Standards for Cooperative Intelligent Transport Systems
- C-ITS -


Cooperative ITS (C-ITS) is a feature of ITS rather than something different. In C-ITS, different applications share information, both inside an ITS station unit, and accross several such units. Thus C-ITS "breaks" with the traditional "silo-thinking". Standardization of C-ITS is mainly done at CEN/ISO. Reed more ...


ITS standardization events

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ISO and CEN are leading advocates for technologies improving safety, security, efficiency and comfort of the world's transportation system. ISO TC204 and CEN TC278 work jointly together.


Release 2 C-ITS standards

The development of Release 1 standards for Cooperative Intelligent Transport Systems is done. Deployment projects started. Early experience with real operation of C-ITS triggered development of Release 2 standards for C-ITS.


The set of Release 2 standards will be based on the revision of Release 1 standards, and missing complementary standards. If you are interested in learning about Release 2, please contact us.

ITS Application Identifier

ITS application identifiers (ITS-AID) are precisely specified in CEN/ISO TS 17419:2014 and ISO 21217:2016. The specifications given there support the needs of CEN, ETSI, and ISO. The primary purpose of ITS-AID is identification of an ITS application object and at least one of its related ITS-S application processes, e.g. in a service advertisement message, in a localized message (used similarly to a port number), and for security purposes.

As a result of the IEEE/ISO harmonization on LM and SAM (see below), the Provider Service Identifer (PSID) used in IEEE shares a number space with ITS-AID. This sharing of the number space means that PSID and OTS-AID are synonyms, i.e. identifying the same technical meaning. However reality shows that IEEE / SAE experts have slightly different understandings of what is meant with PSID, and these understandings so far are nowhere standardized.

Careful observation of the various thoughts on PSID show that likely most of these thoughts can be managed by the set of specifciations from TS 17419. TS 17419 currently is under revision to be upgraded to a full EN / IS; this offers the opportunity to clarify also the thoughts and views of these IEEE / SAE experts.

It is important to clarify that ITS-AID is not to be used

  • to distinguish different versions of the same ITS application object,
  • to identify C-ITS messages,
  • to identify communication protocols / features!

The following definitions exist:

  • ITS-AID: globally unique, registered number identifying an ITS application object
  • ITS application object: ITS application and ITS application class
  • ITS application class: ITS application with mutually exclusive characteristics designed for operation in different contexts
  • ITS application: instantiation of an ITS service that involves an association of two or more complementary ITS-S application processes
  • ITS-S application process: element in an ITS station unit that performs information processing for a particular application, and may use ITS-S services to transmit and receive information
  • ITS-S application: ITS-S application process residing in the ITS-S application entity

Now about the technical details:

ITS-AID is just a non-negative Integer number with unlimited number range. So far two presentations in ASN.1 and two encodings are specified and used in standards, i.e. the p-encoding and the o-encoding.

P-encoding is based on a complex ASN.1 type with variable length, applying unaligned PER. This presentation is used in LM (WSMP / FNTP) and SAM/SRM (WSA / FSAP) resulting in fields of one up to four octets (larger numbers are possible, but not supported). The first 32 numbers of ITS-AID point to ISO 15628 "application classes". An "application class" - in simple words - can be understood as a Super-Application that requires upon start initial negotiation of an operational context (known from CEN DSRC as BST/VST exchange).

O-encoding is based on the simple ASN.1 Integer type, applying OER. This presentation is used in IEEE 1609.2.

IEEE / ISO harmonization of Localized Messages and Service Advertisement Messages

Harmonization of message formats

  • IEEE WAVE Short Message Protocol (WSMP) with ISO Fast Networking & Transport Protocol (FNTP)
  • IEEE WAVE Service Advertisement (WSA) with ISO Fast Service Advertisement (FSAP)

is finished!


ISO TS 16460:2016 is in the process of publication. The revised IEEE standards 1609..3:2016, 1609.4:2016, and 1609.2:2016 are published.

There is an interoperability mode for the localized message (LM) and the service advertisment message (SAM). ISO specifies enhancements, i.e. additional modes of LM (networking and transport features), enhanced SAM functionality, and the functionality of SRM. The enhanced features are used in FNTP and FSAP, and can be activated in WAVE without breaking binary backward compatibility. Whilst WAVE only supports IEEE 802.11 @ 5,9 GHz communications, FNTP and FSAP are agnostic to the underlying access technology.

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C-ITS interest groups

Currently there are three big interest groups in ITS, i.e.

  • the road operators and city authorities,
  • the car makers, and
  • the cellular network operators.

Whilst the first two groups are visible in standardization, the network operators work in a more silent mode (partly on a competing technology M2M).

Most interesting business will be with the road operators and city authorities with the challenge to consider a hugh amount of existing infrastructure and protocols.

Road safety based on communications between cars is a vision with stringent technical and legal problems. Thus so far car industry decided to implement safety mainly with autonomeous systems. In case you are interested to learn more, please contact us.


Services and tools


ESF GmbH is maintaining an international virtual enterprise with experts covering all parts of C-ITS and all kinds of engineering services and consultancy. Please feel free to contact us.

ASN.1 Tools


TTCN-3 Tools




Some hyperlinks



3. May 2016