Breaking Down the CBRS Rules

As we sit on the cusp of 2017, now is a good time to go back over some of the essential details of the FCC’s plans for the CBRS band. Before this, it does bear noting that while the course is baked and the market planning activities for this new band have been ongoing before the FCC issued its Report & Order on April 17, 2015, a new presidential administration has the power to entirely disrupt the process. The lack of coherent direction other than a stated intent to disrupt government by the incoming President does inject some uncertainty. [For example, several critical aspects of the plan, such as the auction process for Priority Access Licenses (described in the above link) has not yet been determined. While unlikely, a new FCC might upend the current plan that favors small businesses (by envisioning an innovative “eBay-like” auction). However, it could be scrapped in favor of a traditional auction process that requires multimillion dollar reserves, etc. that favor the major carriers.]

With that caveat, let’s begin.

The CBRS band – Citizens Broadband Radio Service – is a spectrum plan that emerged following President Obama’s PCAST initiative at the start of his administration. It tasked the FCC and Department of Commerce’s NTIA sub agency to find an additional 500 MHz that could be re-allocated to serve the public interest, specifically in advancing broadband deployment. Working with the Department of Defense made it more friendly to internal U.S. needs, and the FCC and the NTIA were able to work with the military to decide that current military spectrum allocation from 3.55-3.65 GHz could be re-worked to permit commercial use. This band range is being used by the Navy, but mostly only in coastal areas, and even then, only “episodically.” Under previous administrations the DoD had been unwilling to give up total control of any allocation. Under Obama, the DoD agreed with both the FCC and the NTIA that technology in radio has advanced enough where shared use was possible while still insuring that military “incumbent” use would be protected.

Another benefit to this band range is that it sits directly below and adjacent to the current NN Rural Broadband band of 3.65-3.70 GHz. Additionally, the band range is already in commercial use in almost the entirety of the rest of the world, creating a global opportunity for some level of regulatory harmony, which would thus spur mass adoption by vendors and markets at large. The trick though was to find the balance of technology policy that could do the job of protecting the military incumbent use, and that meant removing humans for whom “cooperation” (a requirement under the NN rules) would only spur dispute. Additionally, if the intent was to merge this 100 MHz of new band at 3.55-3.65 GHz with the existing NN 3.65-3.70 GHz band, some accommodation needed to be made to be minimally disruptive and protect current market investments (and real broadband consumers) in the 3.65 GHz band.

The authorities decided to look to the techniques adopted in TV White Space (TVWS), which uses a 3rd party spectrum management technology to connect base stations. This technology uses objective technical rules to manage the interference environment, removing human unpredictability and emotion. The difference would be that this technology management regime – to be called the Spectrum Access System (SAS) – would be more advanced than that used in the TVWS.

After extensive internal work, the FCC in December 2012 issued a “Notice of Proposed Rulemaking” (NPRM) announcing its intent and asking for public comment. In the NPRM process, entities that consider themselves potential stakeholders file public comments with the FCC in a formal way and the FCC collects these comments to further refine plans. Public comment periods are for a fixed time frame and anyone may record a comment, from the largest company to an individual citizen.

A second and subsequent further Notice “FNPRM” was issued some 18 months later that tweaked the original plan based on the thousands of comments. Substantial change was made, for example, the original NPRM envisioned this band would have critical municipal and public safety use as high priority users, like hospitals, utilities, etc., with commercial users at a low tier. Instead, the FCC decided to create a Priority Access License level that anyone – company, person, or any entity – could try to obtain.
In any event, after much further wrangling with industry, the DoD, and others, the FCC issued its final Report and Order (R&O) on the band April 17, 2015. Here is the band structure the rules:

Three tiers of users are created, in order of priority for protection:

  • a. Incumbents (fixed satellite users in the NN area and DoD users, and site specific protection of existing registered NN locations). Of these, protection for FS and DoD users is permanent, while NN sites registered before April 17, 2015 have their protection expiring mid-April 2020. Remember, under current NN rules registered sites have no protection as is, so this is a to existing NN users they should like. Note also that I mention protection of registered SITES, NOT protection of a company’s entire network unless every site they operate was registered officially prior to April 17, 2015.
  • b. Priority Access Licenses (PALs). PAL will be made available through as yet undetermined auction process. PALs will only exist in the lower 100 MHz of the CBRS band range – 3.55-3.65 GHz. Within that range there will be UP TO 7 PALs, each 10 MHz in size, for a total PAL availability of 70 MHz of the 100 MHz-wide band. No single entity (including through layers of shells or subsidiaries) may obtain more than 4 PALs.

Additionally, PALs will be matched to U.S. Census Tracts in terms of size. This is new and unusual and has never been tried before. The rational is that it will drive down license costs since there are 74,134 tracts currently in the U.S. With 7 PALs per tract, that’s a lot of availability. In addition, the census tract idea was adopted in recognition that many rural networks may be able to protect their entire coverage with only a few licenses while the big carriers, who may want licenses for cellular offload in urban areas, are in a position to pay more. It is an effective way for the market to establish the value of any given tract based on population density – the more pop/sq. mile, the expected higher the price.

It must also be explained that a PAL license comes with a 3 year term, with the first licensee able to get two consecutive terms for a total of 6 years available for the first PALs. As well, a PAL does not buy you a fixed 10 MHz. Instead, and since the DoD will not tell us where or when a radar may fire — or even within what specific piece of the 100 MHz range – the allocation is for a floating 10 MHz. In reality, this will end of being almost entirely static in most parts of the country (not much Naval radar in Arkansas, for example), but the rules mean the SAS, if it senses radar operations, will have the ability to instantly move a PAL to another band range. Do not worry though, because this will not be common and the equipment, via it’s connection to the SAS service, will do the job without human interaction.

  • c. General Authorized Access (GAA). This is the lowest tier, and to best understand it, think of it as being almost exactly as you operate today in the 3.65 GHz band. No other GAA has rank over another, and they all have to try to cooperate to co-exist, except with the added benefit that theynow have more room to do so. Why? Well, remember, only 70% of the lower 100 MHz is reserved for PALs. That leaves 30% — or 30 MHz – available for GAA use, and this is on top of the 3.65-3.7 50MHz range, which will stay all GAA (except for current registered users who get additional incumbent protection through mid 2020). As well, the expectation that a great swath of the country will not have all the PALs gobbled up, and anything not bought as a PAL gets thrown into the GAA pool, making even further spectrum available for GAA use. So you have 80 MHz minimum that will always be available for GAA in the entire 3.55-3.70 GHz range compared to the 50MHz you now have in the NN band.

Further still, the current rules have the “restricted” and “unrestricted” portions of the 3.65 GHz band (upper and lower 25 MHz).

In practice, how does this all work? Well, operators will buy the gear, which will already be certified by the FCC under the new CBRS Part 96 rules and thus confirmed to perform with a SAS, and then simply go online to register the equipment as they do now. Then they will select one of the SAS vendors, such as Federated Wireless, Spectrum Bridge, Google, Amdocs, Commsearch to which your base stations (what Wi-Fi users might call “Aps”) will connect in the cloud and then it’s done. The SAS will do the work to keep operators off incumbent protected users. If you are not using a PAL, feel free to use 20 MHz channels. If you are using PALs, then use 10 MHz or do carrier aggregation of two PALs, for example, and off you go. You can even combine GAA and PAL use. No problem.

This the general framework within which providers will work. There is much to like and little to complain about overall. We expect wide availability of PALs at extremely low cost (in the hundreds of dollars), since the big carriers want the band mostly for small cell in dense urban corridors to “densify” their LTE networks and alleviate demand pressure on their precious multi-billion dollar traditional spectrum by users doing so much streaming content. In deep rural, these pressures are not acute, and even non-existent so there is little motivation to invest in PALs by carriers in rural markets. And, even if they do, they are limited to 4 PALs, so even non PAL GAA users will be able to compete. There are subtleties about total power output, and that can change to as much a 47 dB EIRP in select rural areas and there are categories of devices called “CBSDs” (Citizen Broadband Service Devices) aka CPEs that have different power rules, but what’s above is the outline of the band.

The last thing to say is that the entire spectrum won’t come online until the auction process is set and occurs. The work to build the SASes is largely done and many vendors, including Baicells, is currently running FCC STA trials with select SAS vendors and rural service providers to iron out any kinks in the system. So right now the gating issue is back in the FCC’s court. Hopefully once the presidential transition is complete the process will continue without disruption because the current model is one that favors the small rural operators immensely. Any disruption would likely mean the rules would be scrapped or made more favorable to the major carriers, by doing things like changing the auction plans to a typical multi-billion dollar carrier auction, eliminating census tract sizing and using traditional spectrum regional allocations, increasing the 3 year term to 10, and preventing any GAA use at all the lower 100 MHz. These are things the huge operators would prefer so WISPs and other interested rural parties should be vigilant and stay vocal with their congressmen and senators about keeping the current plans as is.

If you questions or would like more information, please contact me directly via email at, or my colleague Rick Harnish at

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Showing 2 comments
  • Jamie Price

    Thank you for this information. How does CBRS relate to MulteFire? Thanks in Advance

    • Eva Wang

      thank you for your reply. Strictly speaking, CBRS has nothing to do with MulteFire. CBRS is open unlicensed spectrum at 3.5Ghz according to the United States’ government rules; while MulteFire is a LTE access technology for independent LTE-U and coordination between LTE and LTE-U.

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