T he clamor for more digital connectivity in
vehicles has car designers scrambling to
implement systems that efficiently distribute
audio, video, and other content. These
requirements have led to the design of a future-proof
system and networking architecture that can cope with
the different development time frames in the consumer
and the automotive worlds.
While existing implementations focused on audio,
Media Oriented Systems Transport (MOST) now
provides distributed network protocols for multimedia
high-definition (HD) audio/video networking. MOST
also supports Digital Transmission Content Protection
(DTCP), required by content owners for the secure
movement of video over distributed networks.
MOST offers more than the physical connection
between devices. It also provides the software infrastructure
to manage the complexity of multiple devices
communicating with each other. As telephones, navigation
systems, portable media devices, and infotainment
systems are integrated to provide a rich entertainment
experience, they need to communicate so they don’t
overwhelm the user with the details of moving audio
and video to multiple stations in the car.
Via MOST, designers can tame this complexity by
moving all audio, video, and necessary control signals
over a single cable, using either plastic optical fiber
(POF) or unshielded twisted-pair (UTP) wires.
MOST Technology is the result of the collaboration
among members of the MOST Cooperation, which
consists of 16 carmakers and more than 75 suppliers
working to establish and refine a common standard for
the evolving requirements of automotive multimedia
networking. Through this work, MOST has become
the de facto standard in the automotive industry for
transporting high-bandwidth audio, video, and control
information between various vehicle subsystems.
Its quality of service (QoS) makes it a prime transport
for applications that stream content to provide
consumers with high-quality information, video, and
sound. MOST is used in over 58 vehicle models from
more than 16 vehicle brands from around the world.
The technology started in Europe but has now expanded
into Asia, with Toyota, Hyundai, Kia, and SsangYong
recently introducing several models.
The traditional way of connecting analog signals
between various components and using controllerarea
networking (CAN) to control communications
isn’t viable in the long run. That’s because too many
devices would have to be connected with each other. If
several of the connections involved surroundsound, for
example, each link between devices would need six or
more wires just for the audio signals alone.
Car designers can significantly reduce the complexity
of the wiring harness by using MOST, which
uses a ring structure (Fig. 1). Figure 2 shows an actual
example of one vehicle manufacturer going from a
traditional analog-based system to using MOST.
CONSUMER, AUTO ELECTRONICS CONVERGE
MOST helps car companies connect to the
consumer world. It allows the network backbone in
the car to comply with the robustness and reliability
requirements of the automotive industry and provides
a pipeline for moving audio and video. The long design
cycles of a car make it difficult to quickly adapt to the
latest consumer trends, though.
With the standardized
interfaces of MOST, car
companies can maintain their
infotainment backbone on
their own time schedules and
only need to develop a single
customized gateway device to
connect to the latest consumer
electronics. It would even
be possible to make such a
gateway an accessory that
could be upgraded over time.
Other consumer- and computer-
oriented technologies,
such as Ethernet and USB, are
relevant to the car.
Ethernet’s wide proliferation,
high bandwidth, and the
optimized communication of
bursts or packets of information
make it an excellent connectivity
solution between
the outside world and the
automobile. The protocol can
connect an external Ethernet-based infrastructure to a
vehicle and move large amounts of diagnostic information
between the two, such as downloading software
into the vehicle when the car is in a repair bay.
Many vehicles rely on embedded Ethernet products.
The non-PCI architecture is well suited for the
automobile since it obviates the need for a full personal-
computer infrastructure. Instead, it provides simple
interfaces to the typical microcontrollers used inside
the car while taking advantage of the vast computing
power that exists outside of the vehicle.
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