Consensus Lacking on Types of Drone Communications to Be Allowed in 5 GHz Band

Calls for allowing UAS communications beyond CNPC in the 5030-5091 MHz band ignore aviation safety effects coming from unmanned aerial use of controlled airspace, Aviation Spectrum Resources said. "It is beyond doubt that the entire band will be needed for CNPC for UAS operating in controlled airspace, especially considering overall UAS operations are likely to already reach 1.48 million units by 2024," it said. Because of the difficulties supporting extensive UAS operations on limited spectrum, use of the 5 GHz band focuses on CNPC usage, and eschews detect-and-avoid or vehicle-to-vehicle communications, said Boeing and Wisk Aero.

Along with limiting the band for CNPC use, the Utilities Technology Council said the agency should license the 5 GHz band to promote opportunities for utilities and other CII to access the band for exclusive use licenses, including limiting the size of the spectrum blocks and the geographic area, and dedicating one exclusive use channel block for utility and CII as well as public safety use

However, efficiencies would come from allowing other types of communications to coexist with command and control communications in the 5030-5091 MHz band, CTIA said. As the FCC looks at rules for spectrum for UAS, it said, the agency should avoid "inhibit[ing] or burden[ing] use of other spectrum bands that can support UAS communications, such as the commercial wireless bands; and ensure that any service and technical rules adopted for the 5030-5091 MHz band are technology neutral and neither require use of this band, nor preclude its use by any class of UAS user." CTIA said the FCC also shouldn't foreclose the ability to use other spectrum bands for UAS in any future proceeding.

Noting the time and effort it will take to design and build a network using the 5 GHz band to serve UAS, Ligado said the 1670-1675 MHz band should also be made available. That licensed spectrum would "provide a layer of security and reliability for critical public safety use cases that unlicensed spectrum cannot match," it said. Verizon said the FCC should remove airborne restrictions on any spectrum band where UAS operations don't pose a demonstrable interference risk that can't be resolved under existing rules, with the 800 MHz cellular band being "a strong candidate for such consideration." The few parties raising red flags about UAS operations in flexible-use spectrum haven't shown any evidence that such operations create interference that can't be mitigated, Verizon said. Existing FCC rules on flexible use spectrum "can sufficiently manage interference concerns," the Small UAV Coalition said, cautioning against new rules for UAS use of that spectrum. Xcel Energy said more spectrum beyond 5030-5091 MHz will be needed for UAS and the FCC should develop a record on opening flexible-use spectrum and other bands available.

The UAS spectrum NPRM raises three issues that should be dealt with separately, said the Aerospace Industries Association: the VHF rule change, which has broad support and should be dealt with quickly; a technical analysis needed to authorize use of flexible-use spectrum for uncrewed aircraft; and CNPC use in the C band. AURA Network Systems also supported breaking up the NPRM. Globalstar said it expects the UAS industry to develop receivers "that are robust enough to operate without issue" in spectrum adjacent to its gateway facilities, but it had no technical concerns about adjacent UAS operations.