Wireless companies are starting to build next-generation 5G networks around the world. The new agreement is intended to allocate radio frequencies on which 5G equipment can transmit a signal. But some of these frequencies are dangerously close to the range used by meteorologists.
International standards for wireless technology could negatively impact very important satellite measurements of water vapor, meteorologists say.
The International Agency for the Regulation of World Telecommunications on November 21 agreed on new radio frequency standards. But meteorologists say the long-awaited decision poses a threat to weather forecasts around the world, as cellular networks will degrade the quality of Earth observations from space.
Wireless companies are embarking on a new generation of networks around the world known as 5G. The new agreement is intended to allocate radio frequencies on which 5G equipment can transmit a signal. But some of these frequencies are dangerously close to the range used by satellites to collect important weather and climate data. To prevent these signals from interfering with each other, scientists have proposed to reduce the allowed amount of interference generated during 5G transmission.
The participants in the meeting of the International Telecommunication Union, held in the Egyptian Sharm el-Sheikh, agreed to create two levels of protection for frequencies in the range of about 24 gigahertz. This range is close to the frequencies used by meteorological satellites, which determine the amount of water vapor in the atmosphere. 5G network operators will not have very strict standards and regulations until 2027. After that they will be tougher. The idea is for 5G companies to start building and developing their networks now, and then when the volume of transmission in their range increases, they will add additional protection measures.
But eight years without strict rules and regulations is a major concern for the meteorological service, said Eric Allaix, a meteorologist from Toulouse, who leads the World Meteorological Organization's radio frequency coordination group. According to him, WMO is so concerned about the current situation that it issued a statement on this matter, including it in the minutes of its meeting.
“The race for 5G is going too fast,” said Renee Leduc, a Washington-based consultant with Narayan Strategy for spectrum allocation. “Until the mid-2020s, we will see a surge Therefore, although additional protection measures will enter into force in 2027, I am very worried about the period until then."
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BUFFER ZONE
Transmission in 5G networks will be carried out on many frequencies, but the 23.8 GHz band is most often discussed. Water vapor in the atmosphere naturally generates a weak signal at this frequency, and satellites use it to measure air humidity. These data are included in weather forecasts. But if a 5G transmitting station transmits a signal at a frequency of 23.8 GHz, the weather satellite could mistake it for a signal of the presence of water vapor. And this erroneous data will negatively affect the quality of weather reports.
Meteorologists say the problem is solvable, but a noise buffer must be created between 5G transmissions and water vapor signals. This buffer is measured in decibel-watts and is akin to how you turn down the sound on your stereo so as not to disturb your neighbors.
Before the conference in Egypt, meteorologists, wireless companies, and government regulators were arguing over how to determine the appropriate level of interference. WMO insisted on the largest buffer at 55 decibel-watts. European regulators have agreed to a less stringent 42 dB-watt recommendation for 5G base stations. The US FCC was in favor of a less stringent 20 decibel-watt limit.
The harmonized standards are closest to European recommendations. Until September 1, 2027, they will be 33 decibel-watts, and after that 39 decibel-watts.
“These two values have been established as a result of lengthy negotiations between member countries,” World Meteorological Union adviser David Botha said in a November 22 media briefing. - The participants considered these values to be adequate in the sense that they would protect meteorological and Earth exploration satellites. However, we noted that we have certain concerns."
FORECASTING Trouble
Even a stricter level is not enough to eliminate interference with water vapor measurements, says Leduc. "39 is not the value it should be." NASA worked with the National Oceanic and Atmospheric Administration to study and find that base stations must transmit a noise buffer of 52.4 decibel-watts to reliably protect water vapor observations.
Meteorologists will have to think about how to reduce the negative impact on satellite observations. They may have to work with wireless companies to find ways to turn off or reroute 5G transmissions while the satellites take their measurements. Botha said the new agreement requires "continuous monitoring" of how 5G networks are affecting weather observations, but did not elaborate on what such monitoring entails, or what the implications will be if the quality of weather data deteriorates.
This week in Sharm el-Sheikh, other agreements were also signed, in particular on how quickly large constellations of satellites should be launched (so as not to interfere with the radio frequency spectrum), and on what frequencies "pseudo-satellites" (such as high-altitude airships and drones).
Alexandra Witze