Verizon is pushing back against what it sees as some perceived limitations of its newly acquired C-band compared to T-Mobile’s lower 2.5 GHz mid-band for 5G.
Ahead of the C-band auction all eyes were on Verizon, with industry analysts and observers describing how the carrier needed to win key mid-band spectrum to be competitive in 5G.
Then came the auction with its cumulative price tag of more than $81 billion (not including clearing costs and incentive payments), of which Verizon accounts for more than $45 billion. The carrier secured an average of 161 MHz nationwide including 60 MHz of the earlier available A block that covers 46 markets and comes into play later this year.
Verizon plans to spend $10 billion more over three years to deploy C-band, initially using its existing AWS/PCS macro network grid for early deployments. It expects to have between 7,000-8,000 C-band equipped sites this year.
However, competitor T-Mobile, as well as some investment analysts, have turned attention to propagation characteristics of the upper mid-band spectrum and how Verizon would need to spend a lot more to densify its network sufficiently for ubiquitous coverage using C-band.
For example, during its investor day, T-Mobile said it would take 1.5-times the number of 2.5 GHz sites and 2-times the number of PCS/AWS sites to reach the same amount of coverage with C-band.
“That is not accurate,” Verizon VP of Technology Development and Planning Bill Stone said in an interview with Fierce. And he is “very confident that the number of sites required at 2.5 GHz and C-band are roughly the same.”
The laws of physics still apply, he acknowledged, (higher 3.7-3.98 GHz frequencies experience more propagation loss than lower 2.5 GHz frequencies), but emphasized that’s not the full picture as other key elements come into play during real world deployments.
“To design and engineer a network you need to look at all the pieces and that’s how you determine how many sites are needed in the different frequency bands,” Stone said.
To look at it end-to-end (or “the full budget link” in engineering terms) the main components for signal reach include transmit power levels, propagation loss, and antenna gains at each cell site location.
“The limiting factor almost always is the uplink,” Stone said, speaking about capabilities of the receiver at the base station.
C-band’s higher frequency means it can take advantage of Massive MIMO more efficiently, with higher antenna gains at the base station uplink – around 28%, versus EBS/BRS – that balance out the roughly 25% ding to C-band’s reach compared to 2.5 GHz because propagation loss due to the physics of higher frequencies.
“The antenna gains we’re going to be able to get with Massive MIMO product in 3.5 GHz are far – 4db or more – greater than what can be realized at the similar size antennas in EBS or BRS, the 2.5 GHz or PCS/AWS,” Stone said. “That antenna gain more than offsets the difference in the propagation loss.”
Carrier aggregation, low-band spectrum for uplink
T-Mobile has said it can extend mid-band coverage range by about 30% using carrier aggregation, with low-band for uplink (having widely deployed 600 MHz for 5G already).
And investment research firms also pointed to this as an advantage. In a March 15 note to investors, New Street Research analysts said T-Mobile will still have a strong advantage with its 85,000 cell sites versus Verizon’s 68,000 and because T-Mobile plans to use low-band uplinks aggregated with 2.5 GHz to extend reach.
“Verizon could close the gap, if they chose to, by either deploying more cell sites or using supplemental low-band uplinks themselves,” wrote the New Street team. “Both would require more capital than they have committed to so far; the latter may also require an acquisition of or partnership with Ligado to get access to their L-band uplinks.”
But coverage extension with carrier aggregation and using low-band for uplink is something Verizon can do too, using the 850 MHz it has deployed for its 5G nationwide service, according to Stone.
“We can use carrier aggregation between the 5G Nationwide 850 MHz, as well as C-band,” Stone said. “So the extension capability is something that we have as well.”
When it comes to carrier aggregation, or combining different spectrum channels to extend coverage, there are two options, including uplink using one band and downlink aggregating two.
“In the far edge conditions of coverage you could be using the 850 MHz 5G band for the uplink, while on the downlink you’re combining both through carrier aggregation, both the mid-band – in our case C-band – as well as the 850 MHz 5G band,” he said.
Eventually, Verizon will be able to utilize carrier aggregation on the uplink as well, Stone added. “But all you need is that first example … with 850 [MHz] on the uplink and C-band and 850 MHz on the downlink to get that coverage extension.”
RELATED: C-band focus turns to densification
And Verizon sees no issue with aggregating its CBRS holdings in the future – the band sits right next to C-band, but power levels are more restricted.
“No limitations [with CBRS],” Stone said in terms of using carrier aggregation. “We will be doing carrier aggregation across all our 5G frequency bands as we move forward,” though he noted capabilities vary by device type. That also includes mmWave, which Verizon has deep holdings and has deployed more widely than other carriers (though availability is limited).
While uplink is the most limiting factor, there are also some considerations when it comes to downlink. That includes stricter power limitations on EBS/BRS under FCC rules than for C-band – a difference which become more marked as beamwidth widens and in rural areas, according to Stone.
“There’s the puts and takes,” he said. “C-band has advantage in transmit power, 2.5 has the advantage in propagation loss, but when you do the math in rural areas in particular, the downlink for C-band has an advantage and that becomes more pronounced at wider beamwidths for EBS/BRS, and those restrictions don’t apply at wider beamwidths for C-band.”
Prioritizing macro sites, small cells, in-building part of the picture
When it comes to overlaying C-band on its existing AWS/PCS sites, Stone reiterated that Verizon has been densifying its network for years, particularly in the urban and suburban areas of the country, and already has the requisite macro site density in most of those areas.
“We’re starting from a great position with the best network, already engineered for AWS/PCS, C-band is going to fit perfectly with that and just as we have been doing for decades we’re going to continue to densify and we’ll see improvements in C-band coverage in the outer suburban and rural areas,” Stone said.
Verizon aims to cover 100 million people with C-band within a year, and 250 million by 2024. T-Mobile, meanwhile, says it’s on track to reach 200 million with mid-band 5G by the end of this year.
Wells Fargo in a Sunday note to investors about implications of C-band builds for tower companies wrote the firm’s “discussions would suggest that VZ is likely to upgrade the vast majority of its 68K macro tower sites, while it also continues to add +2K new macro sites per years (although our view is that smaller private towercos win many of these new site builds at more favorable pricing).”
Initially Verizon will prioritize C-band deployments on macro sites, but small cells and in-building are also in the picture.
“We will certainly deploy C-band over time on small cells and also upgrade many of our in-building systems with C-band capabilities as well,” Stone said. He added that in some cases small cells will be in the high priority category as will in-building deployments, though it will take time to get to all cell types.
For in-building coverage, again some critics have sometimes pointed to C-band’s ability to penetrate. Verizon’s indoor coverage from C-band will come from both macro deployments and in-building networks, according to Stone.
“We fully expect C-band will penetrate buildings so that the macro cell deployment will result in in-building coverage,” Stone said. But he added that building types, materials and size vary widely, so it will be augmenting “outside-in” coverage with C-band from macro sites with in-building set-ups over time.
“We fully intend to have in-building solutions, and in fact we have vendors lined up to supply us with products this year for that purpose,” he said.
Another benefit of C-band is the contiguous channels (the FCC is moving toward a 2.5 GHz white space auction and has worked to streamline a somewhat messy licensing makeup).
“Verizon is the only U.S. operator to have 140-200 MHz of contiguous mid band spectrum across the 48 contiguous states,” Stone said, enabling the carrier to accelerate deployment and use spectrum efficiently.