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Could the U.S. Lose Vehicle Safety Applications?

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May 18, 2021—On Nov. 18, 2020, the Federal Communications Commission unanimously voted to reallocate a majority of the 5.9 GHz band away from connected vehicle technologies.

Sounds complicated, right? Well, here’s a little more background: The vote makes the lower 45 megahertz available for WiFi use and the upper 30 MHz available for cellular vehicle-to-everything (C-V2X) technology.

That’s all to say that a significant amount of bandwidth was reallocated away from potential connected vehicle technologies and instead to WiFi.

In a statement, DoT said it, "is deeply concerned about the Federal Communications Commission’s Report and Order to transfer 60 percent of existing transportation safety spectrum from the 5.9 GHz ‘Safety Band’ for unlicensed Wi-Fi uses. For the USDOT, our top priority is safety, including reducing the number of injuries and fatalities resulting from crashes. Dedicated spectrum, such as that currently provided by the Safety Band, is vital to enabling critical safety advances through connected vehicle technology.

"The entire dedicated spectrum in the Safety Band is needed for ‘Vehicle to Everything’ (V2X) communications to deliver the full range of safety benefits," DoT added. "One aspect of V2X would enable connected vehicles to communicate with each other and to alert drivers to imminent hazards. The American auto industry has committed to installing at least 5 million such devices in the next five years.

“Another aspect of V2X would empower ‘smart’ infrastructure to reduce traffic congestion, provide quicker first responder dispatch, and assist with roadway management. These technologies are already being deployed across the country. Without enough shared spectrum, the American people may miss these opportunities and fall further behind foreign competitors who are expanding their dedicated safety spectrum.”

During the vote, Commissioners stressed that the spectrum has gone largely unused since the Commission allocated it to DSRC more than 20 years ago, and that the need for more WiFi bandwidth was imminent.

In response, both the House transportation infrastructure committee chair and officials from the US DOT have both written letters to the FCC expressing concern regarding the reallocation of the lower 45 megahertz and the limited spectrum it would provide.

On a recent webinar from the University of Michigan, Shailen Bhatt, president and CEO of Intelligent Transportation Society of America, said, “It’s the best of times and the worst of times. The technology is finally at a point now where we’re able to look at deployment and you can look at connectivity. The V2X part is incredibly important. It’s connecting vehicles to pedestrians and infrastructure, and it’s paving the way.”

Sue Bai of Honda went so far as to say, “I really have trouble understanding how the U.S. can be a connected automation technology leader moving forward in the world, when we’re lacking spectrum to do that.”

The problem comes down to the effect that a more limited spectrum would have. Bai emphasized that it’s damaging to both future and current safety applications, because an influx of vehicles on one channel could diminish the quality of the communication. In fact, it would diminish the quality and create interference in more than 27 states.

”We’re already seeing an impact of the FCC’s action,” says Ken Leonard of the U.S. DOT. “All those apps are potentially at risk as you try to jam fewer apps and safety messages into too small of a bandwidth that is already being interfered upon. We don’t know yet whether what the FCC has proposed will work. So I wouldn't expect to see a rush of states deploy making changes based on what we know about the report and order.”

Bhatt suggested that sharing the full 75 megahertz bandwidth would be preferable—as long as a lack of leakages could be guaranteed.  

“We’ve been working to study which V2X messages and apps can function in a 30 megahertz environment,” he says. “Limited V2X applications can function in 30 megahertz but a number of safety tools would be lost, including advanced vehicle-to-pedestrian applications and collective perception messages.”

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