Key technology fibre optics: speed of light in the software-defined vehicle

Data networks with fibre optic connections are already widely used at home or in the office if high data transmission speeds are required. In the automotive sector, however, fibre optic technology is only just on the verge of a breakthrough.

The technology group ZF has further developed its high-performance computer ProAI for optical multi-gigabit Ethernet in automotive applications. With newly developed chips and connectors, data can be transmitted via automotive-grade optical fibres in accordance with the IEEE 802.3cz standard. ‘This ultra-fast transmission is a key technology for future on-board networks of software-defined vehicles,’ explains Oliver Briemle, Head of Cross-Domain Computing at ZF. The technology enables both short and long-distance transmissions of up to 40 metres. Series production is possible as early as next year.

Optical multi-gigabit Ethernet offers considerable advantages for various vehicle classes. Intensive tests have confirmed the suitability of this technology for use in cars, lorries, buses and shuttles and have proven its robustness under various operating conditions. The results show that optical multi-gigabit Ethernet is a versatile and future-proof solution for data communication.

Basics of optical data transmission

Optical data transmission is a key technology used in many modern communication systems, including the automotive industry. It is based on the transmission of light signals via fibre optic or plastic fibre optic cables. Fibre optic cables offer high bandwidth and low losses.

The propagation of light in these fibres is based on the principle of total internal reflection. When light enters the fibre, it is reflected at the interfaces between the core and cladding of the fibre, causing it to remain trapped in the core and propagate along the fibre.

Optical data transmission in the automotive industry

High data transmission rates and reliability are advantages of optical data transmission systems in the automotive industry. Optical systems such as ‘Media Oriented Systems Transport’, or MOST for short, were introduced in the automotive sector around 20 years ago. These older systems relied on polymer fibres as the physical layer for data transmission. In contrast, the new standards, such as the optical multi-gigabit Ethernet according to IEEE 802.3cz-2023, are based on glass fibres, which offer a higher bandwidth and lower losses.

ZF sees the following main advantages in the use of optical multi-gigabit Ethernet for the automotive industry:

1. High data transfer rates: The standard supports data transfer rates of 2.5 Gbit/s, 5 Gbit/s, 10 Gbit/s, 25 Gbit/s and 50 Gbit/s. These high speeds are crucial to cope with the growing data volumes generated by modern applications such as autonomous driving (ADAS), infotainment (IVI) and networked services.
2. Increased transmission distance: The new standards enable a significantly greater transmission distance compared to older optical systems or copper-based data transmission systems. Optical multi-gigabit Ethernet can transmit data over distances of up to 40 metres, which is suitable for both short- and long-range applications in all types of vehicles.
3. Weight saving: Compared to copper cables, the use of fibre optics significantly reduces weight, which in turn helps to reduce fleet consumption.
4. Reliability and longevity: The use of optical fibres (OM3) in accordance with the IEEE 802.3cz-2023 standard improves the reliability and longevity of data transmission systems. Glass fibres are not susceptible to electromagnetic interference and offer stable data transmission even under extreme environmental conditions. Galvanically isolated data communication between different voltage levels can also be realised. They are also more resistant to ageing problems, which enables long-term use.
5. Energy efficiency: Optical data transmission systems based on the IEEE 802.3cz-2023 standard are more energy-efficient than conventional copper-based systems. They require less energy for data transmission, which leads to a reduction in overall energy consumption in the vehicle. This is particularly important for modern automobiles, where energy efficiency plays a decisive role.
6. Scalability and future-proofing: Optical multi-gigabit Ethernet is future-proof and scalable, as it is possible to upgrade new high-performance computers (HPCs), electronic control units (ECUs) and multi-domain computers (MDCs) to higher data transmission speeds without having to change the existing optical cabling components. This facilitates the integration of new technologies and functions in future vehicle generations and ensures that the systems fulfil the increasing requirements.
7. Lower costs due to high production volumes: The OM3 optical fibres specified in the IEEE 802.3cz-2023 standard are widely used worldwide and are already being produced in large quantities. The current high production volumes of VCSELs (laser diodes) and photodiodes for use in the specified wavelengths are also very high. This leads to cost savings in production and makes the technology economically attractive for series use in the automotive industry.

Improved communication channels: Optical multi-gigabit Ethernet offers almost ideal communication channels with low physical layer complexity. This results in lower equalisation complexity, no echo cancellation and therefore lower power consumption, lower latency and more cost-effective solutions overall. A specially dedicated operation, administration and maintenance channel (OAM) also ensures high reliability and efficient link management.

You can read this and other articles on the topic of electromobility & autonomous driving in the current issue of eMove360° magazine in german language. Download the free PDF or order the print version in the shop.

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