Overview
ISO 21806-1:2020 - Road vehicles - Media Oriented Systems Transport (MOST) - Part 1: General information and definitions provides the foundational terminology, symbols and access information for implementing MOST (Media Oriented Systems Transport) networks in automotive applications. This Part 1 document establishes the vocabulary, scope and pointers to normative MOST specifications (including referenced MOST Specification revisions) used across the ISO 21806 series. It explains that MOST is a synchronous time-division-multiplexing (TDM) network designed for low-latency transport of audio, video, control and packet data in road-vehicle multimedia systems.
Key topics and technical requirements
- Definitions and terms: comprehensive glossary covering jitter, phase variation, frames, channels, control data, streaming data, logical node addresses and other MOST-specific terms.
- Network architecture: describes MOST as a synchronous TDM network with separate channels for streaming, control and packet data; network clock and timing behavior are defined.
- Timing and signal quality: concepts such as jitter, accumulated jitter, alignment jitter, eye diagram, Golden PLL and lock conditions are defined for reliable data reception.
- Bandwidth allocation: mechanisms like boundary descriptors, bits-per-frame and reserved bandwidth for isochronous streaming.
- Variants and bit rates: references to MOST50 (50 Mbit/s) and MOST150 (150 Mbit/s); support for different bit rates and physical layers is noted.
- Access and maintenance: guidance on accessing MOST specifications via the ISO standards maintenance portal and MOST versions directory structure (including MOST versions 4V0, 3V1, 3V0, 2V5).
- Normative/informative resources: Annexes list implementation-relevant and supplemental documents useful for conformance and implementation.
Applications
- Implementation and interoperability of automotive multimedia and infotainment systems (audio, video, navigation and telematics).
- Defining test plans and conformance procedures for MOST-based devices and test tools.
- Guidance for integration of streaming and packet services in ECUs and network controllers where deterministic low latency and QoS are required.
Who uses this standard?
- Automotive OEMs and system architects
- Tier-1 suppliers and ECU/module manufacturers
- Test-tool vendors and certification bodies
- Network and firmware engineers implementing MOST-based interfaces
Related standards
- ISO 21806 series (other parts: protocol, conformance)
- ISO/IEC 7498-1 and ISO/IEC 10731 (OSI model references)
- ISO/IEC/IEEE 8802-3 (Ethernet - referenced for scalable automotive-ready Ethernet)
- MOST Specifications (referenced normative documents)
ISO 21806-1:2020 is essential for anyone implementing or testing MOST networks in road vehicles, ensuring consistent vocabulary, access to the correct MOST specification versions, and a basis for conformance and interoperability.
Open preview (PDF)Road vehicles — Media Oriented Systems Transport (MOST) — Part 1: General information and definitions
