Overview
CEN ISO/TR 21186-2:2021 - "Cooperative intelligent transport systems (C-ITS) - Guidelines on the usage of standards - Part 2: Hybrid communications" - is a technical report that explains the concept of hybrid communications and the supporting functionalities needed for C‑ITS services implemented in conformance with the ITS station architecture. Endorsed by CEN and prepared in collaboration with ISO/TC 204 and CEN/TC 278, this guidance helps designers and standardizers combine multiple access technologies and protocols to deliver reliable, interoperable C‑ITS services.
Key topics and requirements
- Hybrid communications concept: Definition and rationale for composing multiple access technologies and protocols to provide complementary or redundant channels for C‑ITS.
- ITS station architecture: Detailed description of ITS‑S layers and design principles that enable hybrid operation (facilities, networking & transport, access layers, management & security).
- Support functionalities: Roles of the ITS station management entity, ITS‑S capabilities, and ITS‑S service managed entities (ITS‑S MSE) in coordinating hybrid communication.
- Communication adaptation layer (CAL): Functions and protocols that adapt diverse access technologies to the ITS networking and transport layer.
- Unified communication and data management: Requirements for architectures that support diverse applications with varying latency, reliability and bandwidth needs.
- Operational elements: Management of data flow types, communication paths and profiles (ITS‑S flow type, ITS‑S path, ITS‑SCP), handovers and globally unique identifiers.
- Use-case driven guidance: Example applications described include road hazard notification, emergency call, and public transport scenarios that require hybrid access.
- Standards development guidance: How to define ITS application processes, specify data flow communication requirements, register communication requirements and transmit data.
Applications and practical value
This guideline is practical for:
- Vehicle OEMs and telematics suppliers designing C‑ITS on-board units that use combined radio, cellular (V2N), and short-range (V2V/V2I) links.
- Road operators and infrastructure vendors deploying roadside units and backend services that need resilient hybrid links.
- ITS application developers defining communication requirements (latency, reliability, redundancy) for services such as hazard warnings, emergency calls and public transport priority.
- Standards developers and SDOs aligning new application standards with the ITS station architecture to ensure interoperability.
Who should use this standard
- C‑ITS solution architects, ITS software developers, system integrators, regulators and procurement teams seeking guidance on hybrid communications and harmonized deployment of cooperative intelligent transport systems.
Related standards
- ISO/TR 21186 series (Part 1: Standardization landscape; Part 3: Security)
- ISO 21217 (terms on access technology and CAL)
- ISO/TS 21184 and ISO 22418 (related C‑ITS frameworks and service announcement mechanisms)
Keywords: C‑ITS, hybrid communications, ITS station architecture, ISO/TR 21186‑2:2021, cooperative intelligent transport systems, communication adaptation layer, access technologies.
