FCC Actions, Incompatible Options Muddy V2X Outlook

February 24, 2020

Terry Costlow

Vehicle-to-vehicle/infrastructure (V2X) communications often is touted as a critical technology for automated driving and even to derive the utmost benefit from advanced driver-assistance systems (ADAS). But despite plenty of verbal support from industry developers, there’s been little actual deployment. What critics label “foot-dragging” by the industry may catastrophically stall market implementation.

V2X technology had a bright future in 1999, when the FCC allocated 75 megahertz of spectrum in the 5.9 GHz radio band for Dedicated Short-Range Communications (DSRC). Years of development and demonstrations seemed ready to pay off in 2014 when the National Highway Traffic Safety Administration (NHTSA) appeared ready to issue a mandate requiring deployment. But the U.S. mandate never came, nor did a European edict. That created uncertainty that led to chaos in the market.

Now, DSRC proponents are trying to stymie an FCC plan to sell a portion of the 5.9 GHz range originally earmarked only for transportation purposes. Then came another wild card. While DSRC languished, a cellular-based alternative, cellular V2X (CV2X) came onto the scene. Though there’s uncertainty about the prospects of V2X, advocates say the technology can do a lot to prevent accidents today and improve the operations of autonomous vehicles when they emerge.

“Driverless vehicles cannot exist without being connected,” said Guillaume Devauchelle, innovation and scientific development vice president at Valeo. “When you’re running at high speed, it tells you about things happening at distances that are far longer than on-vehicle sensors [can detect]. That helps guarantee safety and it makes driving more pleasant. You can slow down one kilometer before construction work instead of quickly stopping when you get close.”

At the SAE Government/Industry Meeting in Washington in January, Continental’s Bettina Erdem explained that 45% of all accidents occur at intersections, where V2X can provide far more safety-related information than on-vehicle sensors. She highlighted the importance of V2X by saying that 60% of serious and fatal intersection accidents cannot be prevented by onboard safety systems, they need V2X input.

Though it’s largely viewed as an important element in safety and autonomy, V2X has to date seen little acceptance. Volkswagen has announced plans to ship cars with DSRC capability, but Toyota scuttled its plans to deploy DSRC in the U.S. Still, proponents feel there are many reasons to deploy.

While OEMs and infrastructure providers waited for DSRC to catch fire, others stepped into the void. Industries hungry for more wireless bandwidth convinced the FCC to sell some of the spectrum set aside for DSRC, while concurrently, mobile-phone suppliers developed CV2X, which leverages on-board modems to provide many of benefits of DSRC with reduced design-in and dedicated infrastructure costs.

Bandwidth for sale

FCC Chairman Ajit Pai proposed making the lower 45 MHz of the 5.9 GHz band available for unlicensed uses such as Wi-Fi, while retaining the upper 25 MHz of the 5.9 GHz spectrum for CV2X. The upsides of the potential sale could be significant. A 2018 study by the Rand Corp. estimated that opening automotive’s 5.9 GHz band for Wi-Fi could provide gains to economic welfare for consumers and producers that range from $82.2 to $189.9 billion.

The proposed auction is equally huge for DSRC’s outlook. If the FCC proceeds with its plan and the bandwidth is used for non-automotive services, interference from Wi-Fi could render the V2X spectrum “useless,” according to John Kenney, director and senior principal researcher at Toyota InfoTech Labs. He told attendees at the SAE conference that if automotive lost 60% of V2X spectrum, the industry would lose 60% of potential V2X benefits.

Proponents need to quickly coalesce around a workable deployment strategy, he added. “There needs to be a consensus regarding V2X technology or people are not going to deploy. Once we have a consensus, we can go to the FCC and say, ‘This is what we want you to do.’” Kenney said.

While the FCC ponders its auction, fellow government officials at NHTSA contend that the auto industry needs the bandwidth in question; NHTSA division chief Bob Kreeb predicted that selling the bandwidth will “limit deployment of existing technology that’s ready and usable. We’re disappointed in the FCC’s current proposal that they’ve outlined. We also think it’s going to limit innovation and creativity.”

Another plus for DSRC is that it’s undergone plenty of real-world testing, which helped developers weed out bugs and verify performance. Maturity often is a desired trait given the high reliability levels demanded in automotive markets. Supporters also note that DSRC has far better latency performance than CV2X, which can be critical in high-speed safety environments.

“Some of the key performance parameters of CV2X are not as good as DSRC,” said Huanyu Gu, senior product manager for V2X at NXP Semiconductors. “While over time CV2X performance may further improve, it will take many more years. The question is: Should society be kept waiting for C-V2X to mature, while the mature technology DSRC is ready for deployment?”

Cellular challenge

The challenge from CV2X began gaining ground around 2017. Cellular and chip providers created specifications and groups such as the 5G Automotive Association (5GAA) voiced endorsement. Regulators in the world’s largest Chinese automotive market are actively supporting the technology, and Tier 1 suppliers are following suit now that a Chinese mandate appears imminent.

“China represents about one third of the market; everyone will have to develop CV2X for China,” Devauchelle said. “In the U.S. and Europe, it’s difficult to invest. It’s not that one is that much better, it’s more a matter of regulations and a battle between different stakeholders.” Momentum for CV2X also comes from Ford, which is planning CV2X rollouts while supporting the FCC’s spectrum auction. On the semiconductor side, major cellular chip suppliers including Qualcomm, Intel, Samsung, Huawei and CATT/Datang S have 5GAA’s CV2X technology in their road maps.

Foggy future

Support for both DSRC and CV2x creates questions for product planners at all levels. Design teams don’t want to support different technologies in various geographies. That adds complexity for design and support teams. On the upside, the price of implementing either option isn’t too onerous. “The add-on cost to equip a car is around $15-$20, it’s not that high,” Devauchelle said.

Automakers would like to see one technology emerge globally so they can trim overhead and benefit from volume pricing. As the two specifications vie for acceptance, only one can operate efficiently in each region. The benefits of V2X grow as more cars and roadside beacons share data. Nor is it practical for a country or region to have vehicles with incompatible technologies sharing the roads. Accidents could still happen when vehicles with different technologies encounter one another.

“Cars that utilize different technologies cannot ‘talk’ to each other, which greatly compromises the effectiveness of each technology,” Gu said. “To utilize both technologies within a given region, a theoretical solution could be to equip V2X stations that support both technologies and translate one into the other. The additional latency caused by translating one standard to the other will likely make such a solution a non-starter for safety-critical applications.”

All the uncertainty surrounding V2X is driving some autonomous vehicle developers to eschew the technology. TuSimple, a trucking startup that plans to begin delivering freight hauled by its driverless vehicles next year, isn’t settling on either technology. Instead, design teams will rely strictly on on-vehicle sensors. “V2X is nice to have, but we must be able to determine our surroundings without it,” said Chuck Price, TuSimple’s chief product officer. “Even if we just talk to our own vehicles, V2V can enhance operations. But given all the things that can happen, we have to assume we can’t talk to other vehicles.”

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