When Verizon, T-Mobile and AT&T held their respective investor days earlier this month, questions immediately surfaced as to how much densification is going to be required in their C-band rollouts.

Densification is one of the themes for a panel discussion next week during the FierceWireless 5G Blitz Week, which features four days of events March 22-25. A panel on Wednesday will discuss 5G infrastructure opportunities, use cases and what’s ahead in 2021.

Now that the C-band auction has closed and the quiet period is over, operators that won spectrum as part of the first batch are eager to start deploying it when the spectrum becomes available later this year.

Getting ready for deployments is one of the big priorities right now for Michael Wolfe, vice president, Wireless Network Engineering – Mobility Solutions at CommScope.

Wolfe and his team were able to lay some groundwork before, but now that the quiet period is over, it’s easier to refine what their operator customers need. “It’s really kind of looking at where they’re going with their networks and making sure we have the right product to plug in to help them do that,” he said. “We’ve been developing antenna capabilities that we thought would be needed.” 

CommScope has been working with Nokia for years on a Massive MIMO integrated antenna solution for network densification. Nokia today announced it will be supplying its portfolio to support AT&T’s C-band deployment in parts of the U.S., both indoors and outside.

RELATED: Verizon answers some of those big C-band questions

Verizon held its investor meeting as soon as the quiet period lifted, with executives saying the C-band buildout will be focused on existing locations, tracking closely to its earlier PCS and AWS deployments. That suggests they don’t expect to add a lot of new macro sites to satisfy their C-band deployments.  

Analysts beg to differ. MoffettNathanon analysts evaluating all three operators’ investor days concluded in a March 15 report that a clear take-away is Verizon and AT&T are going to need more towers to support C-band 5G coverage – “lots more towers.”

Of course, T-Mobile says C-band at 3.7-3.98 GHz is going to require a lot more sites and antennas than its own robust 2.5 GHz holdings. In fact, T-Mobile says its engineers estimate C-band will require 50% more cell sites for meaningful and continuous coverage, and in some areas, such as inside buildings, the required densification can be 4x higher than 2.5 GHz.

Urban coverage 

The consensus is the first deployments for most C-band networks are going to be on macro sites, although demand for small cells is also expected.

“Out of the gate, they’re going to focus on urban coverage because that’s where all the customers are and that’s where they need the most capacity, so it’s going to be heavily dominated by the high-end radios,” and Massive MIMO, according to Wolfe.

Verizon has been a big proponent of millimeter wave (mmWave) for 5G, and it has access to a lot of mmWave spectrum. But from a general deployment perspective, mmWave is challenging, covering very limited areas.

At least for the foreseeable future, the role of mmWave likely will be overshadowed by C-band, which doesn’t provide as much capacity but offers better coverage. That said, Verizon ended 2020 with more than 17,000 mmWave sites and expects to build another 14,000 in 2021.

For indoors, Verizon has refined its fixed wireless access (FWA) offering that uses mmWave, but for mobility, it’s a tough nut to crack because it costs a lot of money to provide coverage at the higher frequencies.

It’s worth noting that Massive MIMO was a big part of Sprint’s 5G strategy before its 2.5 GHz spectrum went to T-Mobile. A lot of propagation loss can be overcome by way of the beamforming that Massive MIMO offers, Wolfe said.

So, where does that leave small cells, which were often cited as ideal for the nearby Citizens Broadband Radio Services (CBRS) 3.5 GHz deployments? C-band is higher on the spectrum, at 3.7-3.98 GHz.

According to the Small Cell Forum (SCF), small cells will play a key role in the deployment of 5G networks, providing a cost-effective solution to provide the additional radio sites required. Basically, a small cell is a radio access point with low RF power output, footprint and range. It’s often considered for indoor deployments, but larger units also can be used outdoors. The question is: When do small cells become a thing in C-band?

Small cells weren’t part of the 2G deployments and really started gaining steam with 4G, notes Ravi Sinha, strategy analyst at Reliance Jio and chair of 5G & Tech Group at the Small Cell Forum.

RELATED: Open RAN moves beyond hype into trial phase and reality

Small cells are going to play a big role in future network requirements, he said, and the SCF has been a big believer in the concepts and tech behind open Radio Access Network (open RAN). Part of that is being able to mix and match, taking a product from one radio vendor and managing that with the gear from another vendor, eliminating the vendor “lock in” that many operators want to avoid. 

Rules can vary by jurisdiction, but generally speaking, if a change is being made to an existing structure – such as adding a C-band antenna – the operator or entity making the change for the operator needs to get permission from whoever they’re leasing the site from. That’s a lot of what’s happening now – submitting designs through the site acquisition process.

“I do think C-band is going to be deployed on small cells,” but it won’t be the initial priority, Wolfe said. Instead, they’re going to achieve nationwide coverage as fast as they can using the macro and micro sites. There will be a role for small cells, but probably more of a secondary role for the next year or two, he said.

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