I. Introduction

This report updates and expands on a paper the author presented nearly a decade ago at the Research Conference on Communication, Information and Internet Policy (TPRC), which predated the Federal Communications Commission’s (FCC) adoption of a use-it-or-share-it approach in several underutilized bands. These use-it-or-share-it precedents should pave the way to an authorization of opportunistic access as the default policy for a growing number of underutilized and newly allocated or auctioned bands, both federal and commercial.¹ A national goal of not merely universal access to broadband, but of truly pervasive connectivity—high-capacity connectivity anywhere and anytime at affordable prices—will require an enormous increase in available spectrum capacity. By promoting bandwidth abundance, a use-it-or-it-share policy can play a central part in any effort aimed at expanding spectrum access for rural and non-traditional internet service providers (ISPs), as well as for enterprise, home, and institutional use. A use-or-share rule expands productive use of spectrum and facilitates more communication and consumer welfare without undue risk of harmful interference or undermining of primary licensees’ deployment plans.

Conceptually, use-it-or-share-it rules authorize opportunistic access to licensed or federal spectrum that is unused or underutilized in a specific area. This approach expands productive use of spectrum without risking harmful interference or undermining the deployment plans of primary licensees. Although the use-it-or-share-it approach can be applied to most bands, the authorization of opportunistic access is inherently band-specific. Access rights and conditions can vary widely depending on the propagation characteristics and size of the band, the nature of the incumbent users, the nature of the shared use requested, the availability of a coordination mechanism (e.g., a geolocation database coordinator), and other factors. Some underutilized bands can be most effectively shared based on frequency separation (adjacent channel sharing), or based on geographic separation (e.g., co-channel sharing), or on a temporal basis—and some based on a combination of methods that exploit unused spectrum capacity.

The bedrock principle of opportunistic spectrum sharing is that secondary users and the coordination process itself should have little if any impact on incumbent services. In practice, this means that opportunistic use of a band is premised above all on avoiding harmful interference to the primary incumbent service (e.g., broadcasting, military radar). An authorization for opportunistic, shared use can (and should) ensure licensees that opportunistic users will vacate the spectrum once notified that the licensee is ready to commence service in that local area and will never result in harmful interference to the primary licensee’s operations. However, as we will explore below, the authorization of opportunistic but non-interfering use can be accomplished in a variety of established ways. These methods include automated frequency coordination (a geolocation database), sensing systems, use restrictions (such as low-power, indoor-only operation), and specific technical conditions (such as antenna directionality).

Lawmakers and regulators are increasingly recognizing that meeting the increasing demand for wireless data will ultimately require a greater focus on shared, dynamic access to unused and underutilized bands. For example, Congress in 2018 mandated development of “a national plan for making additional . . . bands available for unlicensed or license by rule operations,” which included examining “existing and planned databases or spectrum access systems designed to promote spectrum sharing.”²

While Congressional recognition of the importance of unlicensed and dynamic spectrum sharing is relatively recent, the FCC has incrementally pursued a policy of leveraging new technologies to unlock fallow spectrum capacity through sharing for nearly two decades. The FCC’s Spectrum Policy Task Force Report recognized this opportunity in 2002:

Preliminary data and general observations indicate that many portions of the radio spectrum are not in use for significant periods of time, and that spectrum use of these “white spaces” (both temporal and geographic) can be increased significantly . . .³

The National Broadband Plan similarly recommended in 2010 that “[t]he FCC should spur further development and deployment of opportunistic uses across more radio spectrum.”⁴ In its rationale for that recommendation, the National Broadband Plan observed that opportunistic and cognitive radio technologies “could allow access to many different frequencies across the spectrum chart that may not be in use at a specific place and time and could do so without harming other users’ operations or interests.”⁵ The National Broadband Plan went on to urge the FCC to allow opportunistic use of unassigned spectrum currently held by the FCC and “to extend the geolocation database concept, currently being implemented in the TV bands, to additional spectrum bands that are made available for access by opportunistic radios.”⁶

While the FCC has led the world in pioneering both unlicensed and dynamic spectrum access policies, regulators in other nations are recognizing the benefits of direct local access to unused spectrum capacity. The next section notes that a growing number of countries have adopted the TV White Space (TVWS) framework first approved by the FCC in 2010, including reliance on a geolocation database to manage access and protect broadcast services. The United Kingdom’s spectrum regulator, Ofcom, observed in a 2015 report that “[g]eolocation databases are making it easier for devices to identify spectrum that is available for sharing while protecting the operation of existing services. While the current focus is on the use of databases to manage access to TV white spaces within 470–790 MHz, the fundamental principle is not frequency specific and can extended to a broader range of frequencies.”⁷

As Section II describes, the FCC has adopted a number of world-leading precedents since 2014 in opportunistic spectrum sharing that apply a variation of the use-it-share-it approach. These important precedents, all adopted on a bipartisan basis, include:

• authorizing continued unlicensed use of post-auction 600 MHz band spectrum until a licensee notifies the TVWS database it is ready to commence service;
• the new Citizens Broadband Radio Service (CBRS), a three-tier dynamic sharing framework that both opens U.S. Navy spectrum for commercial use and authorizes use-or-share access to the licensed portion of the band auctioned in 2020;
• the April 2020 order authorized unlicensed sharing, on a non-interfering basis, with incumbent services in the 6 GHz band—allowing both a low-power, indoor-only underlay across all 1,200 megahertz, and use of two sub-bands (850 megahertz) at standard power subject to control by Automated Frequency Coordination systems;
• emergency Special Temporary Authorizations (STAs), in response to the pandemic-induced surge in home broadband use, in multiple bands to both major mobile carriers and to more than 100 mostly rural wireless internet service providers (WISPs).

Section III describes how a use-it-or-it-share-it approach promotes important public policy objectives, including more intensive use of fallow spectrum capacity, lowering barriers of entry to a diverse range of uses and users, facilitating more innovation and competition, improving choices and lowering costs for consumers of wireless services, and promoting service in rural and other underserved areas to narrow the digital divide. Unleashing opportunistic, shared access to fallow spectrum also creates a general incentive for licensees to build out services more quickly, or to make greater efforts to lease unused spectrum, since opportunistic use of the band demonstrates that other (typically smaller) operators are finding value in the unused portions of their license area. A use-it-or-share-it policy adds a more affirmative, non-punitive approach than the more draconian use-it-or-lose-it build-out requirements. Instead, the regulator could decide to permit licensees to attribute all or a portion of the areas served by opportunistic users to their own performance in relation to build-out requirements.

Section IV revisits a consideration largely absent from recent debates about the assignment of rights to access the public airwaves: The First Amendment. Because spectrum is a government-controlled resource essential for wireless communication, FCC decisions on access to spectrum must be consistent with First Amendment principles. Unlike publishing or any other form of communication, the government requires a license to communicate over the public airwaves. As a result, and as federal courts have consistently held, the assignment of rights to communicate cannot be based solely on economic criteria or the whims of regulators. First Amendment jurisprudence on the FCC’s right to regulate spectrum access rests on the so-called “scarcity rationale.” This refers to the idea that because the frequency bands most useful for communication are finite and in demand by many potential users, the FCC must allocate and assign spectrum rights to avoid harmful interference. While the scarcity rationale has been used to justify licensing, auctions, licensing conditions, and other FCC regulation of spectrum use, this paper explains why the FCC must clear a high hurdle (intermediate scrutiny) to justify barring non-interfering communications.

Section V connects this right to communicate with the practical constraint of harmful interference. When it comes to petitions or proposals for use of occupied (but underutilized) spectrum, the FCC operationalizes the scarcity rationale by deciding if and to what degree a new use or user poses an undue risk of harmful interference to current users. The FCC has been clear that not all interference is harmful interference. Accordingly, the FCC has explicitly authorized new users in occupied bands where, despite acknowledging some additional interference, it finds that with technical restrictions (e.g., low power, indoor-only use), or with minor accommodations by incumbent users (e.g., notifying a database), the degree of harmful interference that would justify excluding the new use can be avoided. In recent proceedings, the commission has become more explicit about the nature of this balancing approach to interference, an approach that is correctly premised on the actual performance of incumbent services or systems—and not on mere hypothetical, fleeting, or de minimis disruption.

Finally, in Section VI, the paper discusses a number of near-term opportunities to extend shared access to additional and substantial underutilized federal, commercial, and FCC-held bands. Federal bands that deserve a near-term focus include 700 megahertz of mid-band spectrum between 2900 and 4500 MHz. An additional 700 megahertz of commercial mid-band spectrum is currently in use, but offers a potential opportunity for a use-it-or-share-it approach that could be particularly valuable for enabling high-capacity fixed wireless in rural and unserved areas, as well as low-power, indoor-only (LPI) unlicensed use nationwide. A third category represents FCC-held spectrum that is fallow and should be made available on a use-or-share or dynamically-shared basis, even if that use is time-limited.