Insight - Spectrum Interference: 5G and Meteorological Observations

Thursday, October 10, 2019

By Krystal Wilson, Director of Space Applications Programs and Josh Wolny, Project Manager

In the race to establish the 5G telecommunications network for enhanced cellular phone bandwidth, increasingly accurate weather forecasts may be a casualty. An on-going negotiation over radio frequency spectrum allocation, among different entities of the U.S. government and the wireless industry, continues to evolve as time runs out before the 2019 World Radiocommunications Conference which is being held October 28 - November 22, 2019, in Sharm El-Sheikh, Egypt. On October 1, 2019, at the Joint Satellite Conference in Boston, Secure World Foundation (SWF) hosted a panel discussion on this topic.

Spectrum is used all across the globe for the transmission of information and observation of phenomena. Television, microwave ovens, cellular communications, and WiFi join other non-domestic, non-commercial uses like military communications, deep-space observations, and even sensing of water vapor or temperature in the atmosphere from orbiting satellites. All of these various benefits derived from the use of the finite radio spectrum must be coordinated to avoid interference. Similar to chatting with a friend in a crowded public place, radio signals can be drowned out among other local noise.

To avoid interference, national regulators like the U.S. government’s Federal Communications Commission (FCC) and National Telecommunications and Information Administration (NTIA) manage spectrum usage for commercial and government purposes, respectively. Because radio signals do not respect national boundaries and coordinated regulation is good for international common usage, the International Telecommunication Union (ITU) serves as a forum for coordination and negotiation on spectrum issues. Every four years, a highly specialized community of experts gather at the ITU’s World Radiocommunication Conference (WRC) to reevaluate and possibly redesignate the global allocations of spectrum. The WRC-19 will see national delegations gather in Egypt at the end of this October for a month-long conference to decide highly technical minutiae that can make or break industries and established practices.

In recent years, improvements in the accuracy of weather forecasts has become as common as the release of new generations of smartphones. For example, in a presentation at the Joint Satellite Conference, Director General of the European Centre for Medium-Range Weather Forecasts (ECMWF) Dr. Florence Rabier cited the decisive impact of satellite data in her organization’s modeling of Hurricane Dorian. Emergency managers in Florida had such confidence in the information provided by the National Weather Service, including data from new-generation satellites and model data from both NOAA and ECMWF, that they correctly did not order massive evacuations, as was done in response to past forecasts of  hurricanes in proximity to the United States.

 Many of these improvements have come from innovative and enhanced uses of satellite data to better understand and model the behavior of the atmosphere. Space-based passive remote sensing of water vapor in the atmosphere by microwave sounders on environmental satellites provide critical data on the state of the atmosphere so that computer models can assist human meteorologists who then forecast the weather. All of these capabilities are underpinned by special allocations of spectrum that are reserved for the collection and transmission of hydrometeorological data. These spectrum allocations allow for real time rebroadcasts of geostationary weather satellite imagery and the transmission of NOAA data to academia and industry as well as to state and local governments and commercial weather partners. Data received through these allocations are paramount to achieving the best possible timeliness and quality of weather forecasts and warnings, are major contributors to weather and climate research, and improve the predictions from numerical weather prediction models.

While there are many spectrum matters related to 5G deployment that are up for decision at the WRC 2019, reallocations around the 24, 37 and 50 GHz or millimeter-wave bands have brought (or may yet bring) the meteorological community, telecommunications companies, and different parts of the U.S. government into conflict. Telecommunications companies have requested a reallocation of spectrum for 5G deployment near a passive sensing band that meteorologists rely upon as a key input to weather models.  The telecom companies are supported by the FCC and the factions of the current Administration that are focused on advancing 5G deployment in the United States in advance of other national 5G deployments around the world. The deployment of 5G requires considerably increased access to spectrum in multiple frequency ranges to support its bandwidth requirements, and the FCC and NTIA has prioritized identifying new areas of spectrum to reallocate for exclusive or shared access.

The disagreement comes from the amount of acceptable “emissions,” or essentially how loud, the 5G signals can be before they are disruptive to surrounding allocations. These nearby allocations are used for the sensing of water molecules in the atmosphere, which emit a natural, but very low level signal. The government entities most concerned about the impact on weather observations include the Department of Commerce and its sub-agency the National Oceanic and Atmospheric Administration (NOAA) as well as NASA, key areas of Department of Defense, and a growing bipartisan group of members of Congress. They argue that other spectral areas can fulfill the needs of the wireless industry, while also arguing for more stringent emissions standards on 5G bands adjoining the passive microwave bands to minimize impacts on numerical weather prediction. This conflict has played out in the buildup to WRC-19, but much of the analysis concerning acceptable protections has been restricted to within the government until recently.

On September 30, 2019, the Chairwoman of the House Committee on Science, Space, and Technology, Rep. Eddie Bernice Johnson (D-TX 30), sent a letter to the Chairman of the FCC, Ajit Pai, citing her Committee’s bipartisan concern about the potential for harmful interference stemming from the FCC’s position. This letter also contained the first public release of past studies by NOAA and NASA that suggest the need for more restrictive limits on out-of-band emissions than what was defined by the FCC in the auction of 24 GHz earlier this year. Earlier in 2019, Commerce Secretary Wilbur Ross and NASA Administrator Jim Bridenstine also corresponded with Chairman Pai on this issue, sharing technical analyses from their organizations. In a June hearing before the Senate Commerce, Science, and Transportation Committee, Chairman Pai dismissed the analyses, calling them flawed. Chairwoman Johnson’s recent letter requests any internal or external analysis that the FCC used to determine the flaws in the NOAA/NASA studies, and their out-of-band emissions thresholds be provided to their congressional committee.

In the days following Chairwoman Johnson’s letter, SWF’s panel of experts discussed the aforementioned background, future implications, and possible solutions to this challenging issue. Panelist Jordan Gerth, a Physical Scientist from NOAA’s National Weather Service Office of Observations, discussed the effects of unmitigated 5G expansion at the cost of meteorological observations, and pushed for increased engagement and advocacy from the members of the scientific community who rely up this data. Ryan Terry of Lockheed Martin suggested that spectrum sharing among Federal and commercial partners should be a two-way street, whereas historically sharing has been commercial entities gaining access to protected Federal spectrum. Elliot Eichen, the 2018-2019 IEEE Congressional fellow and former head of R&D at Verizon, outlined the contentious political history of this issue and proposed a technical solution for reducing signal noise as satellites pass over 5G regions. And David Lubar, of the Aerospace Corporation, gave a technical analysis on the need for noise reduction surrounding passive sensing bands. The panel discussion stressed the importance of this issue for the national weather enterprise and indicated that, no matter what is agreed to at the WRC, concerned stakeholders will need to continue to engage as 5G roll-out is only beginning. An audio recording and the event presentations are available on SWF’s event page here.

The topic of spectrum reallocations and out-of-band emissions is highly technical, and as has been demonstrated, also highly political. Because scientists and other users of weather data, such as the public, do not typically follow these complex and technical government spectrum proceedings, there is limited advocacy from those who could be impacted most and could best convey the true value of certain spectrum allocations for science. After WRC-19, future national spectrum regulatory development and implementation will require more public engagement, and this issue will likely continue to be hotly contested but hopefully resolved to accommodate all stakeholders.