What You Need to Know About the 3.5 GHz Band on Campus

This frequency could provide a cost-effective link between cellular and WiFi.

• By Dian Schaffhauser
• 04/05/18

Rare is the campus with total coverage of cellular service. Maybe the problem surfaces for your institution in its basement-level spaces, or that oldest building on campus with walls built to bomb-shelter standards, or the newest, LEED-certified facility that uses energy-efficient glass or other construction materials that block radio frequency. Whatever the site or cause, it's a big problem. Most mobile traffic originates inside buildings (ABI Research pegs it at more than 80 percent), so people get frustrated when they can't use their devices to make a phone call — particularly in an emergency.

"Cellular has never been easy, especially in higher ed," asserted Rod Perry, principal of Cellular Savvy Consulting. "You have to have infrastructure from four carriers; the carriers don't have the money to build everything out; and historically [they] were only interested in covering sports arenas and stadiums, with a particular focus on the 'big schools.'" Forget about that basement where nothing cellular penetrates. You just have to suffer with "cellular dead zones."

While some schools have purchased distributed antenna system equipment to improve cellular performance, DAS is an expensive option ($2-$4 per square foot for coverage of all major carriers), said Perry, and most institutions have decided it makes more sense to put that money into robust WiFi. And even where DAS has gone in, he noted, campuses still need cellular radios to power the system, and "carriers are not always willing to provide those at no cost."

Of course, there are WiFi and even wired connections that may exist in cellular dead zones, but use of those comes with its own complexities (like needing to log in) and still aren't widely used for voice applications.

What's needed is a service that's as simple to use as cellular but as pervasive and inexpensive as WiFi. 3.5 gigahertz Citizens Broadband Radio Service (CBRS) may be the answer.

The Basics of 3.5 GHz CBRS

This frequency exists halfway between the existing WiFi bands (2.4 GHz and 5 GHz) and is used right now by naval radar systems and for satellite ground communications. Importantly, it taps a 150-megahertz band of contiguous spectrum.

Under the previous administration, the Federal Communications Commission began studying the possibility of setting up new rules for making excess spectrum available to as wide a set of users as possible. The agency came up with a three-tier spectrum-sharing framework: "incumbent," "priority access license" (PAL) and "general authorized access" (GAA). A "spectrum access system" (SAS) would coordinate usage among those incumbent military and satellite users and the new "commercial" users.

As described by the trade association CBRS Alliance, the SAS is an "advanced, highly automated radio spectrum coordinator" within the CBRS band in charge of "protecting" the incumbent users from the new ones and "optimizing efficient use of the available spectrum in the band for all users." The 150 MHz of spectrum would be dynamically shared. According to the new FCC rules, at least 80 MHz of the spectrum would be made available for "general authorized access," but sometimes, where there are no incumbents or PAL users in an area, the entire 150 MHz would be opened up for use by GAA users.

Although the incumbents take priority over everything else in the spectrum, there's a "struggle afoot," said Perry, regarding the PALs. "Historically, the PALs were going to cover a fairly small area and be for a three-year duration. This means that non-traditional users like higher ed could economically purchase a PAL and reserve some spectrum for their specific users." Now, however, there's a big move by the mobile operators to pressure the FCC to structure PALs like their regular cellular spectrum leases — with big areas and 10-year-plus terms. "This move," he warned, "would essentially just turn the PALs over to the cell carriers and that spectrum would look like cellular spectrum today — proprietary and expensive."

The rule-making is still ongoing, but some observers believe the FCC could act as early as this year in settling the spectrum questions.

Whatever happens, however, the GAA usage provides a big use case for CBRS to help fill in-building cellular gaps by deploying LTE networks indoors. You probably recognize that acronym "LTE." It's the same one that pops up on many phones when they have access to a 4G network.

That's where higher ed really steps into this story. Given the right equipment, users could gain LTE connectivity, "with all the LTE bells and whistles for security, authentication and throughput," Perry explained," and "be able to make and take phone calls, text and use data as if they were on their home cellular network."

A big advantage is that, unlike cellular service, the access would be provider-neutral. Neither the person carrying the phone nor the institution delivering the LTE service would be beholden to any given carrier. And because the institutions themselves typically own their buildings, should they choose to tap the unlicensed portion of the spectrum, noted Perry, "they'll have clear signal and it'll be dedicated to their users. It will be a private LTE network that they control."

What's Needed to Make Indoor LTE a Reality

What kind of equipment would be required? First, the space would require an access point that's refreshed to the new standards.

Ruckus Wireless, for instance, recently announced new products for the 3.5 GHz band to set up what the company refers to as "private LTE." The Ruckus Q710 is a 3.5 GHz indoor LTE access point that covers about 10,000 square feet. The Ruckus Q910 is meant for outdoor use, covering the area within a city block. Both products expected to be released in the second half of the year — after the FCC has certified the spectrum.

However, during the Educause Annual Conference last year, what was more intriguing was a demonstration that used an existing Ruckus access point, the H510, with a snap-on LTE module. This combination WiFi/LTE access point intended to provide 3.5 GHz in-building LTE would provide "a thousand square feet of coverage, supporting something like 16 active users with 150 megabits per second throughput," said Rich Nedwich, global director of education at the company. "It's a nice little solution." Compared to the "million-dollar DAS projects sitting on [their] desks," he claimed, the CIOs who visited the Ruckus booth "were just blown away."

Of course, Nedwich added, just having the access point isn't enough. That gets to the second piece of equipment needed for CBRS to succeed: Handsets or mobile devices outfitted with a 3.5GHz-enabled chip. "Every major handset vendor knows about this right now," he said. While the Ruckus products "are targeting basically to coincide with FCC certification around 3.5 GHz," after that, it's a "chicken-and-egg issue."

The CBRS Alliance, of which Ruckus is a founding member, has drawn participation from the major telecom equipment companies, including Ericsson, Nokia and Qualcomm, as well as the major carriers, AT&T, Verizon, Sprint and T-Mobile. Also on the board of directors: Google — or rather Alphabet — an interesting addition considering that its brethren Apple, Microsoft and Amazon aren't part of the alliance.

The Google Play

According to Perry, "Google has shown a keen interest in the technology." In a presentation last year at the Wireless Innovation Forum, Google shared some of its thinking about the allure of CBRS:

• CBRS could provide indoor capacity that otherwise would be "impractical [or] impossible" to deploy at the necessary density;
• The building owner already has access to the power, siting and backhaul that would be needed — and "at marginal cost";
• The expense of adding the 3.5 GHz capability to a WiFi access point would likely be "less than" $50-$100 per AP; and
• There would be "no capex, no spectrum and potentially less marginal cost/bit."

In other words, suggested Perry, if Google were successful in deploying gear as widely and inexpensively as it deploys office productivity applications (not to mention Google Fiber in those early communities lucky enough to get it), very quickly "they'd have 80 percent marketshare where it matters — inside the building."

Right now the company's Access division is dabbling in trials for all kinds of next-generation wireless bands, including 3.5 GHz. But Perry foresees the day when Google will show up on campus and offer its Access products in a play to become the go-to "neutral" carrier. "Instead of Google apps just being on your laptop, it now will give you voice as well on mobile devices — and all that will extend to your handset." What's in it for Google? There's plenty of money to be made in the services and gear. (After all, those Fiber customers are paying $70 a month for their high-speed internet access.) But just as vitally, it gets the analytics. "They get to look under the hood and see where everybody's connecting and then steer them towards advertisers," said Perry.

What's Next

As soon as the FCC has wrapped up the rules around 3.5 GHz CBRS, vendors are primed to kick into action.

Until then, campus IT leaders have the opportunity to "get educated," Perry advised. His suggestion: "Talk to your WiFi vendors about their timeline for inclusion of this capability in products they're producing." Once that's done, "put it into the budget, put it into the deployment plan."

The major cellular carriers won't be cut out altogether, he emphasized. "My client schools have been very successful in getting investment from the carriers in macro, rooftop and small cell sites for outdoor and umbrella coverage. If properly managed, the carriers have funding for outdoor network improvement." Then as students, faculty and staff go in buildings, their devices will get on WiFi or 3.5 GHz. "It's just another tool in the toolkit. It's not magic in and of itself, but it helps."