For frequency coordinators serving the public-safety community, it may seem that the only constant is change, which has made their tasks increasingly difficult in recent years, even though the big influx of applications associated with narrowbanding below 512 MHz is only just beginning.

“The bottom line is that, with more and more demand for radio communications, when somebody comes to us and says, ‘I need a channel for this,’ or ‘I need five channels for a trunked system,’ it is a real challenge to find them,” said Ralph Haller, chairman of the National Public Safety Telecommunications Council (NPSTC) and executive director of the Forestry Conservation Communications Association (FCCA).

“It is almost an impossible job to find frequencies for all the stuff that people want. … People bring [their ideas to build or expand systems on new spectrum] and you just throw up your hands and say, ‘How are we going to do that?’”

It's not that all airwaves in the public-safety bands are used, but most agencies with the financial and personnel resources to pursue new buildouts typically serve populous areas of the country, where public-safety spectrum is at a premium. This is particularly true in the UHF and VHF bands, where the spectrum has better propagation characteristics — i.e., greater range and the ability to penetrate though foliage — than in the 700 MHz and 800 MHz bands.

“If we could take open spectrum in rural Nebraska and use it in New York, there wouldn't be a problem, but you can't do that,” Haller said.

More spectrum in the VHF and UHF bands could become available as agencies move from 25 kHz channels to 12.5 kHz channels as part of the FCC mandate to narrowband systems below 512 MHz by Jan. 1, 2013. In fact, the FCC has expressed its intent to move to 6.25 kHz-equivalent channels in these bands eventually, but no dates have been established for that migration.

At the very least, each licensee in these bands will have to change the emissions designator for their systems when they narrowband, said Alan Tilles, who represents several public-safety agencies as a partner in the law firm of Shulman Rogers Gandal Pordy & Ecker. In addition, frequency coordinators will be receiving new applications for spectrum in the band from licensees hoping to take advantage of the more efficient use of airwaves enabled by narrowbanding.

“The hard part will be all the new applications for opportunities that are now becoming available because of narrowbanding,” Tilles said. “Those require, in many cases, a higher level of review than perhaps applications did in the past. You have to be a lot more careful with regard to channels that are adjacent, in order to find holes, so to speak.”

As with many transitions, timing may be crucial in terms of which new opportunities are granted in VHF and UHF, Haller said. And the approach frequency coordinators will take in the band likely will be decidedly different after the 2013 deadline passes, he added.

“Right now, in coordinating, we have protect the incumbent wideband licensees,” Haller said. “That prevents coordinating some channels that would otherwise be available in an area if everyone were narrowbanded.

“Once we quit protecting the wideband licensees [after 2013], that will open up some opportunities that today we can't do because there would be unacceptable interference.”

Although narrowbanding is designed to double — at least — the spectral efficiency of communications systems below 512 MHz, Haller emphasized that there will not be twice as many channels available for new opportunities. Because of the manner in which VHF and UHF bands are used — and the fact some licensees already are on narrowband channels, using systems that double capacity but do not necessarily make spectrum available — Haller said he “conservatively” projects a 10-25% increase in new available channels after narrowbanding.

Meanwhile, frequency coordinators are increasingly concerned that many public-safesty officials are not aware of the narrowbanding mandate or do not fully comprehend its implications and consequences, Haller said.

“There's a lot of misunderstanding,” he said. “There are a lot of people out there that think they will just become secondary in 2013 [if they do not narrowband]. That's not true. … You don't become secondary, you become illegal.”

With this in mind, the Land Mobile Communications Council (LMCC) asked the FCC to release a public notice — a draft of which the LMCC provided — to remind affected licensees of the need to narrowband and to clarify several aspects of the mandate, including the procedures associated with modifying licenses and the penalties associated with not meeting the mandated deadline.

The LMCC made its request for a public notice more than a year ago. With a new FCC now in place, the industry needs the agency to take action on the item, Haller said.

“The commission has done nothing to be proactive on this,” he said. “I don't want to sound like I'm down on the commission, but we really need the FCC to be a full partner in helping to get the word out.”

Steve Devine, interoperability program manager for the state of Missouri, said he believes frequency coordination “absolutely” is more difficult today than ever, particularly in the VHF and UHF bands. Ultimately, the spectrum could be used more efficiently if several agencies combined spectral and financial resources to build shared trunked systems. But establishing such agreements is difficult and connectivity needed for trunking can be a problem in the rural areas where such an approach might make the most sense, he said.

“Coordination is a challenge, but the lack of loading hurts,” Devine said.

Of course, issues for frequency coordinators extend beyond the spectrum affected by narrowbanding. Finding available 800 MHz airwaves long has been a problem in urban areas, although the availability of interleaved channels vacated by Sprint Nextel in the rebanding process provides new hope in this arena.

Meanwhile, even at 700 MHz — spectrum that became available nationwide only this summer, although it has been utilized in some parts of the country for years — airwaves designated for narrowband voice applications already have become scarce in states like Colorado, which has a statewide system operating on the frequencies.

In cases where there is a lot of 700 MHz spectrum, Haller said it is questionable whether it is economically feasible for public-safety agencies to use it.

“In the areas where there is plenty of 700 MHz left — the rural areas — 700 has issues, because you need a lot more infrastructure to cover an area,” he said. “If you're in a forest, 700 MHz essentially stops; it won't go through the trees. So it's not an answer for all of public safety's needs.”

The myriad challenges facing frequency coordinators associated with new technologies could be overwhelming were it not for significant technical advances in the tools used to do the job, Tilles said.

“Ten years ago, if we had to use these same criteria for coordinations back then, it would have been a nightmare,” Tilles said. “I used to have to wake up every two hours to dial into my office to have my computer run some more contours. It literally would run all night. Now, what does that take, a couple of seconds to do?

“As coordinations have become more sophisticated, so have the tools that are available to us. So I think most of the coordinators have been able to keep an even keel.”

In addition, Haller said frequency coordinators are working to develop new tools that allow them to model mobile interference instead of just relying on metrics collected near base stations. Haller said he is very interested in the results of that project.

“I think that can cut two ways,” he said. “In some cases, perhaps mobiles aren't being protected enough by our current techniques. In other cases, we may be protecting them way more than we need to, because we just don't have a good model to go on.”

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