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Benefits of time-sensitive networking over Ethernet

Posted: 09 Feb 2016 ?? ?Print Version ?Bookmark and Share

Keywords:Time-sensitive networking? TSN? Advanced Driver Assistance System? ADAS? Ethernet?

Time-sensitive networking (TSN) is not exactly a new topic but an area that has certainly been attracting a lot of attention in the recent years, especially in the automotive market. A collection of Ethernet sub-standards, TSN enables deterministic real-time communication over Ethernet. As more and more systems are incorporated into cars, the need for TSN increases. These systems are often being re-engineered and shifting from hydro-mechanical to electro-mechanical, creating the need for more software and dependencies between the systems. To add to the complexity, hundreds of automotive systems must communicate with one another, while maintaining safety and reliability. To successfully deliver these systems, designers should understand current and emerging automotive technologies that require TSN over Ethernet, and how IP can be leveraged to meet the complex requirements.

Today's automotive networking landscape and challenges
In today's car, everything from the engine to the electronics is being re-engineered to enable many new applications such as collision avoidance, automatic parking, in-vehicle infotainment and Advanced Driver Assistance System (ADAS). As always, re-engineering introduces many challenges. Increasing software and hardware content that is more interdependent, product quality and reliability that complies with the ISO-26262 standard, and interoperability of aftermarket products that does not compromise security are all critical. In addition, meeting drivers' expectations to have their cars become automotive living rooms that offer quick access to their contacts, music, social networks, app ecosystem and more, is becoming mandatory. All this can only be achieved by the convergence of data traffic into a single network in the car.

To handle the massive amount of data in the car, it is compressed as it travels from one system to another. For example, a car's rear camera collects the data and then compresses and transmits it to the in-vehicle infotainment system display where it is uncompressed for the driver's viewing. Additional hardware is needed to execute the compression, which is not ideal. By enabling a gigabit network, the need for compression and the additional hardware is eliminated and, ultimately, reduces the system cost.

To enable a fast and reliable communication between the systems, designers can choose from several popular networking technologies such as controller area network (CAN), Ethernet, Local Interconnect Network (LIN), WiFi and FlexRay. According to a December 2014 Gartner survey, the top two anticipated in-vehicle networking technologies by 2023 will be CAN and Ethernet, in that order. CAN is the networking technology of choice for safety-critical systems, however Ethernet has substantially closed the gap in rankings as a viable networking technology option for today's as well as tomorrow's designs.

Emerging technology trends in the car
Historically, drivers focused more on their car's engine size and horsepower. Today's driver is interested in the car's technology features such as autonomous driving, infotainment and connectivity options.

Semi-autonomous cars are expected to be available in the not too distant future. Companies like Mercedes Benz, Volvo and Google have been testing vehicles on the road for some time. These cars can feature technologies such as vehicle-2-vehicle and vehicle-2-infrasturcture communication that notify the driver about road hazards and conditions. For example, the driver can be alerted when an emergency vehicle is approaching a nearby traffic light or when an oncoming car is about to turn into their path. Having this level of real-time communication gives drivers a safer driving experience and also enables municipalities to build a more robust infrastructure.

As deterministic real-time communication becomes necessary, especially in critical applications such as ADAS, TSN over Ethernet becomes an ideal networking choice. For example in ADAS, the systems need to account for the break distance and human reaction time for when drivers have to take over. To enable ADAS, multiple systems must synchronise, which requires a lot of data to be deployed over the network. If you consider a collision avoidance system like the Subaru EyeSight system, when an obstacle is detected, the driver is notified and the breaking system is applied. Communication between the detection and breaking systems is critical and delays in applying the breaks could be catastrophic.

Benefits of TSN over Ethernet
Why is Ethernet becoming a more popular networking technology? According to a December 2014 survey by Gartner, the benefits of the automotive Ethernet technology are:

???Long-term usefulness to address growing in-vehicle data communication needs
???Lower cost for in-vehicle data communication per vehicle
???Ability to enable new data-centric services and applications for end users
???Faster time-to-market
???Reduced wiring complexity and positive impact on assembly and engineering processes
???Improved diagnostics connectivity and software update capabilities
???Improved in-vehicle data communication reliability
???Improved customer experiences
???Enhanced product differentiation

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