ISO/TR 21186-2:2021 PDF

Overview - ISO/TR 21186-2:2021 (Hybrid communications for C-ITS)

ISO/TR 21186-2:2021 is a technical report in the ISO 21186 family that provides guidelines on hybrid communications for Cooperative Intelligent Transport Systems (C-ITS). The document explains how to combine multiple access technologies and communication protocols to support C-ITS services in conformance with the ITS station architecture. It is intended as guidance for standards developers, ITS application designers and implementers to harmonize interoperable, future‑proof C-ITS deployments.

Key topics and technical requirements

• Definition and motivation: explains hybrid communications, hybrid ITS services and why diversity of access technologies (complementary or redundant channels) is required for safety, efficiency and comfort in connected mobility.
• Use-case examples: illustrative services needing hybrid communications, such as road hazard notifications, emergency calls and public transport services.
• Hybrid communication technologies: conceptual overview of combining short-range and wide-area access technologies and different protocol stacks to meet application needs.
• Unified communication and data management architecture: requirements for a single framework able to support diverse applications, communication paths and access protocols.
• ITS station architecture and functionalities: detailed description of the ITS-S reference architecture (facilities, networking & transport, access layers), ITS‑S managed service entities (MSE), capabilities and the ITS‑S management entity that enable hybrid support.
• Operational elements: management of ITS‑S flow types, flow identifiers, communication paths, ITS‑S communication profiles (ITS‑SCP), handovers and globally unique identifiers.
• Standards coordination and development guidance: lists standards necessary to support hybrid communications and advises how to specify ITS application processes, register communication requirements and define data flow types.

Practical applications - who uses this standard

ISO/TR 21186-2 is useful for:

• Standards development organizations (SDOs) and technical committees defining C-ITS releases.
• Vehicle OEMs, telematics and module vendors implementing ITS stations and hybrid communication stacks.
• Road operators, smart city planners and mobility service providers deploying C-ITS services that require reliable multi‑path communications.
• Software architects and systems integrators designing ITS applications that must manage flows, profiles and handovers across access technologies.

Practical outcomes include improved reliability and redundancy for V2X services, better service continuity for emergency and public transport applications, and a clearer roadmap for implementing hybrid ITS services.

Related standards and references

• ISO 21186 series (Part 1: Standardization landscape; Part 3: Security)
• ISO 21217 (ITS station architecture concepts)
• ISO/TS 21184, ISO 22418, ISO/TS 21176, ISO/TS 21177, ISO 21210, ISO 24102-6 (referenced frameworks and protocols)

Keywords: ISO/TR 21186-2:2021, C-ITS, hybrid communications, ITS station architecture, ITS‑S communication profile, V2X, cooperative intelligent transport systems.