[Design View / Design Solution]
Get The MOST Out Of Your Automotive Communications
The MOST network protocol for cars offers support for music, video, telecom, and anything else engineers can imagine.
While Ethernet is an efficient data-transport technology that relies on packet switching, MOST provides for efficient audio and video streaming by using a circuit switched architecture. It establishes a direct channel between a source of streaming data and one or more users of that data. By combining Ethernet and MOST, vehicle makers can use the best functionality that each technology has to offer.
USB has become the interface of choice for many consumer electronics devices. When a consumer brings an MP3 or video player, memory card, digital camera, or even a cell phone into the car, its connection is likely to be over USB. Within the automobile, USB provides the connection to the consumer world. However, standard consumer USB cables introduce significant electromagnetic emissions to the vehicle.
Instead of using cables to a central location, USB ports can be located where consumers will connect their devices while sending content from those devices over the MOST network backbone. MOST enhances the single host/multiple device architecture of USB by providing the distributed control architecture (multiple controllers and slaves) and simple mechanisms for allocating the entertainment content that’s stored in various consumer products.
Here again, the connection to the external world is through a ubiquitous consumer interface. But the transport of audio, video, and control within the vehicles is over the stable MOST infotainment backbone.
Wireless technologies such as Bluetooth and Wi-Fi are also used to connect nomadic devices to MOST. They can’t completely replace wired solutions due to the need to charge the batteries of these portable components, but they’re complementary to the systems in the car. These technologies allow for seamless transfer of information without having to be tethered to the car.
Many nomadic devices use a standard mini-USB connector. Cell phones, media players, GPS receivers, and other devices are adopting it, even if they don’t need to communicate data, because it provides a common way to charge the batteries in these devices. MOST, Ethernet, and USB provide the next generation of automotive interfaces that enable feature-rich and easy-to-use information and entertainment systems. Ethernet and USB are well understood in the market.
MULTIMEDIA UNLIMITED A MOST network is very easy to use due to simple connections. Plug-and-play functionality permits the network to identify the characteristics and features of new devices that are added to it. Virtual network management functions include channel allocation, system monitoring, addressing, and power management. The synergy with the consumer and PC industries is possible with consistent PC streaming and because it operates with or without a PC.
The most efficient and cost-effective way to continue automotive innovations in all of these areas is to develop the devices independently and then connect them together via a MOST gateway using standard hardware and software interfaces.
The clear trend is to enable the automotive system to attach the required features instead of providing every possible upcoming interface. With the gateway, MOST will offer a way to successfully decouple the automotive development cycles from the consumer electronics cycles.
The latest MOST Specification is at Rev. 3.0. It’s 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. Designers now can use a higher bandwidth of 150 Mbits/s, an isochronous transport mechanism to support extensive video applications, and an Ethernet channel for efficient transport of IP-based packet data.
MOST 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 HD video streams and multichannel surroundsound with premium QoS can be transmitted while simultaneously moving high loads of packet data around.
The latest version adds Ethernet and isochronous channels to the well-known synchronous, packet, and control data channels of previous specification versions. The Ethernet channel can transport unmodified Ethernet. This permits software stacks and applications from the consumer and IT domain, where innovation is much quicker, to be seamlessly migrated into the car. TCP/IP stacks or protocols utilizing TCP/IP can communicate via MOST without any modification.
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