How CBRS Is a Model for Spectrum Management

How CBRS Is a Model for Spectrum Management

As digital habits continue to change and adapt to new realities, consumers are using more wireless devices. This growth means there is a need to ensure access to ample wireless spectrum to power these emerging technologies.

As policymakers consider how to squeeze more spectrum from an already crowded spectral landscape, new and innovative solutions can enable more efficient use of the finite amount of wireless spectrum available. One such solution lies in the band of spectrum known as Citizens Broadband Radio Service, or CBRS.

What Is CBRS?

CBRS refers to an innovative spectrum-sharing regime established in the 3.55 GHz to 3.7 GHz spectrum band, which was previously primarily used by the Department of Defense (DoD). After years of analysis by the executive branch, the FCC, and other stakeholders, the FCC opened the band to shared-licensed use. The CBRS band has, as a result, become a case study for how sharing can be implemented successfully. 

How Does CBRS Work?

By utilizing smart-spectrum management through a highly-automated frequency coordinator, known as a Spectrum Access System, federal incumbent users retain the highest priority access to the spectrum. Priority Access Licenses (PAL) are the next highest priority tier and have access to the spectrum when it is not used by the DoD for their critical missions. General Authorized Access (GAA) users are the lowest priority tier and may use PAL spectrum when it is not used by the licensee. This dynamic spectrum management allows not only for new commercial use without displacing important incumbent uses but also maximizes use among the commercial entities.

  • If two signals are competing for priority, the CBRS model looks at which signal has the top-tier access and puts that one ‘in line’ first. 
  • A lower-tier user in the band can ‘yield’ to the incumbent’s ‘right of way,’ and the SAS will place the lower-tier user on another channel.
  • This shared-licensed use is powered by a combination of dynamic channel sharing, smaller geographic license areas, and lower power limits than in many licensed-exclusive bands.

Why Does the CBRS Model Work Well?

In 2020, the FCC opened the CBRS band to a shared-licensed model at auction.

  • Using a three-tiered system for different players, the band prioritizes incumbent users while safely opening the band to commercial use without signal interference. For example, the U.S. Navy can continue its critical missions without interruption, while commercial applications like wireless cell service can also benefit from the band.
  • Previously, spectrum licenses have been limited to larger bands that demand very high prices at auction, which have kept out some players. But because the CBRS band has created much smaller limited licenses, more players have been able to get involved and benefit from spectrum auctions.

Why Should More Spectrum Be Managed in a Shared-Licensed Way?

Given that our airwaves are already crowded, policymakers can implement changes that foster innovation and competition, bolstering the U.S. economy. While wireless spectrum is a finite resource, engineering can make its use more and more efficient.

  • CBRS-style shared-licensed management is a 21st century solution that can both serve the needs of incumbents as well as open more opportunities for innovation.
  • CBRS is currently used for manufacturing, automotive, agriculture, energy, retail, commercial real estate, communications, media, and supply chain industries, as well as schools, libraries, and civil society groups, and also by traditional cellular networks.

Federal agencies like NTIA agree that successful, proven models like CBRS improve spectrum management while better positioning wireless spectrum for the future.