ISO/TS 16460:2016

TECHNICAL ISO/TS
SPECIFICATION 16460
First edition
Intelligent transport systems —
Communications access for land
mobiles (CALM) — Communication
protocol messages for global usage
Systèmes intelligents de transport — Accès aux communications
des services mobiles terrestres (CALM) — Messages de protocole de
communication pour une utilisation globale
PROOF/ÉPREUVE
Reference number
ISO/TS 16460:2016(E)
©
ISO 2016

---------------------- Page: 1 ----------------------
ISO/TS 16460:2016(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/TS 16460:2016(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Localized communications messages . 2
5.1 Purpose . 2
5.2 Localized message protocol . 3
5.3 Message formats . 3
5.4 Networking features. 4
5.4.1 Subtype values . 4
5.4.2 Networking feature 0 . 5
5.4.3 Networking feature 1 . 5
5.4.4 Networking feature 2 . 6
5.4.5 N-Extensions . 7
5.4.6 TPID values . 7
5.5 Transport features . 8
5.5.1 Transport feature 0 . 8
5.5.2 Transport feature 1 . 9
5.5.3 Transport feature 2 .10
5.5.4 T-Extensions.11
5.5.5 ITS port numbers .11
5.6 Procedures .11
6 Service advertisement messages .11
6.1 Purpose .11
6.2 Unique identifiers .12
6.2.1 ITS-AID/PSID .12
6.2.2 ITS-PN .12
6.3 Service advertisement protocol .13
6.4 Service advertisement message .13
6.4.1 Messages .13
6.4.2 Message structure .13
6.4.3 Message header .14
6.4.4 Message body .16
6.5 Service response message .21
6.5.1 Message structure .21
6.5.2 Message header .22
6.5.3 Message body .22
6.6 Count N .26
6.7 Procedures .26
6.7.1 General.26
6.7.2 Privately allocated channels .26
6.8 Secured messages .27
7 Structure of extension elements .28
Annex A (normative) ASN.1 modules .30
Bibliography .43
© ISO 2016 – All rights reserved PROOF/ÉPREUVE iii

---------------------- Page: 3 ----------------------
ISO/TS 16460:2016(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
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
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
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 204, Intelligent transport systems.
iv PROOF/ÉPREUVE © ISO 2016 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/TS 16460:2016(E)

Introduction
This document is a member of the set of International Standards for communications access for land
[2]
mobiles (CALM). An introduction to this set of International Standards is provided in ISO 21217.
Localized communications, i.e. communications without networking through a cloud, and service
advertisement are essential protocol functionalities in Cooperative Intelligent Transport Systems
(C-ITS). ISO and IEEE developed protocols with similar functionality, i.e. the
[6]
— ISO Fast Networking and Transport Protocol (FNTP) standardized in ISO 29281-1,
[13]
— IEEE WAVE Short Message Protocol (WSMP) standardized in IEEE 1609.3,
[5]
— ISO Fast Service Advertisement Protocol (FSAP) standardized in ISO 24102-5, and
[13]
— IEEE WAVE Service Advertisement (WSA) standardized in IEEE 1609.3,
[2]
where ISO considered the architectural context of an ITS station specified in ISO 21217 and IEEE
TM [11]
considered the architectural context of a WAVE device specified in IEEE 1609.0 .
Although initial versions of these protocols from ISO and IEEE are very similar, there are differences
in details of the message formats and the functionality. These differences were identified by the EU/US
[16]
task force HTG 3, from which a recommendation resulted to harmonize the protocols.
The result of harmonization of FNTP with WSMP, and of FSAP with WSA is presented in this document,
distinguishing interoperability modes and enhanced features only specified in this document. The next
revisions of ISO 24102-5, ISO 29281-1 and IEEE 1609.3, and the new standards from other SDOs can
align their message specifications with the protocol message elements specified in this document in
order to achieve global interoperability of equipment designed for different architectures.
© ISO 2016 – All rights reserved PROOF/ÉPREUVE v

---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 16460:2016(E)
Intelligent transport systems — Communications access
for land mobiles (CALM) — Communication protocol
messages for global usage
1 Scope
This document specifies the following:
— the Localized Message (LM) format: an NPDU of a networking and transport layer protocol that
does not support routing of a packet through a network;
— the Service Advertisement Message (SAM): an APDU to be transported in for example, an LM;
— the Service Response Message (SRM): an APDU acknowledging a SAM that offered a service based
[8]
on an ITS application class to be transported in for example, an LM;
— the related basic requirements for procedures.
TM
Specifications are partly done by normative references to IEEE 1609.3 -2016.
NOTE These message format specifications and basic procedures need to be complemented by complete
[2]
procedures and SAP specifications according to the context of usage, i.e. an ITS station specified in ISO 21217,
TM[11]
or a WAVE device specified in IEEE 1609.0 or any other context.
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 8824-1, Information technology — Abstract Syntax Notation One (ASN.1): Specification of basic
notation
ISO/IEC 8825-2, Information technology — ASN.1 encoding rules: Specification of Packed Encoding
Rules (PER)
TM
IEEE 1609.3 -2016, Standard for Wireless Access in Vehicular Environments (WAVE) — Networking
Services
3 Terms and definitions
No terms and definitions are defined in this document.
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 http://www.iso.org/obp
© ISO 2016 – All rights reserved PROOF/ÉPREUVE 1

---------------------- Page: 6 ----------------------
ISO/TS 16460:2016(E)

4 Abbreviated terms
CIP communication interface parameter
C-ITS cooperative ITS
FNTP fast networking and transport protocol
FSAP fast service advertisement protocol
HTG harmonization task group
IPv6 internet protocol version 6
ITS intelligent transport systems
ITS-AID its application identifier
LM localized message
MAC medium access control
NPDU network protocol data unit
OSI open system interconnection
PSID provider service identifier
RX CIP receiver CIP
SAM service advertisement message
SAP service access point
SRM service response message
TPID transport protocol identifier
TX CIP transmitter CIP
VANET vehicular ad hoc network
WAVE wireless access in vehicular environment
WSA WAVE service advertisement
WSMP WAVE short message protocol
5 Localized communications messages
5.1 Purpose
Localized communications is used to communicate with nearby peer stations, e.g. ITS station units or
WAVE devices. These stations are uniquely identified with an OSI data link layer address, typically by
the Medium Access Control (MAC) address. Networking in the sense of IP networking, where stations
route packets to other nodes through a network (cloud), is not supported. Nevertheless multi-hopping
can be performed in different ways, e.g.
— N-hop broadcast or N-hop multicast, which requires careful means to avoid flooding of the
communication channel;
2 PROOF/ÉPREUVE © ISO 2016 – All rights reserved

---------------------- Page: 7 ----------------------
ISO/TS 16460:2016(E)

[2]
— dedicated forwarding performed at higher layers, e.g. at the ITS-S facilities layer of an ITS station ;
this is a feature useful for geo-dissemination of information;
which creates so-called “Vehicular Ad hoc NETworks” (VANETs). Routing of packets through a network
in ITS will use the Internet protocol version 6 (IPv6).
5.2 Localized message protocol
As this document does not specify a specific localized communications protocol but just the structure
of messages of such protocols and related basic requirements, a hypothetical localized communications
protocol with the name “Localized Message Protocol” is used to simplify reading of the document.
5.3 Message formats
Figure 1 illustrates the basic format of the Localized Message (LM). Unaligned packet encoding rules
(UPER) applied to the ASN.1 type LMnpdu defined in A.2.1 results in the intended binary presentation
of this LM format.
Figure 1 — General format of the LM NPDU
TM
NOTE 1 In Figure 1, the “TPID” field (specified in IEEE 1609.3 -2016 as a one-octet unsigned integer field
completely allocated in the WSMP-N-Header) is split into a “Feature selector” field of the “N-Header” and a
“T-Extensions flag” field of the “T-Header” (according to the general rules of the OSI model). However, the two
presentations result in identical binary presentations.
The LM consists of three parts:
— “N-Header”
— a 4-bit unsigned integer “Subtype” number in the range of 0 to 15 indicating a networking
related feature;
— a 1-bit “N-Extensions flag”;
— a 3-bit unsigned integer “Version” number in the range of 0 to 7 indicating the version of the
localized message protocol. In case a receiver does not support the version, the received packet
TM
cannot be processed. The first version number used is three as specified in IEEE 1609.3 -2016;
[13]
NOTE 2 The format presented in Figure 1 is such that WAVE devices implementing version 2 of WSMP
can identify LMs as WSMP messages with version number 3 or higher.
— a networking related feature specified in 5.4 and selected by the value contained in the field
“Subtype”;
— “N-Extensions” being present if the “N-Extensions flag” is set to ‘1’b;
— a 7-bit unsigned integer in the range of 0 to 127, the “Transport Protocol Identifier (TPID)
feature selector”, indicating content in the “T-Header”.
— “T-Header”
— a 1-bit “TPID - T-Extensions flag”;
© ISO 2016 – All rights reserved PROOF/ÉPREUVE 3

---------------------- Page: 8 ----------------------
ISO/TS 16460:2016(E)

— a transport related feature specified in 5.5 and selected by the TPID feature selector value
contained in the “N-Header”;
— “T-Extensions” being present if the “T-Extension flag” is set to ‘1’b;
— a one or two octet field indicating the number of octets contained in “User data”.
— Body
— the “User data”.
The distinction of “N-Header” (networking related features) and “T-Header” (transport related features)
is in support of the ITS-S networking and transport layer that combines OSI layers 3 and 4 as illustrated
[2]
in ISO 21217.
The field “Length of User data” has a length of one or two octets dependent on the value contained in it:
— one octet size: Values from 0 to 127. The most significant bit is always set to zero. Presented as 0x00
(=0) to 0xEF (=127); i.e. the remaining 7 bits contain an unsigned integer number.
— two octet size: Values from 128 to 16383. The most significant bit of the first octet is always set to
one and the second most significant bit of the first octet is always set to zero. Presented as 0x8080
(=128) to 0xBFFF (=16383); i.e. the remaining 14 bits contain an unsigned integer number.
NOTE 3 This presentation results from the unaligned packed encoding rules applied to ASN.1 types of
unconstraint variable length.
5.4 Networking features
5.4.1 Subtype values
Networking features are identified by a subtype value. Subtype values are presented in Table 1.
Table 1 — Subtype values
N-Extensions Networking related
Subtype N-Extensions Remark
flag features
0 ‘0’b Not present Null-Networking Mandatory feature specified in
TM
IEEE 1609.3 -2016. Format
‘1’b Present
described in 5.4.2.
1 ‘0’b Not present ITS station-internal Format specified in 5.4.3.
forwarding
‘1’b Present
2 ‘0’b Not present N-hop forwarding Format specified in 5.4.4.
‘1’b Present
3 ‘0’b Not present Geo-forwarding Reserved. Not specified in this
document.
‘1’b Present
4–7 ‘0’b Not present Reserved for ISO Allows for further four
networking features.
‘1’b Present
8–15 ‘0’b Not present Reserved for IEEE Allows for further eight
networking features.
‘1’b Present
N-Extensions and related basic procedures shall be as specified in 5.4.5.
New networking features can be specified and linked to so far reserved subtype values at a later stage
without breaking backward compatibility.
NOTE Updates of N-Extensions will be published in the ISO/TS 16460 folder of the ISO standards
maintenance portal at http://standards.iso.org/iso/ts/16460.
4 PROOF/ÉPREUVE © ISO 2016 – All rights reserved

---------------------- Page: 9 ----------------------
ISO/TS 16460:2016(E)

5.4.2 Networking feature 0
Subtype 0 selects the “Null-Networking” feature introduced in 5.4.1.
NOTE Procedures on how to use this feature in the context of an ITS station unit, or a WAVE device or any
other context are outside the scope of this document.
The “Null-Networking” feature with Subtype 0 is the uppermost simple feature, as it requires only
processing of the TPID feature selector field specified in 5.6. Figure 2 presents the N-Header format for
Subtype 0 with N-Extensions being absent.
Figure 2 — N-Header for Subtype 0 without N-Extensions
Figure 3 presents the N-Header format for Subtype 0 with N-Extensions being present.
Figure 3 — N-Header for Subtype 0 with N-Extensions
N-Extensions and related basic procedures shall be as specified in 5.4.5.
5.4.3 Networking feature 1
Subtype 1 selects the “ITS Station-Internal Forwarding” feature introduced in 5.4.1.
NOTE Procedures on how to use this feature in the context of an ITS station unit, or a WAVE device, or any
other context are outside the scope of this document.
[3]
ITS station-internal forwarding is a feature applicable in ITS stations compliant with ISO 21218 (Link-
[4]
ID) and ISO 24102-1 (ITS-SCU-ID). It is used to forward packets between router units and host units
that are part of the same station/device. The field “Direction” contains an unsigned integer number with
the two possible values “0” (“from host to router”) and “255” (“from router to host”). The field “Counter”
contains a one octet unsigned integer cyclic packet counter being unique in the unit that forwards a
packet. Figure 4 presents the N-Header format for Subtype 1 with N-Extensions being absent.
Figure 4 — N-Header for Subtype 1 without N-Extensions
Figure 5 presents the N-Header format for Subtype 1 with N-Extensions being present.
© ISO 2016 – All rights reserved PROOF/ÉPREUVE 5

---------------------- Page: 10 ----------------------
ISO/TS 16460:2016(E)

Figure 5 — N-Header for Subtype 1 with N-Extensions
N-Extensions and related basic procedures shall be as specified in 5.4.5.
5.4.4 Networking feature 2
Subtype 2 select the “N-hop Forwarding” feature introduced in 5.4.1.
NOTE Procedures on how to use this feature in the context of an ITS station unit, or a WAVE device, or any
other context are outside the scope of this document.
N-hop forwarding is a feature that allows extending the communication range for information
dissemination (MAC broadcast or multicast mode) beyond the next directly reachable neighbour
stations. It uses parameters that allow avoiding flooding of the communication channel. Figure 6
presents the N-Header format for Subtype 2 with N-Extensions being absent.
Figure 6 — N-Header for Subtype 2 without N-Extensions
The 22-bit Message ID is generated from a random number generator and is unique within the N-hop
communication range with a “high” likelihood. In case of duplicate Message ID values, forwarding might
not be performed correctly in a station.
The 2-bit unsigned Integer Hop Count indicates to a receiver whether a forwarding shall be performed
or not. If Hop Count equals zero, forwarding is prohibited. Prior to forwarding of a packet, the Hop
Count shall be decremented by one. Consequently, a maximum of four hops is possible.
Forwarding shall be performed also if the TPID value contained in the received message is not supported
or reserved.
Figure 7 presents the N-Header format for Subtype 2 with N-Extensions being present.
Figure 7 — N-Header for Subtype 2 with N-Extensions
N-Extensions and related procedures shall be as specified in 5.4.5.
6 PROOF/ÉPREUVE © ISO 2016 – All rights reserved

---------------------- Page: 11 ----------------------
ISO/TS 16460:2016(E)

5.4.5 N-Extensions
The structure of the N-Extensions is specified in Clause 7. Extension elements presented in Table 2 may
be used in the “N-Extensions” field.
Table 2 — N-Extensions elements
Element ID Element type (ASN.1) Element name
TXpower80211
c-TxPowerUsed80211 = 4 Transmit Power Used (specified in
TM
IEEE 1609.3 -2016)
ChannelNumber80211
c-ChannelNumber80211 = 15 802.11 Channel Number used
TM
(specified in IEEE 1609.3 -2016)
DataRate80211
c-DataRate80211 = 16 802.11 Data Rate used (specified
TM
in IEEE 1609.3 -2016)
TXcip
c-LMtxCip = 80 Communication Interface transmit
parameters
RXcip
c-LMrxCip = 81 Communication Interface receive
parameters (RX-CIP)
LMchannelBusyRatio
c-LMchannelBusyRatio = 82 Channel Busy Ratio
The “Transmit Power Used” element is optionally included in the LM N-Header for use by the LM
TM [10]
recipient; see also IEEE 802.11 .
The “Channel Number” element is optionally included in the LM N-Header for use by the LM recipient;
TM [10]
see also IEEE 802.11 .
The “Data Rate” element is optionally included in the LM N-Header for use by the LM recipient; see also
TM [10]
IEEE 802.11 .
The “TX CIP” element is optionally included in the LM N-Header indicating Communication Interface
Parameter (CIP) settings used by the transmitter of the LM.
The “RX CIP” element is optionally included in the LM N-Header used with Subtype 1 indicating
Communication Interface Parameter (CIP) settings of the ITS-SCU that received the LM from a peer
station.
The “Channel Busy Ratio” element is a one octet unsigned integer optionally included in the LM
N-Header reporting the observed channel busy ratio in percent (0 % up to 100 % in steps of 0,5 %). The
integer values 201 to 255 indicate “unknown ratio”.
5.4.6 TPID values
Table 3 — TPID values
TPID
Transport related
T-Extensions Remark
Feature T-Extensions
feature
selector flag
0 ‘0’b Not present Information Mandatory feature specified in
TM
dissemination IEEE 1609.3 -2016. Format
‘1’b Present
described in 5.5.1
1 ‘0’b Not present General session mode Format specified in 5.5.2
‘1’b Present
2 ‘0’b Not present LPP mode Format specified in 5.5.3
‘1’b Present
© ISO 2016 – All rights reserved PROOF/ÉPREUVE 7

---------------------- Page: 12 ----------------------
ISO/TS 16460:2016(E)

Table 3 (continued)
TPID
Transport related
T-Extensions Remark
Feature T-Extensions
feature
selector flag
3–10 ‘0’b Not present Reserved for ISO Allows for further 8 transport
features.
‘1’b Present
11–127 ‘0’b Not present Reserved for IEEE Allows for further 117 transport
features
‘1’b Present
New transport features can be specified and linked to so far reserved TPID feature selector values at a
later stage without breaking backward compatibility.
5.5 Transport features
5.5.1 Transport feature 0
The TPID feature selector 0 selects the “Information Dissemination” feature specified in 5.4.6.
Figure 8 presents the T-Header for TPID = 1, i.e. with T-Extensions being present.
Figure 8 — TPID 1 — Information dissemination with T-Ext
...