Tomorrow's cars are moving to Automotive Ethernet to get the bandwidth they need and lower the weight of wiring harnesses.
As you may have already noticed via that pesky “check engine” light, cars today are highly computerized. From monitoring engine temperature to whether your gas cap is open, even the least-expensive, bare-bones car has some sort of computer in it.
Data is usually being passed around on a megabit, half-duplex communication Controller Area Network (CAN). While there are a few more notable schemes, they all share the similarity that they communicate over a single twisted pair using differential signaling. They are very robust and very well tested. However, they are exceedingly slow compared to modern technology.
In order to get around this limitation, automotive manufacturers have started cramming more and more CAN buses into a car. In fact, today’s automotive processors usually have three or four integrated CAN transceivers. Because of this, the wiring harness assembly is, surprisingly, one of the heavier and more expensive components in a vehicle.
Today’s fully loaded luxury sedan comes complete with an accident avoidance system, 360-degree cameras, adaptive cruise control, and satellite navigation system. These systems are far too bandwidth intensive to run over the existing CAN bus, so dedicated systems usually integrate high bandwidth communication. These require high-quality cabling, which adds cost to the already expensive wiring harness.
These schemes are point-to-point, and every high-bandwidth device needs its own cable. The growing problem is that the already heavy and expensive wiring harness is getting even heavier and more expensive to keep up with the consumer demand for infotainment and integrated technology.
This situation has fostered Automotive Ethernet. Using a single twisted-pair cable similar to that used by a CAN bus, an Automotive Ethernet link can currently provide 100 MByte/s of bandwidth, with a GByte/s in the works. This increase in speed allows the thick bundles of CAN cabling to be replaced with a single twisted pair.
By moving from a simple half-duplex messaging system to a full-on TCP/IP network, we gain the ability to have multiple data streams running simultaneously over the same network. Using Precision-Time-Protocol and Audio-Visual-Bridging technologies, it becomes possible to run your infotainment and 360-degree camera system over the same network that your time-sensitive engine and traction control systems use. In the end, the automobile turns into more of an Internet of Things system.
For the driver, this means a great deal more by way of features and benefits. In the past few years, the addition of the reverse camera has become standard on even the most basic models of cars. With Automotive Ethernet handling connectivity in the car, it will become cheaper to implement technologies such as this, to the point where a base-model car will come with a large amount of technology.
— Alex Seiger is the Gigabit Ethernet Consortium Manager and BroadR-Reach Development Leader at the University of New Hampshire Interoperability Laboratory.