The forced relocation of CBRS licensees to other bands would irreparably damage a growing industry and its ecosystem
Some recent press articles and an open letter from Senator Cantwell to Defense Secretary Hegseth have suggested that the Department of Defense (DoD) and the Federal Communications Commission (FCC) may be actively looking at a plan, originally advocated by AT&T, to change the nature of an important shared military/commercial spectrum band called CBRS (Citizens Broadband Radio Service).
Forced relocation of CBRS licensees to other bands, and/or a fundamental change to the technical operations, would irreparably damage a growing industry and its ecosystem of enterprise and connectivity providers. It would extinguish competitive offerings and stifle the FCC’s successful “innovation band” concept based on shared spectrum. U.S. policymakers should listen to all stakeholders, and do everything possible to protect the existing CBRS allocation and its technical characteristics. They should also recognise that the costs would likely far outweigh any probable auction receipts.
DoD’s reported proposal forms part of a wider desire by the mobile industry and parts of the administration to identify a so-called “spectrum pipeline” for clearance and future auction to cellular carriers for public 5G network capacity. In addition to the 3.55-3.7GHz CBRS band, there are also efforts to clear and repurpose the lower 3GHz band – despite its use for critical systems such as missile defense – and 7-8GHz, which is also widely used by the military.
Since its beginning as a new shared band in 2019, CBRS has become critically important for a wide range of national and local wireless Internet service providers (WISPs) and an increasing variety of enterprises which use it as the basis for private 4G and 5G networks. Numerous carriers, such as Verizon, also use it for meeting additional capacity needs. It is a centrepiece of spectrum-sharing innovation, an exciting area of technology of which the US is one of the world’s leading exemplars.
Proponents such as CTIA falsely argue that the US has a deficit of mid-band spectrum compared to international peers, using a spurious definition which allows it to avoid counting T-Mobile’s large allocation in the 2.5GHz range, and which mis-classifies other countries’ shared bands. It is more accurate to say that there is a competitive imbalance between the different US carriers’ mid-band holdings.
To counter this, the AT&T plan involves re-locating the CBRS band, and its various users, to some other frequency range – perhaps in the 3.1-3.45GHz space. In AT&T’s vision, the vacated spectrum could then be auctioned for new exclusive, high-power licenses for 5G, conveniently creating a contiguous block with the adjacent C-band (3.7–3.98 GHz) and 3.45–3.55 GHz band that mobile carriers already use. However, the lower 3GHz band is seen as extremely difficult to share – and made harder still if CBRS’s existing navy radar incumbents are also moved to that range.
CBRS 101
CBRS works in the 3.5 GHz band (between 3.55-3.70GHz). It was launched as an innovative spectrum-sharing framework, with a three-tiered system managed by a Spectrum Access System (SAS) to coordinate different groups of users.
Incumbents (mainly U.S. Navy radars along coastlines, plus some satellite users) have top priority and are protected from interference. Priority Access Licenses (PALs), auctioned in 2020 make up the next tier, giving rights to use specific frequencies in localized areas, yielding if an incumbent needs the spectrum — although that is obviously unlikely for areas far from the coast.
The third tier, General Authorized Access (GAA), is “licensed by rule” but available as open access to any unused frequencies on a “first come, first served” basis, but under SAS control to prevent harmful interference to incumbents and PAL rights-holders.
In July 2024, a revised set of rules and processes, known as CBRS 2.0, relaxed some of the geographic restrictions, allowing many more enterprises and citizens to benefit from unimpeded access to the band. The FCC has also been consulting on the next update.
The value of the innovation band
This dynamic sharing model ensures DoD radars can operate when and where needed, while making unused spectrum available to others. In short, CBRS has opened mid-band spectrum to a wide range of new users and innovative applications – from rural broadband providers to localized enterprise private 5G networks.
While some commentators rightly point to auctions as a way of gaining appropriate market value for spectrum, the typical process involves wide-area licenses for expansive geographic regions, rather than the small areas needed for a factory, farm or airport. The FCC’s 2020 CBRS auction, by contrast, awarded licenses for smaller, county-sized areas – while raising billions of dollars for the U.S. Treasury.
Given that many of the most highly-valued use-cases for 5G are for specific sites — factory automation, AR/VR in hospitals, campus networks at universities, warehouse robots, energy asset monitoring or precision agriculture — CBRS now has a central role in driving digitalization of industry and enhanced economic productivity.
These use-cases are typically poorly suited to carriers’ public 5G offerings, or for Wi-Fi, for instance because of the coverage areas or the need for service-quality guarantees. The overhyped concept of 5G network slicing does not offer a viable alternative in most cases – it is also dependent on adequate coverage in those often hard-to-reach locations, as well as commercial guarantees and liability clauses that cellular carriers are unwilling to provide.
The business sector’s desire for private networks is not confined to CBRS in the US. Similar models of local spectrum allocation are occurring worldwide — more than 40 countries have parallel approaches, albeit without the sophistication of the automated US SAS system. The idea of private cellular networks has over 20 years of history, and has hit a major inflection point in recent years.
Furthermore, as well as enterprise networks, CBRS spectrum is widely used by rural WISPs (wireless Internet service providers) for delivering connectivity that bridges the “digital divide” for broadband in small towns, villages and isolated farms and homesteads. While such FWA services are not new, the addition of CBRS has allowed WISPs to increase their performance and competitive position significantly, either with their own private 5G systems, or proprietary wireless alternatives from certain vendors. WISPA, the WISP industry association, reports huge uptake of CBRS across its members – it is seen as “indispensable.”
Why the plan to move or close CBRS is a mistake
As Senator Cantwell noted: “Transferring control of this band would also undermine an innovative ecosystem of commercial wireless technology that will be extremely valuable.”
By every metric, CBRS is a hotbed of wireless innovation. GAA commercial service began in 2020 and PAL licenses were issued in 2021, initially with 4G equipment, with 5G arriving in 2022. In just a few years, organizations large and small have invested in CBRS-based networks.
In total, over 400,000 CBRS radio devices have been deployed. Organisations ranging from John Deere to Dallas Fort Worth Airport rely on private CBRS networks. Major infrastructure vendors such as Nokia have built entire product lines for private CBRS networks, while system integrators have spent years refining deployment strategies and hiring staff for different verticals.
You can’t copy-paste an ecosystem
Imagine that the FCC decided to push forward and relocate CBRS to 3.1-3.3GHz, despite all these challenges. Even in the rosiest scenario, replicating CBRS’s functionality in a new band would be a multi-year journey, fraught with technical and commercial hurdles.
Existing DoD operations in the 3.1-3.3 GHz band could preclude outdoor operations by a revised CBRS if they were moved to that band, unless a new and unproven concept called “highly dynamic spectrum sharing” proves workable. There would also likely be very different geographical protection areas to today, some of which may render existing CBRS-based services impossible.
Further, all current CBRS equipment, from base stations (called CBSDs) to smartphones and IoT modules, is tuned for the current 3.5GHz range. Shifting to another band would mean years of delay as manufacturers design new radio hardware and chipsets to cover that range (if they chose to do so at all). Today’s devices do not support 3.1–3.3 GHz frequencies.
Getting a new frequency band adopted into global standards by industry body 3GPP, then designing chipsets, and developing and deploying new devices is not quick. It typically takes years from regulatory decision to widespread device support. Enterprises that only recently deployed CBRS gear could wait years for “NextGen CBRS” equipment to catch up – and then be forced to spend on replacements. Similar constraints exist for CBSDs, as well as design, planning and operational tools.
Furthermore, the CBRS SAS and Environmental Sensing Capability (ESC) framework would have to be re-designed from the ground up to address different incumbent operations. Different incumbent systems would mean very different challenges, especially for faster-moving and less-predictable airborne radars compared to the 3.5GHz naval radars.
Overall, the rich ecosystem that exists for 3.5GHz would, in effect, be abandoned and would need to be re-established from scratch in the new range. The industry would essentially go back to square one in terms of standards, testing, proofs-of-concept, systems integration, application integration – and also skills and training for engineers and others.
While these are probably not insurmountable tasks, it is a significant undertaking to duplicate a whole ecosystem in terms of both cost and time. Furthermore, equipment manufacturers “burned” by the FCC nullifying years of R&D investment and production scaling in the current generation of CBRS hardware may hesitate to commit to starting over in new bands. There is a high risk of a regulatory limbo, where neither the old band nor the new band is fully utilized.
Moreover, these technical and supply-chain considerations in implementing AT&T’s proposal add to the considerable legal uncertainty if the FCC attempts to cancel current CBRS PAL spectrum licenses, possibly re-auctioning those frequencies to competitors. This is certainly likely to extend timelines for the auctions, and thus reduce the time-and risk-discounted value of any forecast proceeds.
Huge disruption for enterprise and rural WISPs
The cost of downtime and general disruption for enterprises with existing CBRS private networks for critical business systems would be immense. Others currently in the planning and deployment phase might be forced to delay their technology evolution.
Consider a factory that is implementing a CBRS private 5G system for its robots, inspection cameras and industrial automation systems, plus human workers and visitors with handhelds and smartphones. It will have gone through a lengthy and expensive process of planning and designing its network, selecting and integrating applications and devices, and then the disruption of installing the equipment and commissioning the system. It may have linked it to existing Wi-Fi in the factory and relied upon CBRS modules built-into a variety of other systems such as industrial robots, XR headsets, gateways and guided vehicles.
Ripping out all of this, sourcing new equipment and devices (where the industry would have to support a new and unusual band, at the same prices), and learning the complexities of accessing a new SAS type database would all be horribly expensive. Worse, any downtime for the factory’s production would be unlikely to be covered by any “incentive” compensation scheme related to the spectrum repackaging.
As noted above, device and equipment support is a particular issue here. Work on CBRS Band 48 chipsets and devices started about 10 years ago, and is still scaling up. If the innovation band was moved to 3.1GHz, for instance, it might take another decade for an equivalent base of devices to be standardized, developed and sold
Being cynical, cellular carriers hoping to sell alternative approaches to private networks might view this disruption, cost and uncertainty in a different light – it might give them an opportunity to try to market less-mature and suboptimal solutions such as network slicing.
In many ways, the fact that AT&T has seriously proposed such a disruptive concept points to either a complete lack of understanding of the importance of wireless systems to enterprises – or a deliberate and cynical attempt to undermine confidence in CBRS and shared spectrum, just as acceleration is occurring in adoption, innovation and iteration of the use of that band.
Many enterprise customers would lose trust in AT&T – and potentially the FCC as well – if they incur direct costs in replacing equipment, consequential losses because of downtime of operations, and perhaps end up with “stranded assets” if alternatives are not available rapidly.
The myth of “underutilization”
Proponents for reorganizing the 3GHz band often try to assert that CBRS is “under-utilized,” despite still being a new band intended specifically for innovation and new deployment models. They use tools and metrics such as drive-tests intended for measuring legacy wide-area macro coverage, which misses the objective entirely.
It is a straw man argument.
Of course, a band intended for localized or private deployments will not produce a ubiquitous signal on every street corner – that is not its purpose. The value of CBRS lies in enabling different deployment models, targeting coverage and capacity where needed.
Drive tests cannot measure spectrum usage across agricultural land, inside warehouses and factories, or across the ramp areas of airports. They may fail to record FWA use in deep rural areas or on college campuses. Averaging the use of the band over not just an automated manufacturing site but also the surrounding 100 square miles is obviously misleading.
Similarly, a utility company using the band to create a private network to respond to emergencies and power-down the grid, before a falling cable starts a fire, will not have a high overall utilization rate.
In other words, such complaints miss the point entirely. It is unclear whether this is deliberate obtuseness, or a simple lack of understanding of enterprise and community wireless needs.
Furthermore, it is a bit hypocritical for the industry to criticize CBRS for patchy usage, when many of the cellular bands are similarly spotty in nature. Operators’ C-band and mmWave assets are themselves deployed sparingly or not at all – and in particular, often have no indoor coverage, despite that accounting for the bulk of mobile usage.
The true metrics of success are in the new applications, services and communities connected. Federated Wireless noted that CBRS has seen “faster, more widespread deployment by a wider and more diverse range of users than perhaps any other spectrum band in history” over its first few years.
Conclusion
We are reaching diminishing returns on the old “clear and auction” model for spectrum. That is precisely why spectrum sharing approaches such as CBRS are being explored more. Pragmatically, it’s the only way to unlock some bands without spending huge sums or waiting decades — or both.
CBRS is a pioneering model that has already yielded substantial success — claims it has somehow failed after just a couple of years of commercial use (including during a pandemic) and upending its users would be spectacularly short-sighted.
Years of wrangling would likely ensue if a forced relocation was to proceed. During that time, many constructive and innovative uses of 3.5GHz could stagnate, as investment froze pending the outcome. Ironically, a proposal purportedly intended to “maximize 5G potential” could sideline a chunk of mid-band spectrum for half a decade or more during litigation and eventual re-farming – an ill-afforded pause when 5G deployment and private network momentum is needed now, not later.
Furthermore, the CBRS approach has been one of iteration, progressively making it more useful and accessible. The sharing approach with the defense sector meant understandable initial conservatism about where and when it could be used.
To some, it appears that various interests are coalescing around a plan to effectively dismantle CBRS as we know it — reassigning its frequencies to the highest bidders and shunting aside the myriad smaller users who have embraced the sharing model.
The result would be lost broadband coverage in rural areas, stalled private 5G projects, and a chilling effect on any new wireless initiatives outside the big national carriers. It would also harm a key area of US innovation leadership in spectrum sharing that will be essential in the 2030s – handing spectrum-sharing commercialization to both allies and foes.
U.S. policymakers should protect, defend and extend the CBRS model — not bend to the will of carriers that seem happy to disrupt American companies and communities.
