In-Vehicle Optical Multi-Gigabit Communications: Page 2 of 3

August 26, 2019 //By César Esteban, KDPOF
In-Vehicle Optical Multi-Gigabit Communications
10GBASE-SR is the current standard by IEEE that establishes a communications channel in optical fiber at 10 Gbps. Although well-established for industrial use, it is not suitable for automotive applications. Reasons are the temperatures and live ranges, among others, the industry demands. Consequently, a new automotive standard is urgently required.

Automotive Requirement: Harsh Environment

For automotive, the number of in-line connections is larger than supported by 10 GBASE-SR. In addition, the insertion loss of in-line connections is going to be larger due to dust, aging, and cost restrictions.

Vibration

Currently available in-line connectors increase their insertion loss when vibrations are present. Thus, the number of allowable connectors will be reduced for a 10GBASE-SR link.

Aging

Present fiber and connectors age quickly when operated in a harsh automotive environment. This translates into a link power budget degradation (shorter lengths and/or fewer in-liners).

Dust

Modern connectors are not designed to withstand automotive dust specifications. As a result, they will get soiled and insertion losses will be increased (smaller number of in-liners and/or shorter link length allowed).

Dynamic Temperature Changes

Automotive applications require the communications system to adapt to quick temperature changes without any impact on the error rate or link performance. This means that the system needs to adapt its operation depending on the operating temperature. This is not possible with 10GBASE-SR: the system remains the same when temperatures change, and the impact on the performance translates into different parameter degradations such as link length, error rate, etc.


10GBASE-SR, the current standard by IEEE that establishes a communications
channel in optical fiber at 10 Gbps, is well-established for
industrial use but does not meet the stringent requirements
for automotive applications.

Further Automotive Requirements

There are also further automotive requirements that affect 10GBASE-SR and make it unsuitable for in-vehicle usage.

Harness Routing

Automotive environments involve a high number of in-line connectors (up to 4) in a single link. This is not the case for applications that 10GBASE-SR was designed for. Automotive routing practices are aggressive with tight bends, which 10GBASE-SR also does not support.

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