Federated Wireless launches new DAS initiative for CBRS

• CBRS-enabled Active DAS can help carriers boost indoor 5G capacity without using licensed spectrum

• Federated envisions carrier-grade deployments across stadiums, airports, hospitals and large enterprise campuses

• Early operator interest is emerging, with Active DAS positioning CBRS as a lower-cost way to extend coverage in large indoor venues

Federated Wireless hopes to stoke mobile operators’ interest in the Citizens Broadband Radio Service (CBRS) with the launch of its Active Distributed Antenna System (Active DAS), providing carriers with a new way to expand indoor 5G capacity without using their precious licensed spectrum.

Why is Active DAS such a big deal? According to Federated Wireless CTO Kurt Schaubach, CBRS requires that every radiating element be registered, authenticated and actively managed by a Spectrum Access System (SAS), a service that Federated provides. That process is relatively straightforward when antennas are directly connected to a collocated base station node (gNB), but it becomes far more complex in a DAS, where RF is generated and distributed across many remote nodes within a building, he said. 

“To make CBRS work in Active DAS environments, we had to develop new methods to model and manage these devices within the SAS, certify the individual system components and create installer training and compliance programs,” he told Fierce. “All of this required formal FCC approval, which we successfully obtained late last year, clearing the path for today’s product launch.”

Active vs. passive DAS

There’s a good reason for calling it out as “Active DAS.” That’s because Active DAS uses fiber to distribute digitized baseband signals to remote radio nodes, which then convert those signals into RF emissions at the point of transmission. Because it relies on fiber, Active DAS can cover large, complex indoor environments efficiently, which is why it has become the dominant architecture for in-building wireless, he said.

Passive DAS, by contrast, distributes RF signals directly over coaxial cable, an approach that suffers from higher signal loss and limited reach, making it far less suitable for large or dense indoor deployments, Schaubach explained.

Target market

Broadly speaking, the target market for Active DAS includes mobile network operators, large enterprises, tower companies and system integrators. DAS deployments today are typically funded by one of three parties: the carrier, the enterprise itself or an intermediary such as a tower company.

“Our focus is on enabling CBRS for whichever party is funding or upgrading the DAS infrastructure,” Schaubach said.

He isn’t ready to name specific customers, but Federated worked closely with DAS OEMs, including ADRF, Andrew, Airspan-Corning and SOLiD to enable this new Active DAS capability. A dedicated working group also was recently launched within the OnGo Alliance and it’s focused on CBRS Active DAS deployment models and ecosystem readiness, he noted.

According to Schaubach, they’re already seeing “meaningful interest” from mobile operators, although he didn’t name any names.

Verizon bought CBRS Priority Access Licenses (PALs) in 2020 and has tapped CBRS in part to enhance coverage and capacity inside stadiums, but T-Mobile and particularly AT&T have been less enthusiastic, saying higher power levels would make CBRS more useful. 

That said, CBRS was carved out in part to free up spectrum for non-traditional users and it’s found success in the private network sector, as well as with smaller Wireless Internet Service Providers (WISPs), cable companies and various verticals.

Currently there is a proposal before the FCC to raise CBRS power levels that all three big wireless carriers have endorsed. But Dave Wright, policy director for Spectrum for the Future (SFTF), which represents cable interests among others, told Fierce that it’s not so much a “wireless vs. cable” fight as a “wireless carriers versus everyone else” kind of battle, with the big wireless carriers as the primary proponents of higher power levels.

It remains to be seen how successful Active DAS will be in getting the mobile operators to jump on the CBRS train to expand indoor capacity.

Airspan Director of Product Management Isaac Nissan said many organizations see the benefits of CBRS but struggle with the cost of building dedicated networks.

“Extending CBRS over shared Active DAS infrastructure dramatically reduces that barrier – allowing operators and venues to introduce CBRS without duplicating infrastructure,” he said in a statement. 

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