The New New Spectrum: 3.5GHz

Wireless Wonk

The New New Spectrum: 3.5GHz

By Barlow Keener, Attorney  |  August 10, 2016

The FCC (News - Alert) is making headway with making more efficient use of spectrum. Think of it as re-organizing closets that have not changed in 70 years. One closet is the highly reported TV Incentive Auction. It is newsworthy because TV stations have lined up to auction off their airwaves and go off the air. Mobile carriers are lined up to purchase the TV spectrum. To manage the newly available TV spectrum, the FCC is using a unique spectrum database system built and tested by the TV White Space broadband radio entrepreneurs. The database will allow regulators and mobile carriers to make efficient use of the newly licensed TV spectrum and allow the TV White Space broadband providers to use the remaining unlicensed spectrum.

The other FCC reorganized spectrum closet is 3.5GHz. The finalized 3.5GHz order was released by the FCC on May 2, and is called the Citizens Broadband Radio Service. The method employed by the FCC for managing the reorganized spectrum is innovative and advanced. It is using the same TV White Space database to manage this newly freed spectrum. The FCC calls the database in the 3.5GHz order the SAS, or Spectrum (News - Alert) Access System. This spectrum re-org will free up 150MHz of new spectrum, from 3500 to 3700MHz, for both licensed and unlicensed use.  When the FCC first opened the proceeding in 2012, mobile carriers were interested in the 3.5GHz spectrum for small-cell backhaul. The carriers are now looking to it for handset device use for delivering more megabits per second to the handset.  

The FCC is establishing small zip code-size census areas, which will be auctioned off. Spectrum auctions may deliver drops of water to the ocean of debt obligated by U.S. Treasury, but such funds would be put to better use to deliver broadband to libraries, the poor, and rural areas.

There will be three primary users of the spectrum with three levels of priority: the original government users, or incumbent access user, like Navy radar; mobile carriers paying for licenses in auctions, called priority access licenses, that are subject to government use IA from time to time and place to place; and General Authorized Access, which is licensed use by devices that are required to shut down or move if directed by the SAS (News - Alert) database. The FCC has experimented with and is now authorizing a never before used device for determining if spectrum is available: spectrum sensing called Environmental Sensing Capability. ESC (News - Alert) will sense if Navy radar is being used and will deliver the results to the SAS database, which will instruct the 3.5GHz cellphone or broadband device and base station to stop interfering by moving to another channel.

The FCC balanced the traditional users of the spectrum, which included Fixed Satellite Service ground stations – providing TV communications to satellites using 3700-4200. FSS earth stations will be able to notify the SAS database if they are experiencing interference in a particular location, which will cause those PAL and GAA devices to move to another non-interfering channel, or if none are available to turn off. For the first time, all devices operating in the spectrum will receive instructions not from a person but from a database, automatically, just as TV White Space broadband radios do today.

Mobile carriers will have the opportunity to add additional spectrum, through the auctions and through GAA general non-paid license use, if desired. The mobile carriers will be able to roll out new high-bandwidth devices with radios and base stations capable of using the 3.5GHz spectrum. Mobile carriers will be able to bid on PAL licenses in micro geographies from 3550-3650MHz, enabling the mobile carrier to hold 40MHz of spectrum in a small census tract at any given time.

GAA devices using free, or non-paid for, licenses will be able to use the SAS database to operate across the full 150MHz including the PAL licenses, as long as the spectrum as directed by the SAS database is show to be available and not occupied. By using the SAS data, the FCC will now be able free up spectrum in micro-geographies and in small segments of time when the spectrum is not in use, making a huge leap in spectrum efficiency. We are on the verge of a new era of database-directed agile radios thanks to the vision of the FCC Office of Engineering and Technology and the TV White Space entrepreneurial pioneers. No longer will radio devices operate as unconnected cowboys off the grid, but all will be soon connected, and spectrum and power directed over the internet by a database enabling dramatically re-organized, highly-efficient, spectrum closets.

Barlow Keener (News - Alert) is the principal with Keener Law Group (

Edited by Alicia Young