ETSI TS 102 724 V1.1.1 (2012-10)

Technical Specification
Intelligent Transport Systems (ITS);
Harmonized Channel Specifications for
Intelligent Transport Systems
operating in the 5 GHz frequency band

2 ETSI TS 102 724 V1.1.1 (2012-10)

Reference
DTS/ITS-0040016
Keywords
ITS, radio
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ETSI
3 ETSI TS 102 724 V1.1.1 (2012-10)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 7
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 7
4 General Overview. 8
5 Channel Operation . 9
5.1 General Considerations . 9
5.2 Access layer Channel monitoring . 9
5.3 Void . 9
5.4 ITS G5A . 9
5.4.1 Channel allocation . 9
5.4.2 Channel Usage CCH / SCH1 / SCH2 . 9
5.4.3 Channel Access Requirements / Operations . 10
5.4.3.1 Introduction . 10
5.4.3.2 Access layer requirements based on DCC Profiles . 10
5.5 ITS G5B . 13
5.5.1 Channel allocation . 13
5.5.2 Channel Usage and Operations SCH3 / SCH4 . 13
5.5.3 Channel Access Requirements . 14
5.6 Multi-hop Channel Operations . 16
5.6.1 ITS G5A . 16
5.6.2 ITS G5B . 16
Annex A (informative): Adjacent Channel Interference . 17
A.1 Introduction . 17
A.2 Mitigation Strategies . 17
Annex B (normative): Cross-layer DCC operation . 19
B.1 Channel Configuration Entity processing of messages . 19
B.2 Access layer DCC entity control . 19
Annex C (informative): Deployment examples . 20
C.1 Introduction . 20
C.2 CAM . 20
C.2.1 Scenario . 20
C.2.2 Access layer operation . 20
C.2.3 Conclusion . 21
C.4 SPAT . 22
C.4.1 Scenario . 22
C.4.2 Access layer operation . 22
C.5 MAP . 24
C.5.1 Scenario . 24
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4 ETSI TS 102 724 V1.1.1 (2012-10)
C.5.2 Access layer operation . 24
C.6 Coexistence to CEN DSRC . 26
C.6.1 Example of duty cycle restriction . 26
Annex D (informative): Functional transceiver configuration . 27
D.1 Introduction . 27
D.2 ITS G5 transceiver channel configuration . 27
D.3 ITS station channel configuration . 28
D.3.1 Introduction . 28
D.3.2 Single transceiver ITS station . 28
D.3.2.1 ITS station for safety related ITS services . 28
D.3.2.2 ITS station for non-safety related services . 28
D.3.3 Multiple transceiver ITS station . 28
D.3.3.1 ITS station for safety related services . 28
Annex E (normative): Access Layer Requirements summary . 29
Annex F (informative): Bibliography . 30
History . 31

ETSI
5 ETSI TS 102 724 V1.1.1 (2012-10)
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 Intelligent Transport System (ITS).
Introduction
The present document describes the access layer configuration and derives requirements of the higher-layer use of the
ITS-G5 channels allocated for road safety and efficiency in Europe. The specification is the bases for the detailed
definition of the cross layer Decentralized Congestion Control (DCC).
The present document is centred on the notion of routing different communication traffic streams to different channels,
depending on the current congestion state of the respective channels, and assigning channel-access priorities.
Furthermore, it introduces rate control in order to keep traffic offered on the channels below reasonable bounds. The
configuration settings of channel routing and rate control are under full control of the Management Layer.
ETSI
6 ETSI TS 102 724 V1.1.1 (2012-10)
1 Scope
The present document specifies details of the channel usage in the ITS G5A and ITS G5B bands including multi-
channel operation support which includes
• Control and service channels operation for ITS G5;
• Usage of ITS G5 channels for road safety and traffic efficiency ITS applications;
• ITS G5 transmit and receive policies, channel selection and configuration;
• Per-traffic-stream and per-channel rate control;
• Reference usage scenarios and parameters;
• ITS G5 adjacent channel interference considerations.
The specified parameters and procedures will be used in the definition of the cross layer DCC algorithms and
management entities.
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 302 665: "Intelligent Transport Systems (ITS); Communications Architecture".
[2] ISO/IEC 7498-1: "Information technology - Open Systems Interconnection - Basic Reference
Model: The Basic Model".
[3] ETSI ES 202 663: "Intelligent Transport Systems (ITS); European profile standard for the physical
and medium access control layer of Intelligent Transport Systems operating in the 5 GHz
frequency band".
[4] 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".
[5] IEEE Std. 802: "IEEE Standard for Local and Metropolitan Area Networks: Overview and
Architecture".
[6] ETSI EN 302 571 (V1.1.1): "Intelligent Transport Systems (ITS); Radiocommunications
equipment operating in the 5 855 MHz to 5 925 MHz frequency band; Harmonized EN covering
the essential requirements of article 3.2 of the R&TTE Directive".
[7] Commission Decision 2008/671/EC of 5 August 2008 on the harmonised use of radio spectrum in
the 5 875-5 905 MHz frequency band for safety-related applications of Intelligent Transport
Systems (ITS).
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7 ETSI TS 102 724 V1.1.1 (2012-10)
[8] 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
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 102 636-4-1: "Intelligent Transport System (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".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in [1] to [5] and the following apply:
channel configuration: act of assigning traffic offered to the Access Layer to one of a discrete, fixed set of available
channels
DCC profile: set of transmission parameters for the identification and control of a traffic stream (like CAM, DENM,
SPAT, etc.) and the basis for traffic discrimination in the Access and Network and Transport Layers
NOTE: The DCC profiles are managed in the DCC management entity.
rate control: act of controlling the rate of traffic offered to the Access Layer by delaying the transmission of frames or
dropping them
safety related applications and services: applications and services whose aim is to reduce the number of traffic
fatalities or accidents using vehicle-to-vehicle or roadside-to-vehicle communications
safety critical context: context in which a vehicle is operating safety related services and the vehicle is detecting a
potentially dangerous situation
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in [1] to [5] and the following apply:
CAM Cooperative Awareness Message
CCH Control Channel
CP Communication Profile
DCC Decentralized Congestion Control
DENM Decentralized Environmental Notification Message
DP-ID DCC Profile Identifier
DSRC Dedicated Short-Range Communications
ITS Intelligent Transportation System
P Maximum allowed TX power on the CCH channel in DCC state Relaxed
CCH_rel
P Maximum allowed TX power on the CCH channel in DCC state Active
CCH_act
P Maximum allowed TX power on the CCH channel in DCC state Restricted
CCH_res
P Maximum allowed TX power on the SCH# (# = 1 …4) channel in DCC state Relaxed
SCH#_rel
P Maximum allowed TX power on the SCH# (# = 1 …4) channel in DCC state Relaxed
SCH#_act
P Maximum allowed TX power on the SCH# (# = 1 …4) channel in DCC state Relaxed
SCH#_res
SAP Service Access Point
SCH Service Channel
SPAT Signal Phase And Time
ETSI
8 ETSI TS 102 724 V1.1.1 (2012-10)
TC Technical Committee
4 General Overview
In addition to the functional entities already included in the ETSI profile standard [3] covering the Access Layer of the
ITS G5A and ITS G5B systems the present document will define the channel mapping under the control of the
decentralized congestion control (DCC) algorithm. The needed functional blocks and the requirements will be specified.
The overall architecture of an ITS G5 station is depicted in Figure 1 including the distributed DCC functional blocks in
the different layers.
Applications
MA FA
SA
Facilities
F F
S
M
DCC Facilities
t
NF
n
e
y
t
m i
r
e
Networking & Transport
u
g
N
N c
a S
M
e
n
DCC NET S
a
C
M
C
C D
IN
C
D
Access
I
I
S
M
DCC Access
MS
Figure 1: The ITS Communication Architecture including DCC functionality
In the present document, the Channel Configuration entity distributes traffic offered to the Access Layer via the
IN-SAP over a fixed set of channels available, according to certain requirements under control of the Management
Layer and the corresponding DCC Management entity. The Channel-Configuration is part the Access Layer of the ETSI
TC ITS Protocol Stack, which is shown in Figure 1, adapted from [1].
The Channel-Configuration entity manages the transmission to and reception from multiple channels. For the
three-channel ITS-G5A and the two-channel ITS-G5B, this is shown schematically Figure 2. In Figure 2, we have
omitted some of the internal interfaces for readability. Also, except for the IN-SAP and the interfaces to the IT G5
channels, the internal structure shown may not be adhered to in actual implementation. It is chosen in order to explain
the overall over all functionality of the Access Layer. The Decentralized Congestion Control functionality is an inherent
part of the overall Access Layer operation. The Access Layer DCC is not a separate entity but a distributed functionality
provided by the Access layer.
Figure 2: Functional Structure of the Access Layer
ETSI
Management
Security
9 ETSI TS 102 724 V1.1.1 (2012-10)
The ETSI TC ITS Access Layer is responsible for the Physical and Data Link Layers of the ISO/OSI RM [2] of each
physical interface, through a single, unified SAP, viz., the IN-SAP. The Channel Configuration Entity represents a new
sub-layer in the Access Layer. Its purpose it to distribute traffic offered through the Access Layer IN-SAP interface
over multiple bands and within each band, across multiple channels. More details are given in the informative Annex E.
5 Channel Operation
5.1 General Considerations
ITS stations equipped with ITS G5A and G5B transceiver shall adopt channel access requirements for all transmitted
messages based on cross layer DCC as defined in the following clauses.
5.2 Access layer Channel monitoring
The Access Layer shall monitor the following status indicators of the ITS G5A and G5B channels as defined in
clauses A.1 and A.2 in [3]:
• Channel Busy Ratio: Relative time in % the channel is busy based on the Channel Busy time definition in the
relevant specification [3], where the NDL_defDCCSensitivity is assumed as default for the CCA Threshold.
• Receiver Signal Strength Indicator statistics (RSSI statistic).
• Frames transmission indication (if a message has been successfully transmitted or dropped).
In addition the access layer shall:
• Notification of Tx power reduction on a per message base in case the message could not be transmitted using
the asked TX power level.
The Access Layer shall provide this information to the DCC_Management Entity via the MI-SAP.
5.3 Void
5.4 ITS G5A
5.4.1 Channel allocation
The ITS G5A band (5,875 GHz to 5,905 GHz) contains the channels CCH, SCH1 and SCH2 [6]. They are dedicated to
road safety related service [7].
5.4.2 Channel Usage CCH / SCH1 / SCH2
The usage of the CCH, SCH1 and SCH2 channels shall be under control of the decentralized congestion control (DCC).
CCH:
The Control Channel (CCH) is basically dedicated to cooperative road safety. It is the default channel for the
transmission of DP1 and DP2 messages. The transmissions of messages using different DCC profiles (DP3 to DP8) on
the CCH are allowed in the DCC state "RELAXED". In this DCC state the channel is not crowded and therefore no
restrictions occur.
SCH1:
The Service Channel 1 (SCH1) is the default channel for announcing and offering ITS services for safety & road
efficiency under the DCC state ACTIVE and RESTRITIVE of the CCH. The transmissions of other message-types on
the SCH1 are allowed if channel conditions according to the restrictions in the present document permit.
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10 ETSI TS 102 724 V1.1.1 (2012-10)
SCH2:
The Service Channel 2 (SCH2) is the second service channel on ITS G5A and is used as an alternate channel for traffic
safety-related services. Due to its frequency band allocation between the CCH and the SCH1 and the resulting potential
adjacent channel interference issues, the flexibility of the deployment of the SCH2 is limited. The limitations are taken
into account in the requirement descriptions for the SCH2.
5.4.3 Channel Access Requirements / Operations
5.4.3.1 Introduction
The present document relies on the DCC definition as described in the DCC document [4]. Additionally, extended
specifications for access restrictions are considered based on the DCC states (RELAXED, ACTIVE, RESTRICTIVE)
for each channel. The basic interactions between the layers are given in annex B.
5.4.3.2 Access layer requirements based on DCC Profiles
In the following tables the access layer requirements for the different DCC profiles (DP0 to DP32) are given for each
channel (CCH, SCH1, SCH2, …). An ITS station operating on an ITS G5A channel shall comply with the parameters
given for the different channels and DCC states in Table 1 to Table 3. For a single transceiver ITS station only one of
the following tables is relevant at a given time. For a multichannel operation with a multi transceiver stations a set of
tables covering the active channels shall to be taken into account for the multichannel DCC operation.
For DCC profiles related to more than a single channel the following usage order shall be deployed by the ITS station:
1) Control Channel, CCH
2) Service Channel 1, SCH1
3) Service Channel 2, SCH2
The message received by the access layer will be transmitted using the first possible channel in the usage order
depending on the congestion status and the DCC profile of the message. Examples for the usage are given in the
informative annex C.
In Table 1 to Table 5 the following definitions are used:
• DP-ID: DCC profile identifier of a message (DP0 to DP32)
• Q#: Physical Queue of the ITS G5 transmitter
• T : Time between two messages (packet interval) sent on the same physical ITS-G5 channel for a DCC
off
profile per ITS station
• T : Absolute minimum time between two messages sent on all physical ITS-G5 channels across all active
off_min
transmitter queues and DCC profiles except the messages with DP0. This parameter can be raised by the
Coexistence Management entity
• P : TX power recommended for a messages and passed as part of the message via the IN-SAP
TX
• P : Maximum TX power set by the DCC Management entity including the coexistence management. The
#
actual TX power used shall be equal or smaller than P
#
ETSI
11 ETSI TS 102 724 V1.1.1 (2012-10)
Table 1: CCH: Access layer requirement table based on DCC profiles and congestion state
DCC_Profile CCH Relaxed CCH Active CCH Restrictive Note
DP P < P P < P P < P Additional parameter to be
TX CCH_rel TX CCH_act TX CCH_res
controlled in future releases:
T = T T = T T =T
off_min CHH_min off_min CHH_min off_min CHH_min
D : Data rate (fixed in CCH)
TX
R : Variable CCA threshold
CCA
DP0 Q1 Q1 Q1 For emergency messages only,
T ≥ 50 ms T ≥ 50 ms T ≥ 50 ms
values overwrite the general
off off off
default values given in the
P < P P < P P < P
TX CCH_rel TX CCH_rel TX CCH_rel
heading, this DP is only for
restricted use in emergency
cases.
DP1
Q1 Q1 Q1
T ≥ 95 ms T ≥ 190 ms T ≥ 250 ms
off off off
DP2
Q2 Q2 Q2
T ≥ 95 ms T ≥ 190 ms T ≥ 250 ms
off off off
DP3
Q3 Q3 Q3
T ≥ 250 ms T ≥ 500 ms T ≥ 1 000 ms
off off off
DP4
Q4 see note see note
T ≥ 500 ms
off
DP5 Q4 see note see note
T ≥ 1 s
off
DP6 Q4 see note see note
T ≥ 5 s
off
DP7 Q4 see note see note
T ≥ 10 s
off
DP8 Q4 see note see note
T ≥ 10 s
off
DP9 to 32
Not Used Not used Not used
NOTE: Switch to next available channel or drop message.

ETSI
12 ETSI TS 102 724 V1.1.1 (2012-10)
Table 2: SCH1: Access layer requirement table based on DCC profiles and congestion status
DCC_Profile SCH1 Relaxed SCH1 Active SCH1 Restrictive Note
DP P < P P < P P < P Additional parameter to be
TX SCH1_rel TX SCH1_act TX SCH1_res
control in future releases:
T = T T = T T = T
off_min SCH1_min off_min SCH1_min off_min SCH1_min
D : Data rate (fixed in CCH)
TX
R : Variable CCA threshold
CCA
DP1 Not available Not available Not Available
DP2 Q2 see note see note
T ≥ 95 ms
off
DP3 Q3 Q3 see note
T ≥ 95 ms T ≥ 500 ms
off off
DP4 Q3 Q4 see note
T ≥ 500 ms T ≥ 500 ms
off off
DP5 Q4 see note see note
T ≥ 500 ms
off
DP6 Q4
see note see note
T ≥ 500 ms
off
DP7 Q4 see note see note
T > 1 s
off
DP8 Q4 see note see note
T > 1 s
off
DP9 Q1 Q1 Q1
T ≥ 100 ms T ≥ 200 ms T ≥ 250 ms
off off off
DP10
Q2 Q2 Q2
T ≥ 100 ms T ≥ 200 ms T ≥ 250 ms
off off off
DP11 Q3 Q3 see note
T ≥ 100 ms T ≥ 500 ms
off off
DP12 Q4 see note see note
T ≥ 500 ms
off
DP13 Q4 see note see note
T ≥ 1 s
off
DP14
Q4 see note see note
T ≥ 5 s
off
DP15 Q4 see note see note
T ≥ 10 s
off
DP16 Q4 see note see note
T ≥ 10 s
off
DP17 to 32 Not Used Not used Not used
NOTE: Switch to next available channel or drop message.

ETSI
13 ETSI TS 102 724 V1.1.1 (2012-10)
Table 3: SCH2: Access layer requirement table based on DCC profiles and congestion status
DCC_Profile SCH2 Relaxed SCH2 Active SCH2 Restrictive Note
DP P < P P < P P < P Additional parameter to be
TX SCH2_rel TX SCH2_act TX SCH2_res
control in future releases:
T = T T = T T = T
off_min SCH2_min off_min SCH2_min off_min SCH2_min
D : Data rate (fixed in CCH)
TX
R : Variable CCA threshold
CCA
DP1 Not available Not available Not available
DP2 Not available Not available Not available
DP3 Not available Not available Not available
DP4
Q1 Q2 Q2
T ≥ 500 ms T ≥ 500 ms T ≥ 500 ms
off off off
DP5 Q3 see note see note
T ≥ 500 ms
off
DP6 Q3 see note see note
T ≥ 500 ms
off
DP7 Q3 see note see note
T ≥ 1 s
off
DP8 Q3 see note see note
T >2 s
off
DP9
Q4 Q4 Q4
T ≥ 2 s T ≥ 5 s T ≥ 10 s
off off off
DP10 Q4 Q4 Q4
T ≥ 5 s T ≥ 10 s T ≥ 10 s
off off off
DP11 Q4 Q4 see note
T ≥ 5 s T ≥ 10 s
off off
DP12 Q4 see note see note
T ≥ 5 s
off
DP13 Q4 see note see note
T ≥ 5 s
off
DP14 Q4 see note see note
T ≥ 10 s
off
DP15
Q4 see note see note
T ≥ 20 s
off
DP16 Q4 see note see note
T ≥ 20 s
off
DP17 to 32 Not Used Not used Not used
NOTE: Switch to next available channel or drop message.

5.5 ITS G5B
5.5.1 Channel allocation
The ITS G5B band (5,855 GHz to 5,9875 GHz) contains the channels SCH3 and SCH4. It is considered for general
purpose ITS services (e.g. road efficiency, service announcements, multi-hopping, etc.). The ITS G5B band is not
allocated European wide. Thus local usage restrictions might apply.
5.5.2 Channel Usage and Operations SCH3 / SCH4
All traffic shall be compliant with DCC. An ITS station operating on the ITS G5B channel shall comply with the
requirements given in Table 4 and Table 5.
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14 ETSI TS 102 724 V1.1.1 (2012-10)
5.5.3 Channel Access Requirements
For DCC profiles related to more than a single channel the following usage order shall be deployed by the ITS station:
1) Service Channel 3, SCH3
2) Service Channel 4, SCH4
The message received by the access layer will be transmitted using the first possible channel in the usage order
depending on the congestion status and the DCC profile of the message. Examples for the usage are given in the
informative annex C.
In Table 4 and Table 5 the access layer requiremen
...