Overview
ISO 16460:2021 - Intelligent transport systems - Localized communications - Communication protocol messages for global usage defines standardized message formats and basic procedures for localized (non‑routed) communications in cooperative ITS (C‑ITS). It specifies the binary message structures and related requirements for three core message types:
- Localized Message (LM) - an NPDU for networking & transport layers that does not support IP routing;
- Service Advertisement Message (SAM) - an APDU (carried in an LM) used to announce services;
- Service Response Message (SRM) - an APDU acknowledging a SAM.
The standard harmonizes prior ISO and IEEE message formats (e.g., FNTP/WSMP and FSAP/WSA) to enable global interoperability of ITS/WAVE devices and refers to ASN.1 encoding (UPER) and IEEE 1609.3 for normative details.
Key topics and technical requirements
- Message formats and encoding: ASN.1 modules (Annex A) and Unaligned Packed Encoding Rules (UPER) determine LM/SAM/SRM binary presentation.
- LM structure: N‑Header, transport header and payload; subtype fields and feature selectors allow interoperability modes and extended features.
- Service advertisement protocol: Unique identifiers (ITS‑AID / PSID), ITS port numbers (ITS‑PN), SAM‑ID and SAM‑Count semantics for service lifecycle and change tracking.
- Networking & transport features: Options for networking features, transport features, and extension elements to support N‑extensions and T‑extensions without IP routing.
- Procedural basics: Basic procedures for SAM/SRM exchange, Count N handling, and support for privately allocated channels.
- Security considerations: Reference to secured messages and the need to complement message formats with security/SAP procedures appropriate to the deployment context.
- Normative cross‑references: IEEE 1609.3 (WAVE networking), ISO 29281‑1 (FNTP), ISO 24102‑5/EN ISO 22418 (FSAP), and ISO 21217 (ITS station architecture).
Practical applications and intended users
- Who uses it:
- Automotive OEMs and telematics suppliers implementing C‑ITS features
- Roadside infrastructure vendors and RSU manufacturers
- Wireless device vendors targeting WAVE/DSRC profiles
- System integrators, firmware and protocol stack developers
- Standards bodies and test labs validating interoperability
- Typical use cases:
- Local service announcement and discovery (V2V, V2I) for traffic safety, hazard warnings, and real‑time traffic services
- Geo‑dissemination and VANET applications using multi‑hop broadcast/multicast techniques without IP routing
- Interoperable service provisioning across devices designed to ISO and IEEE architectures (ITS station, WAVE device)
- Implementation note: ISO 16460 provides message formats and basic procedures; full implementations must complement it with context‑specific procedures and SAP definitions (e.g., ISO 21217, IEEE 1609.0).
Related standards
Keywords: ISO 16460:2021, intelligent transport systems, localized communications, LM, SAM, SRM, ITS‑AID, ITS‑PN, IEEE 1609.3, WAVE, VANET, service advertisement, ASN.1, UPER, global interoperability.
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