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.