5 GHz Reply Date Extended

Reply comments in the proceeding on 5 GHz unlicensed operation are now due July 24.

In February we reported on an FCC proposal that would not only add new 5 GHz frequencies but also overhaul – maybe even simplify – a confusing stretch of the rules. One possible upshot would be the opening up of 195 MHz of spectrum for Wi-Fi-type operation.

Comments were filed on May 28. The FCC has extended the date for reply comments, originally June 24, to July 24.

Update: Comment Deadlines Set in U-NII 5 GHz Rulemaking

In February we reported on an FCC proposal that would not only add new 5 GHz frequencies but also overhaul – maybe even simplify – a particularly confusing stretch of the rules. One possible upshot would be the opening up of 195 MHz of spectrum for Wi-Fi-type operation.

The Notice of Proposed Rulemaking (NPRM) has now been published in the Federal Register which, as our regular readers know, establishes the relevant filing deadlines. Comments in response to the NPRM are due to be filed by May 28, 2013, and replies by June 24.

FCC Proposes to Simplify and Expand Unlicensed 5 GHz Use

Suggested rules would combine and harmonize the rules for various sub-bands, and open another 195 MHz for Wi-Fi-type operation

Blame it all on Congress. The Middle Class Tax Relief and Job Creation Act of 2012, best known for extending the since-expired payroll tax cuts, took just a few lines for that task, but continued on for another hundred pages of unrelated legislation. The statute has been good for CommLawBlog; we reported on incentive auctions, microwave issues, 911 implementation, and lots more. Now the FCC has responded to yet another mandate in the act: to expand unlicensed operations in the 5 GHz band.

But the FCC is doing more: it has issued a Notice of Proposed Rulemaking  (NPRM) that would not only add new 5 GHz frequencies but also overhaul and (we hope) simplify a particularly confusing stretch of the rules. We will touch on that first, and then take up the proposed expansion.

It is hard to overstate the importance of having enough unlicensed spectrum. The vast majority of radio transmitters in use today are unlicensed. We would be hard pressed to get along without Wi-Fi, Bluetooth, cordless phones, nursery monitors, automatic toll payment, automatic braking in cars, and myriad other such consumer conveniences. Industry as well relies on unlicensed communications and, increasingly, on unlicensed radar. Equally important, though less often mentioned, is the importance of unlicensed spectrum as a technology test bed. Licensed frequencies, if auctioned, are usually too expensive to risk on untried technology, while non-auctioned, site-licensed spectrum is governed by technical rules so restrictive as to preclude experimentation. Much innovation benefits from the technical flexibility inherent in the FCC’s unlicensed rules.

Updating Rules on the Present Bands

Unlicensed operations in the frequency range 5.15-5.825 today are governed by four sets of technical rules. Three are collected under the heading of “Unlicensed National Information Infrastructure Devices,” or U-NII, detailed in Section 15.407 in the FCC rulebook. The fourth comes under the “digital modulation” rule, in Section 15.247. Here is the breakdown:

Below 5.725 GHz, the U-NII rules are the only choice. The power limits are relatively low, and the need to avoid certain airport weather radars adds complication. The region above 5.725 GHz is popular because it offers the highest power for Wi-Fi standards a and n (and also the proposed standard ac). The band is a favorite of wireless Internet service providers, or WISPs, which offer Internet service via a roof antenna, mostly in regions not served by either broadband cable or telephone.

Before 2003, most manufacturers working above 5.725 GHz opted for the U-NII standards, which have no express limit on data speed, because Section 15.247 then limited speeds to about 11 megabits/second. But a rule change that year eliminated the limit in Section 15.247, and thus put the two sections on an equal footing for speed. Today Section 15.247 is the favorite because in fixed point-to-point applications it allows more focused antennas with no penalty in transmitter power, offers 125 MHz of bandwidth versus 100 MHz for U-NII, allows more power per megahertz, and has more relaxed limits for out-of-band emissions.

The FCC now proposes to harmonize the two rule sections. In some respects it suggests changing the U-NII provisions to match those in Section 15.247: namely, extending the upper bound on U-NII-3 by 25 MHz, to 5.85 GHz, and allowing the same power-per-megahertz as Section 15.247. In other respects, however, the harmonized rules would follow the U-NII provisions: a power penalty in fixed point-to-point applications for antenna gains above 23 dBi, and the more stringent U-NII limits on unwanted emissions.

A separate proposed harmonization would amend the rules for U-NII-1 at 5.15-5.25 GHz to more closely match those for U-NII-2 at 5.25-5.35 GHz in three respects: raise the power limit from 50 mW to 250 mW; raise the power-per-megahertz to match U-NII-2; and drop the limitation to indoor-only operation. As an alternative, also up for discussion, is raising the U-NII-1 power limits to U-NII-3 levels (1 watt), and again allowing outdoor operation. Neither proposal would require DFS or TPC in the U-NII-1 band.

The NPRM revisits the stubborn problem of U-NII-2 devices causing interference to airport weather radars operating at 5.6-5.65 GHz. Dynamic frequency selection (DFS) capability is required in the U-NII-2A and U-NII-2C bands specifically to protect those radars: the U-NII device must “listen” for the presence of a radar signal and, if found, move to a different frequency. Interference has persisted nonetheless, some from illegally operated U-NII devices that may lack DFS, but also from fully compliant systems.

Some interference to radars comes from users unlawfully changing the frequency of a certified device. This can result in a transmitter possibly overpowered for its band, with no DFS, operating on the same frequency as the radars. The FCC has found that some U-NII transmitters are easily modified in this respect. It proposes to require security safeguards to prevent such reprogramming, and/or the transmission of ID information to help locate offending units. It also asks for comment on these additional measures:

  • built-in geolocation capability in combination with database registration and access, so that units within a certain distance of a radar will automatically avoid its frequencies;
  • tighter limits on unwanted emissions to reduce interference from U-NII transmitters operating close by a radar frequency;
  • improved sensing capability; and
  • changes to certification test procedures to better assess sensing capability.

(Note to manufacturers and test labs: The above is only a rough summary. Please consult the proposed rules and measurement procedures in NPRM at pp. 39-45.)

Expanding into New Bands

As shown in the table above, the FCC is considering an expansion into 195 MHz of new U-NII spectrum. It hopes to find 120 MHz in the tentatively-named U-NII-2B band at 5.37-5.47 GHz, and another 95 MHz in the U-NII-4 band at 5.85-5.925 GHz. This would yield an unbroken sweep of 775 MHz, albeit subject to differing technical rules in the various sub-bands.

The problem, of course, is that both of the proposed new bands are occupied. The 5.37-5.47 GHz U-NII-2B band houses military and other government radars, weather radars (some used by broadcasters), NASA systems, unmanned aircraft, satellite observations of the planet, and border surveillance. At 5.85-5.925 GHz, U-NII-4, are more military and other government radars, automatic communications with and between vehicles, and a secondary amateur band.

U-NII, being an unlicensed service, will be required to protect licensed services, i.e., all of the above. We expect it will be a challenge to accomplish adequate protection to the satisfaction of the federal government (not to mention the amateur radio folks) while leaving enough technical elbow room for U-NII to be useful.

As a starting point for discussion, the FCC proposes:

  • U-NII-2B to operate under the same rules as the adjoining bands, U-NII-2A and U-NII-2C, providing 475 MHz of contiguous and consistently regulated spectrum; and
  • U-NII-4 to operate under the same rules as U-NII-3, with the same rules also applying to the 25 MHz in between. This would provide another 200 MHz that is contiguous and consistently regulated, at somewhat higher power.

The FCC seeks comment on whether DFS and TPC requirements should apply to U-NII-2B and U-NII-4, and if so, what the technical characteristics should be.

Manufacturers of future devices and present users of the proposed expansion bands should pay close attention. Reading between the lines, we have the sense that the FCC is tired of tinkering with these rules. The outcome of the proceeding may set the technical provisions for many years to come.

Comments and reply comments will be due 45 days and 75 days, respectively, after publication in the Federal Register. Watch this space (or subscribe) and we will let you know when that happens.

FOIA Request Turns Up Info on Non-FCC-Compliant Transmitters.

Persistent sleuth Michael Marcus obtains, posts document shedding light on recurring interference to airport weather radars.

In our recent blog post about an AT&T wireless Internet service causing interference to an airport weather radar in Puerto Rico, we asked whether the FCC had charged AT&T with the wrong offense. Because the transmitter operated outside its FCC-certified frequency range (among other problems), the FCC determined it did not qualify for unlicensed operation, and so fined AT&T for not having a license – even though AT&T could not have obtained a license for that service.

Our friend Michael Marcus, a spectrum-savvy engineer (and former FCC official), asked a different question: how did the transmitter get to be operating on a non-certified frequency? Where most of us would be content to mull this over in our idle hours (if it occurred to us at all), Marcus is made of different stuff. He not only took the question to the highest reaches of the FCC, but managed to get some answers.

Modern radio transmitters, like most other modern devices, are controlled by software. The FCC recognizes a category of transmitters called “software defined radios,” or SDRs, which can be legally updated or modified by software changes, including those downloaded over the air. But most transmitters do not qualify as SDRs. Once certified by the FCC, their properties have to be locked in. The software is supposed to be secure against changes, particularly those that would take the transmitter out of compliance and lead to, say, interference to airport radar.

AT&T’s Puerto Rico transmitter was certified for operation over 5735-5840 MHz, but it was being operated at a frequency outside that range. Moreover, the transmitter lacked the required capability to listen for weather radar signals, and if it found them, to avoid the frequencies on which they occur – a feature called “dynamic frequency selection,” or DFS.

The transmitter was manufactured by Motorola, which knows how to comply with FCC technical rules. But the transmitter was non-compliant when FCC inspectors found it in operation – on a non-certified frequency and lacking DFS – in AT&T’s Puerto Rico system. Moreover, the FCC has identified other non-compliant transmitters operating in the same band. In every case we know of, the transmitter was made by Motorola, and all came from the same “Canopy” product line. 

What went wrong?

One clue comes from a “consent decree” between Motorola and the FCC released in April 2010. Motorola paid $9,000 to settle charges that it violated FCC rules relating to DFS requirements in the frequency bands relevant here. The document contains no specifics. But it does mention that the FCC’s Enforcement Bureau asked Motorola for certain information related to the suspected offense on April 20, 2009. And that Motorola responded on May 20, 2009.

That was all the opening Marcus needed. In August 2011, he filed a request under the Freedom of Information Act (FOIA) seeking a copy of Motorola’s May 20, 2009, response letter.

Motorola had requested and received confidential treatment of that letter, under a FOIA provision that protects trade secrets and confidential commercial information. The FCC notified Motorola of Marcus’s document request (as the FCC’s FOIA protocol requires). Motorola provided the FCC with a version of the letter from which it redacted the parts it said would harm its competitive position, and also sent a copy of the redacted version directly to Marcus. The Enforcement Bureau issued an order (not publicly released) agreeing with Motorola that the FCC need not disclose the redacted material.

Marcus appealed that decision to the full Commission, asking for access to specific redacted information. He argued, in part, that release of the information is in the public interest because it may shed light on the root causes of interference from the Canopy transmitters into airport radars, and thus promote air safety.

The FCC’s decision gave Marcus a partial victory. One question in the FCC inquiry asked about a particular transmitter used in Puerto Rico – although not the same one that got AT&T in trouble. The one mentioned in the inquiry lacked an FCC ID number, which is required evidence of required FCC certification. The FCC asked if the transmitter was certified, and if so, under what FCC ID number, and why the number was not marked on the device. The FCC also asked when and where various Canopy transmitters were marketed in prior years, and under what FCC ID numbers. The answers to these questions would not harm Motorola’s competitive position, the FCC ruled, so Marcus was entitled to obtain them.

Marcus has now posted Motorola’s response on his blog. Motorola’s explanation: it thinks it sold the unit outside the United States (for which no certification or FCC ID is required), after which the unit was “somehow imported” back into the U.S. If true, that would put the responsibility squarely on whoever imported the unit and sold it domestically, and also on the people who installed and operated it despite the missing FCC ID.

The mystery continues, as does occasional interference to airport radars. Users of the Canopy transmitters have no easy way to check the operating frequency or the presence of DFS capability. But those within the U.S. can – and should – look for an FCC ID number on the unit. If the number is missing, the user is on notice that the device is not only unlawful, but also a potential threat to air safety. For the sake of all air travelers, please turn it off.

AT&T Fined for Not Having Unobtainable License

FCC action follows interference to airport weather radar.

The FCC has confirmed a fine of $25,000 against AT&T for operating a Wi-Fi-type device that caused interference to a weather radar at a Puerto Rico airport. Yes, it appears that AT&T slipped up. But we think the FCC fined it for the wrong offense.

The problem stems – as do many FCC problems – from the fact of an overcrowded spectrum. Almost every useful frequency is shared by multiple users. Part of the FCC’s job is to set priorities among them.

One such choke point occurs in the band at 5470-5725 MHz. Since 1998, the FCC has allowed relatively high-powered devices to use highly directional antennas in this region, all without a license. The band is popular among companies – called “wireless Internet service providers,” or WISPs – that provide Internet service to locations not easily reached by other broadband facilities.

A 2003 expansion of the band produced an overlap with frequencies also used for radars that detect “wind shear” near airports. This condition is potentially dangerous to aircraft flying close to the ground, as when approaching the runway to land, so the radars are important to flight safety. They operate at 5600-5650 MHz, squarely within the 5470-5725 MHz WISP band. The initial rules for WISPs (and other unlicensed users of the band) required devices to (a) sniff the air for radar signals, and (b) if those signals are found, to avoid the frequencies on which they occur  – a capability the FCC calls Dynamic Frequency Selection (DFS). After interference occurred anyway, the FCC worked with device manufacturers and radar operators to clarify the rules. When some interference persisted, the FCC refrained from shutting down the WISPs, as it had a right to do, and instead sought the WISPs’ cooperation in heading off the problem.

Then came the AT&T event.

According to an FCC notice back in February 2011, AT&T’s transmitter was certified for use under a different set of rules at 5735-5840 MHz, but was operating outside that band, at 5605 MHz, and had no working DFS. The 5605 MHz frequency is inside the weather radars’ operating range. Based on that fact and other data, the FCC concluded the AT&T facility was responsible for the reported interference to the nearby weather radar.

Inasmuch as the transmitter was not certified for 5605 MHz and had no DFS, the FCC could properly have dinged AT&T for using non-certified and noncompliant equipment. In fact the FCC proposed a fine for that offense. But it also did more. Since a transmitter operating outside its certification does not qualify for unlicensed operation, the FCC reasoned that AT&T needed a license. Since AT&T did not have one for 5605 MHz, the FCC added on the more serious charge of operating without a license.

We thought that was wrong. Under the FCC’s rules, AT&T’s transmitter could not possibly qualify for a license at 5605 MHz. The only licensable services at that frequency are maritime radionavigation, meteorological aids (weather radar) and radiolocation (other radar). AT&T’s WISP operation does not fit any of these. So the FCC proposed to fine AT&T for not doing something it could not legally have done. This is a little like a police officer ticketing me for not using my siren at an intersection – I being an ordinary citizen not allowed to use a siren.

A year and a half later, the FCC has now confirmed the fine and ordered AT&T to pay the money. AT&T did not raise our issue about the impossible-to-obtain license. Instead it presented evidence that it was not operating on the 5605 MHz frequency claimed by the FCC, but rather on 5685 MHz. Unfortunately that frequency is also outside the certification, and apparently also lacked DFS, making AT&T just as culpable. In AT&T’s favor, though, a 5685 MHz transmitter could not have interfered with the airport radar. But the FCC stuck to its story, insisting its field agents had detected AT&T operation at 5605 MHz.

In a footnote, the FCC even explained how AT&T could have falsified its frequency data. Frankly, we think this is out of place. The FCC has had reason to doubt the veracity of some respondents in the past, but we don’t think AT&T is one of them. The FCC should have taken AT&T’s assertions at face value. It could still have disagreed as to the operating frequency, but did not have to imply that AT&T may have been deliberately untruthful.

Now AT&T has three basic options: it can pay the $25,000 and move on with life; or it can pay the fine and then challenge the FCC’s order in the U.S. Court of Appeals; or it can wait to be sued for the money and raise its defenses.  (In some parts of the country, AT&T’s legal options may be limited, as explained in this earlier post.)

Simultaneously with the AT&T order, the FCC issued a public notice reminding WISPs and others to avoid interfering with weather radars, and mentioning the potential penalties for noncompliance, up to and including imprisonment.

To the best of our knowledge – and we try to keep track of these things – the FCC has not yet jailed anyone for operating an unlicensed device on the wrong frequency. But WISP equipment transmits in both directions. So if you rely on WISP service for watching videos of insanely complex Lego contraptions, the threat of imprisonment is definitely something to keep in mind.

FCC Calculates Major Fine For Minor Error

Use of unlicensed transmitter on non-certified frequency brings fine for operation without a license

The FCC has proposed a $25,000 fine against AT&T for the offense of . . . well, let’s talk about that.  In its zeal to protect the spectrum, the FCC may have charged AT&T with the wrong offense.

A little background may help.

The FCC allows unlicensed operation in a band up above 5 GHz. The applications tend to be a lot like Wi-Fi, but under a different set of rules, called U-NII, for “unlicensed national information infrastructure.” (No, that won’t be on the exam.)

A few years ago the FCC expanded the U-NII band into a region of the spectrum also used by airport weather radars. The radars are used to detect wind shear in the vicinity, important to flight safety. In careful collaboration with the FAA, the FCC added rules that require U-NII devices to listen for the radars and avoid their frequencies – a capability called dynamic frequency selection, or DFS. The band is now popular for wireless Internet access service, among other applications.

But the technical rules did not work as planned.

A number of radars have experienced interference even from compliant, DFS-equipped transmitters. The FCC could have come down hard on the U-NII operators: an unlicensed transmitter, even in full compliance, is not permitted to interfere with an authorized or government service, like airport radars. Instead, though, and to its credit, the FCC took a collaborative approach with the providers causing the problem. It did mention, though, that transmitters not in compliance with the rules would be subject to enforcement action.

The airport in San Juan, Puerto Rico, is one of those that reported interference to its radar. The FCC traced the signal to a roof-mounted transmitter a few miles away, made by Motorola and operated by AT&T. The unit was FCC-certified for U-NII operation at 5735-5840 MHz. But it was operating outside that band, at 5605 MHz, and had no working DFS.

The FCC cited AT&T for two offenses. One was operating a transmitter outside the frequency range in the certification, and without the required DFS. The other charge is a little more complicated. Because the transmitter operated outside the band where it was certified for unlicensed operation, it did not qualify for unlicensed operation. Therefore, reasoned the FCC, by definition AT&T needed a license. But AT&T did not have one for 5605 MHz. So the FCC added on the more serious charge of operation without a license.

The base fine for the outside-the-certification problem is $5,000, and for operation without a license, $10,000. The FCC doubled the latter, explaining that it did so because AT&T is a large and profitable company, to reach a total of $25,000.

We have two questions.

In cases where a transmitter fails to match its certification, as here, the FCC usually cites the manufacturer. Going after AT&T makes sense only if the FCC thinks the transmitter was compliant when shipped, and that AT&T took it out of the box, re-tuned it to an unauthorized frequency, and turned off the DFS. That would indeed be a blatant offense. But the FCC does not accuse AT&T of doing this. The farthest it goes is to say AT&T “consciously” operated at the unauthorized frequency. Contrast the delicate touch with another recent case, in which the FCC flatly accused the provider both of disabling the DFS and of fitting the unit with an unauthorized antenna that pushed the effective power to hundreds of times above the maximum permitted. (Despite the more egregious offense, and the improper use of two systems on two frequencies, the fine there was the same $25,000).

Usually, before the FCC proposes a fine, it sends a Letter of Inquiry to the suspected offender to get the other side of the story. There is no indication that it sent one to AT&T. We don’t know all the facts; but if AT&T has an explanation, we think it should have the chance to say so before its alleged offense is splashed over the public record.

Our other question concerns the charge of operating without a license at 5605 MHz. That frequency is part of the U-NII band, and AT&T’s operation appears to have been within the power limit for that frequency. So far as we can tell, Motorola (or AT&T) could have had the same transmitter re-certified to include 5605 MHz. AT&T was at fault for not making sure this happened. But calling that omission “operation without a license” is a stretch.

The only licensable services at 5605 MHz are maritime radionavigation, meteorological aids, and radar. AT&T’s use of the transmitter is none of these. The communications function it provided is lawful only as an unlicensed service. Had AT&T sought a license for this application at that frequency, it would have been turned down.

Think about this. AT&T was fined for failing to do something it could not have done. And the fine was doubled, to boot.

Plainly some kind of enforcement action is needed. There was interference to an important radar system from a transmitter that failed to meet the requirements of its certification. Given the actual circumstances, though, AT&T’s only real offense was the use of unauthorized equipment (base fine, $5,000). Yes, the rules can be read to permit an allegation of operation without a license, and that might be justified in some cases. Here, though, the main effect of the added charge was to greatly boost the allowable fine.

The FCC may simply have wanted to make an impression on AT&T. That’s reasonable. But we would also like to see the Commission stay within a common-sense interpretation of the rules. We think that’s only fair.