Peaceful Coexistence within the Radio Spectrum

November 8, 2024

By: Dr. Chris Anderson, Institute for Telecommunication Sciences (ITS), Theory Division Chief

In an increasingly congested wireless spectrum, conflict is both inevitable but often resolvable.

Between commercial applications (e.g., terrestrial and non-terrestrial wireless communications, navigation, and telemetry), scientific activities (e.g., radio astronomy, polar research, earth observation), and other vital spectrum-dependent uses (e.g., air traffic control), competition for spectrum access will only increase with new and emerging applications and technologies.

Finding ways to create additional access to this limited and valuable resource thus comes with many potential benefits, including faster, higher capacity and lower latency communications; new astronomical and scientific discoveries; more energy-efficient cities; increased highway capacity and safety; and more accurate weather predictions.

One important way to achieve these benefits is to integrate coexistence measures into spectrum-using applications at an early stage. This includes greater use of dynamic spectrum sharing systems, which enable spectrum users to operate safely in close proximity-whether geographically or in frequency-without causing harmful interference. Additionally, it involves enabling spectrum users to share spectrum access more rapidly than is currently possible with traditional and largely manual spectrum management approaches.

NTIA's research laboratory, the Institute for Telecommunication Sciences (ITS), is at the forefront in assessing scientifically advanced technological spectrum coexistence solutions, in collaboration with the Spectrum Innovation Initiative (SII) of the National Science Foundation (NSF). Here's a closer look at some of our work on peaceful coexistence.

Spectrum Innovation Initiative (SII) Workshop: Catalyzing Coexistence

In mid-September 2024, I joined researchers from the University at Albany - State University of New York and the National Radio Astronomy Observatory (NRAO) to organize the capstone event of workshop series sponsored by the NSF SII National Radio Dynamic Zones (NRDZ) program.

The major goals of the series were to promote fundamental spectrum research, foster collaborative activities, and serve as a forum for the exchange of ideas and research results. The workshop, "Catalyzing Coexistence via the National Radio Dynamic Zone," was in-person at the Green Bank Observatory in the heart of the United States National Radio Quiet Zone in West Virginia. The NRDZ is an area or volume with automatic spectrum management mechanisms that control electromagnetic energy entering, escaping, or occupying the zone.

National Radio Quiet Zone: A Case Study on the Need for Spectrum Coexistence

The NRAO operates a number of highly sensitive radio telescope facilities for NSF under cooperative agreement by Associated Universities, Inc., including the largest fully steerable single-dish telescope in the world (the 100-meter diameter Robert C. Byrd Green Bank Telescope), and the Karl G. Jansky Very Large Array (VLA) in New Mexico. NRAO enables leading edge radio astronomy research by offering telescope, facility, data and advanced instrumentation access to the astronomy community. NRAO has also become a prime example of the urgent need for viable spectrum coexistence solutions.

Dr. Chris Anderson of NTIA's Institute for Telecommunication Sciences (seventh from left) stands among other participants of an early September spectrum coexistence workshop at the historic Green Bank Observatory. Participants discussed potential solutions for addressing the satellite and ground communications that interfere with radio telescopes and radiometers essential to space and weather research. Behind the group is the Green Bank Telescope, the largest steerable single-dish telescope in the world, with a diameter of 105 meters. The workshop was held in collaboration with the Spectrum Innovation Initiative (SII) of the National Science Foundation (NSF).

Telescopes at Green Bank Observatory in the NRQZ are protected from all radio frequency interference by local regulations that prohibit any radio transmissions within a 10-mile radius of the site, unless they are coordinated for use within the NRQZ, as well as federal requirements for coordination of permanent fixed transmitters. Certain radio frequency bands used by the NRAO's telescopes are also exclusively allocated to radio astronomy research on a global basis (e.g., the band that contains the neutral hydrogen line at 1420 MHz).

However, as less utilized spectrum bands-especially in remote locations-have become highly desirable for other data-rich wireless applications, NRAO has seen increasing interference across all frequencies over the past few years. Remoteness, long sought out to allow important research to go forward, is increasingly no longer a guarantee of spectrum availability.

Out-of-band emissions from commercial systems that operate close to protected radio astronomy bands are costly to mitigate and potentially catastrophic to these sensitive receivers. There is no do-over when an observation is interrupted by interference. Therefore, it is critical for wireless operators to coordinate with the NRQZ to ensure that their operations do not interfere with the critical work of NRAO and that both commercial and scientific missions can thrive.

The National Spectrum Strategy: Testing Dynamic Spectrum Sharing

The National Spectrum Strategy (NSS) established a blueprint to help meet our nation's spectrum needs, harness innovation, and build economic and national security for years to come. Key aspects of the NSS require collaborative long-term planning and unprecedented spectrum innovation and technology development efforts. The NSS directed the White House Office of Science and Technology Policy, in coordination with NTIA and other federal agencies, to develop the National Spectrum Research and Development Plan that will guide government and private sector spectrum-related research, including into new technologies that advance coexistence. And under the NSS Implementation Plan, ITS has been charged with creating a National Dynamic Spectrum Sharing (DSS) Testbed with the goal of coordinating dynamic spectrum sharing experiments across a network of sites.

NTIA is the leader in implementing a whole-of-Nation approach to achieving a comprehensive strategy to modernize spectrum policy and make the most efficient use possible of this vital national resource. Collaboration with the NSF SII and development of the National DSS Testbed are just two of the ways ITS is currently working to ensure spectrum remains available to continue our Nation's economic growth, maintain and improve our global competitiveness, and support critical public services and missions.