CommLawBlog : Broadcast & Communications Lawyers & Attorneys : Fletcher Heald & Hildreth Law Firm : Telecommunications, FCC Regulation, Communications Act

• Allow fixed service wireless into the 7 and 13 GHz bands currently occupied by broadcast auxiliary services (BAS) and cable TV relay service (CARS). Broadcasters and cable operators use BAS and CARS to transmit video programming, both over fixed links (e.g., from TV studio to transmitter) and through TV pickup operations (those news vans with telescoping antennas on top). While sharing among fixed users is feasible, mobile and fixed operations don’t mix as well. News gathering vehicles must respond to breaking news quickly, without stopping to formally coordinate with other spectrum users, while fixed service systems need protection from interference to assure a high level of reliability.

The FCC divided the baby along demographic lines: it authorized fixed service operations in the BAS and CARS bands only in areas that have no TV pickup licenses. That’s half of the nation’s land mass, but only 10% of its people.  Allowing sharing in these areas may encourage rural buildout, as the FCC hopes, but will not go far to ease the congestion in urban areas caused by millions of data-hungry smartphones and tablets. The fixed wireless industry is therefore likely to continue exploring other workable spectrum arrangements, such as sharing with government spectrum at 7125-8500 MHz.

*** NOTE: If you’re a BAS or CARS licensee, make sure your information in ULS is correct, so that the Commission does not authorize an overlapping fixed service link. We have previously provided tips on how to do that here. The new rules also require registration of TV pickup receive stations. ***

• Permit adaptive modulation. The Part 101 rules governing fixed service operation require a minimum payload capacity (in megabits per second) for fixed links. Sometimes, though, passing atmospheric conditions interrupt a signal at this data rate, a condition called a “fade.” The connection is lost and the system has to be resynchronized, which can take several minutes. The Fixed Wireless Communications Coalition (FWCC) asked the FCC to allow “adaptive modulation”, a process which temporarily slows the data rate during a fade so as to keep the connection intact. The FCC agreed, but with a catch:  for efficiency, a fixed link using adaptive modulation must maintain the minimum payload capacity 99.95 percent of the time, or all but four hours of the year. This is a design requirement, not a performance requirement: links must be designed to comply, but the FCC will not require reporting of actual adaptive modulation use.

• Eliminate the “final link” rule.  Broadcasters have generally been permitted to use fixed Part 101 fixed service stations as part of the process of delivering programming to their transmitters – provided, that is, that fixed service stations not be used as the final RF link in that process. The Commission has now re-thought that rule, concluding that there may be significant benefits to be realized from eliminating it, with no associated costs. Result: the “final link” rule is now history.

The FCC rejected a proposal to allow fixed service licensees to deploy smaller “auxiliary” transmitters, all sharing the same spectrum as the primary station and all located within that primary station’s coordinated service contour. Proponents claimed that this would lead to more efficient use, or re-use, of the spectrum. Not so fast, said the Commission, which wasn’t convinced that primaries and auxiliaries could really co-exist without causing interference . . . or that the spectrum isn’t already extensively re-used, and re-useable, under existing rules. Plus, the “auxiliary” proposal would create a “perverse” – that’s the Commission’s word, not ours – incentive for applicants to propose excessive power for their primary stations, since the bigger the primary contour, the more auxiliaries could be crammed into it.  And anyway, a variety of other bands (think LMDS, 24 GHz and 39 GHz) already available could be used for the types of operations contemplated for “auxiliary” stations. Bottom line: a big negatory on the auxiliary proposal.

Finally, in the concurrent NPRM, the Commission has requested comment on:

• Allowing smaller Category B antennas in the 6, 18, and 23 GHz bands (three-foot, one-foot, and eight-inch antennas, respectively). Smaller antennas potentially cause more interference because they disperse energy more broadly, but are cheaper to manufacture, install, and maintain, and typically generate fewer zoning objections. There are no proposed changes to the more stringent Category A antennas, which are required wherever Category B antennas would cause interference.
• Exempting licensees from payload and loading requirements in non-congested (mostly rural) areas – specifically, in areas where Category B antennas are allowed. The goal is to lower costs and increase investment in rural broadband deployment. In congested areas, the Commission proposes exempting licensees that can make a special showing that: (a) the efficiency standard is preventing deployment; (b) there are no reasonable alternatives; and (c) relaxing the standard would result in tangible and specific public interest benefits.
• Allowing wider channels, or channel “stacking,” in the lower 6 and 11 GHz bands, as proposed by the FWCC. Where traffic demand is high, wider channels would result in lower costs, improved reliability, elimination of intermodulation issues, and increased spectrum utilization. The Commission seeks comment on allowing 60 MHz channels in the lower 6 GHz band and 80 MHz channels in the 11 GHz band.
• Revising waiver standards for microwave stations that point near the geostationary arc to conform to International Telecommunications Union (ITU) regulations.
• Defining the term “minimum payload capacity” as used in the efficiency standard rule. To accommodate application of the rule to Internet protocol radios, the Commission proposes rules, put forward by Comsearch, defining the term to include only capacity that is available to carry traffic, excluding overhead data used by the network itself, such as error correction and routing information.

The newly adopted rules will become effective 30 days after publication in the Federal Register. Check back here for updates on that front.  Comments on the issues teed up in the NPRM are due on October 4, 2011, and reply comments on October 25.

Wireless backhaul falls under the FCC’s Fixed Microwave Service (FS) rules in Part 101 of the rules. The Commission is examining a range of regulatory options to increase the “flexibility, capacity, and cost-effectiveness” of the microwave bands located below 13 GHz, while protecting incumbent licensees in these bands. 

Not all options, though. Some backhaul-related proposals – for example, proposals advanced by the Fixed Wireless Communications Coalition (FWCC) for combining adjacent channels and shared use of government spectrum – will be considered in separate rulemakings. But now on the table for consideration and comment are the following proposals advanced in the NPRM portion of the proceeding:

Allowing adaptive modulation. Part 101 spectrum is subject to certain minimum payload requirements (in terms of megabits per second per hertz). Those limits are intended to assure the efficient use of the frequencies. However, in some instances, ambient conditions create adverse effects such as atmospheric fading or “rain fade”, which cause an increase in bit errors and, on occasion, complete loss of communications. One technique for dealing with such conditions is to briefly reduce the data rate by temporary change in modulation type, a process called “adaptive modulation”. While adaptive modulation is already permitted by the rules, its use is subject to the minimum payload requirements. The problem is that, in order to maintain communications during some adverse propagation conditions, the payload capacity must sometimes be reduced below the required minimum.

In order to allow users to take advantage of adaptive modulation without unduly undercutting the goal of efficient use of the spectrum, the Commission proposes to maintain its minimum payload requirements “except during anomalous signal fading, when lower capacities may be utilized in order to maintain communications”.  Beyond that vague articulation, however, the NPRM lacks any detail. Instead, the FCC solicits suggestions for specifics (such as, e.g., how “anomalous signal fading” might be usefully defined, or how use of adaptive modulation should be (a) reflected in coordination notices and (b) recorded or logged).

Auxiliary FS stations. The NPRM seeks comment on allowing FS operators to deploy “auxiliary” stations. The concept of such “auxiliary” stations was first proposed to the FCC by Wireless Strategies, Inc. (WSI) in 2007. WSI envisages “simultaneously coordinate[d] multiple links whose transmitter elements collectively comply with the Commission’s antenna standards and frequency coordination procedures”. Essentially, the concept contemplates the re-use of a coordinated primary frequency by additional “auxiliary” links operating nearby on the same frequency. A number of opponents have questioned major elements of WSI’s thinking, arguing among other things that it would lead to excessive interference to other users, impair the integrity of existing systems, and generally be incompatible with traditional point-to-point FS operations.

While the Commission expresses interest in the notion of “auxiliary” stations, it offers no specific proposals. Instead, it poses a long laundry list of questions concerning regulatory limits that might be imposed on “auxiliary” stations.

Additional spectrum for FS.  The Commission proposes to allow FS operations in two additional bands (6875-7125 MHz and 12.7-13.2 GHz).  A variety of channel widths would be made available for FS operations, to provide opportunity for flexibility and increased use of digital technology. Those bands are currently allocated only to Broadcast Auxiliary Service (BAS) and Cable TV Relay Service (CARS). FS operations in the 6875-7125 MHz band would be subject to the same overall technical rules that currently apply to the adjacent Upper 6 GHz band, since common technical rules would allow use of similar equipment across the two contiguous bands. Technical specs for use of 12.7-13.2 GHz would not change, although the proposed rules would impose on that band the minimum payload capacity and loading requirements currently applicable to the 11 GHz band.

FS operations would be subject to existing frequency coordination procedures – that is, new FS users would have to coordinate with existing BAS and CARS users, whose existing licenses would not be modified as a result of the proposed rules.

With respect to coordination, though, the Commission asks whether the identification of BAS TV pickup stationary receive-only sites in the 6875-7125 MHz band should be made mandatory. Such identification is only optional at this point, and frequency coordination in that band is not as formalized.   The Commission recognizes that broadcasters use their BAS facilities for electronic news gathering (ENG) operations, and it specifically questions how use of the spectrum for FS might affect the flexibility of ENG. The Commission also asks whether FS use of the 12.7-13.2 GHz band would have any adverse effect on present or future use of that spectrum by cable operators.

Eliminating the “Final Link” rule.  The NPRM proposes to eliminate the “final link” rule which prohibits broadcasters from using licenses subject to Part 101 regulation as the final RF link in the distribution chain of broadcast programming. The Commission expects that this will encourage fuller use of Part 101 spectrum.

In addition to the relatively specific points addressed in the NPRM portion of the Commission’s action, a number of more general questions are presented for comment in the NOI portion. They include:

Lower efficiency standards in rural areas.  Would lowering efficiency standards (minimum payload capacities) in rural areas lower backhaul costs while maintaining spectrum efficiency? And in connection with this query, the Commission questions how
“rural” should be defined.

Smaller antennas.  Should Part 101 be revised to permit smaller antennas – the idea being that such antennas would likely also be cheaper, more flexible, more easily deployed, etc.?  Anyone who thinks the answer to that question is “yes” is invited to provide detailed information about the particular FS bands that might be affected, new standards that might be applied, the geographical areas in which the new standards could or should be applied, and so forth. 

Other modifications.  What other modifications to the Part 101 rules – or any other policies or regulations, for that matter – might be made to promote flexible, efficient and cost-effective provisions of wireless backhaul service?

Comments are due October 25, 2010. Reply comments are due November 22, 2010.

Conditional Licensing

To obtain a microwave license is time-consuming. The applicant must: (1) design the system; (2) go through frequency coordination, which limits harmful interference to other systems and warns the applicant about any harmful interference coming in; (3) file an application with the FCC; and (4) wait for the FCC to issue the license. 

But there is a shortcut. Under a procedure called “conditional licensing,” the applicant can flip the ON switch after step (3).  The system can thus provide service while the application wends its way through FCC processing, conditioned (hence the name) on having to shut off if the application is turned down. That rarely happens.

Demands for service can arise quickly, while the FCC – and we say this with the deepest affection – sometimes moves slowly. This makes conditional licensing an important tool for microwave service providers.

Two of the changes pending at the FCC are intended to make conditional licensing easier.

Of the several frequency bands allocated for microwave operations, the 6 GHz band is the long-haul workhorse. Low frequencies go farther; and in much of the country, 6 GHz is the lowest available. For links that must span tens of miles or more, 6 GHz is often the only choice.

The band has two segments, called the “Lower 6” and the “Upper 6,” which differ in two important ways. The Lower 6, shared with over four thousand C-band satellite uplink earth stations, tends to be more congested than the Upper 6, which has no earth stations. On the other hand, the Lower 6 allows microwave channels up to 30 MHz wide, while the Upper 6 maximum is only 10 MHz. An operator who needs 30 MHz, but cannot find room in the Lower 6, is not entirely out of luck. It can ask the FCC for a waiver to use 30 MHz in the Upper 6. Such waivers are usually granted. But an application that needs a waiver does not qualify for conditional licensing, and so the system cannot turn on until after several weeks of FCC processing.

The Fixed Wireless Communications Coalition (FWCC) asked the FCC to amend its rules to add 30 MHz authorization to the Upper 6.

The FWCC also had a request concerning the 23 GHz band. Suitable for shorter distances, this band is ideal for transporting cell phone and mobile Internet signals to and from cell towers. The catch (there always seems to be one) is the federal government, which shares the band. On the one hand, the government long ago set aside four channels in the band for conditional licensing. On the other hand, those are everyone’s first choice; they tend to be crowded, and are not available everywhere. An applicant for any other channel does not qualify for conditional licensing, and so cannot operate until the FCC grants the license. In addition to the usual FCC processing, a non-conditional 23 GHz application requires government sign-off, which further delays the grant.

The industry was pleased back in 2007 when the government freed up two additional channels for conditional licensing. But they were of no immediate benefit. The conditional-licensing channels are listed in the FCC rules, so adding two more requires a full-scale rulemaking proceeding. The FWCC formally requested that change in November 2007.

The FCC has now issued a Notice of Proposed Rulemaking to accommodate the FWCC’s requests in both the 6 GHz and 23 GHz bands. Comment and reply dates will be announced on publication in the Federal Register, which has not yet occurred. The language of the NPRM suggests that the FCC intends to adopt both of the requested rules, barring unexpected surprises. The docket is WT Docket No. 09-114.

On the 23 GHz item, the FCC took an additional and very welcome step: it granted a request from the FWCC for a waiver during the rulemaking. This makes the two additional channels available for conditional licensing now, even before the FCC has received and reviewed comments. In the unlikely event that the FCC declines to add the two channels to the rules, an applicant then operating on conditional authority would have to shut off until the license issues.

Adaptive Modulation

To a microwave signal, air is tricky stuff. Depending on the frequency band and atmospheric conditions, air can severely weaken a radio beam, or even bend it away from the receiver. “Fades,” as these conditions are called, can interrupt communications and make it harder to achieve “six nines” availability, or whatever the application needs. A modern microwave system automatically steps up the power to counter a fade. But power increases can only go so far, and if used to excess, can cause interference to other systems.

There is another approach, similar to one we use every day. When talking to someone in a noisy room, or shouting over a distance, people instinctively speak slowly. We know from experience that a slower message is more likely to get through. The same is also true of data carried via radio: slowing the data rate – the bits per second – makes communications more reliable. (This is embodied in Shannon’s Theorem, the central tenet of communications theory.) In addition to boosting the power, a microwave operator can combat an atmospheric fade by throttling back the data rate.

In a given system, the data rate depends primarily on the “modulation,” the technique used to impress payload data on the radio signal. A system that automatically changes to a slower modulation when needed is said to be using “adaptive modulation.”

But there is a catch, as usual. The FCC, seeking to ensure that spectrum is used efficiently, requires a microwave system to be capable of carrying certain amounts of data. In the 6 GHz band, for example, a channel 30 MHz wide must be able to carry at least 134.1 million bits per second. (For comparison, an Internet signal this fast would download an entire movie in about four minutes.) Adaptive modulation, to be useful, must sometimes drop the data rate below the specified minimum. Does that violate the FCC rules?

The FWCC, together with several microwave manufacturers and service providers, thinks not, and has asked the FCC to interpret the data-rate requirement in a way that allows the use of adaptive modulation. In a word, they want the FCC to treat the minimum in the rules as an average, not an instantaneous value. That would let a system occasionally drop below the minimum, for brief periods, so long as normal operation between fades meets the minimum, as does average operation over a period of time.

This makes sense. A system without adaptive modulation runs a greater risk of having a fade cut off communications altogether. That gives a data rate of zero, hardly efficient use of the spectrum. Worse, the system may need several minutes to resynchronize, during which critical payload communications cannot get through. Data transfer at a reduced rate is better than none at all.

The FCC has issued a public notice soliciting public input on the request posed by FWCC et al. Comments are due on July 27, and reply comments on August 11, in WT Docket No. 09-106.