4 challenges of designing communications systems with automotive Ethernet
Electrification, autonomous driving, cloud connectivity – these are just a few of the major trends that are having a significant impact on the way automobiles are designed and manufactured today. By 2025, it’s estimated that plug-in electric cars will comprise 23% of new passenger vehicle sales globally, and about 75% will be fully electric.
But that’s not all that’s changing. McKinsey projects that up to 15% of new cars sold in 2030 could be fully autonomous – and that will require seamless Vehicle-to-Everything (V2X) communication over cellular and dedicated short-range communication (DSRC) networks, as well as cloud connectivity for real-time data transfer.
All of these requirements drive up complexity and cost. As a result, network communication architectures are evolving to provide scale and efficiency, along with additional processing power and performance.
However, even as networking architectures evolve, traditional protocols are still central to the communications network. These protocols must support AUTOSAR, the industry’s de facto standard for automotive design. Automotive Ethernet is increasingly being used in automotive network design because of its ability to provide the necessary bandwidth for cameras, sensors and other new technologies. An established protocol, automotive Ethernet is well understood among developers and provides a common network stack that’s suitable for handling gateway traffic between protocols.
However there are several design challenges associated with using Ethernet as the communication protocol for automotive networks. Here are four of them:
Signal-based or SOA?
A primary consideration is whether to use a service-oriented architecture (SOA) or a signal-based architecture. SOAs offer better flexibility, scalability and reusability, but have higher resource needs, and securing them can be costly. Signal-based architectures are mature and stable, but they’re not really cloud-compatible and cannot process complex data. A hybrid approach is common, because it optimizes performance for various domains. However, it can add CPU load to the ECU.
Quality of Service (QoS)
The Ethernet backbone connects various domains, each with different requirements for bandwidth, latency, safety and cost – and there are eight traffic classes to determine the priority of traffic in the automotive network. Allocating bandwidth according to these classes is critical for delivering on QoS. For example, about 90% of automotive control data isn’t critical, and latency will not impact safety or performance. This “best-effort traffic” must take a backseat to high-priority traffic.
There are several legislative and safety retirements when it comes to the timing of signals between the sensor and the actuator (i.e. between the stimulus and the response). As traffic travels through various communication buses and gateways, latency builds, which can be extremely dangerous for many functions. It’s critical to analyze the timing of different functions to ensure that signals arrive on time and no data is lost.
Many designs that leverage an Ethernet backbone experience data loss, so it’s important to understand where bottlenecks may lie, and how to ensure QoS for critical functions. There are multiple protocols, traffic classes, switches and other parameters to balance.
Model-based E/E systems development with Siemens Capital enables design teams to control performance, safety, reliability, weight and costs by developing software in a platform context. This makes early validation of the network communication system possible, while automating software integration with an AUTOSAR methodology.
Using Capital for Communication Network Design
Building systems using Ethernet is no simple task, but Siemens Capital helps to optimize communication design in the following ways:
- Provides insights into design efficiency with a single, automated tool
- Simplifies collaboration throughout the design lifecycle
- Supports all modern protocols, and enables hybrid architectures
- Enables early design verification, including timing analysis to ensure deliverability
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