FCC Seeks 411 on LTE-U

Making good on the Chairman’s promise, the FCC is looking for input into Unlicensed LTE and LAA.

As we recently reported, when the Commission created the new Citizens Broadband Radio Service which will use the 3.5 GHz band, Chairman Wheeler promised to open a separate docket in which folks could “file their perspectives” on LTE-Unlicensed (LTE-U) and Licensed Assisted Access (LAA) technology. And sure enough, the Office of Engineering and Technology and the Wireless Telecommunications Bureau have promptly issued a Public Notice (PN) seeking comment on “current trends” in that technology.

LTE-U/LAA presents one of the most controversial aspects of the future unlicensed use of the 3.5 GHz and 5 GHz bands. That’s because LTE-U/LAA is designed to use some of that same spectrum, spectrum which is viewed by Wi-Fi proponents as vital to handling ever increasing Wi-Fi traffic.   

The PN seeks information on LTE-U/LAA “technologies and the techniques they will implement to share spectrum with existing unlicensed operations and technologies such as Wi-Fi that are widely used by the public.” 

The PN suggests ten topics for comment, including:

  • the types of LTE-U (and related LAA) technologies being developed;
  • their specific technical characteristics, and the state of development of each;
  • plans for their deployment and use; and
  • methods and plans for future upgrades. 

What has stirred some controversy within the Commission, however, are the PN’s questions directed to what’s happening within the industry standards setting committees that are working on standards relevant to LTE-U. (The two standards setting committees identified in the PN are the Third Generation Partnership Project (3GPP) and the Working Group 802.11 of the Institute of Electrical and Electronics Engineers (IEEE Working Group 802.11).) Obviously the FCC has an interest in those standards, as they will likely determine the extent to which LTE-U/LAA can co-exist with Wi-Fi. But normally, the establishment of industry standards is left largely to the private sector. While the FCC makes a practice of having its own experts attend standards-setting meetings to monitor the discussions, provide informal advice and keep tabs on things, the FCC generally leaves standards setting to the industry participants.

Still, the PN asks questions that probe into the standards setting processes. For example, “What is the status of coordination between 3GPP and the IEEE 802.11 on LTE-U and LAA, and what is the process for coming to agreement on appropriate sharing characteristics to ensure coexistence with the IEEE 802.11 family of standards?” And “What tests or analyses have been performed to understand the impact of LTE-U and LAA on the existing commercial wireless and unlicensed ecosystems?” 

Such questions prompted Commissioner O’Rielly to pull out the yellow caution flag. Noting that the PN “walks a fine line between reasonable oversight and inappropriate interference with the standards setting process”, he has vowed to be “vigilant” to prevent the Commission from taking sides in the standards-setting debate.

Those interested may file comments on or before June 11, 2015, and reply comments on or before June 26. Comments and replies may be filed through the FCC’s ECFS online filing system; refer to Proceeding No. 15-105.

The FCC Raises the Curtain on the Citizens Broadband Radio Service

Shared use of 3.5 GHz band promises greater efficiency, but much work still needs to be done before operations can begin.

In a move described by the Commissioners as a “significant step forward” (Chairman Wheeler), history-making (Commissioner Rosenworcel), and “excit[ing]” (Commissioner O’Rielly), the FCC has opened up the 3.5 GHz (3550-3700 MHz) band for a wide variety of new uses. The band will now be home to the new Citizens Broadband Radio Service (CBRS). Perhaps most importantly, the new users will share the spectrum with themselves and incumbents through a three-tiered access model that depends on an automated frequency assignment and control database mechanism known as the Spectrum Access System (SAS). A number of details still need to be worked out in a further rulemaking, but the FCC’s action unquestionably reflects an innovative approach to increasing the efficient use of spectrum.

Historically, the 3.5 GHz band has been used by the Department of Defense for radar systems. Radar, of course, is a notoriously difficult technology to share with. A portion of the band has also been used for delivery of commercial broadband service, another sensitive use not ordinarily open to sharing. The Fixed Satellite Service (FSS) is another incumbent which has been pushed around to accommodate the CBRS. Through a system of priorities embodied in the tiering approach, the Commission believes that those incumbent uses can be protected from interference while the band is opened to other users. And those new users will enjoy the flexibility of opting for either priority access when reliability is important (at least in license areas where there is demand), or general access when it is less critical.

The new scheme contemplates that the licensed incumbents in the band will be joined by two new categories of users: those with Priority Access (who would hold Priority Access Licenses (PAL)) and General Authorized Access (GAA), whose use would not be subject to individually-issued licenses. The amount and type of incumbent spectrum use will determine the amount of spectrum available for new entrants in each license area. Spectrum availability for all three tiers of users will be determined continuously by the SAS. While this database system is modeled after the TV White Spaces database system – whose readiness for prime time has recently come under heavy fire – the FCC’s 3.5 GHz plan relies on Google’s promise that its prototype SAS will be capable of even more complex database control than is required of the TV White Spaces database. To maximize database control and incumbent protection, CBRS systems will have to be capable of operating across the entire band and automatically shutting down or changing frequencies at the direction of the SAS. 

The sharing system will work like this.

Incumbent Access (IA) users will enjoy the most protection of all, primarily through the creation of “exclusion zones” with respect to which the SAS will exclude or control access by new entrants. The size of these exclusion zones has been the subject of much wrangling. The FCC has convinced the National Telecommunications and Information Administration (NTIA) – which is generally responsible for spectrum allocated for government use, including radar systems – to reduce the size deemed necessary for such zones. The zones adopted by the FCC are 77% smaller than originally proposed. But concerns remain. In a separate statement Commissioner O’Rielly noted that even the shrunken exclusion zones “capture several of this country’s largest cities, where the shortage of spectrum is most acute. Thus, we must exercise diligence in ensuring that the zones continue to shrink.”

PAL: The FCC will reserve a maximum of 70 MHz (in seven 10 MHz unpaired channels) in each license area for PA licensees. Any unused channels may be accessed by GAA users. As proposed, a PAL area will consist of census tracts (of which there are more than 74,000, ranging in size from less than 1 square mile to 85,000 square miles). PA users will have to protect IA users and each other.

Contrary to its initial proposal last year, the FCC has decided to offer these licenses for three-year license terms (with an optional two consecutive terms the first time around). This will provide for more predictable business planning than the one-year license term originally proposed, although we agree with Commissioner Pai that it’s not clear that even this concession will be sufficient to encourage investment, at least by certain types of potential users. Unlike most FCC licenses, PALs will not be subject to any “renewal expectancy” at the end of a license term. While that may be a good tactic to prevent spectrum warehousing, it could also discourage those with longer range business plans looking to use equipment for, say, 15-20 years.

PA licensees will obtain multiple contiguous channels when available, and they may aggregate up to four licensees (i.e., 40 MHz of spectrum). When demand for the PALs exceeds the supply of available spectrum, the FCC will apply its usual auction process (luckily, one that is much less complex than the incentive auction). However, no auction will be held – and no PALs will be issued – when there is only one applicant in a license area; in such a case, only GAA use will be available in that area. (Commissioner O’Rielly has criticized both the spectrum aggregation limit and the unavailability of PALs when there are no other applicants.)

GAA: The rules provide for opportunistic use of the spectrum by GAA users, which means that such users can operate wherever spectrum is unused by higher-tiered (i.e., IA and PA) users. In license areas where there are no PALs (or incumbents), GAA users may have access to all 150 MHz of the band; in other areas where PALs are in high demand, but there are no IA users, GAA will have access to at least 80 MHz. (Note that this is a change from the percentage-based plan originally proposed, which the Commission concluded would be confusing and uncertain.) GAA is licensed by rule, meaning that GAA users have the status of licensed users (i.e., priority above unlicensed users), but are not required to obtain (or pay for) individual licenses. However, GAA has no interference protection from, and must not cause harmful interference to, higher tier users.

The CBRS technical rules are complex, with different rules for “Category A” devices (designed for lower power, often indoor and/or small cell use) and “Category B” devices (designed for professionally-installed, longer range outdoor backhaul). Devices in each of those categories may be used by both GAA and PAL users. For tech geeks, we recommend a read of the section on received signal strength limits to see how the FCC mandates receiver requirements without actually mandating receiver requirements. Another twist from the norm is that holders of adjacent channel or geographic licenses may consent to alternative reception thresholds by working with the SAS.

An additional note: the FCC has imposed special rules for the upper 50 MHz (3650-3700 MHz) that grandfather existing wireless services and allow GAA access around a “Grandfathered Wireless Protection Zone.” 

What the Future Holds

There is a substantial to-do list before commercial CBRS service can begin: 

The Commission must refine its rules in a number of respects. Among other things, it must: (1) define “use” of spectrum by PAL, a determination that will affect the amount of opportunistic use by GAA; (2) develop certain auction-related rules and procedures to govern PAL auctions; (3) establish secondary market (i.e., spectrum leasing) rules; and (4) craft more specific rules to protect FSS earth stations (one incumbent that was pushed around to make room for CBRS). The FCC has issued a Second Further Notice of Proposed Rulemaking (SFNPRM) seeking comments on these questions.

The Commission must request proposals for and, eventually, approve one or more commercial SAS. Before they can be approved, of course, the FCC will have to review them and confirm that they do the job. Given the complexity of the SAS, this step may require considerable time.

Environmental Sensing Capability (ESC) will have to be developed, authorized and deployed. ESC will involve systems of sensors that detect federal uses in and adjacent to the 3.5 GHz band. The ESC will interface with the SAS so that the SAS in turn can direct commercial users to vacate a channel when their commercial use threatens interference to federal operations. ESCs will be developed by the private sector, but before deployment any ESC will first have to be reviewed, certified and approved by the FCC, much like SAS.

Priority Access Licenses will have to be auctioned. (GAA use can occur on CBRS spectrum prior to licensed use by a PAL).

But still more questions lurk, including whether to permit use of technologies such as LTE-Unlicensed (a/k/a LTE-U)/Licensed Assisted Access (LAA) in the 3.5 GHz band. This controversy has brewed for some time. LTE-U/LAA is a new technology, promoted most vigorously by Qualcomm, that relies on bonded channels in licensed bands. By placing an additional chip in cell phones, wireless carriers using LTE-U/LAA can use unlicensed frequencies in additional to their licensed frequencies. Verizon already has announced its intent to use both 3.5 GHz and 5 GHz unlicensed spectrum for LTE-U by 2016. Broadband proponents, led by Microsoft, have fought against this, arguing that LTE-U/LAA will interfere with Wi-Fi. Further complicating matters is the fact that LTE-U/LAA is not yet standardized worldwide: Europe and Japan require listen-before-talk protocols to prevent interference to Wi-Fi, but other forms do not. Rather than address this conundrum in the SFNPRM, Chairman Wheeler has promised to open a docket specifically devoted to LTE-U/LAA questions in the very near term.

Several Commissioners have categorized the CBRS as a “playground” or “sandbox” for technological development. This may be true. But it remains to be seen what type(s) of business for this spectrum (other than offloading data) can be designed and successfully implemented given the rules the FCC has adopted. The answer will depend on the type and availability of equipment that is developed for the band, and whether investment in that equipment is  sound business decision in view of the varying spectrum access that the Commission has provided. Certainly, a great range of businesses have become successful on other unlicensed bands (902-928 MHz being the granddaddy of them all), but the CBRS scheme has enough new twists, such as database control, that the outcome for the 3.5 GHz band remains to be seen.

Update: 3550-3650 MHz Replies Extended to August 15

No need to read the post; the headline says it all.

A recent item in in our series of posts on the FCC’s novel spectrum-management proposals for the 3550-3650 MHz band (and possibly 3650-6700 MHz as well) told you the reply comment date was … well, it doesn’t matter what we told you, because the FCC has now extended the reply comment date to August 15.

Resume your vacation.

Update: Comment Deadlines Set in 3.6 GHz Citizens Broadband Radio Service Proceeding

Back in April we reported on a sweeping Further Notice of Proposed Rulemaking (FNPRM) on the evolving creation of a Citizens Broadband Radio Service in the 3.5 GHz band. The proposal incorporates a new approach to how the world might handle spectrum use, including on-the-fly frequency coordination with priority up for sale via auction. The FNPRM has now been published in the Federal Register. As a result, we know the deadlines for comments and reply comments directed to the FCC’s proposals. Comments are due by July 14, 2014 and replies by August 1. Anyone wishing to comment now may do so by uploading their submissions in Proceeding No. 12-354 at the FCC’s ECFS filing site.

FCC Proposes New Approach to Spectrum Management

Out for comment: The Citizens Broadband Radio Service for the 3550-3650 MHz band, featuring multiple priority levels, an annual auction, and an unprecedented Spectrum Access System.

As we have known for years, the FCC – and the rest of us – face a daunting problem: too many spectrum users and not enough spectrum. Even the most ambitious reallocation (and associated re-packing) plans offer at most limited and impermanent responses to the problem. Now the FCC has a new idea that could completely remake how the world handles spectrum and, in the process, dramatically increase the efficiency with which spectrum is used.

But the FCC’s plan to create a new “Citizens Broadband Radio Service” (CBRS) in the 3.5 GHz band sure has a lot of moving parts.

The plan is, in a way, simplicity itself: it calls for spectrum users to take turns. But while the basic concept may be kindergarten simple, its implementation is not, by a long shot. After all, not all users’ communications are equally urgent or important. Is there a way to get the more urgent and important stuff through first, and still give everybody else a fair shot?

After a year and a half, a previous Notice of Proposed Rulemaking, a follow-up public notice, hundreds of comments, two full-scale workshops, and too many meetings to count, the FCC has come up with a highly promising approach that is almost ready to test.

The CBRS would be established at 3550-3650 MHz, possibly combined with the adjacent 3650-3700 MHz band. This is an odd choice, at first glance. The incumbents at 3550-3650 MHz are high-powered ground and airborne military radars, and earth stations that receive satellite signals – on the face of it, poor candidates for sharing. The 3650-3700 MHz segment is widely used for delivery of commercial broadband service. Both bands have long been regarded as so sensitive that they are closed to most unlicensed devices.

The FCC nonetheless thinks it has a way to introduce new users to these frequencies without causing interference either to incumbents or to each other. The details appear in a Further Notice of Proposed Rulemaking (FNPRM).

Like an earlier plan, the proposal would establish three priority levels to govern access to the shared spectrum – but there the similarities mostly end.

The new plan would give the highest priority to Incumbent Access (IA) use. As the name suggests, IA would be limited to incumbent users. They would be permitted to operate at any time, and would be free to cause interference to anybody (except, in some cases, to each other). They would also enjoy protection against interference from everybody else, using geographic “exclusion zones” within which no one else could operate on the incumbents’ frequencies.

Next in the pecking order would Priority Access (PA) use. PA users would have to protect the incumbents, and would in turn be protected against interference from General Authorized Access users (discussed below). PA use would be auctioned in ways that are novel for the FCC. Auction areas would be small census tracts – about 74,000 of them nationwide, each with only a few thousand people, generally following political boundaries such as city lines. Each auctioned license would cover 10 MHz and be valid for only one year. Bidders would be free to aggregate licenses so as to cover a greater geographic area, or more bandwidth (up to 30 MHz) or more time (up to five consecutive years in a single auction). The FCC would conduct auctions for the entire system annually.

The lowest priority would be General Authorized Access (GAA). GAA use would provide access, free of charge, to spectrum not occupied by the two categories above. How much spectrum remains available for GAA will depend in part on the success of the PA auctions. But the FCC proposes limiting PA auctions to no more than 50% of the bandwidth in each census tract, after accounting for the incumbents, with the other 50% reserved for GAA. Still, because multiple users may compete for that 50%, no single user could be assured of getting a signal through quickly.

Certain “critical facilities” such as hospitals, public safety organizations, and local governments would get an advantage: they could reserve up to 20 MHz of GAA spectrum, but for indoor use only. Other GAA users would not be permitted to operate on those frequencies in those buildings. The FCC expects the building walls to largely isolate the users in these critical facilities from the great mass of other GAA users outside.

The key to making all of this work is a Spectrum Access System (SAS) that, as envisioned by the FCC, will manage all users (except the incumbents) on the fly, in real time. Every device will have to check in with the SAS, report its own location, request permission to transmit, and wait to be assigned a specific frequency. The SAS’s job will be to keep everybody off the incumbent spectrum in the exclusion zones, prioritize PA users, and assign GAA slots to others. Although a PA license would entitle the user to 10 MHz (or more) at any time, it would not specify a particular slot. For maximum flexibility, the SAS would be able to move each user’s actual operating frequency around in the band as needed.

The proposed technical rules are complex; those interested will have to plow through the FNPRM. Power limits will be higher in rural than in non-rural areas, and higher still for fixed systems, ranging overall from 1 watt up to 200 watts EIRP. But tighter controls will apply at the boundaries of a license area. A licensee that buys just one or a few census tracts will often be close to a boundary, and so in practice may have less power available. Presumably the SAS will set power so as to protect the boundaries.

Taken together, the technical demands on the SAS are unprecedented. The FCC describes it as an extension of the database that controls TV white space devices, but the tasks that would be assigned to the SAS would be vastly more complex. The design and operation of a successful SAS will be a major technological achievement.

All of these considerations listed here, plus a great many more, are open to comment.

Of the FCC’s earlier proposal for the 3550-3650 MHz band, we said, “Not content with crossing that tightrope, the FCC wants to juggle at the same time.” Now it wants to do the whole thing balancing tiptoe on a unicycle. But if the FCC and its industry participants can bring this off, and then extend the same ideas to other bands, the day when we finally exhaust the spectrum may not come as soon as we had feared.

The deadlines for comments have not yet been established. Check back here for updates. Anyone wishing to comment now may do so by uploading their submissions in Proceeding No. 12-354 at the FCC’s ECFS filing site.

FCC Calls for Technical Papers on 3550-3650 MHz

Public is invited to help design a novel, on-the-fly frequency coordination system.

The FCC wants your help in designing its on-the-fly frequency coordination system for the 3550-3650 MHz band – a concept that has the potential to remake spectrum management for many other bands as well.

The central idea is to establish priorities among user groups that a “spectrum access system” enforces automatically in real time.

The FCC first floated the idea in a Notice of Proposed Rulemaking almost a year ago, and more recently refined its ideas in a highly detailed public notice. It announced (and then rescheduled) a workshop to discuss the public notice, now set for January 14.

And it has now issued a call for technical papers to be discussed at the workshop.

The request for papers is detailed and specific. We urge interested persons to consult it directly.

The deadline for papers to be considered in connection with the workshop is January 3, 2014. File submissions in GN Docket No. 12-354.  (You can do that through ECFS.) The FCC has promised to release an agenda prior to the workshop.

The requested papers, the workshop, and comments on the above-mentioned public notice will all help to form the basis of a forthcoming Further Notice of Proposed Rulemaking. But don’t count on waiting till then to change the FCC’s direction. If you have ideas on how it should proceed, submit them now.

New Date for FCC Workshop on 3550-3650 MHz

Event is rescheduled to January 14.

The FCC has rescheduled a workshop on proposed technical requirements, architecture, and operational parameters for the 3550-3650 MHz band. Originally set for December 11, the event is now on for January 14.

We originally posted on the workshop here, giving the old date. Now that the FCC has released a public notice that considerably revises and expands its original proposals, the workshop should take on added interest for those interested in the band.

Update: FCC Seeks Further Comment on 3550-3650 MHz

Public notice lays out ideas based on industry responses so far.

We reported a year ago on the FCC’s novel proposals for spectrum management in the 3550-3650 MHz band.

Following the receipt of comments and a workshop, the FCC is rethinking the details. Its evolving ideas, on which the FCC requests comment, are set out in a public notice.

Ordinarily at this point in a blog piece, we would summarize the public notice. Not this time. It runs to 18 single-spaced pages and is dense with information; an accurate summary would be almost as long as the document itself. We recommend that interested persons consult the public notice directly.

This is not the last word. The FCC has signaled that the next stage will be a Further Notice of Proposed Rulemaking, before it proceeds to adopt rules. Usually, this sequence means the FNPRM will be largely a formality, setting out whatever rules the FCC expects to adopt. Those who want to affect the course of the proceeding should consider submitting their views in response to the public notice.

Comments are due by December 5, 2013 and reply comments by December 20. File in GN Docket No. 12-354.

FCC Announces Workshop on 3.5 GHz Proposal

Session will explore technologies to govern interactions between and among devices.

Those interested in the FCC’s novel, on-the-fly spectrum management system proposed for the 3.5 GHz band may be interested in an FCC workshop, scheduled for December 11, on the technical requirements, architecture, and operational parameters of the system. Details are here.

Update: Reply Deadline Extended in 3.5 GHz Proceeding

Postponement allows time after March 13 workshop.

Last December we reported on a proceeding that proposes novel spectrum management techniques to accommodate small cell operation in the 3.55-3.65 GHz band.

The FCC has moved back the due date for reply comments until April 5. This will allow time for reflection following the FCC’s public workshop on the 3.5 GHz issues to be held on March 13.

Brave New Spectrum World: Proposal Would Accommodate Many More Users in a Sensitive Band

The FCC has proposed an innovation that might vastly increase the ability of multiple users to share the same band.

The FCC has proposed a set of rules that look innocuous enough, and would apply only to a single, underused band. But they may herald a new way of managing spectrum – a suite of techniques having the potential to vastly increase the number of users that can share a given range of frequencies.

All of the radio spectrum is occupied – at least, all of the most useful parts, below about 60 gigahertz. But the demand for spectrum continues to increase. What the FCC needs most is a way to squeeze new users into spectrum that is already in use, without causing interference to either the incumbents or the newcomers.

Current spectrum management relies on “allocating” each band of frequencies to (usually) several categories of users. Those categories, in turn, come in three different priorities. Those designated as “secondary” may not cause harmful interference to, and must accept all interference from, those called “primary.” Unlicensed users, permitted in most bands, must protect all other users (except each other) from interference, and must accept all interference that comes their way. A few bands, like that used for GPS reception, have only one active user category; a few have as many as seven or eight. Three to five is about typical.

Yet even supposedly occupied spectrum is quiet in most places, for much of the time. Some services, like those using two-way radios, occupy their frequencies only sporadically; others, like some types of satellite earth stations, operate only at wide separated locations. All such users, however, vigorously resist letting others into their bands. A police officer at the scene of an accident, picking up his microphone to request an ambulance, hopes to find an empty channel to make the call. The satellite operator may want the option of installing earth stations at new locations, without interference from other kinds of transmitters nearby.

As we explain below, the FCC thinks it can fully protect all such users while still letting new entrants share the same frequencies.

It proposes a scheme that prioritizes some classes of users over others, and – here’s the hard part – implements those priorities in real time, automatically, on the fly. A good trick, if the technology can be made sufficiently reliable.

This is not the FCC’s first foray into technical rules meant to protect users from each other. Unlicensed transmitters in the 5.25-5.35 and 5.47-5.725 GHz bands are required to sniff the air for certain radars, including those that detect adverse weather conditions at airports, and must avoid transmitting on radar frequencies in use. (In practice, though, sometimes even compliant equipment causes interference.) Similarly, the unlicensed “white space” devices that operate on vacant TV frequencies must avoid interfering with TV reception, some wireless microphones, and many other services. The rules for white space devices are complex, requiring self-geolocation, use of a central database to identify locally non-interfering frequencies, and spectrum sensing. Large-scale deployment having just begun, the jury is still out on how well the techniques will work in practice

Now the FCC proposes an ambitious expansion of these ideas. Its test bed is the 3550-3650 MHz band, possibly combined with an adjacent band at 3650-3700 MHz. Current users of 3550-3650 MHz are high-powered ground and airborne military radars, and non-federal earth stations that receive signals from satellites. Both of these applications are ordinarily ill-suited to sharing. Typically a radar combines a high-powered transmitter with a highly sensitive receiver, and is thus prone to both cause and receive interference. Downlink earth stations are also sensitive, as they must receive useable signals from tens of thousands of miles away. The 3650-3700 MHz segment is widely used for delivery of commercial broadband service. Both bands are part of a larger swath that the FCC has long kept closed to most unlicensed devices, out of interference concerns.

In short, this is not the first part of the spectrum one might look to for additional sharing.

Not content with crossing that tightrope, the FCC wants to juggle at the same time. It proposes to add in new users having urgent communications needs: hospitals, utilities, state and local governments – not usually good candidates for already-occupied spectrum. These will implement “small cell” applications; think of Wi-Fi service, but with better coverage at specific locations. Other new users are expected to offer additional small cell services over areas such as homes, office suites, stadiums, shopping malls, hospitals, and parks. These might be set up by consumers at home, by the management of a mall, say, or by a service provider trying to improve coverage in hard-to-reach places.

All such users will be “licensed by rule,” a legal fiction that entails no actual applications or licenses. This means the FCC will have no record of where the devices actually are. If one of them does cause interference, there will be no way of tracking it down.

The scheme rests on three levels of priority, comparable in some ways to the classic primary, secondary, and unlicensed partitions.

The highest priority, called “Incumbent Access,” consists of the federal radars and satellite downlink earth stations already in the band. Other users would be excluded from regions where they could cause interference to these facilities. Additional precautions, described below, would apply outside those regions.

The second level, called “Priority Access,” includes qualified users needing certain levels of service quality, like the hospitals and utilities mentioned above. Each of these users would be permitted to operate only in a specified geographic area: a utility, for example, might be restricted to regions where it provides service. The FCC expects Priority Access usage to be primarily indoors. These users might have access to half the band, leaving the other half for lower priority users. But no operation would be permitted in areas where the devices might cause interference to, or receive interference from, the Incumbent Access users.

The lowest priority, “General Authorized Access,” would comprise use by the general public. These operations would have to avoid causing interference to the other two categories and accept any interference received.

Keeping track of these levels and locations would be a “spectrum access system,” an ever-changing database that all Priority Access and General Authorized Access devices must consult on when, where, on what frequencies, and at what power they can operate. Devices would use geolocation (presumably via GPS) to report their whereabouts to the database. In some respects this system would be modeled after the database used to control white space devices; in practice, it might be an extension of that same database.

The FCC is considering whether to include the adjacent 3650-3700 MHz, which has been the topic of some controversy. Among other users, that band houses self-coordinated fixed links at more than 25,000 sites. But there is no proposal to explicitly grandfather these; instead, current users in the band might have to transition to operate under the new rules.

The FCC requests public input on all of the above, and on many possible variations. The Notice of Proposed Rulemaking is complex. Those interested should give it careful study. Comments are due on February 20, 2013, and reply comments on March 22.

FCC Declines To Clarify Enigmatic Interference Rules

Unilateral and unsuccessful measures held to satisfy requirement for “cooperation” in 3650-3700 MHz band.

The FCC has reviewed its interpretation of a rule that some parties found to be unhelpfully vague. In refusing to make changes, the FCC has left those affected uncertain of their obligations.

As is generally expected of rules, most at the FCC take the form of “Thou shalt” or “Thou shalt not.” Sometimes there is room for dispute on how a rule applies to a novel situation. But in ordinary cases, the requirements are usually pretty clear.

These principles fail to hold, some think, in the policies governing the 3650-3700 MHz band. The procedures are unique in the FCC rulebook. There is no formal frequency coordination, as in most licensed bands, to protect first-in users against interference from later arrivals. But neither is there an everybody-into-the-pool approach like that governing Wi-Fi. The FCC does keep a database of users, much like the ones frequency coordinators rely on, but its implementation is strictly on a do-it-yourself basis, and arguably optional.

Back in December 2009, we reported on a decision by the FCC’s Wireless Telecommunications Bureau concerning this band.

An incumbent licensee in Puerto Rico complained of interference from a newcomer. The incumbent accused the newcomer of failing to check the database before firing up its transmitters, failing to coordinate, and operating before its transmitters showed up in the database (making it hard for the incumbent to find the cause of interference). Once the source had been identified, said the incumbent, the newcomer failed to cooperate in clearing it up.

In most licensed bands, the newcomer would be at fault. The rules for 3650-3700 MHz do say that applicants and licensees “shall cooperate in the selection and use of frequencies” so as to minimize interference. But when it comes to specifics, the tone of the rules changes. Incoming users “should” consult the database, and “should” try to avoid causing interference. When interference does occur, all users “are expected to” cooperate in resolving it. “Thou should,” in other words, rather than “Thou shalt.”

The 2009 Bureau decision on the Puerto Rico incident found for the newcomer. The rules, it said, do not give the incumbent any priority in the interference food chain.

The incumbent sought review by the full Commission, restating the arguments it had raised before the Bureau. It also proposed that the rules, properly read, require the newcomer to reach out to the incumbent before filing its application, so the two can cooperate in devising a plan for coexistence.

The Commission has now firmly rejected that view. It reiterates that all parties have equal status in the 3650-3700 MHz band, regardless of their sequence of arrival. Moreover, the cooperation the FCC requires in selection and use of frequencies need not entail the parties actually working together. Here, it found, certain actions by the newcomer (installing directional antennas), although unilateral and apparently unsuccessful, constituted all the cooperation required. The order did note that if either party causes interference to the other, they must act in good faith to help eliminate it. But it offered nothing in the way of particulars.

In principle, the all-in-it-together attitude has considerable appeal. But things happen; interference occurs; someone must spend money or suspend service to fix it. When a choice is available, there is a natural human tendency to point fingers rather than write checks. The Fixed Wireless Communications Coalition (a client of FHH) has asked the FCC to at least drop the “should” terminology and make compliance mandatory. It would also help if the FCC were to clarify what compliance consists of.

FCC Interprets Novel Licensing Scheme

Better understanding of do-it-yourself licensing arises from interference dispute

Down here in the Commlawblog bunker, we always get excited when the FCC tries out a new approach to licensing. (Maybe we need to get out more.) True, auctions have their place; and the file-your-application-and-wait procedure has a long and venerable history. But we sat up and took notice back in 2005 when the FCC announced it would try do-it-yourself licensing in the 3650-3700 MHz band. It goes like this:

  • All channels are shared by all licensees wanting to use them.
  • Every user initially obtains a non-exclusive, nationwide license that does not specify locations of operation.
  • Transmitters must incorporate a “contention-based protocol” capable of automatically avoiding interference to other users on the same frequency.
  • Users must register their specific locations and frequencies in a database on an FCC website. They are requested to consult the database first, to avoid interfering with existing operations.
  • The FCC gives new registrations a cursory review before accepting them into the database, but does not ordinarily check for interference to other users.
  • “Licensees of stations suffering or causing harmful interference are expected to cooperate and resolve this problem by mutually satisfactory arrangements” – i.e., without running to the FCC.

The rules have been challenged by advocates of other arrangements – especially those who favor auctions for exclusive licenses – but the FCC has held fast.

Now, thanks to an interference dispute in Puerto Rico, we have a clearer idea of how the FCC expects the rules to work.

Licensee Neptuno Networks complained that another licensee, World Data, had failed to check the database before turning on its transmitters, failed to coordinate with Neptuno, and caused harmful interference to Neptuno. Moreover, said Neptuno, World Data began operating before its transmitters showed up in the database, thus making it hard for Neptuno to track down the source of interference.  Neptuno expressed its displeasure in an enforcement complaint about the premature operation, and also filed two Petitions to Deny against World Data’s efforts to register its stations. One of those asks the FCC to bar all World Data operations in the band within six miles of a registered Neptuno base station.

World Data largely admitted the relevant facts (while blaming its contractor), but argued the FCC should leave it alone anyway.

In a decision that may surprise those accustomed to the more traditional licensing regimes – in which causing harmful interference to an earlier-licensed station draws a strong rebuke at the very least – the FCC here pretty much sided with World Data.

Most significantly, the FCC rejected Neptuno’s contention of entitlement to protection from interference because it was there first. In the same vein, the FCC rejected Neptuno’s argument that World Data was required to coordinate its operations with Neptuno. Rather, the FCC insists that every user has equal responsibilities regardless of their sequence of arrival in the band. “[T]he licensing scheme imposes on all licensees the mutual obligation to cooperate and avoid harmful interference to one another.” The FCC found that World Data had met its obligation in that regard by choosing a modulation that could synchronize with Neptuno’s, installing directional antennas, and using a polarization opposite from Neptuno’s.

On the charge of premature operation, the FCC noted it had earlier issued a Notice of Violation against World Data, and did not see any reason to doubt the company would comply in the future. A possibly sarcastic footnote reminds Neptuno that the FCC had previously extended a similar courtesy to Neptuno.

Procedural buffs may be interested in the FCC’s ruling on the applicability of a Petition to Deny. The Communications Act allows any party in interest to file a Petition to Deny against a common carrier application. This could include some 3650-3700 MHz applications. But the FCC reads this provision as applying only to the application for the initial non-exclusive nationwide license, not to the database registration of a particular site. Challenges to a registration, says the FCC, are within its discretion. While it chose to consider Neptuno’s petition in this case, it did not have to.

Read the FCC’s order here.