Why Cars Are Migrating to Zonal Electric Architecture

Marvell Technology explains how the zonal architecture’s Ethernet backbone is crucial for software-defined vehicles.

Dan Carney, Senior Editor

February 28, 2023

7 Min Read
A car with zonal architecture.Marvell Technology, Inc.

As we enter the age of software-defined vehicles, with their continuously updated capabilities and features, we should recognize the change to their underlying hardware that permits this software-definability.

These cars will employ a zonal architecture that breaks the car into several zones within which the various functions are managed by the same computer processor. This differs from the siloed approach, where each component has its own processor and supporting wiring.

For a clear look at zonal architecture and its benefits, Design News sat down with Amir Bar-Niv, vice president for automotive at semiconductor company Marvell Technology Inc. to discuss the issue.

Q: Why is the industry shifting toward cars employing zonal architecture?

Amir Bar-Niv: If you look at the history of automotive, I would say probably before 2016, most of the cars would work with what they would call a device-centric focus for the electronic systems like radio and CD and GPS and others. Each one was totally autonomous in its own processor.

The transition after 2016 was what we call the application-centric [model], where we start to have again a lot of electronics in the car and they were centered around specific applications like the infotainment, like the ADAS, the telematics is another example, and the gateway. These are usually the four that are typical for each vehicle or new vehicle that you see today.

Q: So where does that leave us today?

Amir Bar-Niv: What we see now is a transition to another phase that we call data- and software-centric. Where we have in the car, a lot of compute, storage, and network. People like to use the buzzword “data center on wheels.” And it is of course in a different magnitude but there is really a single entity that includes a lot of storage, compute, and networking that is really one data center. The whole idea is really to build a system that can be programmed over time with your application and your capabilities. This is the promise of what's called the software-defined vehicle.

That transition from application-centric to data-and software-centric required also a change of the architecture inside the car. So if we look at the cars that are built today -- I will talk about the mid-and high-end type of cars -- they are what we call domain architecture.  It means that there are different domains that I mentioned before like infotainment, ADAS, et cetera. Each domain has its own processor.

[In this slide] I'm showing, for example, the red domain that has a processor and it's connected to all its agents around the car with cables located it's running all over the car. And then we have another domain, the blue one, and again, it's connected to its agents and the same with the yellow one.

The issue with this architecture is really the cable harness. What you see here is really how it looks in the car. Tons of cable. Expensive, because the installation of cables cannot be done by robots like everything else in the car. It needs to be people who install the cable and connect them and run them in the car. Heavy. You know there is a lot of cable.

The Volkswagen Golf, which is a small car, has more than one and a half kilometers of cables. So the solution, that the OEMs developed with the semiconductor [companies], is the architecture and the components that support what's called the zonal architecture.

Marvell-zonal architecture 2-22-23[78].jpg

Q: How does that work?

Amir Bar-Niv: We divided the car into zones, so in this case, we see six zones, two in the front, two in the middle, and two in the back in each zone. You still have all the different agents of the different domains, but they are connected now to a gateway which is really an Ethernet switch that aggregates all the traffic from all these devices and then send it on a single pair of very thin Ethernet cable at the high speed, which is the backbone of the car.

That was the first step, the transition, to reduce the cable harness in order to make sure that the backbone is an Ethernet and then you don't need to run the long cables that need to run back and forth in the car.

Q: Are there benefits beyond the reduction in wiring?

Amir Bar-Niv: Once we move to zonal architecture, part of this transition will develop a lot of other advantages, that are based on the fact that the whole backbone is now Ethernet-based. First of all, we could now start to think of central compute. Each zone has its own compute, and usually, it's on storage now that we have everything connected through Ethernet.

We start to think maybe one or two or three compute entities are now controlling the whole car. That's important because it's also related to leveraging software.

When you move from one model to another, and you have a central compute, it's easier to leverage the software. That's also related to storage. Instead of having storage in each of those devices, and sometimes even in different areas on the car. You have one potentially you can have one central storage that serves all the different domains inside the car.

Now it's all become secure. We didn't have much security between the domains because the vendors use different protocols. But everything is based on the Ethernet. We use the security of Ethernet to secure the whole backbone of the car.

Q: What about simpler lower-end cars?

Amir Bar-Niv: It's the scalability that you can employ. Let's say you start with a high-end car and now you want to design another model that is very low end. You can say, “I don't want six zones. I want three zones.” Very easy, because Ethernet can adapt itself to the new architecture, and the other intelligent nodes that were on the network like the virtualization, that is part of Ethernet and everything else that is part of this promise of this Ethernet-based backbone.

Marvell-zonal architecture 2-22-23[79].jpg

Q: When do you think we will see these cars in showrooms?

Amir Bar-Niv: Everyone is talking about it, but we want to see when. We have a very interesting survey that was done by one of the Tier Ones that we worked with, which showed here the percentage of OEMs that are moving to zones. They did it with about 23 to 25 of the biggest OEMs, all around the world. What they're showing is that by 2026 50 percent of the OEMs are already going to market.

But what's interesting is that this is a survey that was done in 2021. In the second one with the same OEMs in 2022, this is what they found out: it's moving much faster than everyone thought as a matter of fact, now it's close to 80 percent by 2026 of the OEMs will be fully zonal or semi-zonal depending on how they develop their nervous system. And by 2029, it will be close to 96 percent.

Q: And this will start with high-end models first?

Amir Bar-Niv: Like everything new and advanced and you know, with different types of new capabilities, it starts with the high end.  Zonal architecture already started. I think that now it is gradually moving to the mid-end. Just the mid-and the high-end cars, you know, it's already tens of millions of cars that can justify all their effort. It's a market that is big enough already even with [only] the high-end and mid cars.

Q: And the carmakers’ motivation here is the savings from the simplification of the wiring harness?

Amir Bar-Niv: Originally the intention was to reduce the cost of the cable harness. What you did is you replace cable with silicon because now you need to have more switches and more files and higher speed. So obviously it saves on the cable harness but you add more silicon. But it's adding so much so many capabilities, new capabilities, to the car so some of the OEMs don't even care anymore about the savings on the cable harness.

The cable harness, by the way, has two things: one is the cost but also the weight. If [Ethernet] is in the car, it has a longer range, because of its lower weight. This is exactly what they're looking for. I don't think overall it will reduce the total cost of the system in the car. But the idea is that it's adding a lot of capabilities that were not there before it was a zonal architecture.

About the Author(s)

Dan Carney

Senior Editor, Design News

Dan’s coverage of the auto industry over three decades has taken him to the racetracks, automotive engineering centers, vehicle simulators, wind tunnels, and crash-test labs of the world.

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