NEWS
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Specification Rev. 3.0 launched
MOST Cooperation specifies next generation infotainment backbone
The MOST Cooperation, the organization through which the leading
automotive multimedia network Media Oriented Systems Transport (MOST)
is standardized, has created MOST Specification Rev. 3.0 for the next
generation infotainment backbone. It is a complete overhaul of the
specification structure offering several new features. While the
specification is independent of speed grade, it can already work with
the newly defined MOST150 physical layer. Thus it enables the use of
higher bandwidth of 150 Mbps, an isochronous transport mechanism to
support extensive video applications, as well as an Ethernet channel
for efficient transport of IP-based packet data.
MOST Specification Rev. 3.0 provides the specification for audio and
video signals to be transported with high bandwidth efficiency and
without any overhead for addressing, collision detection/recovery or
broadcast. This way it offers capacity that packet-switched networks
can only achieve with much higher gross bandwidth. Consequently
multiple high-definition (HD) video streams and multi-channel surround
sound with premium quality of service can be transmitted, while
simultaneously moving high loads of packet data around.
MOST Specification Rev. 3.0 – The Multi-Channel Network
MOST Specification Rev. 3.0 adds Ethernet and isochronous channels to
the well known channels for synchronous, packet and control data
channels of previous specification versions. The Ethernet channel can
transport unmodified Ethernet frames according to IEEE 802.3. This
permits software stacks and applications from the consumer and IT
domain, where the speed of innovation is much faster, to be seamlessly
migrated into the car. TCP/IP stacks or protocols utilizing TCP/IP can
communicate via MOST without any modification. Thus, the new generation
of MOST provides the automotive-ready physical layer for Ethernet in
the car. In addition, MOST Specification Rev. 3.0 offers an isochronous
channel to support streams which are not synchronized to the MOST frame
rate. A typical use-case is the transport of MPEG streams over a MOST
network, since MPEG streams generally use variable bit-rate. This new
MOST feature enables extensive video applications. MOST Specification
Rev. 3.0 also adds significant enhancements to the control channel
(which is used for real-time control of devices) by doubling the
bandwidth compared to MOST25.
Lessons Learned from Compliance Verification
MOST Specification Rev. 3.0 incorporates several “lessons
learned” mainly driven by the experience of MOST
Cooperation´s Compliance Verification Program. Emphasis has been
put on clear specification points where conformance can be easily
verified during compliance testing.
Optimized Diagnosability
Diagnosability has been optimized by an overhaul of Ring Break
Diagnosis behavior as well as Detection of Sudden Signal-Off. The
robustness of the procedures has been verified during the early phase
of the specification by using Failure Mode Effects Analysis (FMEA) as
well as reference implementations through virtual prototypes. For
example, to verify Ring Break Diagnosis behavior the functional and
timing behavior was modeled and executed in over 100,000 test sets that
use well-known methods from System-on-Chip (SoC)-Verification. These
measures help to simplify risk assessment and increase confidence in
the readiness to apply the new technology.
Easy Migration
The development of MOST Specification Rev. 3.0 has been accompanied by
a cost/benefit analysis that led, on the one hand, to several
innovations and on the other to a high level of backward compatibility.
Existing applications can easily be reused in the new network just by
modifying their network interfaces. MOST Specification Rev. 3.0
supports the new MOST150 Physical Layer with a bandwidth of 150 Mbps
that allows carmakers to continue to use POF and LEDs as light sources.
They can continue to use their established optical wire harness and
assembly processes. This makes the transition to higher bandwidth
networking a smooth evolution and leads to a high acceptance.
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