Chairman Ajit Pai denied a last-minute request by Commerce Secretary WIlbus Ross and NASA Administrator Jim Bridenstine to postpone a 5G spectrum auction out of concern for weather satellite interference.

This article originally appeared in the March 25, 2019 issue of SpaceNews magazine.

The U.S. Federal Communications Commission began auctioning off radio frequency spectrum for 5G mobile networks right on schedule March 14 despite calls for further discussion and delay by NASA Administrator Jim Bridenstine, Commerce Secretary Wilbur Ross and leaders of congressional committees and subcommittees.

Far from ending the fight between members of the Trump administration who see 5G as an international economic race and meteorologists concerned about interference with weather satellite data, the auction was just round one. The FCC plans to auction additional spectrum this year and meet with international counterparts at the World Radiocommunication Conference in Egypt in October and November to hammer out rules for 5G.

What happens at the global conference is crucial to weather data producers and users because the FCC and its international counterparts will decide which bands to set aside for International Mobile Telephony for 2020, better known as 5G, and how strictly to limit interference. Nations will incorporate the new rules into domestic regulations.

“It’s important to note that global weather models use a worldwide data set,” said a weather data expert who asked not to be identified. “Interference that could contaminate any region of the world would impact everyone’s global model.”

Round One

Everyone involved in weather monitoring knew this fight was coming. President Donald Trump has made 5G a high priority. He tweeted in February he wanted “5G, and even 6G, technology in the United States as soon as possible.” Communications companies are investing billions of dollars in 5G equipment. And GSMA, the mobile communications trade association, estimates 5G will boost the global economy by $565 billion from 2020 to 2034.

Meanwhile, meteorologists and weather data consumers like the Automated Flood Warning Systems Users Group have been warning for years that satellite observations of atmospheric phenomenon could be threatened by interference from 5G transmitters.

Who is likely to win this contest?

“At times it feels like David and Goliath,” said Renee Leduc Clarke, founder of Narayan Strategy, a Washington-based weather and climate policy consulting firm. “The weather and water enterprise don’t have equivalent lobbying capabilities to the large telecom companies.”

Still, in round one, the weather community attracted allies. In recent years, scientists and their advocates struggled to gain the attention of administration officials, journalists and members of Congress to warn the rollout of 5G could compromise weather data transmission and retrieval.

“How do we tell the story of why spectrum matters to users of weather information,” Leduc Clare asked at the American Meteorological Society (AMS) annual meeting in January. “Microwave sounding is not the easiest concept.”

In the days leading up to the March 14 auction, microwave sounding became a frequent topic of discussion in Washington. In a Feb. 28 letter to FCC Chairman Ajit Pai, Bridenstine and Ross expressed concern that the FCC’s proposal for the World Radiocommunication Conference “would have a significant negative impact on the transmission of critical Earth science data — an American taxpayer investment spanning decades and billions of dollars.” Specifically, Bridenstine and Ross expressed concern about the 23.6 to 24 GHz spectrum band, a key data set for passive microwave sensors detecting atmospheric water vapor.

Leaders of the House Science, Space and Technology Committee and three House Appropriations subcommittees wrote Pai March 13, citing similar concerns and urging him to delay the March 14 auction.

Pai responded to Bridenstine and Ross angrily, declining an invitation to a meeting to discuss potential interference with weather sensors. Representatives of U.S. government agencies spent two years discussing the matter, Pai told Bridenstine and Ross in a March 8 letter. When they failed to come to an agreement on how much interference to allow, the FCC with State Department backing opted to retain the interference limits it established decades ago.

“The engineering suggests, and years of experience confirm that these protection limits enable us to have the best of both worlds, so to speak: They enable the 24 GHz band to be an American test bed for 5G innovation (and a signal to the world of American determination to lead on 5G), while protecting the important services that operate in other spectrum bands,” Pai wrote.

Members of Congress who asked the FCC to delay the auction got no response to their letters other than the FCC’s public comment on the matter.

“The FCC’s rules for this band went through the standard interagency coordination process, provide the necessary protection for other spectrum bands, and have been on the books since 2017,” FCC spokesman Brian Hart said by email. “It is therefore perplexing to be asked to postpone this auction the day before it is going to start. While our nation’s international competitors would undoubtedly be pleased if we delayed this auction of greenfield spectrum at the last minute, the FCC will move forward as planned so that our nation can win the race to 5G and the American people can quickly enjoy the benefits of the next generation of wireless connectivity.”

Round Two

5G promises to dramatically accelerate data transfer speeds and increase network capacity. It also promises the proliferation of network antennas on buildings, utility poles and cellphone towers.

Individual antennas won’t disrupt weather data retrieval but together they could produce enough noise to “mask the natural emissions detected by passive instruments in space,” a weather expert said.

The World Radiocommunication Conference will convene in Egypt in October and November to hammer out 5G rules. The last such gathering, WRC-15, was held held in Geneva in November 2015. Credit: ITU via Flickr
The World Radiocommunication Conference will convene in Egypt in October and November to hammer out 5G rules. The last such gathering, WRC-15, was held in Geneva in November 2015. Credit: ITU via Flickr

To prevent that from happening, global weather advocates are turning their attention to the upcoming World Radiocommunication Conference, a meeting the International Telecommunication Union holds every three to four years to revise spectrum rules. The international panel will decide what bandwidth to set aside for 5G and how much signals can spill over into adjacent bands.

Microwave sensors are especially vulnerable to interference because they pick up electromagnetic energy scattered by chemicals in Earth’s atmosphere. Between 1.37 and 1.427 GHz, for example, they monitor soil moisture and ocean salinity.

Malfunctioning circuits on Japanese direct broadcast satellite receivers already interfere with those sensors. Because they operate in the 1.4 to 1.47 GHz range, it is extremely difficult for the European Space Agency’s Soil Moisture and Ocean Salinity satellite and NASA’s Soil Moisture Active Passive satellite to monitor Japan, Sidharth Misra, microwave instrument scientist at NASA’s Jet Propulsion Laboratory, said at the AMS conference.

In Egypt, countries will share proposals for noise thresholds, or how much interference to allow. The FCC is proposing a threshold of -20 decibel watts. European regulators suggest a noise threshold of -56 decibel watts, which is nearly 4,000 times more stringent.

It’s worth noting that despite the Trump administration’s fixation with winning, it’s Europe, not the United States, that currently produces more accurate weather models, Leduc Clarke said.

“So much of the current administration is focused on winning. By trying to win on 5G in a tone-deaf way, they are going to hurt themselves in terms of future weather modeling,” she added.

Debra Werner is a correspondent for SpaceNews based in San Francisco. Debra earned a bachelor’s degree in communications from the University of California, Berkeley, and a master’s degree in Journalism from Northwestern University. She...