fixed MCS for RLAN . 56
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5 ETSI TR 103 319 V1.1.1 (2017-08)
B.2.7 Additional scenarios . 57
B.3 Challenges in spectrum sharing between ITS-G5 and RLAN . 72
B.3.1 Introduction . 72
B.3.2 Detection of ITS transmissions . 72
B.3.3 RLAN interference on ITS transmissions after detection . 72
B.3.4 Evaluation of spectrum sharing algorithms in an indoor scenario . 75
B.4 Coexistence between ETSI ITS-G5 and Wi-Fi systems in outdoor and indoor scenarios . 80
B.4.1 Introduction . 80
B.4.2 Evaluation scenario & methodology . 80
B.4.3 Simulation results . 82
B.5 Summary of simulation parameters . 87
B.5.1 Simulation parameters . 87
Annex C: Summary of detect and mitigate parameters . 89
C.1 Detect and mitigate parameters . 89
Annex D: Summary of regulatory parameters for ITS coexistence techniques proposed in the
present document . 91
History . 94


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6 ETSI TR 103 319 V1.1.1 (2017-08)
Intellectual Property Rights
Essential patents
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 (https://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.
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Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Broadband Radio Access Networks
(BRAN).
Modal verbs terminology
In the present document "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be
interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Executive Summary
The present document contains mitigation technique studies related to RLANs in the 5 795 MHz to 5 815 MHz and
5 855 MHz to 5 925 MHz frequency ranges. These have been triggered by the EC Mandate on 5 GHz [i.1] and by the
activities on WRC-15 Agenda Item 1.1 [i.49] and subsequent work at CEPT. In particular CEPT have requested
clarification on what mitigation techniques RLAN systems intend to employ to protect other systems that presently
operate in the 5 725 MHz to 5 925 MHz band and in adjacent bands.
Some of the parameters within the present document are included in square brackets based upon proposals and
discussions within TC BRAN, these are intended as starting points upon which to continue future work and develop
technical requirements.
At the time of drafting the present document the status of the various sharing and compatibility studies related to Road
Tolling and ITS is as detailed in ECC Report 244 [i.15] and is summarized below:
Compatibility between RLAN and road tolling in the band 5 795 MHz to 5 815 MHz
MCL calculations for both directions of interference have been performed and showed the need for significant
separation distances if compatibility is dependent upon protection to an I/N level of -6 dB. No studies have been
conducted to analyse the actual effects of this I/N level being reached due to intermittent interference.
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7 ETSI TR 103 319 V1.1.1 (2017-08)
As a result, work on mitigation techniques was initiated at ETSI BRAN which focused on the following approaches,
previously suggested in ECC Report 244 [i.15], to enable the coexistence between RLAN and road-tolling:
• Implementation in RLAN of a detection mechanism to detect road tolling applications based on energy
detection. Under the assumptions considered preliminary analysis indicated that for an RLAN system
operating with 23 dBm/20 MHz a detection threshold of the order of -100 dBm/500 kHz and for a RLAN
system with 23 dBm/160 MHz a detection threshold of the order of -90 dBm/500 kHz would be required for a
reliable detection of road tolling. Further consideration is required, including on the feasibility of such a
detection threshold and its impact on the RLAN operation.
• Transmission from the road tolling applications of predefined signals (beacons) which indicate that the used
channels are busy, similar to one of the mitigation techniques used to facilitate ITS and Road Tolling adjacent
channel coexistence.
• Ensure coexistence with the road tolling systems through the detection of ITS. This is based on the assumption
that there will always be ITS systems in the close vicinity of road-tolling road-side units. Under this approach,
once ITS have been detected by RLAN under the conditions described in clause 2 of ECC Report 244 [i.15],
the road tolling frequency band 5 795 MHz to 5 815 MHz will also be considered as occupied and thus, not
available for RLAN use.
• Use of geo-location database approach. The geo-location database should hold actual information from static
and, due to construction sites, temporary tolling installations. The implementation of such a platform, its
access and its maintenance should be addressed. In addition, the role and responsibilities of the stakeholders
have to be clearly defined.
Compatibility between RLAN and ITS in the bands 5 855 MHz to 5 875 MHz (non-safety ITS), 5 875 MHz to
5 905 MHz (safety-related ITS) and 5 905 MHz to 5 925 MHz (ITS extension band)
Compatibility considered in the present document includes Wi-Fi and ITS technology as defined in ETSI
EN 302 663 [i.3]. LTE-V2X and LAA technologies as defined in ETSI TS 136 211 [i.10], ETSI TS 136 101 [i.11] and
ETSI TS 136 104 [i.12] are not part of the present document.
MCL calculations for both directions of interference have been performed and showed the need for significant
separation distances if compatibility is dependent upon protection to an I/N level of -6 dB. No studies have been
conducted to analyse the actual effects of this I/N level being reached due to intermittent interference.
As a result, work on mitigation techniques was initiated at ETSI BRAN to help improve the compatibility between
individual RLAN devices and ITS. These studies have focussed on "listen-before-talk" processes, where the potential
interferer tries to detect whether a channel is busy before transmitting a data packet.
Two possible approaches that have been suggested in ECC Report 244 [i.15] are:
• Generic Energy Detection without any consideration of the interferer and victim signal frames: Under the
assumptions considered, preliminary studies show that in the case of an energy detection threshold
of -90 dBm/10 MHz for an RLAN system operating with 23 dBm/20 MHz, an ITS device with
23 dBm/20 MHz is not reliably detected. Further consideration is required, including on the feasibility of such
a detection threshold and its impact on the RLAN operation.
• Combination of energy detection and carrier sensing, such as one of the Clear Channel Assessment (CCA)
modes defined in the IEEE Std. 802.11™-2016 [i.2]. Further study is required to assess the applicability to ITS
of the interference avoidance techniques currently employed in 5 GHz RLAN systems.
Introduction
The present document studies the feasibility and impact on RLAN operation with regards to proposed mitigation
techniques to enable sharing with Road Tolling and Transport equipment within the 5 795 MHz to 5 815 MHz and
5 855 MHz to 5 925 MHz frequency ranges. The report proposes and evaluates mitigation techniques based upon
simulation and analytical investigation. Some of the parameters within the present document are included in square
brackets based upon proposals and discussions within TC BRAN, these are intended as starting points upon which to
continue future work and develop technical requirements. Recommendations for future work are included in clause
...