# Spectrum Rules and Policies for the Operation of Unmanned Aircraft Systems

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2023-00961

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** February 7, 2023
- **Citation:** 88 FR 7910

## Text

FEDERAL COMMUNICATIONS COMMISSION
47 CFR Parts 1, 87, and 88
[WT Docket No. 22-323; FCC 22-101; FR ID 122915]
Spectrum Rules and Policies for the Operation of Unmanned Aircraft Systems

AGENCY:

Federal Communications Commission.

ACTION:

Proposed rule.

SUMMARY:

In this document, the Federal Communications Commission (“FCC” or “Commission”) seeks comment on rules to promote access by unmanned aircraft system (UAS) operators to licensed spectrum to support UAS operations. First, this document seeks comment on service rules for the 5030-5091 MHz band that will provide UAS operators with access to licensed spectrum with the reliability necessary to support safety-critical UAS command-and-control communications links. Second, due to the increasing interest in operating UAS using existing terrestrial flexible-use spectrum networks, this document seeks comment on whether the Commission's current rules are adequate to ensure co-existence of terrestrial mobile operations and UAS use or whether changes to these rules are necessary.

Third, to further promote the safe integration of unmanned aircraft operations in controlled airspace and facilitate flight coordination, this document proposes a process for UAS operators to obtain a license in the aeronautical very high frequency (VHF) band to communicate with air traffic control and other aircraft. Together, these measures will help to promote the growth and safety of UAS operations.

DATES:

Comments are due on or before March 9, 2023. Reply comments are due on or before April 10, 2023.

ADDRESSES:

You may submit comments, identified by WT Docket No. 22-323, by any of the following methods:

•
Electronic Filers:
Comments may be filed electronically using the internet by accessing the ECFS:
https://apps.fcc.gov/ecfs.

•
Paper Filers:
Parties who choose to file by paper must file an original and one copy of each filing. Filings can be sent by commercial overnight courier, or by first-class or overnight U.S. Postal Service mail. All filings must be addressed to the Commission's Secretary, Office of the Secretary, Federal Communications Commission.

• Commercial overnight mail (other than U.S. Postal Service Express Mail and Priority Mail) must be sent to 9050 Junction Drive, Annapolis Junction, MD 20701.

• U.S. Postal Service first-class, Express, and Priority mail must be addressed to 45 L Street NE, Washington, DC 20554.

• Effective March 19, 2020, and until further notice, the Commission no longer accepts any hand or messenger delivered filings. This is a temporary measure taken to help protect the health and safety of individuals, and to mitigate the transmission of COVID-19. See FCC Announces Closure of FCC Headquarters Open Window and Change in Hand-Delivery Policy, Public Notice, DA 20-304 (March 19, 2020),
https://www.fcc.gov/document/fcc-closes-headquarters-open-window-and-changes-hand-delivery-policy.

People with Disabilities:
To request materials in accessible formats for people with disabilities (braille, large print, electronic files, audio format), send an email to
fcc504@fcc.gov
or call the Consumer and Governmental Affairs Bureau at (202) 418-0530 (voice), 202-418-0432 (TTY).

FOR FURTHER INFORMATION CONTACT:

Peter Trachtenberg, Mobility Division, Wireless Telecommunications Bureau, (202) 418-7369, or by email to
Peter.Trachtenberg@fcc.gov.
For additional information concerning the proposed Paperwork Reduction Act information collection requirements contained in this document, contact Cathy Williams, Office of Managing Director, at (202) 418-2918 or
Cathy.Williams@fcc.gov.

SUPPLEMENTARY INFORMATION:

This is a summary of the Commission's Notice of Proposed Rulemaking (
NPRM
) in WT Docket No. 22-323, FCC 22-101, adopted on December 23, 2022, and released on January 4, 2023. The full text of this document, including all Appendices, is available for inspection and viewing via the Commission's website at
https://docs.fcc.gov/public/attachments/FCC-22-101A1.docx
or ECFS by entering the docket number, WT Docket No. 22-323. Alternative formats are available for people with disabilities (Braille, large print, electronic files, audio format), by sending an email to
FCC504@fcc.gov
or calling the Consumer and Governmental Affairs Bureau at (202) 418-0530 (voice), (202) 418-0432 (TTY).

Synopsis

I. Discussion

A. UAS Communications in the 5030-5091 MHz Band

1. We propose to adopt a band plan and service rules in the 5030-5091 MHz band to enable UAS operators to use interference-protected control-and-non-payload-communications (CNPC) links. We seek comment on our proposal and on options to make the band available for this purpose. We further seek comment on the costs and benefits of any such options, including the costs and benefits of the specific band plan and service rules options discussed below. We seek comment on measures that will facilitate UAS use and promote equity for these underserved populations.

2. Through this proceeding, we seek to provide UAS operators with access to an additional spectrum resource that may complement other spectrum resources that are currently available or in development. We tentatively conclude that, while other spectrum bands are available for UAS communications, licensing the 5030-5091 MHz band specifically for UAS CNPC will have important public interest benefits. We seek comment on this tentative conclusion and the extent to which the 5030-5091 MHz band may offer unique advantages over other bands in supporting UAS CNPC.

1. Band Plan

3. For the purpose of this band and its service rules, and consistent with the Federal Aviation Administration (FAA) definitions of the terms, we propose to define UAS as an unmanned aircraft (UA) and its associated elements (including communication links and the components that control the UA) that are required for the safe and efficient operation of the UA in the airspace of the United States, and to define a UA as an aircraft operated without the possibility of direct human intervention from within or on the aircraft. We seek comment on these proposed definitions and on any alternatives. We further identify two broad UAS use cases for purposes of determining the appropriate band plan and service rules—non-networked operations, generally occurring within radio-line-of-sight (hereinafter line-of-sight or LOS) of the UAS operator, and network-supported operations, which rely on network infrastructure to go beyond radio-line-of-sight of the operator. Non-networked operations involve flights within a sufficiently localized area that can rely on direct wireless links between the UAS operator's controller and the UA and therefore do not require any supporting network infrastructure. In contrast, network-supported operations rely on deployed network infrastructure, such as cell towers and sites, to relay information between the operator and the UA and may therefore extend far beyond the range of direct wireless links between operator and UA. We seek comment on whether any other UAS use cases should be considered in determining the appropriate band plan and service rules.

4. Hereinafter, we use the term Non-Networked Access (NNA) to indicate spectrum or licenses (
e.g.,
NNA blocks) that would be governed by service rules appropriate to support non-networked communications. Likewise, we use the term Network-Supported Service (NSS) in connection with spectrum or licenses to indicate that the relevant spectrum or licenses would be governed by service rules appropriate to support the provision of network-based services. Further, we propose to use NNA and NSS in the rules to designate the spectrum allocated for non-networked and network-supported use cases, respectively.

5. The Aerospace Industries Association (AIA) suggests that RTCA's terminology for these two use cases should be used. RTCA uses the term “point-to-point” for non-networked communications links and the term “Command-and-Control Communications Service Providers” to describe network-supported services. We tentatively find that our proposed terminology is more descriptive of the use cases we seek to support, and that the use of the term point-to-point,

which has been long used in Commission rules and orders to reference systems providing a data communication link between two fixed stations, may itself contribute to confusion in this context. We seek comment on the proposed terminology, and on alternatives.

6. To accommodate both NNA and NSS in the 5030-5091 MHz band, we propose to partition the band, to dedicate different segments of spectrum in the band for each use case, and to license each of these segments in a manner that is appropriate to support the relevant use cases. We seek comment broadly on the placement of NNA and NSS spectrum to ensure efficient, reliable, and safe use of the band. We seek comment on whether to make spectrum available for multi-purpose uses,
e.g.,
expansion bands for temporary NNA or NSS use. We seek comment on our proposals and on alternatives.

7. We specifically propose to dedicate at least 10 megahertz of spectrum for NNA operations, and seek comment on this proposal. AIA argues that 10 megahertz will be sufficient to promote deployment while preserving the opportunity for an incremental approach to licensing the band that will better accommodate developing industry standards. We seek comment on AIA's argument. We seek comment on the placement of the NNA spectrum within the band and whether, consistent with AIA's proposal, we should place 5 megahertz blocks at the bottom (5030-5035 MHz) and top (5086-5091 MHz) of the band for NNA use. Alternatively, should we locate the dedicated NNA blocks somewhere internal in the band rather than at the band edges? If so, should we designate the spectrum at the edges of the band for NSS?

8. An analysis by RTCA based in part on the use of an “online filter-design tool” finds that filters that sufficiently protect services in the adjacent bands “would necessitate guardbands unusable by terrestrial CNPC at both ends of the 5030-5091 MHz bands, reducing the 61 MHz of usable passband width to 42-52 MHz depending on the case.” It further states, however, that “[c]ustom filter designs could probably provide larger usable passbands than those obtained using the online tool, possibly at the cost of increased size and weight.” We seek comment on this analysis, and whether fixed guard bands at one or both ends of the band are warranted to protect services in the spectrum adjacent to the 5030-5091 MHz band, including (1) radionavigation-satellite service (RNSS) downlinks in the 5010-5030 MHz band, (2) aeronautical mobile telemetry (AMT) downlinks to support flight testing in the 5091-5150 MHz band, and (3) the Aeronautical Mobile Airport Communications System (AeroMACS) in the 5000-5030 MHz and 5091-5150 MHz bands. Alternatively, does the need to protect adjacent band services argue for dedicating the edge spectrum to something other than NNA assignments, such as satellite?

9. We further seek comment on whether, instead of designating separate upper and lower NNA blocks, we should place all dedicated NNA spectrum together in one contiguous block. Is placement of the NNA spectrum into two or more separate blocks useful for technical or other reasons? Conversely, would providing the spectrum in a single contiguous block reduce interference challenges (
e.g.,
by potentially reducing the adjacency of NNA and NSS blocks) or better support certain channelizations of the band or important use cases that may require channel bandwidths of more than 5 megahertz? Further, with regard to any technical standards that commenters may recommend applying to services or equipment in the 5030-5091 MHz band, we seek comment on whether these standards require the use of contiguous spectrum.

10. With regard to the remaining spectrum in the band, we seek comment on how to structure it consistent with the goal of dedicating a segment of spectrum for exclusive use NSS licenses. We seek comment on how much of the spectrum to dedicate for NSS operations, and how we should license any remaining spectrum. For the spectrum that we dedicate to NSS operations, we seek comment on the placement of the NSS blocks and on the appropriate block size for NSS licenses to promote investment and competition and support the current and evolving bandwidth needs of NSS services. In the current record, AIA proposes 5 to 10 megahertz blocks, and Wisk supports 10 megahertz blocks. We seek comment on these options and on any other appropriate block sizes. What size spectrum blocks would be necessary to support CNPC services? What block size would be appropriate if we permit NSS licensees to support non-CNPC communications? Would the flexibility of larger block sizes (such as 10 or 20 megahertz) better facilitate mixed CNPC and non-CNPC use?

11. While we anticipate that a significant portion of this remaining spectrum would be designated for NSS, we seek comment on whether we should use a portion of the spectrum for opportunistic use by both NNA or NSS licensees (multi-purpose use). Should we instead use a portion of the spectrum to increase the amount of spectrum dedicated to NNA operations? To the extent we dedicate spectrum for NSS licenses, we also seek comment on making that spectrum available for NNA operations on an interim, opportunistic basis. Under this approach, NNA users, in addition to having access to dedicated NNA spectrum, could use frequencies in a dedicated NSS block in geographic areas where the NSS licensee has not yet deployed an operating network. Once a network is deployed and operational in a particular area, NNA users would no longer have opportunistic access to the spectrum in that area. This approach would enable the NSS spectrum in an area to be used productively prior to the issuance of NSS licenses and deployment of networks, while providing NSS licensees with complete exclusivity once their systems are deployed. We seek comment on the costs and benefits of this approach, including its technical and economic feasibility, and on alternative approaches to NNA opportunistic access or alternative methods of ensuring productive usage of dedicated NSS spectrum prior to network deployment.

12. With these issues and questions in mind, we seek comment broadly on an appropriate band plan for the 5030-5091 MHz band. As one possible option for structuring the band overall, we invite comment on:

• Dedicating 10 megahertz of spectrum for NNA operations, with 5 megahertz blocks at the bottom (5030-5035 MHz) and top (5086-5091 MHz) of the band.

• Dedicating 40 megahertz of spectrum for NSS operations, divided into 4 licensed blocks of 10 megahertz each, with NNA opportunistic access as described above.

• Making the remaining 11 megahertz available for temporary, opportunistic use by either NNA users or NSS licensees (multi-purpose use).

We also seek comment on alternatives to this band plan, including plans that designate the edge spectrum for some purpose other than NNA operations (such as for NSS operations) or that provide different amounts of spectrum for NNA, NSS, and/or multi-purpose use than those presented in the example discussed above.

13. We further invite comment on alternative approaches to allocating the 5030-5091 MHz band for the support of UAS. For example, AIA proposes that we allocate and license the 51 megahertz between 5035 MHz and 5086 MHz on a geographic area basis in a

phased, incremental manner over a period of years—
e.g.,
allocating and licensing only 5 megahertz in the first year, and then licensing additional spectrum over the following years with blocks and geographic areas sized according to user demand and service provider applications. AIA suggests that such an incremental approach would help the Commission to accommodate different UAS markets defined by different UAS missions that are expected to emerge over time. We seek comment on this possible approach, and more generally on whether we should allocate only a portion of the band at this time and defer allocation of the remainder of the band. We further seek comment on whether we should preserve part of the band at this time for experimental use, or for potential future satellite-based CNPC that relies on the aeronautical mobile-satellite route (R) service (AMS(R)S) allocation in the band.

14. As another alternative, Qualcomm recommends that the Commission allocate 20 megahertz for direct UA-to-UA communications, including communications between the aircraft to facilitate detect and avoid (DAA) operations, and communications to broadcast Remote ID information. Qualcomm proposes that the remaining 41 megahertz of spectrum be licensed in two 20.5 megahertz blocks or four 10.25 megahertz blocks to network providers for the provision of NSS CNPC services and for payload transmissions to the extent that capacity is not needed for CNPC. We seek comment on this option and on Qualcomm's assertion that supporting the functionalities of DAA and Remote ID broadcasts will require 20 megahertz of 5030-5091 MHz band spectrum. We also seek comment on the compatibility of UA-to-UA transmissions and UA broadcast with CNPC links between a ground control station and a UA. If they are not compatible, should a portion of the band be designated exclusively for UA-to-UA or UA broadcast transmissions, and if so, how much spectrum should be designated for this purpose?

15. We seek comment on whether we should establish any internal guard bands, such as between the NNA and NSS blocks, or whether we can rely on appropriate technical rules to ensure that UAS operations in one block do not cause harmful interference to UAS operations in adjacent spectrum blocks. We request that parties proposing guard bands provide detailed technical justification and specify the width and placement of the proposed guard bands. We further seek comment on whether fixed guard bands at one or both ends of the band are warranted to protect services in the spectrum adjacent to the 5030-5091 MHz band, including (1) radionavigation-satellite service (RNSS) downlinks in the 5010-5030 MHz band, (2) aeronautical mobile telemetry (AMT) downlinks to support flight testing in the 5091-5150 MHz band, and (3) the Aeronautical Mobile Airport Communications System (AeroMACS) in the 5000-5030 MHz and 5091-5150 MHz bands.

2. Dynamic Frequency Management System

16. To address the complexities involved in coordinating shared interference-protected access to the 5030-5091 MHz band, we propose that access to the band be managed by one or more dynamic frequency management systems (DFMS). We use the term DFMS to describe a frequency coordination system that, in response to requests from UAS operators for frequency assignments in NNA spectrum, would determine and assign to the requesting operator, through an automated (non-manual) process, temporary use of certain frequencies for a particular geographic area and time period tailored to the operator's submitted flight plan. For the duration of the assignment, the operator would have exclusive and protected use of the assigned frequencies within the assigned area and timeframe, after which the frequencies would be available in that area for assignment to another operator. We contemplate that each DFMS would be administered by a private third party, which we refer to as a DFMS administrator. We further contemplate that each system would be capable of coordination-related activities across the entire 5030-5091 MHz band. While we contemplate that NSS licensees would be responsible for the use and coordination of frequencies within the scope of their licenses, requiring a DFMS to be capable of coordination across the entire band would enable a DFMS to provide dynamic access to any portions of the 5030-5091 MHz band that are, in the initial order or subsequently, assigned for NNA use, as well as to implement opportunistic access to portions of the band that are assigned for NSS use as appropriate. We tentatively conclude that these systems could (1) facilitate the efficient and intensive use of a limited spectrum resource for interference-protected CNPC; (2) give UAS operators access to reliable CNPC for operations where those communications links are safety-critical; (3) enable UAS operators to gain spectrum access in a timely, efficient, and cost-effective manner; (4) enforce compliance with frequency assignments through access controls, checking existing frequency assignments, providing updates in authorized databases, and other mechanisms; (5) protect critical communications inside the band and in adjacent spectrum; (6) support opportunistic use in unused portions of spectrum sub-bands designated for exclusive use licenses; and (7) promote rapid evolution of the use of the band in response to technological, market, or regulatory changes, such as if the Commission deploys spectrum in the band incrementally or, in the future, finds that modifying the access rules in a particular sub-band is in the public interest to better meet market demand. We seek comment on our proposal and its costs and benefits.

17. The support in the current record for the use of a DFMS, along with the success of the 3.5 GHz band Spectrum Access System (SAS) and the potential to build on the SAS experience and technology, lead us to tentatively conclude that a DFMS solution can feasibly be implemented to enable near-term use of the band with the benefits discussed above. We seek comment on our tentative conclusion, and the extent of interest in providing such DFMS services in the 5030-5091 MHz band. In addition to the specific questions below, what other aspects of the 3.5 GHz band SAS approach would be appropriate here, and what aspects should be changed? How should the Commission supervise the operations of the DFMS?

18. We propose to permit more than one DFMS to operate in the band, each providing access to frequencies nationwide, and to require coordination and communication between them to ensure that the assignments of one DFMS are consistent with the assignments of the others. We seek comment on this proposal.

19.
DFMS requirements and responsibilities.
We seek comment on the appropriate regulatory framework to establish for a DFMS, including its requirements and responsibilities and the requirements and responsibilities of a DFMS administrator. We seek comment on whether and to what extent we can draw on the requirements and responsibilities governing the SAS and SAS administrators in the 3.5 GHz band. For example, we seek comment on whether to follow our policy for the 3.5 GHz SASs and establish only the minimum high-level requirements necessary to ensure the effective development and operation of fully functional DFMSs, leaving other requirements to be addressed by the

DFMS administrators and multi-stakeholder groups. If we follow this policy, what high-level requirements should we establish?

20. One of the most important responsibilities of the DFMS would be to ensure that UAS operators receiving 5030-5091 MHz assignments and operating consistent with their assignments are protected from harmful interference and that they do not cause harmful interference to other protected operations in the band and adjacent bands, including protected Federal operations. We seek comment on whether the Commission should simply establish an appropriate high-level requirement on the DFMS, such as a requirement to provide protected access to spectrum appropriate to cover a submitted and valid request, to the extent such spectrum is available, and defer to the DFMS administrators, or potentially a multi-stakeholder group, to determine the appropriate means of doing so. To the extent the Commission should codify more detailed requirements, we seek comment on all measures the Commission should adopt to facilitate the ability of the DFMS to provide reliable, interference-protected assignments, including any necessary specifications, requirements, responsibilities, authority, processes, or remedies. We further seek comment on the interference mitigation techniques that can be employed by UAs, such as geo-fencing.

21. At a minimum, we propose to require that a DFMS administrator adopt procedures to immediately respond to requests from Commission staff for information they store or maintain and to comply with any Commission enforcement instructions they receive, as well as to securely transfer all the information in the DFMS to another approved entity in the event it does not continue as the DFMS Administrator at the end of its term. We seek comment on these proposals. In addition, what requirements should we impose on the DFMS or DFMS administrator with regard to retention of records and information, including registration and assignment records? Should we require retention of all such information for at least five years? What requirements should we adopt to ensure data security in DFMS operations, including the security of end-to-end communications between operators and a DFMS and the security of information stored by a DFMS?

22. What requirements, if any, should be imposed on NNA operators in the band to help ensure the DFMS's ability to provide interference-protected access or to promote more robust or efficient use of the spectrum? Should these requirements be high-level, with additional development through a DFMS administrator or multi-stakeholder group, or should they be more detailed? What information should we require operators to provide to the DFMS regarding ground stations and unmanned aircraft stations? Should that information be provided prior to any requests, with an assignment request, or on an ongoing or periodic basis during an operation? For example, should we require operators to provide ground station geographic location, effective isotropically radiated power (EIRP), and/or antenna patterns? Assuming a DFMS has the necessary information about the ground station, is information about the location or transmitter characteristics of the UA unnecessary to prevent harmful interference? Should we require an active UAS relying on an NNA assignment in the band to provide a DFMS with the UA information that must be broadcast under the Remote ID rule or some subset or variation of that information? Should an operator be required to provide the DFMS specific information about the UA, including its manufacturer, model, or other technical or identifying information? Should an operator be required to affirmatively communicate to the DFMS, in real time or within a certain period of time of the relevant event, the initiation and termination of the flight or, alternatively, the initiation and termination of the operator's use of the assigned frequencies? Are there other circumstances or information (aside from the request) that the operator should be required by rule to communicate to the DFMS? Should any requirements be imposed on UAS operators relying on NSS networks to facilitate the DFMS's ability to provide interference-protected NNA assignments?

23. We further seek comment on whether to mandate that a UAS operator register with a DFMS as a precondition to requesting NNA frequency assignments, and if so, what requirements we should impose with respect to such registration. Should the Commission simply require registration and leave the details to be developed by, for example, the DFMS administrators or a multi-stakeholder group? To the extent the Commission should codify further details, what information should be included with registration? Should UAS operators be required to register ground and UA stations? Should we impose requirements with regard to if and when registration should be updated and, if so, what is the appropriate duration of the initial registration term and the renewal term? Under what circumstances should the Commission or the relevant DFMS administrator revoke a UA operator's registration? While we envision that any registration requirements would apply only to operators seeking NNA assignments, we seek comment on whether to require operators relying on a network service in NSS spectrum to register with a DFMS.

24. We also seek comment on what requirements, if any, we should impose with respect to the submission of UAS operator requests for NNA assignments, and conversely what, if any, details of the request process should be left to be developed by a multi-stakeholder group. For example, should we impose specifications of what information should be included in a request, and if so, what data should we require? Should requests include the relevant ground and unmanned aircraft stations that will be used in the operation, and if so, how should these be identified? To the extent we permit mobile ground stations, should requests provide a specification of the route of the mobile ground station over time and the times at which the station will reach specific locations in order to enable frequency assignment to consider the range coverage of the station as a function of time? Should we require submission of a flight plan, and if so, what information should the flight plan include, and in what format? For example, should it specify time of use, and flight positions and flight altitude over the course of the flight plan, as suggested by AIA? Should an operator be required to submit requests no more than a certain specified time period in advance of a flight?

25. As a general matter, should a DFMS grant a frequency assignment for the duration and other parameters requested, provided the unassigned spectrum is available to meet the request? Alternatively, should limits or restrictions be placed on what can be granted?

26. As several parties have noted, operators may need to revise their assignments after a flight has commenced (
e.g.,
where the flight needs to deviate from its anticipated flight path and UAS CNPC transmissions for the revised flight would not be covered by the original assignment, or where a flight takes longer than provided under the assignment). We seek comment on any rules we should adopt to enable or facilitate the filing and timely processing of such requests for revised assignments or to otherwise address an operator's mid-flight need for revised

assignment. Do we need to adopt any rule to address cases where the revised request cannot be granted consistent with other previously granted assignments?

27. In the 3.5 GHz band, SASs may require fixed stations to implement reassignment to new frequencies, reduction of the permitted transmitting power level, or cessation of operations, as necessary to avoid or eliminate harmful interference and implement spectrum access priorities. Is an active management approach feasible and appropriate, and if so, what regulatory requirements should be adopted to enable or implement such an approach? If not feasible, what approaches or mechanisms will be available to the DFMS to ensure the reliability of communications? In particular, given that the proposed assignments would be limited in both frequency, time, and geography, what requirements, procedures, penalties, or other measures should be in place to prevent or address (1) flights that use unauthorized frequencies; (2) flights that occur outside an authorized time period, such as a flight that exceeds its authorized duration; or (3) flights that occur outside an authorized area. If a DFMS's role is merely to reserve appropriate spectrum for UAS flights, and a DFMS takes no other active measures to ensure or enforce compliance with the assignments or the protection of operations, will spectrum access be sufficiently reliable for mission critical purposes?

28.
Fees.
Under the 3.5 GHz rules, an SAS administrator is authorized to charge users “a reasonable fee” for the provision of its services, and the Commission “can require changes to those fees if they are found to be unreasonable.” We propose to adopt a similar provision authorizing the administrator of a DFMS to charge reasonable fees for its provision of services, including registration and channel assignment services, and to permit parties to petition the Commission to review fees and require changes if they are found to be excessive. To encourage efficient use of the limited spectrum resource and discourage any attempt at warehousing, we seek comment on specifically authorizing reasonable usage-based fees, and on standards and approaches for establishing the amounts of such fees.

29.
Selection process.
We seek comment on the process for selecting the DFMS administrators, and whether the 3.5 GHz SAS approval process could serve as a model. Under the approach for SAS approval, the Commission delegated authority to the Wireless Telecommunications Bureau (WTB) and the Office of Engineering and Technology (OET) to administer the process and provided that (1) the Bureaus would issue a Public Notice requesting proposals from entities desiring to administer a SAS; (2) applicants would be required, at a minimum, to demonstrate how they plan to meet the Commission's rules governing SAS operations, demonstrate their technical qualifications to operate a SAS, and provide any additional information requested by WTB and OET; (3) based on these applications, WTB and OET would determine whether to conditionally approve any of the applicants; and (4) any applicants that received conditional approval would be required to demonstrate that their SASs meet all the requirements in the rules and any other conditions the Bureaus deemed necessary, and at a minimum, to allow their systems to be tested and analyzed by Commission staff. We seek comment on adopting this approach. In particular, we seek comment on facilitating the potential selection of multiple DFMSs through an application and certification process by which any entity found to meet the requirements can be the administrator of such a system, and we seek comment on what eligibility requirements should be set and whether (or to what extent) they should be codified or established through a separate process. We also seek comment on whether we should provide a testing or trial phase for DFMS technology prior to the submission of applications, to facilitate or inform the requirements of the application process. Following the SAS model, we propose to delegate jointly to WTB and OET the authority to administer the selection process and make the selection. We seek comment on what role the FAA and National Telecommunications and Information Administration (NTIA) should have in setting up the process, reviewing applications, and making the selection.

30.
Coordination with flight authorization.
In addition to spectrum access,
i.e.,
authorization to transmit, UAS operators also need approved or otherwise authorized access from the FAA to conduct flights in the airspace of the United States. We seek comment on whether and how frequency assignments should be coordinated with airspace authorization for low altitude, high altitude, and terminal (departure/arrival) operations. For example, should a DFMS be required to determine that a requesting party has any necessary flight authority as a condition of granting a spectrum assignment request? If so, we seek comment as to whether and how a DFMS would interact with air traffic control or the relevant UAS Traffic Management (UTM) systems (such as the Low Altitude Authorization and Notification Capability (LAANC) system), or otherwise obtain information regarding airspace approvals, authorizations, or availability.

31.
Alternative approaches to dynamic spectrum access.
We seek comment on other options to enable dynamic spectrum access to the 5030-5091 MHz band. Some parties suggest that we adopt some form of cognitive radio solution, in which UAS radios would directly detect and identify available spectrum channels. They argue that a centralized system like the DFMS will be complex and labor intensive to use, will be inefficient in spectrum assignments and vulnerable to spectrum warehousing, and will have difficulty ensuring link protection and responding quickly to developments such as changes in flight plans while a UA is already in flight. We seek comment on these concerns and whether they can be addressed by a DFMS, and we seek comment on the feasibility, costs, and benefits of alternative options as compared to the DFMS discussed above, and whether such alternatives would be sufficiently reliable to support even the most safety-critical uses such as flights in controlled airspace. We further seek comment on whether there are existing technologies that could be applied or adapted to implement these alternative approaches, and on any standards work or other studies regarding the safety and reliability of links under such systems.

32. We seek comment on whether a similar system to the 6 GHz database or the white space database established in the TV bands could be adopted for NNA operations in the 5030-5091 MHz band, under which 5030-5091 MHz radios would be required to directly and periodically query a central database for available channels. Given that the 6 GHz and white space systems are implemented to enable unlicensed devices to access spectrum without interference protection, we seek comment on whether this type of system could be suitable to implement interference protection for UAS NNA operations. If the Commission adopts rules providing for the establishment of such a system, should we require that the system database be updated in real time with relevant parameters of the NNA systems currently in operation? We further seek comment on whether any such system and any tool used to perform the interference analysis should be certified and approved for use by the

Commission and/or other appropriate authorities prior to operation.

33. In the event that we adopt rules providing for the establishment and operation of a DFMS or some other coordination system or process, there may be a significant period of time before such coordination system is operational in the band and some operators may want protected access to the band during this interim period. Accordingly, we seek comment on whether to establish some method by which operators can get temporary protected access to frequencies in the 5030-5091 MHz band, or a portion of the band, during this interim period.

3. Multi-Stakeholder Group

34. We seek comment on a possible role for a multi-stakeholder group to help develop the requirements and processes applicable to the DFMSs, as well as to study standards and interference issues associated with UAS operations in the band. We seek comment on whether, consistent with the successful approach in the 3.5 GHz band, we should encourage a multi-stakeholder group to address implementation issues in the 5030-5091 MHz band, but without the Commission formally designating such a group or imposing a formal process for how the group reaches its determinations or recommendations. If such a multi-stakeholder group were to be formed by third parties, what selection procedures might be desirable to ensure that the group appropriately reflects the diversity of UAS stakeholders? What role might Federal agency stakeholders have in this process? We seek comment on these and any additional procedures or approaches that a multi-stakeholder group might implement, particularly in light of the positive experience with the 3.5 GHz band stakeholder group.

35. Assuming there is a role for a multi-stakeholder group, we seek comment on the appropriate extent of that role and the responsibilities it might most usefully undertake. We seek comment on the matters a multi-stakeholder group should address with consensus standards or other determinations, or with the development of recommendations to one or more of the stakeholder agencies. We further seek comment on the matters that the Commission should address independently of any multi-stakeholder group and the rules it should adopt to establish a basic regulatory framework to govern the 5030-5091 MHz band and the DFMSs.

4. Scope of Permissible Services

36. As discussed above, the Commission added an AM(R)S allocation in the 5030-5091 MHz band to support UAS communications. AM(R)S is reserved exclusively for communications relating to the safety and regularity of flight, primarily along national or international civil air routes. Consistent with the scope of the allocation and the expressed purpose for its incorporation, we propose to permit only CNPC and to define CNPC as any UAS transmission that is sent to or from the UA component of the UAS and that supports the safety or regularity of the UA's flight. We seek comment on these proposals and on alternatives that would be consistent with the allocation and its purpose. Should we alternatively define CNPC to cover any communications to or from a UA other than payload communications, and to define payload as information sent to achieve mission objectives? RTCA DO-362A, which provides Minimum Operational Performance Standards (MOPS) for UAS CNPC in the 5030-5091 MHz band, states that “payload communications,” for purposes of the standard, “specifically include communications associated with the UA mission payloads, which do not contain safety-of-flight information,” and clarifies that “[s]afety-of-flight information is any information/data sent to or received from the UA that is necessary to ensure the UAS is operated/operating in a manner that protects people and/or property from harm due to unintentional events.” We seek comment on whether to adopt these or similar terms to define the scope of permissible CNPC. NTIA proposes that we limit the band to a subset of CNPC, specifically communications for the control of the UA and other “safety-critical functions,” in order to limit UAS use to “essential services.” RTCA DO-362A similarly provides that CNPC includes “[d]ata and information sent to/from the Pilot Station and the UA for the control of the UA and other safety-critical functions.” We seek comment on this option, on the costs and benefits of limiting the band to only the “safety-critical” communications, on what types of communications would be considered “safety-critical,” and what, if any, types of non-payload but safety-related communications would not be considered “safety-critical.” More generally, should we restrict communications to a subset of CNPC? We seek comment on whether dual-purpose communications should be permissible if one of the purposes falls within the permissible scope.

37. We seek comment on whether, instead of a general definition of scope or, potentially, as a clarifying and non-exclusive supplement to a general definition, we should specify certain categories of communications that are covered, such as (1) telecommands to the UA; (2) telemetry from the UA that is relied upon for flight guidance or other flight safety-related purposes, such as geo-fencing to protect sensitive areas,
i.e.,
Microwave Landing System sites, radio astronomy sites, adjacent licensees, etc.; (3) DAA-related transmissions; (4) video transmissions from the UA relied upon for flight guidance or other flight safety-related purposes; (5) Air Traffic Control communications relayed via the UA; and (6) remote identification transmissions. We seek comment on whether permissible communications should be restricted to communications between the control station and the UA station,
i.e.,
excluding broadcast from the UA or UA-to-UA communications. We further seek comment on whether we should establish priorities among different categories of CNPC, or leave the rules flexible on this matter, with such prioritization potentially to be considered and developed through appropriate standards development by multi-stakeholder groups.

38. We note that the regulatory definition of AM(R)S limits the allocation to communications “relating to safety and regularity of flight,
primarily along national or international civil air routes.”
As the allocation does not require that communications be exclusively for flights along such air routes, we propose not to restrict the scope of permissible CNPC services to such communications. We seek comment on this proposal and the extent to which operations outside civil air routes will need access to the 5030-5091 MHz band for CNPC (as opposed to being able to rely on other spectrum solutions that may or may not provide the same level of reliability or air safety assurance). Assuming some measure is necessary or appropriate to reflect the focus on flights primarily along national or international civil air routes, we seek comment on whether it would be sufficient to ensure that the applicable rules and technical standards provide the necessary reliability and safety to support the use of the band for such flights.

39. We also seek comment on whether we should restrict NNA to CNPC but permit NSS licensees a broader scope such as a scope permitting UAS payload communications or permitting both

UAS and non-UAS communications, provided that licensees ensure the safety and reliability of CNPC and ensure that communications associated with the safety of flight always have both priority and preemption over other communications. We seek comment on whether such an expansion of scope would be permissible under section 303(y) of the Communications Act, which places certain limits on the Commission's authority to “allocate electromagnetic spectrum so as to provide flexibility of use.”

40. If we conclude that NSS licensees should be permitted a broader scope of permissible communications on an ancillary basis, we seek comment on adding an appropriate allocation if necessary, on what type of allocation should be adopted to support the broader scope, on whether to subject the allocation to secondary status under the AM(R)S allocation and to the limitations applicable to the AM(R)S allocation, and on any measures we should adopt to ensure that the primary use of the spectrum is for CNPC. Should we rely on appropriate multi-stakeholder groups to develop the details of requirements to implement prioritization and preemption? Should any mechanisms for implementing preemption and prioritization be subject to specific review and approval by the Commission, the FAA, and/or an appropriate third-party group?

5. Eligibility Restrictions

41. We propose that any entity be eligible to obtain a 5030-5091 MHz NSS license other than those precluded by section 310 of the Communications Act and those that are barred under 47 U.S.C. 1404 from participating in auctions. We seek comment on this proposal and whether eligibility should be more restricted. We further seek comment on how, in this context, we should interpret section 310(b), which imposes restrictions on who can hold or be granted a “broadcast or common carrier or aeronautical en route or aeronautical fixed radio station license.” Under the various authorization proposals discussed herein, would a licensee be considered as holding a “common carrier[,] aeronautical en route or aeronautical fixed radio station license”? If so, how should we evaluate any foreign-ownership holdings?

42. We also seek comment on whether to provide that any entity is eligible to operate NNA stations using assignments from a DFMS other than those precluded by section 310 from holding station licenses. Given our proposal elsewhere to license NNA stations by rule, we seek comment on whether section 310 ownership restrictions, which apply to “station licenses,” apply to operators of stations licensed by rule. We further seek comment, if section 310 does not apply to operators of licensed-by-rule stations, on whether NNA station operators, or the parties receiving assignments from a DFMS for such operation, should be subject to eligibility restrictions comparable to those imposed by section 310 on station licensees.

43. NTIA recommends that, to be eligible for a license for 5030-5091 MHz UAS operations, an applicant be required to certify that it has the requisite FAA remote pilot certification or, in the case of an organization, to certify that it will only utilize individuals with this qualification for its UAS operations in the band. Compliance by 5030-5091 MHz operators with applicable FAA remote pilot regulations will be critical to the safe operation of UAS in the 5030-5091 MHz band, and we seek comment on the best approach to achieve this goal, and on NTIA's proposal as one option. To the extent that we adopt a licensed-by-rule model for NNA as proposed, however, UAS operators will not be required to submit individual license applications, and accordingly, there will be no individual license applications in which UAS operators could make the proposed certifications. Further, provision of network-based NSS would likely involve a network provider's provision of CNPC services to other entities, and thus, it is likely the relevant UAS operator will be neither a licensee nor an employee of a licensee. Accordingly, we seek comment on whether requiring license applicants to certify that they have the requisite FAA remote pilot certification or will utilize operators with such qualifications is a practical option in either the NNA or NSS context.

44. We further seek comment on the costs and benefits of conditioning either NNA or NSS eligibility on a certification that the party has the necessary FAA remote pilot certification or compliance with other FAA requirements. We seek comment on whether it provides a significant regulatory benefit to specifically limit eligibility in this manner, given that UAS operators using 5030-5091 MHz spectrum will in any case be subject directly to FAA rules and enforcement and would not be able to lawfully operate unless they comply with all applicable FAA requirements. We also seek comment on any administrative concerns from having the Commission potentially be required to interpret and enforce the regulatory regime of another agency.

45. To the extent that there should be some mechanism in addition to the FAA's enforcement authority to adequately ensure that use of the 5030-5091 MHz band will be consistent with FAA requirements, we seek comment on whether we can instead rely on the DFMS and NSS licensees to ensure that UAS operators have the necessary FAA approvals. For example, to address NNA users, users registering with a DFMS could be required to make the requisite certification as a condition of registration. Alternatively, we might impose a more general requirement on a DFMS to adopt measures that reasonably ensure that operators have the requisite FAA remote pilot authority, and defer to the DFMS administrator (or a multi-stakeholder group) on specific mechanisms to implement this requirement. We seek comment on these and other alternatives.

6. Non-Networked Access (NNA) Service Rules

46.
Licensing rules.
We seek comment on the licensing regime or mechanism we should adopt to enable authorization of NNA operations in the 5030-5091 MHz band and the costs and benefits of any proposed approach. We propose to reduce the administrative burdens on operators and the Commission by adopting a licensing approach that would not require individual licensing of these numerous operators and/or stations. Specifically, we propose to implement a licensed-by-rule authorization for aircraft and ground stations in the band, as recommended by AIA and others. Under this framework, operators would not be required to apply for individual spectrum licenses for themselves or their mobile or ground stations in order to conduct NNA operations in the band. Instead, parties using rule-compliant stations and operating in compliance with the rules would only need to obtain the requisite temporary frequency assignment from the DFMS in order to transmit in the band in the requested location, frequency, and timeframe. We further propose to permit the stations used by the operator on the ground to send and receive signals to the UA to be either fixed stations or mobile stations (such as hand-held controllers). As used in this document, the term “mobile station” refers to a station “intended to be used while in motion or during halts at unspecified points.” We seek comment, however, on whether to require all NNA ground stations in the band to be fixed stations, and on the costs and benefits of permitting the use of mobile ground

stations. To what extent would prohibiting such stations facilitate coordination in the NNA portion of the band, or reduce the likelihood of harmful interference, failures to comply with assignments, or challenges with administering or policing the system? If we do not permit mobile ground stations, should we differentiate “portable” stations,
i.e.,
stations that can be moved but are not intended to be used while in motion?

47. Section 307(e) of the Act authorizes the Commission to adopt a licensed-by-rule approach for certain specific categories of services, including the “citizens band radio service,” and also expressly delegates to the Commission the discretion to define the scope of the term “citizens band radio service.” In the Commission's rules, the citizens band radio service is defined as “any radio service or other specific classification of radio stations used primarily for wireless telecommunications for which the FCC has determined that it serves the public interest, convenience and necessity to authorize by rule the operation of radio stations in that service or class, without individual licenses, pursuant to 47 U.S.C. 307(e)(1).” We tentatively find that licensing by rule of NNA stations would serve the public interest, convenience, and necessity, and accordingly, we propose to implement licensing by rule by including NNA within the scope of the citizens band radio service. We seek comment on our tentative conclusion and proposal, on the scope of our authority under section 307(e) to adopt a licensed-by-rule approach to UAS operations, and on alternative licensing approaches we might adopt that would not require individual licensing of operators or stations in the band.

48. Section 307(e)(1) also expressly authorizes licensing by rule in “the aviation radio service
for aircraft stations”
but does not provide an equivalent grant of authority to adopt licensing by rule for aviation service ground stations. We seek comment on whether we nevertheless have authority in this case to adopt licensing by rule for both aircraft and ground stations in the aviation service.

49.
Technical requirements.
We seek comment on appropriate technical requirements to govern 5030-5091 MHz NNA equipment and operations. In the current record, NTIA, AIA, and many other parties support adoption of the technical requirements in the RTCA DO-362A standard for this purpose. RTCA DO-362A contains MOPS for terrestrial-based (
i.e.,
non-satellite) CNPC point-to-point or point-to-multipoint links in the 5030-5091 MHz band, including power limits, emission limits, and frequency accuracy requirements. We propose to adopt the RTCA DO-362A standard or technical requirements based on that standard to govern NNA equipment and operations and seek comment on this proposal. We seek comment on the adequacy of the RTCA DO-362A specified equipment and operational performance requirements, including both transmitter power and receiver input power, and required minimum coupling loss (separation distance) between ground and airborne CNPC radios and emissions from other licensed radio services.

50. We seek comment on an appropriate measure of CNPC link reliability to assess RTCA DO-362A and other standards, on the specific anticipated level of CNPC link reliability through radios compliant with the RTCA DO-362A standard, and on any available data that confirms that reliability. We seek comment on any current or past operation of equipment compliant with RTCA DO-362 or RTCA DO-362A, on the results of any such operations, and on the extent to which they support or raise issues or concerns about incorporation of the standard as the governing technical framework for the 5030-5091 MHz band. We also seek comment on whether parties have deployed experimental UAS equipment in the 5030-5091 MHz band in reliance on any other technical standard. Is there any benefit to requiring formal experimental trials or testing for 5030-5091 MHz band equipment?

51. We also seek comment on any costs or disadvantages in imposing the RTCA DO-362A standard. For example, we seek comment on whether and to what extent imposition of this standard may limit the scope of UAS operations that can make use of links in the band. We also seek comment on whether any such limitations are a result of hard constraints codified in the standard on the scope of UAS operations that may occur consistent with the standard specifications, or instead are a consequence of practical constraints, such as if the standard requires the development and installation of radio equipment that may be too heavy for some UA to carry.

52. Canada states that some technical incompatibilities have been identified between RTCA DO-362A and a proposed standard by the European Organization for Civil Aviation Equipment (EUROCAE) for satellite-based CNPC in the same band, designated draft ED-265, and asserts that adoption of the RTCA DO-362A standard without addressing the incompatibilities may create difficulties in managing the operation of CNPC links in support of international UAS operations. We seek comment on these concerns, the nature of the incompatibilities, and what, if any, measures, requirements, or restrictions are necessary to address them. We note that RTCA has been considering the “ED-265/DO-362 interference issue.” We seek comment on any determinations that have been made regarding these incompatibilities and whether the issue is adequately addressed in the current RTCA DO-362A version of the standard or will be addressed in a future version. If revisions to RTCA DO-362A are necessary or appropriate to address these issues, we seek comment on whether the next version of the standard is anticipated to be backwardly compatible with RTCA DO-362A, and if not, whether adoption of final rules should be deferred until these issues are resolved in a new version of the standard. We seek comment on whether any coordination or other requirements are necessary to ensure adequate protection of foreign satellite-based CNPC services in the band, particularly insofar as they may operate near United States jurisdictional boundaries. We also note that footnote 5.443C of the Table of Frequency Allocations limits the use of the 5030-5091 MHz band to “internationally standardized aeronautical systems.” We seek comment on whether this provision requires the Commission to adopt a standard that is compatible with the EUROCAE standard, and whether RTCA DO-362A would meet our obligations under footnote 5.443C.

53. If we incorporate the RTCA DO-362A standard into our rules, we seek comment on whether to do so through adoption of a general requirement that, to be certified for use under or operated under the NNA rules, all radio equipment must comply with the requirements of RTCA DO-362A, rather than to separately incorporate the various technical requirements of RTCA DO-362A (
e.g.,
power, frequency stability, and emission limitations) into the service rules. If we adopt a general requirement to comply with RTCA DO-362A, we propose to also separately codify requirements for power and emission bandwidth based on the RTCA DO-362A standard, to provide clarity and ease of reference in the rules. If, alternatively, we do not have a requirement of general compliance with RTCA DO-362A, but require compliance with only selected

provisions of the standard, which provisions or requirements from RTCA DO-362A should we impose? Which specific provisions of RTCA DO-362A are necessary for compatible use of the 5030-5091 MHz band? Should the Commission's technical framework require compliance more broadly with section 2, the Equipment Performance Requirements and Test Procedures applicable to the link system radios, or both sections 2 and 3, the latter of which includes performance standards for the link system when installed in a UA and ground location? Alternatively, is it sufficient, for purposes of establishing the baseline technical framework, to require compliance with the specific frequency capture range (which includes a frequency accuracy standard), power limits, and emission limits stipulated by the standard?

54. RTCA states that emission limit requirements should also require equipment compliance with the 50 ms Time Division Duplex (TDD) requirements specified under section 2.2.1.3 of the standard. It asserts that use of non-TDD systems or TDD systems with different time length frames operating in the 5030-5091 MHz band within the same radio horizon as RTCA DO-362A compliant equipment will cause unacceptable levels of interference. We seek comment on RTCA's assertion and recommendation, and whether adoption of the standard for NNA will necessarily require all equipment in the band, including equipment in neighboring NSS blocks, to use RTCA DO-362A compliant TDD equipment to avoid harmful interference to NNA operations.

55. We seek comment on whether any of the general technical requirements in subpart D of part 87 should apply to NNA equipment. NTIA proposes, for example, that in addition to meeting the out-of-band emissions limits in RTCA DO-362A, we should also require equipment to meet the out-of-band emissions limit specified in § 87.139(c). RTCA argues, however, that the current requirements of § 87.139(c) are less stringent than those in RTCA DO-362A, and that the Commission should just require compliance with the latter. L3Harris Technologies (L3Harris) asserts that it is not clear whether § 87.139 is applicable, as it applies only to communications using certain specific Emissions Designators and the RTCA DO-362A mandatory modulation makes no reference to these designators. We seek comment on NTIA's proposal, on whether § 87.139(c) may, under its existing terms, apply to UAS communications anticipated in the 5030-5091 MHz band, and whether such application is in the public interest. We further seek comment on whether we need to specify authorized emission classes and designators for this service, such as has been done with aviation services. If so, we seek comment on what classes and designators are appropriate, and whether we should use one of the types of assignable emissions already defined in, for example, § 87.137 of the rules. We propose emission designators of G8D for data and G8F for video and seek comment on their appropriateness for operations subject to RTCA DO-362A.

56. We seek comment on any other requirements we should impose on NNA equipment. For example, what requirements should we adopt to facilitate a DFMS's ability to communicate with or otherwise control such equipment in the execution of the DFMS's responsibilities? Should equipment be required to enable the DFMS to make direct (machine-to-machine) frequency assignments to the UAS equipment, in order to ensure that assignments are accurately programmed? Should this capability be available at all times, or only pre-flight? To the extent DFMS communications or control signals are intended to affect operating parameters of the UA, should such communications or control signals be required to occur exclusively through communications between the DFMS and the relevant ground control station or stations, rather than through direct communications with a UA station? In the 3.5 GHz band, fixed stations must respond automatically to SAS directions to modify certain operational parameters such as frequency or power limit. Should requirements be adopted for NNA equipment to provide the DFMS with similar control? We further seek comment on whether to impose requirements to ensure interoperability between NNA and NSS network services. Potentially, UA flights that initially rely on a network service may extend into areas where no network has been deployed. What requirements, if any, should we adopt to facilitate operations that can seamlessly switch between network service for CNPC and NNA assignments for that purpose?

57. We note that RTCA has also adopted another standard applicable to CNPC in the 5030-5091 MHz band, designated RTCA DO-377A, Minimum Aviation System Performance Standards for C2 Link Systems Supporting Operations of Unmanned Aircraft Systems in U.S. Airspace (RTCA DO-377A). Whereas RTCA DO-362A describes minimum performance standards for the ground and airborne radios used for a direct link, focusing on certain design characteristics of these radios such as power and emissions limits, RTCA DO-377A describes the minimum performance of an overall “C2 Link System,” defined as a system used to send information exchanges between a control station and an unmanned aircraft and to manage the connection between them, and which can be comprised of one or many Air/Ground links and Ground/Ground links. To the extent that RTCA DO-377A applies to NNA operations, we seek comment on whether we should adopt rules requiring compliance with the standard. Alternatively, should we limit our requirements, as AIA recommends, to technical requirements based on RTCA DO-362A and leave system performance, safety, and security requirements, such as those in RTCA DO-377A, to be considered by a multi-stakeholder group or addressed by the FAA?

Incorporation by reference.
As discussed above, we propose to adopt the technical standard RTCA DO-362A in whole or in part; RTCA DO-362A provides technical requirements for NNA operations in the 5030-5091 MHz band. To accomplish this, we propose to incorporate the standard by reference into our rules under 1 CFR part 51. The material is available from RTCA, 1150 18th Street NW, Suite 910, Washington, DC 20036, via email:
info@rtca.org
or
http://RTCA.org.

58.
Application of Part 87 Aviation Service Rules and Part 1 Wireless Radio Service Rules.
We seek comment on where to locate the new NNA services rules within the organization of the Commission's rules. Some parties argue that the new service should be located in part 87, which “states the conditions under which radio stations may be licensed and used in the aviation services.” We seek comment on this option. We seek comment on whether, alternatively, we should locate the new UAS rules in a new rule part rather than in part 87, as reflected in the amendments at the end of this document. We further seek comment on alternative options for the appropriate home for the new rules.

59. Whether we locate the rules for the 5030-5091 MHz band in part 87, a new rule part, or elsewhere, we seek comment on whether and to what extent the generally applicable rules in subparts B through F of part 87 should apply to or be incorporated into the new NNA service, either in their current form or with modifications.

60. As an example, § 87.89 requires that, with certain exceptions, operators of licensed aviation service stations “must hold a commercial radio operator

license or permit.” The operator license requirement is distinct from and wholly independent of the requirement that each station be licensed and requires individuals seeking an operator license to demonstrate, by passing a formal examination, sufficient knowledge of the relevant radio technologies. The operator license requirement stems from section 318 of the Act, which requires operators of transmitting equipment of licensed stations to hold an operator's license, except where the Commission finds that the public interest, convenience, or necessity will be served by waiving such requirement. We seek comment on whether, in addition to the station license (which, as discussed, we propose to provide through licensing by rule), we should require UAS operators using a NNA assignment in the 5030-5091 MHz band to have an individual operator license. Conversely, would it be in the public interest to forgo any such operator licensing or permitting requirements as unnecessary or inappropriate in light of FAA regulation of and authority over UAS remote pilot qualifications, or for other reasons?

61. We also seek comment on whether the new service should be subject to rules under part 1, subpart F, governing “Wireless Radio Service” applications and proceedings. We seek comment on whether NNA services, even if licensed by rule, should be included in and subject to the subpart F rules for Wireless Radio Services to the same extent as other licensed-by-rule services.

62.
Streamlined procedures to update incorporated standards.
We anticipate that any technical standard developed by a standards organization that we incorporate by reference into our rules will be subject to ongoing revisions as parties gain more experience and the UAS industry continues to rapidly evolve. To help ensure that the rules for 5030-5091 MHz UAS operations continue to reflect the most current version of any incorporated standard for 5030-5091 MHz UAS operations, we invite comment on whether we should adopt a comparable delegation of rulemaking authority in this case. Specifically, we seek comment on whether to delegate joint rulemaking authority to WTB and OET to incorporate into the Commission's rules, after consultation with the FAA and NTIA, and notice and an opportunity for public comment, any updated version of a previously incorporated technical standard applicable to UAS operations in the 5030-5091 MHz band. Similar to limitations the Commission has placed in some earlier delegations of rulemaking authority to update standards, should we limit this delegated authority to the incorporation of standard updates that do not raise major compliance issues?

7. Network Supported Service (NSS) Service Rules

63. We seek comment on the license terms and service rules we should adopt for NSS licenses. We seek comment in particular on issuing exclusive use, geographic area defined licenses for a specific term of years, with rights of renewal, subject to specific performance (network coverage) obligations. We seek comment on appropriate technical and operational requirements and on the assignment process rules.

64.
Geographic area licenses.
Consistent with our approach in several other bands that has promoted the deployment of wide area networks for a variety of fixed and mobile services, we propose to license NSS spectrum blocks in the 5030-5091 MHz band for exclusive use on a geographic area basis. We seek comment on this approach, on its costs and benefits, and on alternative licensing approaches. If a party opposes using geographic licensing, it should explain its position, describe the licensing scheme it supports, and identify the costs and benefits associated with its alternative licensing proposal.

65. We further seek comment on the appropriate geographic license area or areas for NSS licenses to support NSS UAS operations and facilitate investment, including investment by small entities, and robust spectrum use. We seek comment on whether we should adopt larger license areas such as Regional Economic Area Groupings (REAG) or nationwide markets to facilitate NSS uses that may often involve flight over long distances, adopt a more granular scheme such as Partial Economic Areas (PEA), which would provide more flexibility to serve a smaller area but still permit parties to achieve a larger area through aggregation, or adopt a mix of large and small license areas for different spectrum blocks. While NTIA supports licensing by REAG, AIA argues in its comments to the
Refresh Public Notice (PN),
86 FR 50715 (Sept. 10, 2021), that license areas corresponding to the Air Route Traffic Control Center (ARTCC) areas or other areas “that make sense in an aviation system context” would be appropriate, and Wisk similarly recommends use of the ARTCC areas to provide “alignment with a general air traffic density basis.” We seek comment on whether to adopt license areas based on a geographic area division of the country that has been developed specifically for aviation purposes, such as the ARTCC areas.

66.
License term.
We propose to issue NSS licenses for an initial 15-year term. AIA and Wisk both support a license term “longer than 10 years,” and we believe that circumstances in the band, including the need to set up a DFMS in the band and integrate its functions with operations in NSS spectrum, as well as the nascent stage of standards development and other technical work regarding NSS networks generally, favor the use of a longer initial license term. We propose to limit subsequent terms to 10 years. We seek comment on these proposals.

67.
Performance (network build-out or coverage) requirements.
We seek comment on performance requirements (
i.e.,
build-out or coverage requirements) that are appropriate for NSS licensees and UAS operation. We seek comment in particular on whether to adopt a population-based performance metric, such as a requirement to cover at least 80 percent of the population in the license area within 12 years of the grant of the license, as the Commission recently adopted for geographic licenses in other bands. We also seek comment on whether to adopt an appropriate interim performance requirement, such as a requirement to cover at least 45 percent of the population in the license area within six years of license grant.

68. AIA argues that aircraft uses require reliable control links for all geographic areas of flight regardless of proximity to population centers, and suggests that a build-out requirement based on “user demand, special diversity and signal strength” would better meet the needs of beyond-radio-line-of-sight UAS operations. We seek comment on AIA's arguments, and on whether we should either require licensees to meet some criteria other than population, such as geographic area coverage of 25% of the license area at year six and 50% of the license area at year 12. Alternatively, should we provide licensees with the option of meeting either a population-based requirement or some alternative? To the extent commenters recommend alternative build-out requirements, we ask them to propose either specific numerical benchmarks or other specific and objectively verifiable buildout criteria.

69. We seek comment on appropriate rules for compliance demonstration and enforcement. As for compliance demonstration, we propose to adopt a process similar to compliance rules applicable to part 27 licensees, requiring a demonstration of compliance with the

performance requirements by filing a construction notification with the Commission within 15 days of the expiration of the applicable benchmark, including electronic coverage maps accurately depicting the boundaries of the licensed area and the boundaries of the actual areas to which the licensee provides service. If a coverage map is used to demonstrate compliance, we seek comment on the appropriate standardized parameters for the propagation model. For example, should there be standardized values for inputs such as cell edge probability, cell loading, and clutter? As for enforcement, we propose that if a licensee fails to meet the final performance requirement, the license authorization will terminate automatically without specific Commission action. If we adopt an interim requirement, we propose that failure to meet the requirement would result in the reduction by two years of both the due date for the final performance requirement and the license term (resulting in a final performance requirement at year 10 and a license term of 13 years).

70.
License Renewal.
We seek comment on the appropriate standard for license renewal. In the
WRS Second R&O,
82 FR 41530 (Sept. 1, 2017), the Commission adopted a unified regulatory framework for the Wireless Radio Services (WRS) that replaced the existing patchwork of service-specific rules regarding renewal with a single unified standard, and safe harbors for meeting that standard for different service categories, including a safe harbor for geographic licensees providing commercial service. We seek comment on whether the regulatory renewal framework for WRS commercial geographic licensees is appropriate for NSS licensees. If we apply this framework, are there any special factors we need to account for or incorporate in the context of networks for support of UAS operations?

71.
Competitive bidding or other assignment procedures.
In the event that mutually exclusive license applications are received, we propose to assign these exclusive-use licenses through a system of competitive bidding. Consistent with the competitive bidding procedures the Commission has used in previous auctions, we propose to conduct any auction for geographic area licenses for spectrum in the band in conformity with the part 1, subpart Q, general competitive bidding rules, subject to any modification of the part 1 rules that the Commission may adopt in the future. We seek comment on whether any of these rules would be inappropriate or should be modified for an auction of licenses in this band. Consistent with the statutory requirement and our longstanding approach, we propose to use a public notice process to solicit public input on certain details of auction design and the auction procedures. Our proposal to assign these licenses through competitive bidding assumes that Congress amends section 309(j)(1) of the Communications Act to extend the Commission's authority to award licenses by competitive bidding. We seek comment on alternate assignment procedures in the event that the Commission's statutory authority to auction licenses is not extended.

72. If we provide for the assignment of these licenses through a system of competitive bidding, we also propose to make bidding credits for designated entities available for this band and seek comment on this proposal. If we decide to offer small business bidding credits, we seek comment on how to define a small business. In recent years, for other flexible-use licenses, we have adopted bidding credits for the two larger designated entity business sizes provided in the Commission's part 1 standardized schedule of bidding credits. We propose to use the same definitions here.

73. The standardized schedule of bidding credits provided in § 1.2110(f)(2)(i) of the rules defines small businesses based on average gross revenues for the preceding three years. In December 2018, Congress revised the standard set out in the Small Business Act for categorizing a business concern as a “small business concern,” by changing the annual average gross receipts benchmark from a three-year period to a five-year period. Thus, as a general matter, a Federal agency cannot propose to categorize a business concern as a “small business concern” for Small Business Act purposes unless the size of the concern is based on its annual average gross receipts “over a period of not less than 5 years.” For consistency with the statutory requirements, we therefore propose to adopt the Small Business Act's revised five-year average gross receipts benchmark for purposes of determining which entities qualify for small business bidding credits.

74. Accordingly, we propose to define a small business as an entity with average gross revenues for the preceding five years not exceeding $55 million, and a very small business as an entity with average gross revenues for the preceding five years not exceeding $20 million. A qualifying “small business” would be eligible for a bidding credit of 15 percent and a qualifying “very small business” would be eligible for a bidding credit of 25 percent. We also seek comment on whether the aviation-safety purpose of the band, the characteristics of these frequencies, or any other factor suggest that we should not make available one or either of these designated entity bidding credits, or that we should adopt different small business size standards and associated bidding credits than we have in the past. Finally, we seek comment on whether we should offer rural service providers a designated entity bidding credit for licenses in this band. Commenters addressing these proposals or advocating for any alternatives should consider what specific details of the licenses or operations in the band may affect whether designated entities will apply for them and whether designated entities should be supported by bidding credits.

75. AIA proposes that the Commission directly select NSS licensees from the submitted license applications based on criteria to be established by the FAA or by a multi-stakeholder group to ensure that applicants meet aviation performance levels and minimum performance standards established in RTCA DO-377A. We seek comment on AIA's proposal or alternative approaches for selecting the NSS licensees and whether such approaches would be consistent with our statutory obligation under section 309(j) of the Act to use competitive bidding to resolve mutually exclusive applications, and with our general responsibility for licensing of spectrum uses under Title III of the Communications Act.

76. Regardless of the assignment mechanism, we seek comment on whether NSS licensees should be subject to a particular limit on the amount of NSS spectrum they can aggregate in the 5030-5091 MHz band, such as a limit of 20 megahertz. To the extent that NSS spectrum is assigned on geographic market basis, are limits on 5030-5091 MHz spectrum aggregation necessary to ensure competition for network-based CNPC services?

77.
Technical requirements.
We seek comment on appropriate technical requirements and parameters for NSS licenses. As an initial matter, the appropriate technical requirements may depend in part on the types of operations likely to be carried out in the band and the network architectures necessary to support such operations. Accordingly, we seek comment on what operations commenters anticipate the NSS licensees will be used to support. Will they include Advanced Air Mobility, package delivery services, or

infrastructure inspection? Are they likely to be predominantly operations above, or below, a certain altitude, or to involve predominantly large or predominantly small UA? Will they involve autonomous operations, and if so, to what extent and for what purposes will such autonomous operations likely require network-based CNPC? For those anticipated operations, we seek comment on what type of network architectures will likely be needed in the band to support such uses. Will they necessarily be like the terrestrial cellular networks, or will there be other architectures, and if so, of what nature? To the extent that parties have already developed or plan to deploy network infrastructure to support UAS NSS operations, we seek comment on what type of network architectures they have developed or plan to deploy for this purpose.

78. We seek to adopt technical rules that will promote efficient use of spectrum and provide licensees as much flexibility as possible in terms of the services they wish to provide, while also providing adequate protection of licensees in the band or adjacent bands. We seek comment on requirements that will achieve these goals in the context of spectrum intended to support network-based UAS CNPC with the level of reliability needed for safety-critical aviation purposes. In particular, we seek comment on whether the RTCA DO-362A standard or equivalent technical parameters, which we propose above for NNA operations, should also apply to NSS licenses. Would adopting similar requirements for NSS help to ensure compatibility between NNA and NSS operations? We ask that commenters discuss the adequacy of the RTCA DO-362A specified equipment and operational performance requirements for NSS operations, including both transmitter power and receiver input power, and required minimum coupling loss (separation distance) between ground and airborne CNPC radios and emissions from other licensed radio services. We also seek comment on whether to require NSS licensees to comply with RTCA DO-377A, which addresses the minimum performance, safety, and security standards for a CNPC link system overall, whether that system relies on a network or a direct link. As noted above, AIA recommends that we require UAS equipment to comply with RTCA DO-362A, but leave the requirements in RTCA DO-377A to be considered by the FAA or an appropriate group of stakeholders. We seek comment on whether to take this approach for NSS licensees. To the extent that NSS licensees are permitted to support communications other than CNPC, we seek comment on whether those services should be subject to the same technical requirements as apply to CNPC.

79. Because the RTCA DO-362A standard is focused on point-to-point or point-to-multipoint (
i.e.,
non-networked) link performance rather than network services, and RTCA DO-377A on establishing the minimum performance, security, and safety standards of a system rather than mitigating interference impacts on other systems, we seek comment on whether application of either of these standards sufficiently address the impact of wide area network operations, including cellular networks, on other services in-band or in adjacent bands. We further seek comment on whether applying these standards, or specific parameters drawn from these standards, to network-based services in the band may unnecessarily restrict the range of services or operations in the band. We seek comment on whether there are any additional or alternative technical requirements that we should consider for NSS licenses and on the extent to which communications under these technical requirements would have sufficient reliability for safety-critical aviation purposes. To the extent that parties argue for alternative technical requirements, we ask that they be specific as to what requirements they propose be adopted in the rules.

80. We note that work is ongoing to develop technical standards for reliable UAS communications over mobile networks. We seek comment on these efforts, on the scope, status, and anticipated completion date of any other current or planned studies or standards development work regarding the reliability of UAS communications over Long-Term Evolution (LTE) or other mobile network technologies, and on whether these studies or standards will address or apply to UAS network-based communications in the 5030-5091 MHz band. If not, we seek comment on whether the development of these studies or standards may nevertheless be helpful in determining the appropriate requirements for networks in the 5030-5091 MHz band. We further seek comment on the extent to which any of these studies or standards are being or will be coordinated with the aviation community or the FAA to ensure that they provide sufficient reliability for all UAS use cases, including aviation flights where communications is safety-critical. We also seek comment on the extent to which mobile networks using LTE or other mobile network technologies can be implemented in the 5030-5091 MHz band consistent with the RTCA DO-362A standard.

81. As an alternative to requiring NSS compliance with the RTCA DO-362A standard generally, are there certain specific requirements of RTCA DO-362A that we should minimally impose, to ensure compatibility with NNA operations or for other purposes? For example, as we noted earlier, RTCA asserts that all equipment in the band must comply with the 50 ms Time Division Duplex (TDD) requirements specified under section 2.2.1.3 of the RTCA DO-362A standard to ensure that UAS operations in the band are compatible with each other. We seek comment on whether, even if we do not require general compliance with RTCA DO-362A, we should mandate compliance with the TDD requirements under section 2.2.1.3. Further, we seek comment on whether we should, at a minimum, require NSS equipment to comply with the power limits and out-of-band emission limits established in the standard to ensure that such equipment is compatible with AeroMACS.

82. We seek comment on any other technical issues that need to be addressed to enable the deployment of NSS networks. For example, in order to prevent harmful interference between geographic area licensees, such licensees are typically subject to market boundary power strength limitations. Because the networks deployed by geographic area licensees are terrestrial in nature, these limitations were developed using certain technical assumptions—
i.e.,
that natural and manmade terrestrial obstacles attenuate signals, reducing the potential of harmful interference between users in adjacent license service areas. Obstacles such as hills, trees, buildings, and other natural and manmade structures attenuate emissions, lessening the interference impact between licensees. UAS operations typically fly above many of these obstacles and, depending on the UA altitude and its distance to the service area boundary border, a UA may be in direct line-of-sight with adjacent license areas and users, greatly increasing the potential for harmful interference. As we anticipate adopting geographic area-based licenses for NSS spectrum, we request comment on an appropriate field strength limit to protect NSS licensees given this increased potential for harmful interference. We seek comment on other necessary technical specifications, such as out-of-band emission limits, and ask

that any proposals include technical justifications and analysis, such as UA altitude assumptions, power levels, antenna assumptions, the increasing interference effects resulting from the increasing number of transmitting UA (aggregate effects), and the victim receiver characteristics such as receiver sensitivity, and adjacent and non-adjacent channel rejection.

83.
Application of requirements from aviation service and wireless radio service rules.
As with NNA service rules above, we seek comment on whether and to what extent the NSS service rules should incorporate or be subject to the rules generally applicable to aviation services under subparts B through F of part 87 of the Commission's rules, either in their current form or with modifications. We also seek comment on whether the NSS service should be subject to rules under part 1, subpart F, governing Wireless Radio Service applications and proceedings. In particular, we seek comment on whether to allow partitioning and disaggregation of NSS licenses in secondary market transactions as well as spectrum leasing, including whether we should consider any competitive impacts associated with such transactions.

84. We anticipate that NSS licenses will be used to provide mobile network services to UAS operators on a commercial basis. Accordingly, we also seek comment on whether and to what extent we should incorporate regulations that regulate commercial mobile networks in other bands, such as the requirements generally applicable to part 27 flexible-use licensees. For example, should we incorporate or apply the requirements of § 27.52 (RF safety), § 27.56 (antenna structure height for the protection of air safety), or § 27.64 (protection from interference)?

85.
Other requirements.
We seek comment on any other service rules we should adopt for NSS licensees. For example, to ensure that UA flights are supported in the event they need to cross license area boundaries, should we adopt a roaming requirement? If anything more than market forces is necessary to address this issue, should the current roaming requirements under § 20.12(e) of the Commission's rules, requiring commercial mobile data service providers to offer roaming arrangements to other such providers on commercially reasonable terms and conditions, be extended to NSS licensees for this purpose? If these requirements are sufficient, how and where should we integrate them in the context of NSS service rules? If they are insufficient, what additional rules are needed to ensure that UAS operate continually and safely across licensing areas? We also seek comment on whether to adopt an interoperability requirement, for example, requiring NSS equipment to be capable of operating over any part of the 5030-5091 MHz band dedicated to NSS operations, or requiring support for the entire band. We further seek comment on whether to impose requirements to enable seamless switching between NNA and NSS services to support flights that may need to rely on both modes of spectrum access. Should we require NSS licensees to provide any other information, including the manufacturer, model, or other details regarding the UAs that will be flown? We seek comment on any requirements or other measures that would promote intensive use of the band. For example, we seek comment on how we might facilitate use of NSS for both low and high altitude uses, and whether we should require NSS licensees to support both low and high altitude uses or should take other steps to ensure that both low and high uses are supported.

86.
Satellite-based networks.
We seek comment on whether to authorize NSS licensees, at their discretion, to provide network-supported service for UAS CNPC through either a satellite or terrestrial network, or alternatively, whether the Commission should provide that certain NSS licenses are dedicated exclusively to satellite-based service. We seek comment on whether and to what extent there is interest in the United States in providing a satellite service for CNPC in the 5030-5091 MHz band, on the costs and benefits of permitting NSS licensees to deploy satellite services for network-supported CNPC, and on the advantages and disadvantages of a satellite option over terrestrial networks in this context.

87. Assuming we permit NSS licensees to deploy satellite-based service, we seek comment on how to permit and integrate the provision of such services and on the appropriate service rules. We seek comment on the application of the Commission's part 25 rules, which govern satellite communications, to such services, and the extent to which the rules applicable to terrestrial NSS networks should also apply to satellite-based NSS networks. We further seek comment on how the DFMS and other proposals discussed above would work for satellite communications. For example, how would a DFMS implement opportunistic access to spectrum in which satellite operations might be deployed? We also seek comment on how to ensure that any such satellite services are compatible with both terrestrial NSS and NNA operations in the band and other in-band and adjacent-band services, and on the circumstances, requirements, coordination processes, and/or restrictions necessary to ensure compatibility and to provide the reliability intended for CNPC in this band. For example, should we permit an NSS licensee to deploy a satellite service only if the NSS license is nationwide or the licensee in question has aggregated all geographic area licenses in a particular block throughout the nation? Are guard bands necessary between blocks with satellite deployments and blocks used for terrestrial networks or operations? Footnote 5.443D of the Table of Frequency Allocations provides that services under the satellite allocation in the 5030-5091 MHz band are subject to coordination under ITU Radio Regulations (R.R.) No. 9.11A, and that the use of this frequency band by the AMS(R)S is limited to internationally standardized aeronautical systems. We seek comment on what rules, if any, we should adopt to implement the requirements under footnote 5.443D.

88.
High-Altitude Platform Stations.
We seek comment on whether to permit NSS licensees to deploy High-altitude Platform Stations (HAPS). The Commission's rules define a “High Altitude Platform Station” as “[a] station located on an object at an altitude of 20 to 50 km and at a specified, nominal, fixed point relative to the Earth.” Potentially, these stations could be used by NSS licensees as a long-range relay of CNPC between two or more stations, and RTCA DO-362A includes extensive analysis of such an option, which it refers to as a “High-altitude Relay System.” We seek comment on whether and to what extent there is current interest in deploying HAPS as all or part of a network solution for CNPC, on the technical feasibility and commercial viability of the use of HAPS to provide all or part of a network service in the 5030-5091 MHz band, and on the costs and benefits of permitting HAPS for this purpose. To the extent it is feasible and economic, are there limitations on the circumstances or uses to which it can be applied? For example, would it be available only to provide relay between two or more UA, or could it also provide relay between UA and stations on the ground? We also seek comment on what technical or other requirements or restrictions are needed either to ensure that NSS use of HAPS to provide network service would be compatible with other operations and services or for

other reasons. For example, we seek comment on whether, consistent with the definition of HAPS in the Commission's rules, we should specify an altitude floor and/or ceiling on the use of such stations. Given the potential footprint of a HAPS-based service, should we permit an NSS licensee to deploy HAPS only if the NSS licensee holds a nationwide market or holds all geographic area licenses on a particular block nationwide? We further seek comment on whether permitting such systems warrants any revisions to the proposals or options for the NSS rules. In addition, because the HAPS acting as network relays for UA communications would also themselves be UA, we seek comment on whether an NSS licensee's operation of such stations may require CNPC (during ascent, descent, or otherwise), whether and to what extent such stations should be permitted to use NNA assignments for CNPC, and if so, what changes to our NNA proposals or other rules are needed. We note that No. 4.23 of the ITU Radio Regulations provides that “[t]ransmissions to or from high altitude platform stations shall be limited to bands specifically identified in Article 5 (WRC-12).” At present, Article 5 does not specifically identify the 5030-5091 MHz band for this purpose. We seek comment on whether, if we restricted such stations to deployments below the 20 km floor for HAPS as defined in the ITU Radio Regulations, permitting HAPS in the band could nonetheless be consistent with No. 4.23 or if, to permit such use, we would need to seek a revision to the bands in which HAPS is permitted under ITU R.R., Article V. We seek comment on whether there is any other legal constraint or consideration to address in permitting such use.

8. Equipment Authorization

89. To ensure that equipment in the new band has the level of reliability and safety required of aviation equipment, we propose to impose equipment authorization requirements similar to those under §§ 87.145 and 87.147 of the Commission's rules to all equipment intended for use in the 5030-5091 MHz band. Section 87.145 requires that each transmitter must be certificated for use in the relevant service, and § 87.147 establishes a specific equipment authorization process for part 87 equipment, which, for the frequencies in the 5030-5091 MHz band among others, requires coordination with the FAA. We seek comment on our proposals.

9. Protection of Other Services

a. Microwave Landing Systems

90. We seek comment on what measures we should adopt to protect Federal Microwave Landing System (MLS) services from harmful interference by UAS communications in the 5030-5091 MHz band. Should we establish exclusion zones around the Air Force bases with MLS deployments, with a process to add or eliminate exclusion zones to the extent Federal MLS stations are deployed or deactivated? AIA proposes that the Commission codify the locations at which MLS operations are conducted and establish a coordination mechanism to enable UAS CNPC operations near those MLS stations. We seek comment on this option, the specifics of any such coordination mechanism, and how this or any option would address the deployment of new Federal MLS stations, particularly in the case of NSS licensees that may have already deployed networks in the area of the new deployment.

91. Because we find no current licensed non-Federal MLS systems in operation, and given that the FAA does not anticipate the future use of these systems at airports, we seek comment on whether any measures are necessary to protect non-Federal MLS. We also seek comment on whether to provide that no future non-Federal MLS licenses (including MLS radionavigation land test licenses at 5031 MHz) will be granted in the 5030-5091 MHz band by amending §§ 87.173(b) and 87.475 of our part 87 rules to remove the 5030-5091 MHz band as a band that can be used for non-Federal MLS. We seek comment on the costs and benefits of this option. Would eliminating the potential for future non-Federal MLS in the 5030-5091 MHz band help to ensure a stable spectral environment that may facilitate the use of the band for UAS CNPC? Would it facilitate the use of the band for other communications, to the extent such communications may be permitted? Given the development and widespread adoption of alternative solutions for instrument-based landing and the apparent abandonment of MLS, is there any need to preserve the option in our rules for licensing of non-Federal MLS in this band?

b. Out-of-Band Services

92.
Radioastronomy.
To address the potential impact on radio astronomy observations from UAS transmissions in the 5030-5091 MHz band, NTIA requests that Footnote US211 continue to apply to any services authorized in the 5030-5091 MHz band. NTIA also recommends that the Commission require coordination of UAS operations within the National Radio Quiet Zone (NRQZ). NTIA further recommends that “additional criteria” be developed to minimize UAS impact to particular radio astronomy sites, particularly from low-altitude operations, but does not elaborate or propose particular criteria. As a further measure, NTIA recommends that the requirements for licensees in the band include passing a test or similar effort to promote awareness of radio astronomy sites.

93. We seek comment on whether additional measures are necessary to protect radio astronomy and on NTIA's recommendations in this regard. We propose, consistent with NTIA's recommendations, to continue to apply the requirements of Footnote US211 in the 5030-5091 MHz band, to prohibit UAS operations within the NRQZ without prior coordination with the NRQZ administrator and, in the case of NNA operations relying on DFMS assignments, to require the submission of a concurrence from the NRQZ administrator with any request to a DFMS for frequency assignment within the NRQZ. We seek comment on these proposals. We note that § 1.924(a) of the Commission's rules establishes required procedures for licensees and applicants that seek to construct or operate new or modified fixed stations to coordinate their deployments in the NRQZ. Should we apply these licensee/applicant procedures for the NRQZ to all UAS operations relying on the 5030-5091 MHz band in the NRQZ? To the extent we require NRQZ administrator concurrence for licensed-by-rule operations, we seek comment on the appropriate procedures to apply. To the extent measures beyond coordination and concurrence requirements for UAS operations are warranted, we seek comment on what other measures are practicable.

94.
AeroMACS.
AeroMACS is a broadband aeronautical mobile (route) service system that will enable communications for surface operations at airports between aircraft and other vehicles and between other critical fixed assets. The Commission has allocated both the 5000-5030 MHz and 5091-5150 MHz bands for such use but has not yet established service rules in either band.

95. We seek comment on whether any special measures are necessary to ensure compatibility between UAS operations in the 5030-5091 MHz band and AeroMACS. AIA indicates that RTCA is currently working on a revision to the AeroMACS technical standard, RTCA DO-346, that will ensure that future

AeroMACS deployments will be compatible with CNPC links that are in compliance with RTCA DO-362A, and that no other special limitations on 5030-5091 MHz operations beyond compliance with RTCA DO-362A are necessary. More recently, RTCA's Program Management Committee (PMC) held its June 2022 meeting approving RTCA DO-346A with these revisions. We seek comment on whether the revised AeroMACS standard and compliance with the power and out-of-band emission limits of RTCA DO-362A are adequate measures to protect AeroMACS operations from harmful interference from 5030-5091 MHz UAS operations, and whether the revisions to the AeroMACS standard require specific service rules for the 5030-5091 MHz band. Should we adopt exclusion zones around airports with AeroMACS deployments, or prohibit use of a certain amount of spectrum at the edge of the 5030-5091 MHz band in the vicinity of such airports?

96.
Radionavigation-satellite service.
The 5010-5030 MHz band also includes an allocation for the radionavigation-satellite service (RNSS) (space-to-Earth) for potential future use. Footnote 5.443C of the Table of Frequency Allocations addresses requirements in the 5030-5091 MHz band for the protection of RNSS downlinks. Specifically, it provides that “[u]nwanted emissions from the aeronautical mobile (R) service in the frequency band 5030-5091 MHz shall be limited to protect RNSS system downlinks in the adjacent 5010-5030 MHz band” and that “[u]ntil such time that an appropriate value is established in a relevant ITU-R Recommendation, the e.i.r.p. density limit of -75 dBW/MHz in the frequency band 5010-5030 MHz for any AM(R)S station unwanted emission should be used.” As CNPC services would be part of the AM(R)S allocation, this requirement applies to such services in the 5030-5091 MHz band. We propose to require 5030-5091 MHz operations to comply with the specific EIRP spectral density limit specified in Footnote 5.443C and seek comment on that proposal. Footnote 5.443C further limits AM(R)S use of the 5030-5091 MHz band to “internationally standardized aeronautical systems.” We seek comment on codifying this requirement as a service rule and on whether any other measure is necessary to implement the restriction. We further seek comment on whether any other special measures applicable to the 5030-5091 MHz band, such as a guard band at the bottom edge of the 5030-5091 MHz band, should be adopted to protect RNSS system downlinks.

97.
Flight testing.
The 5091-5150 MHz band is also allocated for aeronautical mobile telemetry communications from aircraft stations, subject to the technical parameters in ITU Resolution 418 (WRC-12) intended to ensure compatibility with other services. According to NTIA, Federal agencies currently use this allocation in the 5091-5150 MHz band to support flight testing. We seek comment on whether measures beyond generally applicable out-of-band emissions limits are necessary to ensure that 5030-5091 MHz operations are compatible with such services.

c. Canadian and Mexican Coordination

98. In the event of any adjustments made to the agreements with Mexico or Canada regarding use of the 5030-5091 MHz band, we note that our proposed rules, and any rules that may ultimately become effective pursuant to this proceeding, may need to be modified to comply with those agreements. We seek comment on whether we should adopt an interim measure to address UAS communications in the 5030-5091 MHz band that may cause harmful interference to operations in Mexico or Canada during the period prior to any adjustments made to the agreements between the United States, Mexico, and/or Canada regarding use of the band. If so, what should this interim measure provide?

B. Airborne Use of Flexible-Use Spectrum

99. While the Commission remains committed to allowing flexibility in the use of existing spectrum and networks, we are uncertain about the potential interference impacts of UAS use. Therefore, we seek comment on the adequacy of current rules to ensure co-existence of existing terrestrial wireless networks and UAS and on the regulatory solutions that may be necessary to facilitate and encourage such use.

1. Applicable Spectrum Bands

100. The flexible-use spectrum landscape for potential UAS use is varied, consisting of bands that prohibit airborne use (in the Table of Frequency Allocations or by rule) and bands that are silent on airborne operation. For example, parts 22 and 96 explicitly prohibit the airborne use of Cellular Radiotelephone Service and Citizens Broadband Radio Service (CBRS) spectrum. Likewise, the Table of Frequency Allocations precludes aeronautical mobile use for several other spectrum bands, including all or portions of the 1670-1675 MHz, 1.4 GHz, 2.3 GHz (Wireless Communications Service), and 3.7 GHz bands. Other flexible-use bands, however, are silent regarding airborne operations. We seek comment on the spectrum bands that might be utilized for UAS, as well as the spectrum bands that would not be suitable for such operation (
e.g.,
frequency bands with co-channel or adjacent channel services that require protection).

101. To inform our review, commenters should indicate the flexible-use bands in which they are currently operating or testing UAS. In addition, we ask commenters to detail the flexible-use band(s) that they may be interested in using for UAS in the future, including bands with and without explicit rules or allocations prohibiting airborne use. We also ask commenters to identify the type of communication contemplated,
e.g.,
command and control, telemetry, or payload (video, etc.) for the desired band, as well as the type of technology or infrastructure needed to support such use.

2. Sufficiency of Existing Rules

102. Certain entities maintain that our existing service and technical rules for the various flexible-use bands are sufficient to address the potential for harmful interference from UAS operations. While our existing rules promote optimal flexibility for licensees, these rules are largely focused on terrestrial operations and were not designed with airborne operations in mind. Although studies are underway to develop techniques to manage and mitigate the increased risk of harmful interference posed by UAS, at this time it is unclear whether these mitigation techniques and standards enhancements would be sufficient to protect existing wireless users and adjacent service area/band licensees from harmful interference caused by UAS use. Further, the functionality exhibited by UAs may necessitate revising our rules to enable UAS operation on existing flexible-use networks. In light of these interference concerns, we seek comment on whether modifications to our rules to protect existing terrestrial and other airborne operations are warranted.

103.
Interference mitigation.
Use of flexible-use spectrum by UAS can raise interference problems for co-channel and potentially adjacent-channel operations—particularly the high-density use that is expected to occur in the future. The impact of UAs on mobile networks is different than conventional mobile devices due to the high altitude

and high mobility of UAs. The higher altitude of UAs means that they (1) can see and be seen by more base stations than a conventional mobile device; and (2) have more favorable propagation conditions than propagation experienced by terrestrial operations. In addition, this high mobility, coupled with moving velocities up to 100 miles per hour under current FAA restrictions, can result in base station handoff issues and other network issues as described in detail below. These factors underlie two scenarios in which harmful interference can occur in the presence of UAS operating on flexible-use spectrum—downlink interference and uplink interference.

104. In the downlink—communications from the base station to UAs—the UAs may operate at an altitude that is within line of sight of multiple base stations and, as a result, the UAs can receive downlink interference from those base stations. Accordingly, UAs may experience more downlink interference than terrestrial user equipment because the enhanced propagation conditions and greater line-of-sight cause downlink interference resulting from the multiple base stations visible to, and attempting to connect to, the UA. The increased downlink interference leads to increased resource utilization levels in the network and eventually degrades the downlink performance of both airborne and terrestrial equipment.

105. At the same time, in the uplink—communications from the UA to the base station—the same UA can also cause interference to these multiple line-of-sight base stations. Uplink interference could increase as more UAs are introduced into the network. This interference may also increase depending on the UA's intended uses. For example, UAs may generate more uplink traffic than is typical of conventional mobile devices due to the use of data rate-intensive applications, such as video streaming and data streaming; such applications increase spectrum demand and present an increased risk of uplink interference. The increased uplink interference from UAs affects the throughput performance of terrestrial user equipment: as the number of UAs operating in a network increases, uplink resource utilization in the network also increases and at a greater rate than terrestrial-only operation. Eventually, the uplink performance of both UA and terrestrial equipment in the network is degraded.

106. To support use of UAS in terrestrial mobile networks, in 2017, 3rd Generation Partnership Project (3GPP) published a technical report (TR36.777) investigating the ability for UAs to be served using terrestrial LTE networks. The report's findings—which were based on the analysis of field trials performed by various companies analyzing LTE commercial network performance with the introduction of UAs—validated that downlink and uplink interference may result from UAS operation. The report proposed various network and UA enhancements to minimize LTE throughput degradation and interference to the network and to UAs and terrestrial devices.

107. TR36.777 confirmed the effect that UAS operations may have on downlink operations. The report observed that UAs uniformly distributed between 1.5 meters and 300 meters above ground level experienced downlink interference as a direct result of the UAs operating in the direct line-of-sight of more cells than terrestrial user equipment. This causes the UAs to receive downlink intercell interference from multiple cells. The resulting increase in resource utilization to provide for the introduction of UAs further decreases the spectral efficiency in the network and degrades downlink throughput performance of both UAs and terrestrial user equipment.

108. The report similarly validated impacts on uplink interference. To this end, it also was observed that since the UAs experience line-of-sight propagation conditions to more cells than terrestrial devices, the UAs would cause interference to more cells in the uplink than a typical terrestrial device. The uplink interference caused by UAs degrades the throughput performance of terrestrial devices. The increase in resource utilization level further increases interference in the network, which in turn degrades the uplink throughput performance of both UAs and terrestrial user equipment.

109. The report suggested several potential solutions to mitigate both uplink and downlink interference. Many of the solutions can be implemented by network providers independently and do not require an update to the 3GPP standard. To mitigate downlink interference, the report proposed the following solutions:

•
Full-Dimensional MIMO (FD-MIMO)
—This solution would use multiple antennas at the eNodeB (base station) transmitter to mitigate the interference in the downlink to UAs. FD-MIMO can also limit the mean terrestrial user equipment (UE) packet throughput loss.

•
Directional Antenna at UAs
—Interference in the downlink can be mitigated by equipping UAs with a directional antenna instead of an omnidirectional antenna. A directional antenna can be used to mitigate the interference in the downlink to UAs by decreasing the interference power coming from a broad range of angles.

•
Receive Beamforming at UAs
—The UAs are assumed to be equipped with more than two receive antennas to mitigate the interference in the downlink to UAs. Downlink interference mitigation can be achieved in this case by using receive beamforming at UAs. In this solution, multiple cells belonging to the same site are coordinated and data is jointly transmitted to the UAs.

•
Intra-Site Joint Transmission Coordinated Multi-Point Operation (JT CoMP)
—In this solution, multiple cells are coordinated and data is jointly transmitted to the UAs.

•
Coverage Extension
—In this solution, coverage extension techniques via downlink shared channels, physical broadcast channels, and physical downlink shared channels are used to enhance synchronization and initial access for UAs. Because the UA is synchronized with the network, downlink interference is mitigated.

•
Coordinated Data and Control Transmission
—In this solution, multiple cells belonging to the same or different sites are coordinated. Data, common signal/channels (
e.g.,
synchronization signal and Physical Broadcast Channel (PBCH)), and control channels can be jointly transmitted to the UAs. The coordinated cells could construct a larger cell for UAs, and terrestrial user equipment is served by physical cells without coordination, simultaneously. A dedicated downlink resource within the Physical Downlink Shared Channel (PDSCH) region of the coordinated cells can be reserved for these coordinated transmissions.

110. The report proposed the following techniques to mitigate uplink interference:

•
User Equipment Specific Fractional Pathloss Compensation Factor
—In this solution, an enhancement to the existing open loop power control mechanism is considered where a device-specific fractional pathloss compensation factor is introduced.

•
User Equipment Specific Power Output Parameter
—Configuring a lower power output for UAs compared to terrestrial devices improves terrestrial uplink user equipment throughput performance. Such a configuration, however, reduces UA uplink throughput.

•
Closed Loop Power Control
—In this solution, the target received powers for the UAs are adjusted. By applying

closed loop power control, mean terrestrial user equipment uplink throughput improvement can be improved.

•
Full-Dimensional MIMO (FD-MIMO)
—By using FD-MIMO with multiple antennas at the eNB receiver interference in the uplink can be mitigated. In addition, FD-MIMO can limit the mean terrestrial user equipment packet throughput loss.

111. In addition to TR 36.777, 3GPP made changes to Technical Standard TS36.331 to help address UA interference to the base station. In LTE networks, measurement reports are messages sent from a UA to a base station that help the base station make network decisions. The changes to TS36.331 included measurement report triggers for two reporting events: H1 (above) and H2 (below) UA height thresholds sent from the UA to the base station to help the base station see the UA and to deal with potential interference. 3GPP is also making additional enhancements to integrate UAS into LTE networks that do not relate to interference.

112. While the 3GPP TR 36.777 report concluded that it is feasible to use existing LTE networks to provide UA connectivity, the report and its findings have their limitations. The 3GPP quantitative analyses for Release 15 evalu

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2023-00961. Public record. Not legal advice.