Where the FCC Looks for UAS Spectrum Advice
September 20, 2019
The Federal Communications Commission (FCC) is the federal agency responsible for implementing America’s communications laws, including developing rules related to commercial and state and local spectrum use. But you may not realize that much of the FCC’s important spectrum work, particularly with respect to innovative technologies, is aided by the Technological Advisory Council (TAC). The TAC is an advisory committee comprised of experts from government and industry that helps the FCC develop informed technology policies. And for the past couple of years, the TAC has been looking at spectrum for Unmanned Aircraft Systems (UAS).
The TAC has a UAS Working Group (UAS-WG) focused on identifying spectrum for UAS uses. Most drones today are controlled using publicly available, unlicensed spectrum such as WiFi. But as drone operations grow more complex and move to beyond visual line of sight flights, operators will need access to appropriate licensed spectrum for command and control of the aircraft. This is where the TAC comes in.
At their quarterly meeting on September 18, 2019, the UAS-WG gave an update on three areas of research. First, they described their preliminary findings with respect to using WiFi and Bluetooth for UAS operations. They noted that UAS have various needs for spectrum, including command and control, payload, and remote ID. In an unlicensed spectrum environment, there will be difficulties with communications reliability and capabilities, particularly as drones conduct beyond visual line of sight flights. For drones, technologies must work in all conditions—from crowded urban areas to remote areas with dense foliage. The UAS-WG’s analysis of WiFi and Bluetooth for drones will continue this year, but it is clear that these types of technologies have limitations for drones use.
Second, the UAS-WG discussed how it will be evaluating various mobile bands for UAS use. Different bands of spectrum have different characteristics and considerations, such as the extent of use, whether there are co-primary services in the band, the coordination mechanisms required, and adjacent band allocations. In addition, certain mobile terrestrial bands currently have restrictions on aeronautical use. The UAS-WG is working on developing a general approach that will produce guidelines on a quantitative analysis that then can be customized to study each band’s suitability for UAS. Julius Knapp, the Chief of the FCC’s Office of Engineering and Technology, cautioned that the group should consider narrowing the project to the bands that make the most sense for UAS operations. For example, Mr. Knapp noted that out of band emissions limits to protect those aeronautical bands that are adjacent to mobile bands are based on assumed separation distances from the transmitters. Those assumptions do not apply to UAS operations, which could be anywhere.
Third, the UAS-WG updated the group on its work considering whether spectrum currently allocated for “aviation use” would be appropriate for UAS. They noted there are potential barriers to using aviation spectrum for small UAS. Aviation safety spectrum will involve coordination with the FAA, which has its own technical standards, safety and reliability requirements, and other rules related to aviation spectrum use. Requiring additional avionics equipment to meet FAA requirements could add both weight and cost to small UAS. There are also concerns about whether the volume of small UAS operating in such bands would create too much congestion in spectrum designated for aviation use.
The UAS-WG’s work continues, with final recommendations to the FCC expected this December. Although under the radar, the TAC is influential in developing FCC spectrum policy. The TAC is also a great example of how industry experts with on-the-ground experience can provide input to the FCC with respect to emerging technologies. The Wiley Rein UAS Group will continue to monitor the TAC so we can keep our UAS clients in the know on the FCC’s thinking and what to expect on UAS spectrum going forward.