Deterministic Ethernet for Automotive Applications

March 12, 2015 // By Wilfried Steiner, TTTech
Ethernet in the car is a reality today but it’s further technological and ecosystem developments will define to which extent it will be used in existing, emerging and future automotive subsystems.

While Automotive Ethernet is mostly used for diagnostics and data download today, new applications such as camera-vision systems and infotainment systems are emerging. In addition, there is a huge potential for Ethernet to also become the backbone network solution throughout the vehicle. This, in particular includes safety-related and safety-critical applications to enable piloted and autonomous driving which is a current major trend in automotive industry. To enable this, one possible evolution of Ethernet is Deterministic Ethernet.

While Ethernet provides Quality-of-Service (QoS), Deterministic Ethernet adds Guarantee-of-Service (GoS) in a sense that the communication service is guaranteed and robust even in presence of faulty components or after transient disturbances (like disturbances induced by electromagnetic interference). Furthermore, Deterministic Ethernet enables full control of the transmission and forwarding timing of selected Ethernet frames, typically frames for the highest critical applications. This control is achieved by the implementation of a system-wide clock synchronization protocol and pre-planning communication events for critical traffic.

Deterministic Ethernet solutions are available today for example from TTTech. TTTech’s version supports several standards including standard Ethernet (IEEE 802.3), Time-Triggered Ethernet (SAE AS6802) as well as AVB (Audio/Video Bridging) and the evolving TSN (Time Sensitive Networking). In particular the SAE AS6802 part of the solution has been developed to ensure correct clock-synchronization even in the presence of arbitrary single failures and to support standards such as DO 178, DO 254 and ISO 26262. The solution provides highest dependability properties and thanks to these it was also chosen as the on-board avionics network in the next generation of manned spacecraft Orion. Thus it can be said that using Deterministic Ethernet technology in the car provides basically a degree of astronaut safety for automotive passengers as well. Audi has already chosen Deterministic Ethernet for its next generation automated driving platform. To guarantee cost-effective Deterministic Ethernet solutions for the automotive market, NXP currently finalizes together with TTTech a first ASIC version of an automotive switch for Deterministic Ethernet.

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