Ethernet Backbones will Support Many Branches

Ethernet is going mainstream, but CAN and other networks still will be needed as software and electronics do more.

September 1, 2021

Terry Costlow

Ethernet will be a mainstay for high-speed vehicle communications.

Ethernet is displacing CAN (controller area networks) as the primary architecture for automotive networks, but a host of other communications protocols are helping reduce cost and complexity. Multiple consumer networks are being used to carry input from sensors and other devices to Ethernet backbones that transfer huge volumes of data to centralized controllers.

The ubiquitous network used in homes and businesses brings speed and low cost along with integration in both microchips and design tools. That’s making it the mainstay in emerging vehicle architectures.

“We expect Ethernet to be the ‘bus of the future’ and provide the primary interconnect for modern vehicles,” said Danny Shapiro, senior director of automotive at NVIDIA. “This will replace most previous buses and help OEMs realize a software-defined vehicle that is scalable and updatable, with the potential to greatly reduce the cost and weight associated with legacy cabling harnesses.”

However, Ethernet won’t totally displace communication technologies that have been used for years. CAN and LIN will continue as links for many devices and modules, while a range of technologies, many coming from consumer products, are being used to handle data from the many sensors and actuators found in modern vehicles. For example, the cell-phone industry’s MIPI standard is seeing usage as a link for cameras and radar. Still other standards meet other requirements in bandwidth and speed. Many protocols will be used to address needs ranging from high-volume cameras, radar and lidar to low-speed nodes such as window and seat motors.

“Beside classic CAN, other buses like LIN and Ethernet, other short/long distance communication links have emerged in the last decades such as the MIPI standards,” said Davide Santo, ST Automotive Group’s microcontrollers business unit director. “The recent Automotive Serdes Alliance complements and enriches the pre-existing proprietary solutions. All of these specific solutions address the increasing needs for reliable, safe, secure data highways for demanding heavy-payload applications, especially in the space of semi/autonomous driving.”

Mobile-phone technologies are among the many consumer standards that will see more usage in vehicles.

While Ethernet’s broad knowledge base is a key driving force, so too is the auto industry’s experience with CAN. It’s increasingly being seen as a low-speed solution, but an updated version of CAN is expected to see use in some areas where large packet sizes are common. That will make it useful across a fairly broad spectrum.

“CAN has a long legacy and has proven itself for over two decades inside of vehicles,” said Daniel Hopf, system architect at Continental. “For lower-speed applications, CAN will remain the technology of choice mostly due to its cost advantage. Furthermore, CAN is very well known at OEMs and suppliers and is a ‘safe bet’ when designing new systems. With the upcoming 10BASE-T1S automotive Ethernet specification for 10 Mbit/s operation over a shared medium, competition with the upcoming CAN-XL standard will grow, since they will end up in a similar speed- and maybe even cost-range.”

Long-term scalability and openness are major requirements for the many networking architectures being deployed today and into the future. Autonomy requires extensive communications that must meet tight real-time requirements. The addition of electrified powertrains is another factor that requires a holistic approach to intersystem communications.

The Ethernet standard includes a well-planned pathway towards higher speeds while also maintaining compatibility make it a safe choice for long-term planning. The IEEE, which manages the technology, has added an automotive committee that will manage any changes needed to meet automakers’ requirements.

“The automotive Ethernet standards now are also created within the same group, IEEE 802.3, with the OPEN Alliance creating all sets of supplementary specifications for successful operation under automotive conditions.” Hopf said.

Understanding wiring for this range of networking schemes isn’t the only challenge facing communication specialists. Many engineers also will have to add wireless networking to their skillset. Over-the-air updating is expected to soar as software and security become more important elements in connected vehicles; Wi-Fi is another home/business technology that is expected to dominate, again due in part to its integration in semi-conductors and design tools.

“Wi-Fi connectivity is often utilized to enable over-the-air updates and is especially important as we move into the next generation of software-defined vehicles where data will be flowing to and from the vehicle to ultimately increase safety and enable refreshing of HD maps,” Shapiro said. “It will also enable new entertainment options in an autonomous vehicle, such as streaming movies, shows, games and music so that occupants can enjoy the hands-free ride, although most of these services will be enabled by 5G cellular technology.”