This month’s release of the National Spectrum Strategy directs NTIA to study the 7/8 GHz (7125-8400 MHz) band for potential private sector use within two years. In recent years, the mobile broadband industry has called on the government to investigate this band for sharing with commercial 5G and 6G services. The band actually encompasses 14 separate sub-bands, each with different band service allocations containing a mix of fixed, space research, fixed-satellite, mobile-satellite, maritime mobile-satellite, meteorological-satellite, and Earth exploration-satellite services allocated on a primary basis. By way of comparison, the 6 GHz band (5925-7125 MHz) which the FCC opened up for unlicensed use, comprised of allocations for Fixed Services, Mobile Services, and Fixed Satellite Services (FSS) across only four sub-bands with the largest use being fixed point-to-point microwave links used by utilities, commercial and private entities, and public safety agencies. Permitting sharing with unlicensed users in the 6 GHz band required new technologies including Automatic Frequency Coordination (AFC) to allow outdoor use. Additionally, the 6 GHz band was already allocated for primarily non-federal uses prior to the authorization of unlicensed use.
In contrast, the 7/8 GHz band is extensively used by multiple federal agencies for a wide range of important government missions. This diversity of use will make identifying contiguous blocks challenging and require extensive discussion and coordination with stakeholders. The mobile industry is also calling for the band to be made available for exclusive licensed use, which would likely require that federal operations move out of the band entirely, raising questions of relocation cost and where these operations could move to achieve comparable capability. The band already accommodates re-located federal systems from other repurposed bands (AWS-1 in the 1710-1755 MHz band, and AWS-3 in the 1755‑1780 MHz band). Relocation of federal operations out of this band to support exclusive licensed uses will be costly, potentially in the billions of dollars, and take years. If high-power commercial use to support macro 5G and 6G networks is the goal, the complexity in both cost and time will only increase.
NTIA’s 2010 federal spectrum use summary outlines some of the many federal uses in the band, including:
- Fixed point-to-point microwave communication systems for national and military test range communications, and the remote transmission of radar video and other data for functions such as weather, vessel traffic control in harbor areas, and hydroelectric grid power management;
- NASA/NOAA passive sensing of the Earth from space on the Geostationary Operational Environmental Satellite (GOES) in the lower portion of the band up to 7250 MHz as part of the 6425-7250 MHz band. NASA/NOAA use microwave radiometers to obtain measurements of sea surface temperature, a key component in weather forecasting and climatological studies;
- NASA operates its Deep Space Network (DSN) that provides tracking, ranging, and command uplinks to deep space probes including Voyager 1 (Jupiter and beyond), Voyager 2 (Jupiter, Saturn, and beyond), Galileo (Jupiter), Near Earth Asteroid Rendezvous (NEAR), Dawn (Asteroids), New Horizons (Pluto), Cassini (Saturn), Phoenix (Mars), Mars Odyssey (Mars), Messenger (Mercury), the James Webb Space Telescope, and future NASA Artemis missions to the lunar surface; and
- The military agencies operate the Wideband Global SATCOM Satellite (WGS) which is the backbone of the US military’s Wideband satellite communications capability. WGS provides worldwide, flexible, high-capacity communications for US Government Agencies, the Department of Defense (DOD), multiple International Partners, and the North Atlantic Treaty Organization (NATO).
Space-based uses of the band also increase the complexity, cost, and timing for new commercial uses, and NASA/NOAA’s passive use for measuring sea surface temperature may have no alternative. These sensing applications are tied to measured natural phenomena, and dependent on the specific properties of the bands in which they operate. The World Meteorological Association (WMO) recently outlined the risk to climate monitoring and weather forecasting ahead of the 2023 World Radiocommunication Conference (WRC-23).
Should regulators determine that the band is suitable for repurposing – and they may not – the road ahead will require compromise, innovative thinking, and potentially new sharing frameworks for the bands or portions of the bands identified for commercial uses. This challenge for NTIA and the federal agencies, the missions of which may be impacted, will require close cooperation, trade-offs, and potentially new technological innovations and policy changes. Observers should anticipate significant debate over the future of this band, which will test regulators’ ability to balance government priorities like Artemis and national security against the stated needs of commercial 5G and Wi-Fi service operators.
The views and opinions expressed in this blog post are those of the writer and do not necessarily reflect the views or positions of any entities they represent.