radio spectrum

Spectrum sharing moves ahead

With so much of modern society depending on telecommunications, spectrum is increasingly at a premium. And now the nation's first dynamic public-private spectrum-sharing project is starting to take off.

The Citizens Broadband Radio Service (CBRS) is part of a three-tier architecture for sharing a 150 MHz-wide section of radio spectrum between 3.5 GHz and 3.7 GHz that the Navy currently uses for mission-critical radiolocation services.

The Federal Communications Commission adopted rules in 2015 to allow the 3.5 GHz band to be used by commercial wireless providers when not used by the Navy for offshore radar operations.  Companies such as AT&T, Google, Nokia, Qualcomm, Sony and Verizon have expressed an interest in accessing this band to expand their market and upgrade to 5G service.

Verizon recently asked the FCC for permission to conduct CBRS trials at 3.5 GHz spectrum in two Florida locations, according to a report in FierceWireless.  T-Mobile will be testing 3.5 GHz in Las Vegas, Dallas and Richardson, Texas. Comcast has also applied to test mobile and fixed wireless services in Philadelphia.

Smaller ISPs and other entities, including the city and port of Los Angeles, have expressed interest in using the spectrum to expand rural broadband, but a recent rule change to CBRS proposed by the FCC would change CBRS' small license sizes covering a single census tract to much larger areas, effectively limiting license sales to large carriers only, according to a report in Bgov.

Meanwhile, the National Institute of Standards and Technology has been working to develop test procedures and reference implementations so the FCC can certify commercial use on this spectrum band.

In February, the Wireless Innovation Forum, a public-private body to establish standards for the CRBS, announced baseline specifications for the commercial operations in the spectrum band, which sets the stage for the rollout of commercial CBRS networks and devices.  The standards include specifics for operations, security, testing, certification and accreditation as well as an algorithm for protecting military incumbent users designed by NIST.

NIST has also created a model that simulates 45,000 LTE small-cell networks using the 3.5 GHz band. If the Navy should need that band, the model calculates which small cells must be shut down and which can continue transmitting. Similar models "will allow the FCC to test and evaluate how effectively a commercial LTE provider can share the band with the Navy," NIST officials said.

“This will be the first time that commercial broadband users share spectrum dynamically with government users, and if it works, the FCC may allocate other currently protected RF bands for shared use,” Michael Souryal, lead for the project within NIST’s Communications Technology Laboratory, wrote in a recent blog post.

"More spectrum sharing could provide less-congested wireless channels for densely populated areas and more reliable connections for advanced communications needs such as wireless 5G and internet of things applications.” Souryal said. 

More information on the program can be found here.

About the Author

Sara Friedman is a reporter/producer for GCN, covering cloud, cybersecurity and a wide range of other public-sector IT topics.

Before joining GCN, Friedman was a reporter for Gambling Compliance, where she covered state issues related to casinos, lotteries and fantasy sports. She has also written for Communications Daily and Washington Internet Daily on state telecom and cloud computing. Friedman is a graduate of Ithaca College, where she studied journalism, politics and international communications.

Friedman can be contacted at or follow her on Twitter @SaraEFriedman.

Click here for previous articles by Friedman.

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