ISO 21218:2018

INTERNATIONAL ISO
STANDARD 21218
Third edition
2018-06
Intelligent transport systems —
Hybrid communications — Access
technology support
Systèmes intelligents de transport — Communications hybrides —
Support à la technologie d'accès
Reference number
ISO 21218:2018(E)
©
ISO 2018

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ISO 21218:2018(E)

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ISO 21218:2018(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Communication module adaptation . 3
5.1 General . 3
5.2 Communication adaptation layer . 4
5.3 CI management adaptation entity . 4
5.4 CI security adaptation entity . 5
6 Communication interface . 5
6.1 Architecture . 5
6.2 Classification of CIs . 5
6.2.1 CI Classes . 5
6.2.2 CI access classes . 6
6.3 Link identifier . 6
6.4 CI procedures . 7
6.4.1 General. 7
6.4.2 Registration . 7
6.4.3 Deregistration . 9
6.4.4 Inactivation . 9
6.4.5 Activation . 9
6.4.6 Suspension . 9
6.4.7 Resuming .10
6.4.8 Connection .10
6.4.9 Disconnection .10
6.4.10 CI state machine .11
6.4.11 Cross-CI prioritization .12
6.4.12 Protection of CI .14
6.4.13 Regulatory information management .15
7 Virtual communication interface .15
7.1 Concept .15
7.2 VCI procedures .19
7.2.1 Creation of VCI .19
7.2.2 Reset of VCI .20
7.2.3 Deletion of VCI .20
7.2.4 Association of peer with Link-ID .20
7.2.5 Change of I-Parameter settings .21
8 Communication SAP .21
8.1 Addressing .21
8.1.1 IN-SAP nt_protocol_id address .21
8.1.2 IN-SAP source and destination addresses .21
8.2 Service primitives .22
8.2.1 IN-SAP functions .22
8.2.2 IN-UNITDATA.request .23
8.2.3 IN-UNITDATA.indication .24
8.2.4 IN-UNITDATA-STATUS.indication .24
8.2.5 IN-UNITDATAACK.request .26
8.3 Priority .26
8.4 Timeout .27
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ISO 21218:2018(E)

8.5 Queue management .27
8.6 Access parameters .27
8.7 Transmission status .28
9 Management SAP .28
9.1 MI-SAP services .28
9.2 MI-COMMAND service primitive functions .28
9.2.1 Overview .28
9.2.2 ChangePseudonymMACaddress .29
9.2.3 CIstateChange .29
9.2.4 CnConnect .30
9.2.5 MacManagementFrameTX .30
9.2.6 ManufacturerCommand.31
9.2.7 MonitorIparameters .31
9.2.8 PrioritizedRequestToSend . .31
9.2.9 PrioritizedRTSrelease . .32
9.2.10 RegulatoryInformation .32
9.2.11 VCImanagement .32
9.2.12 WakeUpSignal.33
9.3 MI-REQUEST service primitive functions .33
9.3.1 Overview .33
9.3.2 EventNotification .33
9.3.3 MacManagementFrameRX .34
9.3.4 PositionUpdate .34
9.3.5 PrioritizationRegistration .34
9.3.6 PrioritizationRequest .35
9.3.7 PrioritizationRelease.35
9.3.8 RegistrationCI .35
10 Events .36
11 Dynamic data .36
12 Conformance .37
13 Test methods .37
Annex A (normative) I-Parameters .38
Annex B (normative) ASN.1 definitions .44
Annex C (normative) Extended universal 64 bit identifier .60
Annex D (normative) Path and flow management support .63
Annex E (normative) Implementation conformance statement (ICS) proforma .64
Bibliography .78
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ISO 21218:2018(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
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on the ISO list of patent declarations received (see www .iso .org/patents).
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For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
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World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.
This third edition cancels and replaces the second edition (ISO 21218:2013), which has been technically
revised. It also incorporates the Amendment ISO 21218:2013/Amd 1:2014.
The main changes compared to the previous edition are as follows:
— ASN.1 has been aligned with the latest developments in ISO/TC 204;
— provisioning for path and flow management has been added;
— normative annex related to conformance testing, that contains the PICS proforma, has been added;
— management commands have been added;
— minor technical and editorial improvements.
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ISO 21218:2018(E)

Introduction
This document is part of a family of International Standards for communications in Intelligent Transport
Systems (ITS) based on the ITS station and communication architecture specified in ISO 21217.
Hybrid communications, i.e. simultaneous support of different communication protocol stacks with
different access technologies, is essential for ITS.
This document supports
— hybrid communications as requested, e.g. for Cooperative ITS in Europe, and
— path and flow management, enabling abstraction of applications from communications details.
It determines general technical details related to the access layer of an ITS station specified in ISO 21217
and illustrated in Figure 1 which are applicable to all or several access layer technologies. This includes
especially:
— the IN-SAP offered to the ITS-S networking & transport layer for communication purposes;
— functions of the service primitives in the MI-SAP with reference to the generic services of the MI-
SAP specified in ISO 24102-3.
The IN-SAP and the MI-SAP are presented in Figure 1. The specification of the SI-SAP is not within the
scope of the present version of this document.
Figure 1 — ITS station reference architecture with named interfaces
This third edition cancels and replaces the second edition which has been revised and harmonized with
newly developed C-ITS standards.
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INTERNATIONAL STANDARD ISO 21218:2018(E)
Intelligent transport systems — Hybrid communications —
Access technology support
1 Scope
This document specifies general technical details related to the access layer of the ITS station reference
architecture specified in ISO 21217 including:
— the service access point (SAP) of a communication interface (CI) as provided by the communication
adaptation layer (CAL) for communication, named IN-SAP, and related service primitives and service
primitive functions;
— the SAP provided by the CI management adaptation entity (MAE) for management of the
communication interface, named MI-SAP, and related service primitives by reference to ISO 24102-3,
and service primitive functions.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC 8825-2, Information technology — ASN.1 encoding rules: Specification of Packed Encoding Rules
(PER) — Part 2
ISO 21217, Intelligent transport systems — Communications access for land mobiles (CALM) — Architecture
ISO 24102-3, Intelligent transport systems — ITS station management — Part 3: Service access points
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 21217, ISO 24102-3 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
3.1
(V)CI identifier
unique identifier of a (virtual) CI
3.2
communication interface
CI
instantiation of a specific ITS-S access layer technology and protocol
[9]
EXAMPLE An example of an ITS-S access layer technology and protocol is IR specified in .
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ISO 21218:2018(E)

3.3
medium
physical properties of a CI used to transmit a modulated signal, e.g. wireless or on a wire
Note 1 to entry: Medium is also referred to as access technology.
3.4
virtual communication interface
logical entity in a CI that is associated with a peer station
3.5
CI priority manager
logical entity in a CI that is managing priority queues
3.6
Link-ID
identifier of a link given by the address of a VCI
3.7
temps atomique international
time since 00:00:00 UTC, 1 January, 2004, identical with UTC except that no leap seconds need to be added
4 Abbreviated terms
APN Access point name
BC-VCI VCI for transmission to the broadcast MAC address
CAL Communication adaptation layer
CEN Comité Européen de Normalisation (European Committee for Standardization)
CI Communication interface
CIC Communication interface class
CIID CI / VCI Identifier presented in a 64-bit EUI field
DLL Data link layer
DNI Distinct null identifier
DSRC Dedicated short range communication (5,8 GHz back-scatter technology used in Eu-
rope for e.g. road tolling). This term is used in the USA to indicate IEEE 802.11 OCB
[10]
communications in the 5,9 GHz band, see ISO 21215
ETSI European Telecommunications Standards Institute
EUI ESxtended universal identifier
EUI-64 64-bit EUI
ICS Implementation conformance statement
IN-SAP Communication SAP as offered by the CAL to the ITS-S networking & transport layer
ITS-APDU ITS station Access layer Protocol Data Unit
LocalCIID CIID of a local CI
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ISO 21218:2018(E)

LSB Least significant bit
MAC-48 48 bit MAC address
MAE Management adaptation entity
MC-VCI VCI for transmission to a multicast (group) MAC address
MI-SAP Management SAP as offered by the ITS-S management towards the MAE
MSB Most significant bit
OBU On-board unit
[16]
NOTE  Term used for DSRC .
OSI Open system interconnection
OUI Organizational universal identifier
PIN Personal identification number
RemoteCIID CIID of a VCI enabling MAC groupcast transmissions and MAC unicast communication
RX/TX-CI CI capable of operating in receive and transmit mode
RX-CI CI capable of operating in receive mode only
RX-VCI VCI for reception
SAE Security adaptation entity
SIM Subscriber identity module
SNAP Sub-network access protocol
TAI Temps Atomique International
TDMA Time division multiple access
TX-CI CI capable of operating in transmit mode only, either broadcast or multicast
TX-VCI VCI for unicast transmission
UC-VCI VCI for reception from and transmission to a unicast MAC address
UTC Temps Universel Coordonné/Coordinated Universal Time
VCI virtual communication interface
WAVE Wireless access in vehicular environments
NOTE  IEEE work item related to [10].
5 Communication module adaptation
5.1 General
As ITS and the concept of an ITS station as a bounded secured managed domain (BSMD) specified
in ISO 21217 does not only support access technologies (media) which are especially designed for
implementations of ITS, there is a need to adapt the interfaces of these other access technologies to
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ISO 21218:2018(E)

those interfaces expected by the ITS networking & transport layer, the ITS-S management entity, and
the ITS-S security entity.
For these other access technologies, the task is to adapt:
— the interface on top of the access technology to the IN-SAP by means of a communication adaptation
layer (CAL);
— the management interface to the MI-SAP by means of a management adaptation entity (MAE);
— the security interface to the SI-SAP by means of a security adaptation entity (SAE).
The CI adaptation is outlined in Figure 2.
Figure 2 — Architecture
This document provides common basic functional specifications for the communication adaptation
Layer, for the management adaptation entity (MAE), and for the security adaptation entity (SAE). It
specifies the communication SAP (IN-SAP), the station management SAP (MI-SAP), and the security
management SAP (SI-SAP).
5.2 Communication adaptation layer
The CIs built on different media are using the same ITS-S networking & transport layer. All CIs use the
same type of IN-SAP between the ITS-S networking & transport layer and the CAL.
The medium-specific CAL provides an IN-SAP to the ITS-S networking & transport layer.
The CAL can be considered as an access technology (medium)-specific LLC or as an extension of an
existing LLC providing the adaptation of the specific needs of an access technology (medium) to the
common communication IN-SAP.
5.3 CI management adaptation entity
The CIs built on different media use the same ITS-S management, applying the functionality specified
for the MI-SAP.
The MAE provides the MI-SAP to the ITS-S management following the same principles as outlined in
[2]
ISO/IEC/IEEE 8802-11 with respect to the station management entity. The MI-SAP offers the services
presented in Clause 9.
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The MAE can be considered as medium-specific management providing the adaptation of the specific
needs of an access technology (medium) to the common MI-SAP.
5.4 CI security adaptation entity
The current version of this document does not provide the specification of the SAE.
6 Communication interface
6.1 Architecture
This document uses the concept of
— Communication interface (CI), with
— virtual communication interfaces (VCIs).
A CI is a real communication equipment containing functionality of the ITS-S access layer. On top of a CI,
one or several VCIs for transmission (TX-VCIs) to specific peer ITS-Ss, groups of ITS-Ss, or all ITS-Ss, and
on
...