It’s somewhat remarkable how far the 3.5 GHz sector has come in one year. The FCC finalized rules for spectrum sharing in the Citizens Broadband Radio Service (CBRS) band in April 2016, making 150 MHz available for mobile broadband and other commercial uses.

But before any of that spectrum can be shared, a seemingly complex framework needs to be put into place, one that includes three tiers: one for incumbents, a Priority Access tier and a General Authorized Access tier. The three tiers are to be coordinated through dynamic Spectrum Access System (SAS) administrators. Environmental Sensing Capability (ESC) operators and a future auction will also be put into the mix.

Yet if the 3.5 GHz band goes commercial and is ultimately successful, it could pave the way for a whole new way of using spectrum: by sharing it. And even though wireless carriers were not 100% behind the concept a year or so ago, they’re jumping on board the 3.5 GHz train now.

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CBRS Alliance forges ahead

What’s driving a lot of momentum currently is the CBRS Alliance, which was formally unveiled in August by six companies: Google, Federated Wireless, Nokia, Qualcomm, Intel and Ruckus Wireless. Since then, the organization has grown to include more than 30 companies, including all four nationwide U.S. wireless operators. To be clear, the alliance isn’t starting from scratch: The Wireless Innovation Forum has been working on developing standards in the area for some years now, and Google, for one, is applying some of what it learned in the TV white space arena to CBRS.

The requisite SAS administrators are getting lined up and stakeholders are touting all the ways in which 3.5 GHz can be used—including staging a demo that provided a 360-degree video streaming experience from race cars traveling around a Las Vegas speedway at more than 180 mph.

“I think we’ve sort of exited the point where people are thinking ‘what would it look like’ into ‘how do I adopt this and what will it mean to me and how do I run the business plan for it,’” said Federated Wireless CEO Iyad Tarazi. Federated Wireless and the Google-affiliated Access, now part of Alphabet, demonstrated interoperability between their independently developed SASes late last year.

Federated Wireless expects products to be commercially available by the third quarter of this year, and nationwide ESC deployment is on track to be completed by the end of 2017.

Expectations are high, but questions remain. “This is a new way to use spectrum,” said Monica Paolini, principal at Senza Fili Consulting. “It’s a completely new approach, … but we don’t know how it’s going to work out in practice because there’s a lot of questions, obviously. But the implications are huge in terms of—if this works, you can use the same or similar approach to other bands as well, and that’s a very good way to increase spectrum efficiency.”

Operator pushback

It hasn’t always been smooth sailing. CTIA—and the two Republicans on the FCC who now happen to be the majority—cited concerns last year about certain aspects of the 3.5 GHz framework that the FCC agreed to pursue under former chairman Tom Wheeler. CTIA said the FCC failed to put into place appropriate incentives and protections for licensed users and risked undermining the spectrum-sharing model. Commissioner Michael O'Rielly at the time said that the lack of renewability and short license terms for Priority Access Licenses posed a problem.

FCC Chairman Ajit Pai

Commissioner Ajit Pai, now the chairman of the commission, called the 3.5 GHz proceeding an experiment and said he wasn’t sure if the FCC struck the right balance for a variety of providers and technologies to compete in the band. “It remains to be seen whether we can turn today’s spectrum theory into a working reality,” he said back in April 2016.

T-Mobile has said it hopes the FCC will revisit the rules for 3.5 GHz. “The 3.5 GHz band has the potential to provide additional spectrum for LTE but we also think it is ideal for 5G, in alignment with the rest of the world,” the company said in a statement to FierceWirelessTech. “Additionally, the current rules for licensing the CBRS band should be revisited to create more certainty and align with 5G requirements.”

In a filing with the FCC last October, AT&T had this to say: “The novel SAS model adopted at 3.5 GHz has not even been tested, much less proven to effectively manage spectrum allocation and interference coordination. Once the SAS experiment in the 3.5 GHz band is implemented, the Commission should evaluate the results in consultation with affected stakeholders before imposing it on additional bands.”

Art King, director of enterprise services at CBRS Alliance member SpiderCloud, notes that “experiment” is a kind of prejudicial word. But he acknowledges the unique nature of the band compared to the rest of the world, where 3.5 GHz is used but not in this kind of three-pronged shared system. SpiderCloud Wireless offers an enterprise small cell system that simultaneously offers LTE services on licensed spectrum and on the 3.5 GHz CBRS band.

Art King

“The United States, just with the vast market that we have, we’re ending up being this global lab for everyone on the planet to go, ‘Oh my God, there’s a completely different way to allocate spectrum that will just break things open wide across the planet and people are looking at it as an experiment, but really at a global level, it’s opening up a whole new way of thinking across the world,” King said. “If spectrum comes as easily as a leasing request for a piece of spectrum and as long as it doesn’t conflict with anybody else,” it will make a big impact.

It took a while, but operators are coming around. From the outset, the entire effort required cooperation from the Department of Defense, the FCC and private industry.

“Industry has invested a lot in bringing this band to fruition,” said Preston Marshall, principal architect at Alphabet’s Access. “It’s really been a cooperative effort to bring this about.”

CBRS evangelists say the beauty of CBRS is it’s the first multitiered shared spectrum and that’s got enterprises excited. That’s one of the reasons Nokia, Alphabet’s Access group and Qualcomm Technologies staged that race car demo at Las Vegas Motor Speedway earlier this year. The demo showed how new experiences can be offered using the band and how venues and enterprises can deploy a private LTE network to enhance their customers’ experiences.

Chris Stark, head of Business Development at Nokia, said Nokia already has products that support 3.5 GHz, and it’s been a big proponent of the CBRS band from the start. Nokia’s product line is moving along in terms of availability of different types of products.

High and low, it’s small cells

For all the talk about small cells in the industry, the 3.5 GHz space may be where the rubber hits the road. Sure, 5G and high-band spectrum will play host to small cells, there’s no doubt about it. But the 3.5 GHz space offers a different paradigm. For example, in-building coverage has always had its own set of challenges for operators, whether it be distributed antenna systems, Wi-Fi or something else.

If venue owners, which typically want to serve customers regardless of which carrier they use, were to install their own 3.5 GHz LTE systems, they could conceivably host the major operators on the network, with software that makes it appear for the consumer that they’re using T-Mobile’s network or Verizon’s—whoever their carrier happens to be. Then it’s more of a sharing model—not to the extent where they’re sharing networks the way it’s done in other countries, but where U.S. operators remain in control and market forces drive what happens in the band.

“This is the first time we’ve had a band that anyone can go into and they can put any technology they want. The technologies will compete in this band, the different applications will compete in this band,” Marshall said. “That competition is going to create a very, very rich ecosystem for innovation, for new ideas. It could never happen if people spent $30 billion or $20 billion buying spectrum. Innovation will create abundance.”

Verizon has already conducted infrastructure testing and plans to deploy both low-power and high-power small cells in the 3.5 GHz band when it becomes practical to do so. The commercial timelines for actually deploying gear are dictated by the availability of the SAS, commercial-grade network equipment and capable devices, which Verizon expects to occur in early 2018.

Low-power small cells could be deployed indoors in enterprises, hotels, airports, convention centers and the like, while high-power small cells are suitable for outdoor applications like large campuses, metro areas, downtown areas and suburban locations.

CBRS Alliance members have said they expect the FCC to begin to certify devices for the band by the middle of this year, paving the way for commercial deployments of the technology by 2018. At some point, the FCC will need to set an auction for licensed users, but CBRS members are not waiting for that to happen. A number of different players—from wireless carriers to cable operators to stadium and hotel owners—are going to be interested in deploying LTE services in the band.

3.5 GHz as an example for the world

If the United States is successful in deploying spectrum-sharing technologies in the 3.5 GHz band, the effort could set a global precedent. “If this works out, it’s going to have a huge impact, not just in the U.S. but other parts of the world as well,” Paolini said.

That’s exactly what CBRS stakeholders are gunning for. “I don’t see any reason why, if we make this a success like we seem to be, that other countries wouldn’t want to adopt it in some form or another,” Marshall said.

Given the great hunt for spectrum, it’s a pretty strong guarantee that more spectrum sharing will occur, both in the U.S. and probably abroad. It’s just a matter of which bands get invited to the party.

“Spectrum is like the oil of our industry and if it could be so easily used and allocated, it’s revolutionary,” said SpiderCloud’s King. “It’s actually a revolution if you step back and look at it.”