TPRC 2025: The 53nd Research Conference on Communications, Information and Inter

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Abstract:
This paper explores a tension in spectrum policy that is unnecessarily limiting public access to the airwaves and the benefits of more intensive spectrum sharing and connectivity. Most spectrum licenses (including Federal spectrum assignments) confer exclusive or at least primary rights to transmit on designated frequency bands at specific locations, or over defined geographic areas, including inside factories, office buildings and other facilities owned and controlled by others. This traditional form of licensing precludes property owners from using the spectrum inside buildings under their own control even if the transmissions are contained and would not cause harmful interference to the primary licensee’s operations outdoors. While unlicensed operations have been authorized, until very recently the rules have not been crafted to distinguish between how access rights could vary based on indoor-only use.

The potential benefits of different rules for indoor-only use are becoming more evident. In 2020, the Federal Communications Commission (FCC) adopted an order authorizing low power, indoor-only (LPI) use of 1,200 megahertz on an unlicensed basis across the entire 6 GHz band (5925-7125 MHz), which was already in use by incumbent licensees that include more than 50,000 high-power fixed microwave links. LPI use of this spectrum indoors is limited to roughly one-fourth the standard power of Wi-Fi, yet is considered extremely useful since the vast majority of internet data (including at least 80% of mobile device data traffic) is transmitted indoors and over Wi-Fi. LPI highlights the potential to authorize indoor-only use in many other bands where users comply with power, device form factor, or other requirements that protect the primary licensees from harmful interference. 

This paper explores the policy and technical considerations related to expanding indoor-only authorizations to more bands. For example, controlling the spectrum inside a facility is more practical at higher frequencies where transmissions do not readily penetrate building materials or travel long distances. This concept is particularly relevant now, as the National Telecommunications and Information Administration (NTIA) and FCC collaborate to implement the National Spectrum Strategy, which is premised on studying alternative means to expand private sector use of underutilized Federal bands, particularly bands occupied by U.S. military systems. Five Federal bands that may be prime candidates for indoor-only authorizations—1,675 megahertz in total—are discussed in this report. LPI underlays also provide another way to expand on the “use it or share it” approach to spectrum sharing, but without the need for control by a geolocation database.

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Over recent decades, US spectrum policy has transitioned from a case-by-case administrative model to a Coasian one, where market mechanisms allocate exclusive yet flexible spectrum rights. This paper suggests that observing both formal and informal spectrum-management practices calls for a policy framework enabling comparative analysis across various governance structures, from exclusive access to spectrum commons. We propose an alternative framework, drawing on Elinor Ostrom's research on polycentric systems, to evaluate spectrum-sharing solutions, particularly unlicensed spectrum. Our analysis suggests that "unassigned" spectrum bands, like communal ownership or private commons within a flexible-licensing regime, can balance the trade-offs of exclusive and nonexclusive access.

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The Federal Communications Commission (“FCC”) and its counterparts globally keep a keen eye on spectrum concentration. This is because concentration in input markets is conjectured to have the effect of driving anticompetitive behavior in the relevant output markets. Spectrum is a necessity for the provision of mobile wireless services, and by accumulating spectrum holdings mobile carriers could wield their spectrum portfolios to obtain market advantages over competitors. For example, simply preventing spectrum to fall in the hands of your competitors increases deployment costs for them going forward, making them less competitive and in turn allowing the carrier that has accumulated the spectrum to compete less fiercely for customers. More spectrum, however, lowers your own production costs. In this paper, we develop theory describing the pro and anti-competitive incentives of spectrum accumulation and evaluate to what extent these theoretical findings can be empirically supported in the US market for mobile services. Generally, it should be expected that more concentrated markets exhibit lower product quality than less concentrated markets. To empirically test the theory, we will examine a combination of FCC Measuring Broadband America data and Universal Licensing System data to detect any econometrically significant relationships between mobile service quality and spectrum concentration.

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The scarcity of available spectrum bands has prompted the exploration and analysis of strategies for sharing spectrum with existing users. The US is considering several bands as part of its National Spectrum Strategy. In this paper, we consider sharing spectrum with the Broadcast Auxiliary Service (BAS) in the 6, 7 and 12 GHz bands. We develop simple models to examine the impact of interference in these bands to BAS-like operations. Our findings contribute to understanding the feasibility of various spectrum sharing regimes, such as, property rights easement, spectrum commons and spectrum anarchy. The key technical result of this study is that while new spectrum uses in the 6, 7, and 12 GHz bands can cause significant interference, this can be managed effectively through mitigation strategies such as dynamic exclusion zones, lower EIRP levels for indoor use, and advanced detection methods.

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Future G networks will require more dynamic, agile support for the management of radio frequency spectrum on a fine-grained basis. The radio access network (RAN) technologies necessary to enable Dynamic Spectrum Access (DSA) have progressed significantly over the past 20 years, but the challenges of realizing the potential for DSA requires the co-evolution of the technologies, business models/market structures, and regulatory policy for wireless networks. This paper discusses a bottom-up, multi-disciplinary approach to DSA. In particular, we focus on the use of standards-based Spectrum Consumption Models (SCMs), and review on-going research to incorporate SCMs in an automated management framework based on incentive-compatible, technically-sound spectrum access contracts, or Spectrum Access Agreements (SAAs). This work is being undertaken as part of the NSF National Radio Dynamic Zone (NRDZ) research initiative and this paper provides an introduction to the core concepts of the SCM/SAA framework, project goals, and preliminary insights into how the SCM/SAA can help improve spectrum management and advance R&D efforts to enable the transition to a shared spectrum future. The SCM/SAA research represents a bottom-up effort to develop the techno-economic tools to facilitate market-based experimentation and development of spectrum sharing markets, business models, and applications to complement and render more economically viable and relevant emerging DSA technologies and top-down regulatory reforms aimed at lowering spectrum sharing barriers.

If previous timeframes are to be followed, the next generation cellular system, 6G, can expect to roll out around 2030 (i.e., just 6 years from today). Consequently, discussions in the 3GPP and ITU on the development of 6G standards will begin in 2024. Thus, it is timely and relevant to bring together experts who are considering the technical, economic, policy, and regulation that surround the expectations of this emerging standard. In this light, multiple questions need to be addressed to start defining the new standard from multiple perspectives. These questions include but are not limited to the following: Should 6G be 10x faster than 5G? Should it be a lower cost than other standards (e.g., 5G) to reduce the digital divide? Should it focus on programmability and customization? How should spectrum sharing be incorporated into this new standard? The panel will address these and other topics that are likely to emerge over the next several months.

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An open-access market design is presented to manage network congestion and optimize network use and value. Open access eliminates the walled-garden approach; instead, it commoditizes communications network capacity while decentralizing access to a transparent wholesale market. It ensures that scarce capacity is put to its best use by providing a platform for efficient trade. The market operates without friction using flow trading. It allows participants to bid persistent piecewise-linear downward-sloping demand curves for portfolios of products, gradually adjusting positions toward targeted needs. Flow trading allows fine granularity of products in time and location, creating complete markets. Liquidity and computational feasibility are maintained despite trading millions of interrelated forward and real-time products. Participants manage risk and adverse price impact through trade-to-target strategies. The market operator clears the market every hour, finding unique prices and quantities that maximize as-bid social welfare. Prices, aggregate quantities, and the slope of the aggregate net demand are public. The market operator observes positions, enabling it to optimize collateral requirements to minimize default risk. Priority pricing is used to manage real-time imbalances. An application of the model is developed for intersatellite wholesale communications with optical (laser-beamed) mesh networks in space, showing several efficiency gains.

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Defining property rights in the electromagnetic spectrum is challenging because the natural laws governing the behavior of electromagnetic radiations are very different from those describing material resources like land, water, or air. Additionally, the rules for the composition and decomposition of spectrum licenses, thus created for trading in secondary markets, are difficult to derive and are generally not well understood.

In this paper, we employ the framework of dynamical systems theory to introduce a new theoretical model that captures the behavior of a radio service as a dynamical system that operates within a context of concurrently operating radio services. We then introduce the formal framework of assume-guarantee contracts for specifying spectrum operating rights allocated to each radio service. Our proposed model helps unify existing frameworks that rely on an environment-based specification of transmission permissions and reception protections. Our framework is in accordance with the FCC's 2023 Policy Statement that establishes spectrum management principles for transmitters and receivers.

Our work opens up an inter-disciplinary research program between the fields of spectrum management, robotics, control-theory and programming language theory. We illustrate the applicability of our framework with a simple two-system example focusing on FCC's recent 5G-vs-radio altimeter problem.

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Spectrum sharing, including dynamic spectrum sharing, is arguably the most significant overarching feature of the new era of spectrum management. The emphasis on sharing spectrum recognizes the importance of balancing the needs of different users of an exceptionally valuable resource. Despite the equitable features of spectrum sharing, what has been underemphasized in spectrum management is its colonial features from the perspective of Native Nations. This paper proposes ways to decolonize dynamic spectrum sharing and, in the process, improve prospects for a new spectrum era that recognizes Native Nations as collaborators in the American system of spectrum management.