Recommendations and Conclusions

An overwhelming majority of internet data is consumed indoors, including at least 80 percent of the data traffic over personal mobile broadband devices. Private local networks and uses, especially large venues and enterprise Internet of Things (IoT) networks, will require an enormous increase in wireless bandwidth going forward. The evidence from low-power, indoor-only (LPI) unlicensed use across the full 6 GHz band (1,200 megahertz) suggests that LPI operations can be authorized in many more bands without a significant risk of harmful interference to incumbent operations outside the user’s walls. Further, as the list of technical considerations and policy trade-offs discussed above indicates, the specific bands that are most conducive to a new LPI authorization, as well as the allowed power levels and licensing framework, will depend heavily on frequency propagation and the vulnerability of the primary service. For those reasons and others, we expect that proposals and Federal Communications Commission (FCC) proceedings will continue to be undertaken on a band-by-band basis.

As noted at the outset, the precedent of unlicensed LPI in 6 GHz and the success of dynamic sharing at low power with military radar in Citizens Broadband Radio Service (CBRS) suggest that an indoor-only allocation should be at the forefront of the band studies that are just getting underway as part of the U.S National Spectrum Strategy. The two largest frequency ranges that will be subject to studies co-led by the National Telecommunications and Information Administration (NTIA) and Department of Defense (DoD) are the 3100–3450 MHz and 7125–8400 MHz bands, each of which is currently allocated to, and used primarily by, military operations.¹ Military systems are, by their nature, outdoors (or at least outside private sector buildings), and publicly available information suggests that most—if not all—of the current use includes many different radar systems (air, sea, or land), as well as other airborne and satellite operations.

To the extent that the federal government concludes that segments of these bands cannot be reallocated for primary commercial use—or cannot be shared for outdoor commercial use at all, or at least not at a sufficiently useful power level—there would still be the option of indoor-only use. Indeed, in some band segments, the military and other federal incumbents may conclude it’s possible to authorize LPI sharing in the short term, even if the development of new dynamic spectrum sharing technologies might allow sharing with outdoor commercial operations in the future. Several particular band segments within the frequency ranges being studied for sharing as part of the National Spectrum Strategy could be particularly valuable for LPI because of their proximity to the primary band for next-generation Wi-Fi (e.g., 6 GHz) and for private network sharing (e.g., CBRS).

Based on publicly available information, the following federal bands (representing a total of 1,675 megahertz) appear be prime candidates for sharing on at least an LPI basis:

7125–7250 MHz: This sub-band at the bottom of the 7125–8400 MHz range is immediately adjacent to current LPI use at the top of the unlicensed 5925–7125 MHz band. The Department of Energy and other federal fixed-link incumbents in this band segment can have exactly the same protection from LPI use that commercial fixed links do in the U-NII-5/7 band segments (e.g., very low power and indoor-only device restrictions). There appears to be no military radar or other specific DOD allocation here. Extending unlicensed access up to 7250 MHz would enable an additional 80 and an additional 160-megahertz channel for Wi-Fi 6E devices already in use. It would also add an additional 320-megahertz channel for Wi-Fi 7, which is expected to be widely available in 2025, and Wi-Fi 8, which is already in development. Any outdoor commercial use (e.g., mobile broadband outdoors) would likely require the relocation of federal use and, possibly, protection areas around Earth Exploration Satellite Service uplinks (earth-to-space direction) on 7190–7250 MHz,² making this a logical next allocation for Wi-Fi.

7250–7750 MHz: The next 500 megahertz above 7250 MHz also appears to be best suited for sharing on an LPI basis, at least initially. It is primarily a military band often referred to as the “NATO band.” In fact, when the World Radio Conference (WRC-23) last December adopted a future agenda item premised on studying the 7125–8400 MHz band for a possible allocation to IMT—viz., possible use for full-power commercial cellular use outdoors—this sub-band was carved out and put off limits even for study in Region 1, which includes Europe and the United Kingdom.³ In the United States, the band is also a primary military band allocated for both fixed- and maritime-satellite use in the space-to-earth direction.⁴ These uses make coexistence with outdoor and high-power commercial use extremely challenging—an option that is apparently off the table, at least in Europe if not also in the U.S. (which sells NATO and individual member nations systems that operate in the band).

Although the full scope of military or other national security systems operating in the band is not public information, it seems that LPI operations (such as indoor-only Wi-Fi) in all or portions of that 500 megahertz could coexist most easily with federal operations. If so, the proximity to the primary band for LPI unlicensed use, which is currently authorized up to 7125 MHz—and especially in combination with the 7125–7250 MHz sub-band discussed just above—would be an immediately valuable way to expand capacity for the potential multi-gigabit throughput and higher quality of service that will be offered once Wi-Fi 7 becomes commercially available in 2025.

3100–3450 MHz: During the year prior to the National Spectrum Strategy (NSS), as required by Congress under the Infrastructure Investment and Jobs Act of 2021, DoD convened a multi-stakeholder group to study the possibility of sharing this 350-megahertz band, or portions of it, with the private sector. DoD concluded that the band cannot be cleared for high-power and wide-area exclusive licensing but “determined that sharing is feasible if certain advanced interference mitigation features and a coordination framework to facilitate spectrum sharing are put in place.”⁵ Currently, as part of the NSS, the NTIA and DoD are co-leading a follow-up to the Emerging Mid-Band Radar Spectrum Study aimed at exploring additional options and, according to the NSS Implementation Plan, a dynamic spectrum-sharing demonstration and “any other mechanisms and possibilities with the potential to allow for expanded or more efficient uses of the spectrum.”⁶ The study group is in its formative stage at this writing; its final report is not due until October 2026 under the NSS timeline.⁷ Although a dynamic coordination system should enable DoD to share at least portions of the band for low-power use outdoors—as the U.S. Navy does currently with CBRS on 3550–3650 MHz—a broader underlay authorization for LPI use should be considered as an option for this band. It would complement the CBRS ecosystem, and, to the extent geolocation database coordination is needed, Spectrum Access Systems are already in place.

2900–3100 MHz: Even lower in 3 GHz is the 2900–3100 MHz sub-band allocated to federal and commercial shipborne radars required on most passenger and cargo ships for safety under an international maritime treaty, as well as for weather monitoring.⁸ The upper 100 megahertz of the band appears to be used entirely for maritime radio navigation. The lower half of the band is the upmost portion of a 300 megahertz band (2700–3000) that is used for weather monitoring.⁹ According to the Department of Commerce (National Oceanic and Atmospheric Administration), NEXRAD consists of relatively few (160) fixed sites.¹⁰ All of the primary uses of this 200 megahertz, while valuable and potentially vulnerable to interference from secondary use outdoors, may be sufficiently remote and protected by attenuation from a future authorization of LPI use.

10–10.5 GHz: This 500 megahertz of upper mid-band spectrum is principally a federal radar band that DoD clearly does not believe can be shared for commercial outdoor use. The WRC-23 adopted a resolution to allow a number of specified nations in Region 2 (the Americas) to allocate this band for International Mobile Telecommunications, a proposal the United States initially opposed at the regional level.¹¹ Although Resolution 219 limits use to lower-power microcell base stations, the U.S. is not among the countries listed, and the band is not among the federal bands identified for study in the National Spectrum Strategy. In the U.S., a coalition of rural broadband advocates filed a petition for rulemaking in 2022 asking the FCC to make the 10–10.5 GHz band available for point-to-point fixed use on a nationwide non-exclusive basis, with interference protection governed by an Automated Frequency Coordination system.¹² After consulting with NTIA, the Commission declined to even put the petition out for comment. In short, every indication is that the military opposes sharing with even lower power or coordinated commercial use outdoors. However, if the primary use is radar, the FCC and NTIA should consider whether either unlicensed or licensed-by-rule LPI could coexist in all or a substantial portion of the 500 megahertz band.

While each of the five bands above presents challenges for outdoor-shared use that adequately protects federal and other incumbents, they all appear to be viable options for a low-power, indoor-only scheme where built-in geographic separation and physical barriers protect incumbents from harmful interference. They are all good candidates for further study in the short term—and certainly, the National Spectrum Strategy studies just getting underway should specifically consider the option of LPI in the first three bands described above.

In the longer term, the FCC should promote the public interest in spectrum access and innovation and meet the burgeoning data needs of emerging technologies by more readily adopting indoor-only underlays of spectrum use wherever feasible. While authorizations of additional bands for unlicensed LPI is the best way to meet the needs of the general public in the widest variety of locations, the Commission should also consider allowing registered users (on a licensed-by-rule basis) to operate freely indoors across additional bands, provided that they can certify that emissions are contained and not detectable outdoors above a threshold that protects other band licensees or users. Extending authorizations of indoor-only underlays to additional bands is another variation on the “use it or share it” ethos that promises to take spectrum policy from a mindset of scarcity to one of wireless bandwidth abundance.