ETSI TS 103 836-4-2 V2.1.1 (2025-04)

Intelligent Transport Systems (ITS); Vehicular Communications; GeoNetworking; Part 4: Geographical addressing and forwarding for point-to-point and point-to-multipoint communications; Sub-part 2: Media-dependent functionalities for ITS-G5; Release 2

DTS/ITS-0084

General Information

• Status: Not Published
• Technical Committee: ITS WG23 - Architecture & Cross Layers, Networking & Transport
• Current Stage: 12 - Completion
• Due Date: 25-Apr-2025
• Completion Date: 17-Apr-2025

Standards Content (Sample)

TECHNICAL SPECIFICATION
Intelligent Transport Systems (ITS);
Vehicular Communications;
GeoNetworking;
Part 4: Geographical addressing and forwarding for
point-to-point and point-to-multipoint communications;
Sub-part 2: Media-dependent functionalities for ITS-G5;
Release 2
2 ETSI TS 103 836-4-2 V2.1.1 (2025-04)

Reference
DTS/ITS-0084
Keywords
addressing, ITS, network, point-to-multipoint,
point-to-point, protocol
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ETSI
3 ETSI TS 103 836-4-2 V2.1.1 (2025-04)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
Executive summary . 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 . 7
4 Overview . 7
5 DCC functionality at networking & transport layer (DCC_NET) for ITS-G5 . 9
5.1 General . 9
5.2 Maintenance of DCC variables . 9
5.3 Calculation of the global channel busy ratio CBR_G . 10
5.4 DCC_NET . 11
6 Addressing, data structure extensions and field settings for ITS-G5 . 11
6.1 GeoNetworking address . 11
6.2 Location table extensions for ITS-G5 . 12
6.2.1 General . 12
6.2.2 Definition of additional data elements for the location table entry . 12
6.2.3 Maintenance of additional data elements for the location table entry . 12
6.3 Field settings in the GeoNetworking header . 13
6.3.1 General . 13
6.3.2 Field settings in the Common Header . 13
6.3.3 Field settings in the Extended Header of the SHB packet . 14
6.4 EtherType . 14
7 Extensions of packet handling algorithms for ITS-G5 . 15
7.1 General . 15
7.2 Extensions of SHB packet handling . 15
7.2.1 Extensions for source operations . 15
7.2.2 Extensions for receiver operations . 15
8 Mapping of traffic classes to transmission parameters for ITS-G5 . 15
Annex A (normative): GeoNetworking protocol constants for ITS-G5 . 17
Annex B (informative): Extensions of the GeoNetworking MIB . 18
Annex C (informative): Extensions of forwarding algorithms for ITS-G5 . 19
C.1 General . 19
C.2 Enhancements of non-area and area Contention-Based Forwarding (CBF) algorithms . 20
Annex D (informative): Bibliography . 21
Annex E (informative): Change history . 22
History . 23
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4 ETSI TS 103 836-4-2 V2.1.1 (2025-04)
Intellectual Property Rights
Essential patents
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pertaining to these essential IPRs, if any, are publicly available for ETSI members and non-members, and can be
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ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the
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Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Intelligent Transport Systems
(ITS).
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.
Executive summary
The present document specifies media-dependent functionalities for the GeoNetworking protocol when using the ITS
access technology ITS-G5. These functionalities represent ITS-G5 specific extensions of the GeoNetworking protocol.
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5 ETSI TS 103 836-4-2 V2.1.1 (2025-04)
Introduction
The GeoNetworking protocol is a network protocol that provides packet routing in an ad hoc network. It makes use of
geographical positions for packet transport. GeoNetworking supports the communication among individual ITS-Ss as
well as the distribution of packets in geographical areas.
GeoNetworking can be executed over different ITS access technologies for short-range wireless technologies, such as
ITS-G5. In order to reuse the GeoNetworking protocol specification for multiple ITS access technologies, the
specification is separated into media-independent and media-dependent functionalities. Media-independent
GeoNetworking functionalities are those which are common to all ITS access technologies for short-range wireless
communication and are specified in ETSI TS 103 836-4-1 [i.1]. The present document specifies media-dependent
functionalities for GeoNetworking when using the ITS access technology ITS-G5 (see ETSI EN 303 797 [i.2]). The
specification in the present document should be regarded as ITS-G5 specific extensions of the GeoNetworking protocol
specified in ETSI TS 103 836-4-1 [i.1] and does not represent a distinct protocol entity.

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6 ETSI TS 103 836-4-2 V2.1.1 (2025-04)
1 Scope
The present document specifies the media-dependent functionalities for GeoNetworking defined in ETSI
TS 103 836-4-1 [i.1] over ITS-G5 defined in ETSI EN 303 797 [i.2] as a network protocol for ad hoc routing in
vehicular environments.
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 in the
ETSI docbox.
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.
Not applicable.
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.
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 TS 103 836-4-1: "Intelligent Transport Systems (ITS); Vehicular Communications;
GeoNetworking; Part 4: Geographical addressing and forwarding for point-to-point and
point-to-multipoint communications; Sub-part 1: Media-Independent Functionality; Release 2".
[i.2] ETSI EN 303 797: "Intelligent Transport Systems (ITS); ITS-G5 Access layer in the 5 GHz
frequency band; Release 2".
[i.3] ETSI TS 103 898: "Intelligent Transport Systems (ITS); Communications Architecture;
Release 2".
[i.4] 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".
[i.5] IEEE™ Registration Authority.
[i.6] List of assigned EtherTypes at the IEEE™ Registration Authority.
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7 ETSI TS 103 836-4-2 V2.1.1 (2025-04)
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the terms given in ETSI TS 103 836-4-1 [i.1], ETSI EN 303 797 [i.2] and the
following apply:
1-hop channel busy ratio: highest local channel busy ratio that the ego ITS station has received from its 1-hop
neighbourhood over a certain time
2-hop channel busy ratio: highest 1-hop channel busy ratio that the ego ITS station has received from its 1-hop
neighbourhood over a certain time
channel busy ratio: time-dependent value between zero and one (both inclusive) representing the fraction of time that
the channel was busy
global channel busy ratio: maximum of the local channel busy ratio, the 1-hop channel busy ratio and the 2-hop
channel busy ratio
local channel busy ratio: time-dependent value between zero and one (both inclusive) representing the channel busy
ratio as perceived locally by a specific ITS station
3.2 Symbols
For the purposes of the present document, the symbols given in ETSI TS 103 836-4-1 [i.1], ETSI EN 303 797 [i.2] and
the following apply:
CBR_L_0_Hop Local channel busy ratio for a specific frequency channel for ego ITS station
CBR_L_1_Hop Highest received value of CBR_R_0_Hop
CBR_L_2_Hop Highest received value of CBR_R_1_Hop
CBR_R_0_Hop Local channel busy ratio CBR_L_0_Hop disseminated in single-hop broadcast packets
CBR_R_1_Hop Highest received CBR_L_1_Hop disseminated in single-hop broadcast packets
CBR_Target Intended global channel busy ratio
CBR_G Global channel busy ratio for a specific frequency channel
T_Cbr Lifetime of the channel busy ratio
T_Trig Trigger interval to update CBR_G
3.3 Abbreviations
For the purposes of the present document, the abbreviations given in ETSI TS 103 836-4-1 [i.1], ETSI EN 303 797 [i.2]
and the following apply:
LocTEX Location Table Entry eXtension
4 Overview
The present document specifies the media-dependent functionalities necessary to run the GeoNetworking protocol
defined in ETSI TS 103 836-4-1 [i.1] over the ITS-G5 access technology defined in ETSI EN 303 797 [i.2]. The
functionalities are:
• Decentralized Congestion Control (DCC) at the networking & transport layer for the ITS-G5 access
technology, specifically information sharing for DCC (DCC_NET) (clause 5).
• Addressing, data structure extensions and field settings in the GeoNetworking headers for ITS-G5 (clause 6).
• Extensions for packet handling of the GeoNetworking protocol for ITS-G5 (clause 7).
• Mapping of traffic classes to transmission parameters for ITS-G5 (clause 8).
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8 ETSI TS 103 836-4-2 V2.1.1 (2025-04)
The present document also proposes extensions for forwarding algorithms of the GeoNetworking protocol for ITS-G5
(annex C).
Figure 1 illustrates the ITS reference architecture as specified in ETSI TS 103 898 [i.3]. The present document specifies
ITS-G5 specific, media-dependent functionalities for the GeoNetworking protocol, which are found in the Networking
& Transport layer.
Applications
MA FA SA
Facilities
NF
Networking &
Transport
IN
Access
MS
Figure 1: ITS-S reference architecture as specified in ETSI TS 103 898 [i.3]
A GeoNetworking packet transmitted over the ITS-G5 access technology is part of the overall frame/packet structure
depicted in figure 2 (without security) and figure 3 (with security), respectively:
1) The MAC header is the header of the MAC protocol of the ITS-G5 access technology. The MAC protocol
adds an additional protocol element for the trailer for the MAC FCS as specified in ITS-G5 defined in ETSI
EN 303 797 [i.2].
NOTE 1: The MAC header is not specified by the present document. However, the GeoNetworking protocol sets
the MAC address, or more generally the link layer address, in order to define and identify the next hop of
a GeoNetworking packet.
2) The LLC header is the header of 802.2 LLC (see ETSI EN 303 797 [i.2]).
3) The GeoNetworking header is the header of the GeoNetworking packet as defined in ETSI
TS 103 836-4-1 [i.1] extended for media-dependent GeoNetworking functionality over ITS-G5 as specified in
the present document.
4) The optional payload represents the user data that are created by upper protocol entities, i.e. the T-SDU or
GN6-SDU. It is passed to the GeoNetworking protocol for transmission.
NOTE 2: The general packet structure is shown as seen by the MAC protocol of the ITS-G5 access technology.
NOTE 3: Some GeoNetworking packet types do not carry a payload, such as Beacon.
MAC GeoNetworking Payload
LLC Header
Header Header (optional)
Figure 2: GeoNetworking packet structure over ITS-G5 (without security)

GeoNetworking GeoNetworking Secured Packet
MAC
LLC Header Basic with Common Header, Optional Extended Header and
Header
Header Optional Payload
Figure 3: GeoNetworking packet structure over ITS-G5 (with security)
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9 ETSI TS 103 836-4-2 V2.1.1 (2025-04)
5 DCC functionality at networking & transport layer
(DCC_NET) for ITS-G5
5.1 General
An ITS-S operating the ITS-G5 access technology supports Decentralized Congestion Control (DCC) to ensure that the
radio channel is not congested by too many transmissions within a certain geographical range. The DCC functionality is
distributed among the entities DCC_FAC, DCC_NET, DCC_ACC and DCC_CROSS at the different layers and entities
of the ITS reference architecture (see figure 4).

Figure 4: DCC architecture
The GeoNetworking protocol over the ITS-G5 access technology provides the DCC functionality over ITS-G5 access
technology (DCC_NET). DCC_NET shall support the following functionality:
• maintain DCC state variables as specified in clause 5.2;
• periodically calculate the global Channel Busy Ratio CBR_G as specified in clause 5.3;
• process and provide DCC-related information to the DCC_CROSS entity as specified in clause 5.4;
• store and maintain DCC-related information using the Location Table Entry Extension for ITS-G5
(LocTEX-G5) as specified in clause 6.2;
• transmit and receive DCC-related information to other GeoNetworking routers using the extensions for
GeoNetworking packet handling as specified in clause 7.2.
In addition, DCC_NET may provide DCC-related information to the GN forwarding algorithm as specified in annex C.
5.2 Maintenance of DCC variables
If DCC_NET is present, it shall maintain the following DCC variables:
• CBR_L_0_Hop;
• CBR_L_1_Hop;
• CBR_L_2_Hop;
• CBR_R_0_Hop;
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10 ETSI TS 103 836-4-2 V2.1.1 (2025-04)
• CBR_R_1_Hop;
• CBR_G; and
• CBR_Target.
The CBR variables are described in detail in table 1.
Table 1: Description of DCC variables in DCC_NET
Parameter Description
Measured local channel busy ratio CBR, disseminated to neighbouring ITS-S as
CBR_L_0_Hop
CBR_R_0_Hop.The local CBR measurement is p
...