FCC budget endorses spectrum sharing with weather satellites
This article originally appeared in the March 25, 2019 issue of SpaceNews magazine.
The Trump administration’s 2020 budget blueprint reiterates plans to allow wireless broadband to share a portion of the radio frequency spectrum currently reserved for geostationary weather satellite observations and terrestrial sensors monitoring flooding, air quality and wildfires.
The budget plan delivered to Congress March 11 proposes giving the FCC “authority to assign spectrum frequencies between 1675 and 1680 MHz for wireless broadband use subject to sharing arrangements with federal weather satellites.” The proposal is expected to raise $600 million in receipts over 10 years, according to the 150-page “Budget for a Better America.”
The document says this step would only be taken “following successful completion of the [NOAA] Spectrum Pipeline Plan,” which encourages federal agencies to make additional radio frequency spectrum available to private enterprises.
In North and South America, 28,000 sensors send data to NOAA’s Geostationary Operational Environmental Satellite (GOES) Data Collection System in the 401 MHz band. The satellites rebroadcast the information in the 1675 to 1680 MHz band.
“All flood warnings, coastal sensors, most storm surge warnings, wildfire weather information that protects the lives of firefighters and assists wildfire managers, some air quality sensors, some snow sensors are carried on GOES Data Collection System,” said a weather expert who asked not to be identified. “The navigation channel in many of the nation’s inland waterways is maintained using gauges relayed through the Data Collection System.”
Ligado Networks, the company formerly known as LightSquared, petitioned the FCC in 2016 to allow terrestrial communications to share 1675 to 1680 MHz with government users. Ligado is seeking the band along with other frequencies for its planned 5G wireless network linking cell towers with its SkyTerra-1 satellite.
“We commend the Administration and FCC for continuing to support the auctioning of this midband spectrum, which will be critical for next-generation technologies like 5G,” Ligado said in a statement to SpaceNews. “It will also establish a path to making public, critical weather data finally accessible to the entire American public.”
Instead of displacing NOAA traffic, Ligado proposes creating a “protection zone” near NOAA sites and moving NOAA weather data into a cloud-based network. Public, private and academic organizations involved in weather research and forecasting currently obtain imagery and data from GOES instruments through ground antennas. A cloud-based network would expand access to the data and free up spectrum for 5G networks, according to a 2018 Ligado video describing the plan.
Weather experts cite concerns with Ligado’s plan. “An inevitably stronger mobile network would easily interfere with GOES broadcasts,” said Jordan Gerth of the University of Wisconsin’s Cooperative Institute for Meteorological Satellite Studies.“Satellite signals are limited in power.”
Putting Ligado’s network in spectral bands next to bands reserved for weather satellites would be like putting a dance club in one room of a library, said Gerth who chairs the American Meteorological Society’s Committee on Radio Frequency Allocations. The walls would dampen the sound somewhat but “not enough to prevent it from disturbing the quiet of the reading room,” Gerth said.
As for the cloud-based network, meteorologists and weather researchers worry about speed and reliability.
The U.S. government’s service agreement for GOES rebroadcasts allows for only five minutes of downtime in a 30-day period and all outages to be resolved within five minutes, Gerth said at the American Meteorological Society’s annual meeting in January. Service agreements for cloud networks typically allow for 50 minutes of downtime in 30 days. If an outage occurs during a hurricane or tornado it could delay lifesaving forecasts and warnings, he added.