ETSI EN 303 797 V2.1.1 (2024-02)

EUROPEAN STANDARD
Intelligent Transport Systems (ITS);
ITS-G5 Access layer in the 5 GHz frequency band;
Release 2
2 ETSI EN 303 797 V2.1.1 (2024-02)

Reference
DEN/ITS-00445
Keywords
ITS, layer 1, layer 2, MAC, profile, radio
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: +33 4 92 94 42 00  Fax: +33 4 93 65 47 16

Siret N° 348 623 562 00017 - APE 7112B
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° w061004871

Important notice
The present document can be downloaded from:
https://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI
deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
If you find a security vulnerability in the present document, please report it through our
Coordinated Vulnerability Disclosure Program:
https://www.etsi.org/standards/coordinated-vulnerability-disclosure
Notice of disclaimer & limitation of liability
The information provided in the present deliverable is directed solely to professionals who have the appropriate degree of
experience to understand and interpret its content in accordance with generally accepted engineering or
other professional standard and applicable regulations.
No recommendation as to products and services or vendors is made or should be implied.
In no event shall ETSI be held liable for loss of profits or any other incidental or consequential damages.

Any software contained in this deliverable is provided "AS IS" with no warranties, express or implied, including but not
limited to, the warranties of merchantability, fitness for a particular purpose and non-infringement of intellectual property
rights and ETSI shall not be held liable in any event for any damages whatsoever (including, without limitation, damages
for loss of profits, business interruption, loss of information, or any other pecuniary loss) arising out of or related to the use
of or inability to use the software.
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© ETSI 2024.
All rights reserved.
ETSI
3 ETSI EN 303 797 V2.1.1 (2024-02)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definition of terms, symbols and abbreviations . 7
3.1 Terms . 7
3.2 Symbols . 7
3.3 Abbreviations . 8
4 Access layer requirements . 9
4.1 Introduction . 9
4.2 Access layer architecture . 10
4.3 Physical layer . 10
4.3.1 Introduction. 10
4.3.2 Mandatory MCSs . 10
4.3.3 Transmitter requirements . 10
4.3.4 Receiver requirements . 11
4.3.5 Physical Layer parameters . 12
4.4 MAC . 12
4.5 Logical link control . 13
4.6 Decentralized Congestion Control (DCC) . 13
4.6.1 Introduction. 13
4.6.2 Channel Busy Ratio . 13
4.7 CEN DSRC and HDR DSRC protection . 15
5 ITS-G5 radio tests . 15
5.1 Radio tests defined in ETSI EN 302 571 . 15
5.2 Additional radio tests. 16
5.2.1 Dynamic receiver sensitivity. 16
Annex A (normative): Channel models for testing dynamic sensitivity values. . 17
Annex B (informative): Data and management service . 19
B.1 Introduction . 19
B.2 Access layer data service . 19
B.3 Access layer management service . 20
Annex C (informative): Bibliography . 22
History . 23

ETSI
4 ETSI EN 303 797 V2.1.1 (2024-02)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations
pertaining to these essential IPRs, if any, are 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 Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,
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.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its

Members. 3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and of the 3GPP
Organizational Partners. oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and of the ®
oneM2M Partners. GSM and the GSM logo are trademarks registered and owned by the GSM Association.
Foreword
This European Standard (EN) has been produced by ETSI Technical Committee Intelligent Transport Systems (ITS).

National transposition dates
Date of adoption of this EN: 13 February 2024
Date of latest announcement of this EN (doa): 31 May 2024
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 30 November 2024
Date of withdrawal of any conflicting National Standard (dow): 30 November 2024

Modal verbs terminology
In the present document "shall", "shall not", "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.
ETSI
5 ETSI EN 303 797 V2.1.1 (2024-02)
Introduction
The present document outlines the two lowest OSI layers - physical layer and data link layer - for the Cooperative ITS
(C-ITS) direct ITS-S to ITS-S wireless AdHoc Networking communication protocol stack used in the 5,9 GHz
frequency band as allocated in Europe in compliance with Commission Decision 2008/671/EC [i.1],
ECC/DEC/(08)01 [i.2] and ECC/REC/(08)01 [i.3] and specified in the COMMISSION IMPLEMENTING DECISION
(EU) 2020/1426 of 7 October 2020 [i.1]. The two lowest layers together form the access layer. The technology specified
in the present document is part of the so called ITS-G5 stack.
In the ITS-G5 access layer, the data link layer is divided into two sublayers: Medium Access Control (MAC) and
Logical Link Control (LLC). The physical layer and the medium access control layer are specified in
TM TM
IEEE 802.11 -2020 [1] and corresponding extension IEEE 802.11bd -2022 [2]. The logical link control is based on
the IEEE/ISO/IEC 8802-2-1998 [3].
TM
ITS-G5 realizes AdHoc peer-to-peer mode communication functionality as defined in IEEE 802.11 -2020 [1] and
TM
corresponding extension IEEE 802.11bd -2022 [2]. Operating profiles requiring synchronization and authentication as
TM TM
specified in IEEE 802.11 -2020 [1] or any other version of 802.11 are not supported. To manage congestion,
ITS-G5 provides Decentralized Congestion Control (DCC) mechanisms as specified in clause 4.6. How to ensure
coexistence with other systems is handled in clause 4.7.

ETSI
6 ETSI EN 303 797 V2.1.1 (2024-02)
1 Scope
The present document defines the access layer for ITS-G5 consisting of the physical layer and the data link layer, as part
of the ITS station architecture.
2 References
2.1 Normative 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
https://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.
The following referenced documents are necessary for the application of the present document.
TM
[1] IEEE 802.11 -2020: "IEEE Standard for Information technology - Telecommunications and
information exchange between systems - Local and metropolitan area networks-Specific
requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications".
TM
[2] IEEE 802.11bd -2022: "IEEE Standard for Information technology- Tele- communications and
information exchange between systems Local and metropolitan area networks- Specific
requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications Amendment 5: Enhancements for Next Generation V2X". .
[3] IEEE/ISO/IEC 8802-2-1998: "Information technology -- Telecommunications and information
exchange between systems -- Local and metropolitan area networks -- Specific requirements --
Part 2: Logical Link Control".
TM
[4] IEEE 802 -2014: "IEEE Standard for Local and Metropolitan Area Networks: Overview and
Architecture".
[5] ETSI EN 302 571: "Intelligent Transport Systems (ITS); Radiocommunications equipment
operating in the 5 855 MHz to 5 925 MHz frequency band; Harmonised Standard covering the
essential requirements of article 3.2 of Directive 2014/53/EU".
[6] ETSI TS 102 792: "Intelligent Transport Systems (ITS); Mitigation techniques to avoid
interference between European CEN Dedicated Short Range Communication (CEN DSRC)
equipment and Intelligent Transport Systems (ITS) operating in the 5 GHz frequency range".
2.2 Informative 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.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long-term validity.
ETSI
7 ETSI EN 303 797 V2.1.1 (2024-02)
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] Commission Implementing Decision (EU) 2020/1426 of 7 October 2020 on the harmonised use of
radio spectrum in the 5 875-5 935 MHz frequency band for safety-related applications of
intelligent transport systems (ITS) and repealing Decision 2008/671/EC.
[i.2] ECC/DEC/(08)01: "ECC Decision (08)01 on the harmonised use of the band 5875-5925 MHz for
Intelligent Transport Systems (ITS)".
[i.3] ECC/REC/(08)01: "ECC Recommendation (08)01 on the use of the band 5855-5875 MHz for
Intelligent Transport Systems (ITS)".
[i.4] ETSI TS 103 695: "Intelligent Transport Systems (ITS); Access layer specification in the 5 GHz
frequency band; Multi-Channel Operation (MCO) for Cooperative ITS (C-ITS); Release 2".
[i.5] ETSI TS 102 687: "Intelligent Transport Systems (ITS); Decentralized Congestion Control
Mechanisms for Intelligent Transport Systems operating in the 5 GHz range; Access layer part".
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
TM
basic service set: smallest building block of an IEEE 802.11 network
channel: instance of a Wireless Medium (WM) use for the purpose of passing physical layer (PHY) Protocol Data
Units (PDUs) between two or more ITS-S's
NOTE: Unless otherwise stated the channel refers to a 10 MHz bandwidth.
Channel Busy Ratio (CBR): ratio between the time a receiver perceives a radio channel as busy and the total time,
expressed as a percentage
coexistence: situation in which one radio system operates in an environment where another radio system having
potentially different characteristics may be using the same or different channels, and radio systems are able to operate
with some tolerable impact to each other
data rate: number of user data bits which can be transmitted in a stream per unit of time (EG/Mbs)
duty cycle: ratio between the transmitter T time and the total time, expressed as a percentage
on
ethertype: identifier to the network protocol above the data link layer
ITS-G5 access layer: access layer technology to be used in frequency bands dedicated for European Intelligent
Transport Systems (ITS)
spectrum band: specific range of frequencies in the electromagnetic frequency spectrum assigned to specific
applications
3.2 Symbols
For the purposes of the present document, the following symbols apply:
aCWmax Maximum value of Contention Window
aCWmin Minimum value of Contention Window
AIFS Arbitration InterFrame Space
AIFSN Arbitration InterFrame Space Number
aSIFSTime Short InterFrame Space defined by the physical layer
aSlotTime A slot time defined by the physical layer
ETSI
8 ETSI EN 303 797 V2.1.1 (2024-02)
CW Contention Window
CW Maximum value of Contention Window
max
CW Minimum value of Contention Window
min
CBR Channel busy ratio for a specific channel used by the MAC
CH
Cth congestion threshold
�
� control parameter
���
�
� control parameter
���
GCBR Channel busy ratio provided by upper layers derived from all ITS-Ss active in the AdHoc network

GCBR Channel busy ratio for a specific channel provided by upper layers derived from all
CH
ITS-Ss active in the AdHoc network
LCBR Channel busy ratio measured by the ITS-S

LCBR Channel busy ratio for a specific channel measured by the ITS-S
CH
T period of time the channel is busy for a given ITS-S
Lbusy
T period of time for a given ITS-S
LCBR
T duration of a transmission
on
T duration of the previous transmission
on_pp
T minimum time between two transmissions
off
Nss Number of spatial streams
δ T /(T + T )
on on off
α control parameter α
β control parameterβ
δ maximum value of δ
max
δ minimum value of δ
min
δ offset value of δ
offset
t current system time
t time when gate keeper opens
go
t time when the gate keeper closes
pg
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
BPSK Binary Phase Shift Keying
BSS Basic Service Set
CAM Coopearative Awareness Message
CBR Channel Busy Ratio
CEN European Committee for Standardization
CH Channel
C-ITS Cooperative Intelligent Transport Systems
DC Duty Cycle
DCC Decentralized Congestion Control
DCM Dual Sub-Carier Modulation
DSRC Dedicated Short-Range Communication
DUT Device Under Test
ECC Electronic Communication Committee
EN European Norm
EPD EtherType Protocol Discrimination
FiFo First in First out
GCBR Global CBR
HalfBT Half Bathtub
HDR High Data Rate
ID IDentifier
IEEE Institute of Electrical and Electronics Engineers
ITS Intelligent Transport Systems
ITS-S Intelligent Transport Systems Station
LCBR Local CBR
LLC Logical Link Control
LOS Line-Of-Sight
LPD Low Probability of Detection
ETSI
9 ETSI EN 303 797 V2.1.1 (2024-02)
LTF Long Training Field
MAC Medium Access Control
MCO Multi Channel Operation
MCS Modulation and Coding Scheme
MIB Management Information Base
MIMO Multiple-Input and Multiple-Output
NGV Next Generation V2X
NLOS Non Line-Of-Sight
NUM_SS Number of Spetial Streams
N&T Networking & Transport
OFDM Orthogonal Frequency Division Multiplexing
OSI Open Systems Interconnection
PDU Protocol Data Unit
PER Packet Error Rate
PHY Physical layer
PSDU PLCP Service Data Unit
QAM Quadrature Amplitude Modulation
QPSK Quadrature Phase Shift Keying
RF Radio Frequency
RLAN Radio Local Area Network
RSSI Received Signal Strength Indicator
SNAP SubNetwork Access Protocol
SPATEM Signal Phase And Timing Extended Message
TDL Tapped Delay Line
TH Thress Hold
TS Technical Specification
TX Transmitter
VNC Vehicular Networking Conference
4 Access layer requirements
4.1 Introduction
The access layer bundles the data link layer and the physical layer and is situated at the bottom of the protocol stack,
(see Figure 1) for the ITS protocol stack is part of the ITS-S reference architecture. The data link layer includes the
Logical Link Control (LLC) entity and the Medium Access Control (MAC) entity.
Applications
ITS applications
Facilities
Logical Link Control (LLC)
Medium Access Control
Protocols
Networking & Transport
Data link
Physical
Access
Figure 1: Access layer in the ITS-S reference architecture
TM TM
-2020 [1], IEEE802.11bd -2022 [2],
For ITS-G5, the access layer is based on IEEE 802.11
TM
IEEE/ISO/IEC 8802-2-1998 [3] and IEEE 802 -2014 [4] specifications.
ETSI
10 ETSI EN 303 797 V2.1.1 (2024-02)
TM
The Management Information Base (MIB) parameter dot11OCBActivated as specified in IEEE 802.11 -2020 [1]
shall be set to true, with the result that the system communicates outside the context of a Basic Service Set (BSS), by
which neither authentication/association specified procedures nor security specified mechanisms are used. Further, no
access point functionality is present. It also disables the requirement that ITS-Ss should share a common clock and
scanning of available frequency channels for joining a BSS. The effect of operating outside the context of the BSS,
implies that additional functionality is required to manage the congestion in a channel (see clause 4.6).
As the C-ITS operates in a spectrum band where also other systems may be active possible mitigation measures are
identified in clause 4.7.
An ITS-S may support C-ITS data dissemination via multiple radio channels operating in different spectrum bands.
4.2 Access layer architecture
An overview of the functionalities is depicted in Figure 1.
TM
An ITS-G5 Access layer shall be based on the IEEE 802.11 -2020 [1] with the band-specific operating requirements
TM
in Annex E.2.4 [1], and optionally includes NGV operations as specified in the amendment IEEE 802.11bd -2022 [2].
An Access layer shall be implemented according at least one of the profiles as defined in Table 1.
Table 1: Access layer profiles
Profile number MAC-PHY specification Comment
TM
Profile 1 IEEE 802.11 -2020 [1] Profile for ITS low-data rate type of messages.
TM
Profile 2 IEEE 802.11 -2020 [1] amended Profile for ITS lo
...

SLOVENSKI STANDARD
01-april-2024
Inteligentni transportni sistemi (ITS) - Dostopovna plast ITS-G5 v frekvenčnem
pasu 5 GHz, izdaja 2
Intelligent Transport Systems (ITS) - ITS-G5 Access layer in the 5 GHz frequency band,
Release 2
Ta slovenski standard je istoveten z: ETSI EN 303 797 V2.1.1 (2024-02)
ICS:
35.240.60 Uporabniške rešitve IT v IT applications in transport
prometu
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
Intelligent Transport Systems (ITS);
ITS-G5 Access layer in the 5 GHz frequency band;
Release 2
2 ETSI EN 303 797 V2.1.1 (2024-02)

Reference
DEN/ITS-00445
Keywords
ITS, layer 1, layer 2, MAC, profile, radio
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: +33 4 92 94 42 00  Fax: +33 4 93 65 47 16

Siret N° 348 623 562 00017 - APE 7112B
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° w061004871

Important notice
The present document can be downloaded from:
https://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI
deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
If you find a security vulnerability in the present document, please report it through our
Coordinated Vulnerability Disclosure Program:
https://www.etsi.org/standards/coordinated-vulnerability-disclosure
Notice of disclaimer & limitation of liability
The information provided in the present deliverable is directed solely to professionals who have the appropriate degree of
experience to understand and interpret its content in accordance with generally accepted engineering or
other professional standard and applicable regulations.
No recommendation as to products and services or vendors is made or should be implied.
In no event shall ETSI be held liable for loss of profits or any other incidental or consequential damages.

Any software contained in this deliverable is provided "AS IS" with no warranties, express or implied, including but not
limited to, the warranties of merchantability, fitness for a particular purpose and non-infringement of intellectual property
rights and ETSI shall not be held liable in any event for any damages whatsoever (including, without limitation, damages
for loss of profits, business interruption, loss of information, or any other pecuniary loss) arising out of or related to the use
of or inability to use the software.
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© ETSI 2024.
All rights reserved.
ETSI
3 ETSI EN 303 797 V2.1.1 (2024-02)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definition of terms, symbols and abbreviations . 7
3.1 Terms . 7
3.2 Symbols . 7
3.3 Abbreviations . 8
4 Access layer requirements . 9
4.1 Introduction . 9
4.2 Access layer architecture . 10
4.3 Physical layer . 10
4.3.1 Introduction. 10
4.3.2 Mandatory MCSs . 10
4.3.3 Transmitter requirements . 10
4.3.4 Receiver requirements . 11
4.3.5 Physical Layer parameters . 12
4.4 MAC . 12
4.5 Logical link control . 13
4.6 Decentralized Congestion Control (DCC) . 13
4.6.1 Introduction. 13
4.6.2 Channel Busy Ratio . 13
4.7 CEN DSRC and HDR DSRC protection . 15
5 ITS-G5 radio tests . 15
5.1 Radio tests defined in ETSI EN 302 571 . 15
5.2 Additional radio tests. 16
5.2.1 Dynamic receiver sensitivity. 16
Annex A (normative): Channel models for testing dynamic sensitivity values. . 17
Annex B (informative): Data and management service . 19
B.1 Introduction . 19
B.2 Access layer data service . 19
B.3 Access layer management service . 20
Annex C (informative): Bibliography . 22
History . 23

ETSI
4 ETSI EN 303 797 V2.1.1 (2024-02)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations
pertaining to these essential IPRs, if any, are 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 Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,
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.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its

Members. 3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and of the 3GPP
Organizational Partners. oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and of the ®
oneM2M Partners. GSM and the GSM logo are trademarks registered and owned by the GSM Association.
Foreword
This European Standard (EN) has been produced by ETSI Technical Committee Intelligent Transport Systems (ITS).

National transposition dates
Date of adoption of this EN: 13 February 2024
Date of latest announcement of this EN (doa): 31 May 2024
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 30 November 2024
Date of withdrawal of any conflicting National Standard (dow): 30 November 2024

Modal verbs terminology
In the present document "shall", "shall not", "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.
ETSI
5 ETSI EN 303 797 V2.1.1 (2024-02)
Introduction
The present document outlines the two lowest OSI layers - physical layer and data link layer - for the Cooperative ITS
(C-ITS) direct ITS-S to ITS-S wireless AdHoc Networking communication protocol stack used in the 5,9 GHz
frequency band as allocated in Europe in compliance with Commission Decision 2008/671/EC [i.1],
ECC/DEC/(08)01 [i.2] and ECC/REC/(08)01 [i.3] and specified in the COMMISSION IMPLEMENTING DECISION
(EU) 2020/1426 of 7 October 2020 [i.1]. The two lowest layers together form the access layer. The technology specified
in the present document is part of the so called ITS-G5 stack.
In the ITS-G5 access layer, the data link layer is divided into two sublayers: Medium Access Control (MAC) and
Logical Link Control (LLC). The physical layer and the medium access control layer are specified in
TM TM
IEEE 802.11 -2020 [1] and corresponding extension IEEE 802.11bd -2022 [2]. The logical link control is based on
the IEEE/ISO/IEC 8802-2-1998 [3].
TM
ITS-G5 realizes AdHoc peer-to-peer mode communication functionality as defined in IEEE 802.11 -2020 [1] and
TM
corresponding extension IEEE 802.11bd -2022 [2]. Operating profiles requiring synchronization and authentication as
TM TM
specified in IEEE 802.11 -2020 [1] or any other version of 802.11 are not supported. To manage congestion,
ITS-G5 provides Decentralized Congestion Control (DCC) mechanisms as specified in clause 4.6. How to ensure
coexistence with other systems is handled in clause 4.7.

ETSI
6 ETSI EN 303 797 V2.1.1 (2024-02)
1 Scope
The present document defines the access layer for ITS-G5 consisting of the physical layer and the data link layer, as part
of the ITS station architecture.
2 References
2.1 Normative 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
https://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.
The following referenced documents are necessary for the application of the present document.
TM
[1] IEEE 802.11 -2020: "IEEE Standard for Information technology - Telecommunications and
information exchange between systems - Local and metropolitan area networks-Specific
requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications".
TM
[2] IEEE 802.11bd -2022: "IEEE Standard for Information technology- Tele- communications and
information exchange between systems Local and metropolitan area networks- Specific
requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications Amendment 5: Enhancements for Next Generation V2X". .
[3] IEEE/ISO/IEC 8802-2-1998: "Information technology -- Telecommunications and information
exchange between systems -- Local and metropolitan area networks -- Specific requirements --
Part 2: Logical Link Control".
TM
[4] IEEE 802 -2014: "IEEE Standard for Local and Metropolitan Area Networks: Overview and
Architecture".
[5] ETSI EN 302 571: "Intelligent Transport Systems (ITS); Radiocommunications equipment
operating in the 5 855 MHz to 5 925 MHz frequency band; Harmonised Standard covering the
essential requirements of article 3.2 of Directive 2014/53/EU".
[6] ETSI TS 102 792: "Intelligent Transport Systems (ITS); Mitigation techniques to avoid
interference between European CEN Dedicated Short Range Communication (CEN DSRC)
equipment and Intelligent Transport Systems (ITS) operating in the 5 GHz frequency range".
2.2 Informative 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.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long-term validity.
ETSI
7 ETSI EN 303 797 V2.1.1 (2024-02)
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] Commission Implementing Decision (EU) 2020/1426 of 7 October 2020 on the harmonised use of
radio spectrum in the 5 875-5 935 MHz frequency band for safety-related applications of
intelligent transport systems (ITS) and repealing Decision 2008/671/EC.
[i.2] ECC/DEC/(08)01: "ECC Decision (08)01 on the harmonised use of the band 5875-5925 MHz for
Intelligent Transport Systems (ITS)".
[i.3] ECC/REC/(08)01: "ECC Recommendation (08)01 on the use of the band 5855-5875 MHz for
Intelligent Transport Systems (ITS)".
[i.4] ETSI TS 103 695: "Intelligent Transport Systems (ITS); Access layer specification in the 5 GHz
frequency band; Multi-Channel Operation (MCO) for Cooperative ITS (C-ITS); Release 2".
[i.5] ETSI TS 102 687: "Intelligent Transport Systems (ITS); Decentralized Congestion Control
Mechanisms for Intelligent Transport Systems operating in the 5 GHz range; Access layer part".
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
TM
basic service set: smallest building block of an IEEE 802.11 network
channel: instance of a Wireless Medium (WM) use for the purpose of passing physical layer (PHY) Protocol Data
Units (PDUs) between two or more ITS-S's
NOTE: Unless otherwise stated the channel refers to a 10 MHz bandwidth.
Channel Busy Ratio (CBR): ratio between the time a receiver perceives a radio channel as busy and the total time,
expressed as a percentage
coexistence: situation in which one radio system operates in an environment where another radio system having
potentially different characteristics may be using the same or different channels, and radio systems are able to operate
with some tolerable impact to each other
data rate: number of user data bits which can be transmitted in a stream per unit of time (EG/Mbs)
duty cycle: ratio between the transmitter T time and the total time, expressed as a percentage
on
ethertype: identifier to the network protocol above the data link layer
ITS-G5 access layer: access layer technology to be used in frequency bands dedicated for European Intelligent
Transport Systems (ITS)
spectrum band: specific range of frequencies in the electromagnetic frequency spectrum assigned to specific
applications
3.2 Symbols
For the purposes of the present document, the following symbols apply:
aCWmax Maximum value of Contention Window
aCWmin Minimum value of Contention Window
AIFS Arbitration InterFrame Space
AIFSN Arbitration InterFrame Space Number
aSIFSTime Short InterFrame Space defined by the physical layer
aSlotTime A slot time defined by the physical layer
ETSI
8 ETSI EN 303 797 V2.1.1 (2024-02)
CW Contention Window
CW Maximum value of Contention Window
max
CW Minimum value of Contention Window
min
CBR Channel busy ratio for a specific channel used by the MAC
CH
Cth congestion threshold
�
� control parameter
���
�
� control parameter
���
GCBR Channel busy ratio provided by upper layers derived from all ITS-Ss active in the AdHoc network

GCBR Channel busy ratio for a specific channel provided by upper layers derived from all
CH
ITS-Ss active in the AdHoc network
LCBR Channel busy ratio measured by the ITS-S

LCBR Channel busy ratio for a specific channel measured by the ITS-S
CH
T period of time the channel is busy for a given ITS-S
Lbusy
T period of time for a given ITS-S
LCBR
T duration of a transmission
on
T duration of the previous transmission
on_pp
T minimum time between two transmissions
off
Nss Number of spatial streams
δ T /(T + T )
on on off
α control parameter α
β control parameterβ
δ maximum value of δ
max
δ minimum value of δ
min
δ offset value of δ
offset
t current system time
t time when gate keeper opens
go
t time when the gate keeper closes
pg
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
BPSK Binary Phase Shift Keying
BSS Basic Service Set
CAM Coopearative Awareness Message
CBR Channel Busy Ratio
CEN European Committee for Standardization
CH Channel
C-ITS Cooperative Intelligent Transport Systems
DC Duty Cycle
DCC Decentralized Congestion Control
DCM Dual Sub-Carier Modulation
DSRC Dedicated Short-Range Communication
DUT Device Under Test
ECC Electronic Communication Committee
EN European Norm
EPD EtherType Protocol Discrimination
FiFo First in First out
GCBR Global CBR
HalfBT Half Bathtub
HDR High Data Rate
ID IDentifier
IEEE Institute of Electrical and Electronics Engineers
ITS Intelligent Transport Systems
ITS-S Intelligent Transport Systems Station
LCBR Local CBR
LLC Logical Link Control
LOS Line-Of-Sight
LPD Low Probability of Detection
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9 ETSI EN 303 797 V2.1.1 (2024-02)
LTF Long Training Field
MAC Medium Access Control
MCO Multi Channel Operation
MCS Modulation and Coding Scheme
MIB Management Information Base
MIMO Multiple-Input and Multiple-Output
NGV Next Generation V2X
NLOS Non Line-Of-Sight
NUM_SS Number of Spetial Streams
N&T Networking & Transport
OFDM Orthogonal Frequency Division Multiplexing
OSI Open Systems Interconnection
PDU Protocol Data Unit
PER Packet Error Rate
PHY Physical layer
PSDU PLCP Service Data Unit
QAM Quadrature Amplitude Modulation
QPSK Quadrature Phase Shift Keying
RF Radio Frequency
RLAN Radio Local Area Network
RSSI Received Signal Strength Indicator
SNAP SubNetwork Access Protocol
SPATEM Signal Phase And Timing Extended Message
TDL Tapped Delay Line
TH Thress Hold
TS Technical Specification
TX Transmitter
VNC Vehicular Networking Conference
4 Access layer requirements
4.1 Introduction
The access layer bundles the data link layer and the physical layer and is situated at the bottom of the protocol stack,
(see Figure 1) for the ITS protocol stack is part of the ITS-S reference architecture. The data link layer includes the
Logical Link Control (LLC) entity and the Medium Access Control (MAC) entity.
Applications
ITS applications
Facilities
Logical Link Control (LLC)
Medium Access Control
Protocols
Networking & Transport
Data link
Physical
Access
Figure 1: Access layer in the ITS-S reference architecture
TM TM
-2020 [1], IEEE802.11bd -2022 [2],
For ITS-G5, the access layer is based on IEEE 802.11
TM
IEEE/ISO/IEC 8802-2-1998 [3] and IEEE 802 -2014 [4] specifications.
ETSI
10 ETSI EN 303 797 V2.1.1 (2024-02)
TM
The Management Information Base (MIB) parameter dot11OCBActivated as specified in IEEE 802.11 -2020 [1]
shall be set to true, with the result that the system communicates outside the context of a Basic Service Set (BSS), by
which neither authentication/association specified procedures nor security specified mechanisms are used. Further, no
access point functionality is present. It also disables the requirement that ITS-Ss should share a common clock and
scanning of available frequency channels for joining a BSS. The effect of operating outside the context of the BSS,
implies that additional functionality is required to manage the congestion in a channel (see clause 4.6).
As the C-ITS operates in a spectrum band where also other systems may be active possible mitigation measures are
identified in clause 4.7.
An ITS-S may support C-ITS data dissemination via multiple radio channels operating in different spectrum bands.
4.2 Access layer architecture
An overview of the functionalities is depicted in Figure 1.
TM
An ITS-G5 Access layer shall be based on the IEEE 802.11 -2020 [1] with the band-specific operating requirements
TM
in Annex E.2.4 [1], and optionally includes NGV operations as specified in the amendment IEEE 802.11bd -2022 [2].
An Access layer shall
...