Will 5G rollout really bring autonomous driving to our streets?

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Phase 2 of the 5G rollout in the UK has begun – but can it really meet the requirements of autonomous vehicles, asks Martin Keenan, technical director at Avnet Abacus, in the article below:

Way back in mid 2019, UK operators EE and Vodafone announced new 5G networks were live. EE launched in six cities in May, Vodafone switched on 5G in seven UK cities in July 2019. However, behind the headlines was a simple fact – this was a Phase One launch, offering a blend of 4G and 5G connectivity. Since then, operators have been busy rolling out Phase Two, or 5G Standalone (SA), itself vital for autonomous vehicle operation.

Phase Two 5G is beginning
Phase Two is now beginning to become a reality, and this is where the fun really starts. Phase Two of 5G brings a vast array of benefits for a wide range of industries, including enhanced network response times critical for edge computing and AI, as well as ultra-reliable, low-latency communications. As a package, these enhancements are vital for the development of autonomous driving, so in many ways Phase 2 5G can be seen as the start of autonomous transport – purely from a network point of view.

However, the reality is somewhat more complex, especially when viewed from a wider, more global perspective. Autonomous vehicle operation is often viewed in connection with cellular vehicle-to-everything (C-V2X), which will in theory enable autonomous vehicles to connect with a huge variety of fixed and mobile infrastructure, such as traffic signals, street signs, bollards and other vehicles. This would reduce the processing required in the vehicle itself, and enhance safety enormously for more vulnerable road users and transportation methods. Standalone 5G is particularly important for C-V2X because of that very low latency, as well as the future opportunity to dedicate – via network slicing – a portion of any city-wide 5G network to road safety.

US spectrum wars raise questions
A potential issue with this concept came in late 2020, when controversial Trump-appointed Federal Communications Commission (FCC) chairman Ajit Pai proposed a rule change. The change was approved by the FCC on November 18, and allows the previously reserved 5.9GHz communications band for automotive safety applications to be used for other purposes. This band had been reserved for dedicated short-range communications (DSRC) between vehicles and infrastructure, or V2X, since 1999.

This move could potentially force US automotive manufacturers to abandon DSRC-based V2X entirely and adopt the 5G-based C-V2X, but with the loss of a decade-odd of deployment research in the balance, that may not prove palatable. In addition, C-V2X would still need extensive testing before trial public deployments could be officially sanctioned. Either way, the US market remains undecided between mandating either technology, with high-ranking officials citing differing points of view on social media. Pai left the FCC chairman role in January 2021.

Promising C-V2X trials across the globe
Despite this fragmentation, there are promising C-V2X trials going live across the globe, even in the USA itself. One recent example comes from a collaboration between Audi and a host of partners in the state of Georgia that uses C-V2X technology to demarcate and alert vehicles to school zones. The system involves an Audi E-Tron Sportback and a propane-powered Blue Bird school bus – both equipped with C-V2X -– which communicate with a roadside unit (RSU) built into school speed limit zone signs. This triggers warnings to the Audi driver to slow down, and more ingeniously, when the Blue Bird bus extends its stop arm, all local traffic is alerted that children are entering or leaving the bus. The 78.5-square mile trial zone includes more than 130 5G-connected traffic signals synchronized to the system.

Piggybacking existing LTE -– a short-term solution?
On the other side of the world, a partnership between Telstra, Ericsson and Lexus Australia in the state of Victoria has seen a C-V2X trial that even manages to achieve results using the existing LTE network. The higher latency of LTE was mitigated by the use of an optimized version of the 4G network designed by Telstra, which achieved end-to-end latency of less than 50ms in 95% of trials. The solution can be further enhanced with 5G URLLC (ultra-reliable low-latency communication) and edge compute technology, allowing more sophisticated solutions in the future, according to Ericsson, once Phase 2 5G rolls out. The trial is part of ‘Towards Zero’, the Victorian state’s vision to bring road deaths down to zero.

Direction of travel is broadly clear
In short, the rollout of Phase 2 5G will indeed enable the development of C-V2X at a level of sophistication that has not yet been reached by existing solutions. However, fragmentation and inertia will still be inhibitors, in spite of growing support for C-V2X in general. In addition, not all the key components of 5G are yet standardized – notably network slicing, which is due to be ratified in 2022. That said, while the destination may not have been reached, the signposts promise that we are getting closer…

Martin Keenan is the technical director at Avnet Abacus, which assists and informs design engineers in the latest technological challenges, including designing for Industry 4.0 and Industrial IoT manufacturing. 

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