Mobile network capacity augmentation and fixed wireless access broadband are the two use cases driving early deployments in the shared Citizens Broadband Radio Service spectrum at 3.5 GHz, according to industry experts. More than 270 bidders are set to participate in the upcoming auction of CBRS Priority Access Licenses, which is set to begin on July 23.
Due to the Federal Communications Commission’s quiet period requirements, bidders are not able to publicly discuss their CBRS strategies in the lead-up to the auction. But since the CBRS Alliance celebrated the beginning of Initial Commercial Deployment of OnGo – the brand name for certified products that use LTE in 3.5 GHz – last fall, a number of service provider executives have spoken about their CBRS plans and testing.
AT&T plans to use CBRS to help meet its commitment to bring high-cost fixed broadband service to areas of 18 states as part of the Connect America Fund program. AT&T’s first-generation equipment for that program leveraged licensed WCS spectrum at 2.3 GHz, according to Hank Hultquist, AT&T’s VP of Federal Regulatory, during remarks at the launch of ICD. At the time, Hultquist said that between the end of 2019 and early 2020, AT&T expected to have CBRS spectrum deployed on 170 sites in Ohio and Tennessee to help meet its CAF commitments.
“Over time, we expect to get it on up to 1,100 towers covering around 82,000 living units in 11 states,” he went on. The CAF program requires speeds of at least 10 Mbps downlink/1 Mbps downlink, but “with next-generation fixed wireless, we are looking at higher speed tiers as well, including both 25/3 and 100/20,” Hultquist said.
in describing AT&T’s chosen CBRS architecture, Hultquist said that “at the cell sites, we will be using a traditional distributed RAN architecture with massive MIMO. Each radio is a CBRS Class B device (CBD). The baseband controllers will be kept indoors or in shelters, and connected to the radio by fiber.” At the customer premise, he said, certified installers will put in a high-gain directional antenna with an integrated LTE modem, which will mounted at the roofline and connect to the home’s interior via Ethernet cable. The CPE will also be a CBD, he added, in order to take advantage of the higher permitted power transmit levels.
“In the network core, we have implemented a domain proxy to aggregate [Spectrum Access System] traffic, and we have also set up a dedicated SAS APN for traffic between the customer locations and the SAS. Data traffic APNs will not be established until transmission authority has been received from the SAS,” he said. AT&T was already conducting field tests as ICD kicked off, and Hultquist confirmed that SAS signaling for both the cell site equipment and the customer premise CBDs had already been successfully verified, and that using 20 megahertz channels, AT&T had been able to achieve peak throughput of 140/12 Mbps at a distance up to a little over a mile with line-of-sight to the tower. “Our drive testing so far has shown that the RF characteristics of the band are as expected,” he continued, although the carrier was going to conduct additional testing to look at propagation in hilly terrain and with dense foliage. “We are extremely excited about the prospects of this band,” Hultquist said.
From Verizon, Senior Vice President for Technology Strategy and Planning Adam Koeppe said during the ICD launch event that “OnGo will be a fantastic solution to increase 4G LTE capacity, improve the customer experience and provide robust enterprise solutions,” Koeppe said, going on to add, “We are ready to use this new resource to bolster our award-winning networks by deploying new capacity solutions to high-traffic areas, enterprise locations, stadiums, venues and airports.” He said that Verizon already had both network nodes and SAS partners prepared and ready to go as ICD commenced, and it was looking forward to 5G NR technical assessments going forward in the band. In a video highlighting OnGo use cases, Koeppe said that OnGo “is going to benefit all of our customers nationwide,” and added that, “When we have to put capacity into the hands of our most densely packed areas, it’s a very viable solution that can be quickly deployed.”
“We’ve got a litany of solutions already teed up and ready to go,” he said. “CBRS spectrum is a tremendous capacity solution for those low and tight RF locations where you need to get a lot of capacity in a very densely packed area.”
Charter Communications’ Chief Network Office and SVP of Enterprise Solution Craig Cowden said at the OnGo ICD event that Charter has primarily been working on enabling two use cases: rural fixed wireless broadband with a similar architecture to the one described by AT&T, an area in which he said the company was “pleased with the initial results” of testing in “multiple proofs-of-concepts, multiple markets around the country, in difficult terrain”, including a commercial trial in Davidson County, North Carolina. He outlined plans to use CBRS to target speeds of 25/3 Mbps, but also to offer lower speed tiers that could extend farther into areas that Charter does not currently cover. He also discussed transitioning Charter’s “Wi-Fi-first” MVNO with Verizon, in which Charter tries to offload as much cellular traffic to its Wi-Fi network as possible, to a “small-cell-first” model.
“We’re huge advocates of Wi-Fi,” Cowden said. “That’s important to us. However, we also look at how we can extend and offer a small-cell-first MVNO, going from a Wi-Fi-first MVNO to a small-cell-first MVNO and truly looking at how we can use CBRS or OnGo spectrum to offer licensed capability with the densification of small cell build-out.”
Charter started testing that concept in 2017, he said, and has conducted “massive trials” in Tampa, Florida and Charlotte, North Carolina “to learn the basics of how CBRS spectrum would work.”
At the end of 2018 and through 2019, the cable operator also conducted CBRS trials in New York and Los Angeles, California, and it also has a “constant test bed” in Denver, Colorado, Cowden added. “Those particular trials are sort of the next phase of our evolution of how we think about it,” he continued, saying that CBRS small cells are “really a hand-in-glove fit with cable plant that we have.” Key for Charter’s plans, Cowden said, is not just a robust device ecosystem for CBRS, but specific widespread support within that ecosystem for dual-SIM/dual-subscription capabilities so that one SIM on a device can operate on a Charter CBRS small cell network, and a second SIM connects to Verizon’s cellular macro network as needed.
“We’ve done a lot of trials there, testing the efficacy of the seamless switching between that small cell domain and that macro domain, and we’re very pleased with those results,” he said.
Meanwhile, Tom Rutledge, Charter’s CEO, was asked on the company’s most recent quarterly results call whether the FCC’s recent action to open up 6 GHz for unlicensed use impacted Charter’s appetite for CBRS. “They’re really separate notions,” he responded, adding that he sees 6 GHz as “inside-house type spectrum, so all of our products are delivered wirelessly.
“The CBRS spectrum really allows for a more efficient use of the mobile platform, at least the way we look at it. Although it could be used indoors as well and it could be used indoors, both for mobile service and enterprise environments and externally and so we see them as separate notions and separate values and it hasn’t affected — one hasn’t affected the other, in our view,” Rutledge said.
Comcast appears to be coming at the CBRS opportunity from a very different place than Charter is. Comcast CEO Dave Watson, when asked on a recent quarterly call about Comcast’s MVNO relationship with Verizon and how the company views the CBRS auction, responded that Comcast “[likes]we like our relationship, current one that we have. We’re always going to be staring at ways of making improvements to it over time, but the fundamentals are very good. And in regards to spectrum … We will be opportunistic if it makes sense to our business.”
Looking for more information on the CBRS landscape? Keep an eye out for RCR Wireless News’ upcoming editorial special report on early CBRS commercialization and register for the accompanying webinar.
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