U.S. Cellular, the nation’s fourth largest infrastructure-based wireless carrier, is moving beyond its initial two 5G markets in Iowa and Wisconsin and is beginning to deploy 5G in 11 more states. Michael Irizarry, executive vice president and CTO of U.S. Cellular, said the company is deploying 5G by using an approach that targets “clusters” where there are large numbers of existing customers that are likely to use the upgraded technology.
“We look at traffic patterns and where customers frequent on our system,” said Irizarry. “There’s a concentration in urban areas, but we also look at small and medium towns. That’s very important to us to look at.”
The company will activate 5G in select areas in 11 states including California, Maine, Maryland, New Hampshire, North Carolina, Oklahoma, Oregon, Texas, Virginia, Washington and West Virginia.
U.S. Cellular is rolling out the initial phase of its 5G network on its 600 MHz spectrum. “We had strategically reserved 600 MHz in anticipation for 5G, unlike other carriers who have to share,” said Irizarry, referring to dynamic spectrum sharing. “We don’t have to rob Peter to pay Paul. We can take our clean unused 600 MHz spectrum and use it for 5G.”
Irizarry said that U.S. Cellular’s 5G upgrades also include “LTE Advanced” modernization. “We have many devices that aren’t 5G capable but are LTE-Advanced capable,” he said. “Customers with LTE-Advanced devices could get the benefits of that technology.”
LTE Advanced refers to upgrades that can include 256 QAM and carrier aggregation. 256 QAM provides higher levels of modulation, which enables more bits per sliver of spectrum. And carrier aggregation is a technology that enables wireless operators to combine both contiguous and non-contiguous spectrum blocks as well as spectrum blocks from other bands in order to increase the data speeds to the end user.
In U.S. Cellular’s case, in addition to using its 600 MHz spectrum, it will also carrier aggregate its AWS and PCS spectrum in some cases.
Irizarry said most of the devices the company has been selling support LTE Advanced, and those that don’t can be upgraded via a software push. “We didn’t really have to factor in whether there were enough devices to support LTE Advanced,” he said.
Smartphones that work on U.S. Cellular’s 5G network include the Samsung Galaxy S20, the Samsung Galaxy A71 5G and the LG V60 ThinQ 5G.
mmWave spectrum
U.S. Cellular uses Nokia, Ericsson and Samsung to provide it with gear for 5G mmWave deployments in the 24 GHz, 28 GHz and 39 GHz spectrum bands. U.S. Cellular is beginning its deployment of 5G mmWave now, with commercial availability planned for 2021.
“We view 5G as a technology that depends on low-band, mid-band and high-band spectrum,” said Irizarry. In U.S. Cellular’s case, low band is its 600 MHz, AWS, and PCS spectrum. Mid-band would be CBRS and C-Band spectrum if U.S. Cellular ends up getting any of that spectrum at auction. And mmWave would comprise its high-band spectrum.
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“We believe you need to have enough of each of that spectrum to offer a complete 5G product offering,” said Irizarry. “We’ve got a good amount of low-band and high-band. We’ve been trialing the high-band for a while now, and we’ll be doing some commercial trials in the not-too-distant future. We’ll start to deploy in earnest in 2021.”
5G core
Currently, U.S. Cellular is updating its network with 5G non-standalone equipment that will work with its existing LTE core network. But the company is in the midst of a request for proposal (RFP) for a standalone (SA) core. Irizarry said the RFP will transition to a trial. “It’s a question of when we’ll deploy,” he said. “It depends on if the vendor offerings are really mature enough.”
He said the company cast a wide net in its RFP to vendors for its 5G SA Core. He said its existing vendors Ericsson, Nokia and Samsung are invited to bid along with new vendors.
US Cellular is also a member of the O-RAN Alliance, and it’s evaluating open RAN technologies. “There are O-RAN specs that we think are more optimal that aren’t completed yet,” said Irizarry. “We’re following that and providing our input. When those specs get locked down, we’ll look at how we can leverage.”