Lawmaker raises alarm bells over 5.9 GHz, C-band

Concerns about the 5.9 GHz band came up again during a hearing of the House Committee on Transportation and Infrastructure, where U.S. Department of Transportation Secretary Pete Buttigieg gave testimony on Thursday.

But that wasn’t all. The chair of the committee, Rep. Peter DeFazio, D-Oregon, reiterated his concerns about potential interference from 5G in the C-band – the very band where the likes of Verizon and AT&T just pledged over $80 billion for access to airwaves for 5G. The spectrum currently is used by satellite companies that need to move to the upper part of the band in order to make room for 5G.

Generally speaking, DeFazio said there are two spectrum issues in play: one is ground-based and one is based in space.  

Regarding the C-band, “unfortunately, it was auctioned, but we’re going to have be absolutely certain before it’s implemented [that] we’re not going to lose GPS and radio altimeters because someone wants to make money selling a service so people can see things more quickly on their cell phones,” he said near the start of the hearing, which covered a range of transportation issues.

DeFazio’s concerns about radar altimeters are not new, as aviation officials brought them to the attention of the FCC years ago.

RELATED: Aviation community worries about possible effects of 5G in C-band

Last December, before the C-band auction got underway, DeFazio sent a letter to then-FCC Chairman Ajit Pai urging a delay until further study could be done to understand the full extent and severity of 5G interference. Radio altimeters operating in the 4.2-4.4 GHz band provide pilots with precise measurement of an aircraft’s height above the surface when the aircraft is within 2,500 feet of the ground.

DeFazio acknowledged that the FCC left a 220-megahertz guard band between the auctioned C-band spectrum and the aviation band, but said more recent research shows that’s not enough protection.

Regarding DeFazio’s question about the C-band, Buttigieg replied that “we are very concerned about the potential for harmful interference to radar altimeters, which are, as you know, very important on commercial transport aircraft, general aviation aircraft, business jets, helicopters and increasingly, UAVs. So we’ll be working to ensure that we’re having the right posture” with the inter-agency conversations and conversations with industry, with safety being the No. 1 priority.

On the 5.9 GHz issue, the Department of Transportation, under the prior administration, clashed with the FCC over plans to use spectrum set aside for Dedicated Short Range Communications (DSRC) more than 20 years ago. After years of kicking ideas, tests and studies around, the FCC last year finally voted to make 45 megahertz available for unlicensed use and designated another 30 MHz for auto safety, specifically Cellular Vehicle-to-Everything (C-V2X) technology.

DeFazio expressed his hope that the Biden administration will re-engage with the FCC on this and other issues.

Buttigieg said the 5.9 GHz band, often known as the “safety band,” is a very important priority for transportation communications and public safety. He said he knows the prior administration voiced its concerns and there’s been bipartisan concern about it within the committee.

“We share that concern. We’re going to be engaging with counterparts across the administration on a way forward” and try to establish the best way to handle and share the spectrum, he said.

RELATED: FCC votes to open 5.9 GHz for Wi-Fi, C-V2X

It’s worth noting that three out of the four current commissioners voted for moving ahead on the FCC’s 5.9 GHz plan, and Acting Chairwoman Jessica Rosenworcel spent years, along with then-Commissioner Michael O’Rielly, advocating for changes to the band They often cited the need for more Wi-Fi spectrum and the auto industry’s idleness when it came to using the entire 75 megahertz that was once allocated to them.

DeFazio sent a letter to Rosenworcel earlier this month reiterating his opposition to the FCC’s decision to share the 5.9 GHz band with unlicensed Wi-Fi. In recent weeks, transportation and public safety groups also have expressed their worries about the FCC’s efforts to reallocate spectrum in the 5.9 GHz band, saying it reduces the amount of spectrum available to Vehicle-to-Everything (V2X) technology.

In response to concerns of the Intelligent Transportation Society of America (ITS America) and the American Association of State Highway and Transportation Officials (AASHTO), several other groups reached out to Buttigieg, saying the auto industry had plenty of time to use the spectrum and failed to produce any real-world safety benefits.

“For ITS America and AASHTO now to ask the Administration to intervene with Congress in an effort to overrule the technical analysis and unanimous decision of an independent regulator, after 20 years of illusory promises, is nothing short of breathtaking,” their letter states. “The country cannot afford for the Administration or Congress to fall prey to another generation of smoke and mirrors. We urge you to decline their invitation to undermine the FCC’s independence and its careful technical judgment.”