One of NTIA’s most important responsibilities is working with the Federal Communications Commission (FCC) to find spectrum to support competitive and ubiquitous 5G broadband wireless service in America. Efficient use of spectrum is critical as we look to get more spectrum into the hands of wireless innovators while protecting federal users. To help achieve this goal, NTIA engineers have facilitated the creation of a new concept in flexible spectrum sharing, Dynamic Protection Areas (DPAs), to enable increased access to the 3.5 GHz Citizens Broadband Radio Service (CBRS) band.
On May 22, in response to a letter from NTIA, the FCC issued a waiver Order that allows each spectrum access system (SAS) administrator in the 3.5 GHz band to use DPAs. This action will allow more devices to operate in the band more quickly than anticipated, promoting efficient spectrum use and more investment.
DPAs, a solution developed through government and industry collaboration, represent a solid advance in transforming the older, static model of “exclusion zones” into a dynamic sharing model that can allow multiple uses across time and geography. If shown to be successful, the DPA model could have applicability for future sharing in other bands. The concept of DPAs grew out of an effort to overcome obstacles around expanding commercial use of the 3550-3650 MHz portion of the 3.5 GHz band, which the U.S. Navy uses for radar systems on its ships.
NTIA worked with the Department of Defense (DOD) to develop geographic exclusion zones in which future commercial broadband networks would not be allowed to operate. That initial approach proved unworkable, however, because the zones would have run along U.S. coastlines covering many of the country’s largest cities, making an effective commercial wireless service economically impractical.
A new model was created that applied cutting-edge analysis techniques and geographic information system data. In 2016, NTIA published a technical report proposing smaller exclusion zones that reduced the total impacted geographic area by 77 percent.
A parallel breakthrough came with the development of two new complementary spectrum sharing tools: the SAS database that tracks locations of radio transmitters and controls their operation, and an Environmental Sensing Capability (ESC) that detects the presence of signals from specified sources.
Used together, the SAS and the ESC offer the potential for 5G broadband wireless service and Navy radars to share the same frequencies. The Wireless Innovation Forum, an industry group that advances spectrum technologies, is working with NTIA, DoD, and the FCC to finalize testing software for SAS and ESC systems, which will pave the way for NTIA and the FCC to certify SAS and ESC operations and CBRS equipment.
These advances in spectrum sharing technology are enabling innovations we couldn’t imagine just 10 years ago, but there is still much to be learned about how spectrum can be used more efficiently. NTIA’s engineers are working hard to develop a promising future for managing our nation’s spectrum resources.