The IEEE has published a standard for 50Gbit/s glass optical fibres in automotive designs.
IEEE 802.3cz-2023 (nGBASE-AU) standard adds Physical Layer specifications and management parameters from 2.5 to 50 Gbit/s operation on glass optical fibre in an automotive environment.
“As of today, the IEEE 802.3cz standard technology provides the only existing solution for 25 Gb/s and 50 Gb/s single lane connections with 4 inline connectors and a maximum length of 40 meters in the car over OM3 multimode fibre,” said Luis Manuel Torres, Principal System Architect at KDPOF in Spain and an active member at IEEE Standards Association.
The Ethernet Amendment 7: Physical Layer Specifications and Management Parameters for multi-gigabit glass optical fibre automotive Ethernet has been designed from scratch with the goal of meeting stringent automotive requirements and improving power consumption. In addition, it is more resilient to aging problems with future-proofing to allows ECUs to be upgraded to higher speeds while keeping the same harness.
“We’re very excited about this major milestone for optical automotive multi-gigabit Ethernet,” said Rubén Pérez de Aranda, KDPOF CTO and Co-founder, as well as IEEE Senior Member and active participant in the IEEE 802.3 working group. “The 802.3 Task Force includes numerous individuals affiliated with key carmakers, such as PSA, Toyota, BMW, Ford, GM, and Volvo; Tier 1 suppliers; and components suppliers.”
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The standard specifies speeds of 2.5, 5, 10, 25, and 50 Gbit/s per lane and meets automotive temperature requirements of -40 °C to +105 °C and OEM reliability requirements with a minimum of 15 years of operation with 10 FIT.
The maximum link length is 40 meters with four inline connectors and is designed to be affordable as the higher optical power budget allows lower tolerance connectors and the use of OM3 fibre for high volume production.
The lower diameter of the OM3 fibre results in significant cost efficiency. In comparison, copper-shielded differential pairs (SDP) proposed for 25GBASE-T1 are AWG26 (0.14 mm^2) and AWG24 (0.22 mm^2). For reference, the Cat 6A cable is usually AWG23. As no EMC shielding is needed, the optical connectors are smaller and mechanically more robust.
In contrast to copper, up to four inline connectors for a speed of 25Gbit/s and two inline connectors for 50Gbit/s can be inserted over a length of 40 meters. With copper it is only possible to insert two inline connectors with a maximum length of 11 meters and 25Gbit/s.
The communication channel allows a much simpler physical layer with a lower DSP/equalization complexity and no need for echo cancellation, resulting in lower power consumption, lower latency, a smaller silicon area, and overall lower-cost solution. A specially dedicated Operations, Administration, and Maintenance (OAM) side channel is available for dependability and link management.
The IEEE 802.3cz-2023 Standard is available for download at: https://standards.ieee.org/ieee/802.3cz/10918/