Verizon’s low- and high-band 5G networks, both of which were expanded this week, ride on multiple flavors of SDN.

The operator is using carrier aggregation to combine eight channels of its millimeter-wave (mmWave) spectrum and dynamic spectrum sharing (DSS) technology to make its 850 MHz spectrum holdings, previously reserved for 4G LTE, available on an on-demand basis for 5G. The former allows Verizon to effectively double peak download speeds up to 4 Gb/s on its Ultra Wideband network, while the latter puts previously deployed low-band spectrum in play for a “nationwide” 5G footprint.

On its 5G Ultra Wideband network, Verizon customers with 5G devices can now access a total of 800 megahertz of spectrum, explained Bill Stone, VP of technology development and planning at Verizon. “It provides us with additional capacity, but also enables much higher throughput for the individual user or customer,” he told SDxCentral in a phone interview.

“In most cases, we were deploying the spectrum already,” but prior to its use of carrier aggregation the “device in the network was only capable of aggregating up to 400 megahertz,” Stone said. “So even though we had 800 [megahertz] deployed, the device in the network, on an individual user base, would only be able to take advantage of 400 megahertz.”

The peak data rates now being promoted by Verizon on its 5G Ultra Wideband network are only available in “ideal conditions,” and that comes down to the signal or radio frequency conditions of each device, he explained. “The closer the device and the customer are to the millimeter-wave node, the better the probability is that you're going to experience very good radio conditions.”

Signal interference, which is mostly managed through network design and engineering, is the other factor getting in the way of those “ideal conditions,” Stone explained. “Generally speaking, the radio conditions will vary. So you won’t always get the peak data rates, but there’s a higher probability of getting those peak data rates the closer you are to the radio node.”

While Verizon is focusing on what it’s capable of delivering today, it hasn’t reached the ceiling of what it eventually intends to achieve on mmWave spectrum, according to Stone. “We are nowhere near done.”

The operator is also, as was always its plan, leaning heavily on DSS to offer a nationwide 5G footprint on low-band spectrum. That decision, which was effectively a prerequisite for the carrier’s more extensive 5G aspirations, factored mightily into it being the last of the large domestic operators to deploy 5G at scale. 

Verizon was ready to activate its nationwide 5G footprint via DSS in August, Adam Koeppe, the operator’s SVP of technology, architecture, strategy, and planning, said at the time. 

“It was our strategy all along to start with millimeter-wave,” as much as part of that plan was to also deploy 5G in other legacy frequency bands with DSS, Stone said, adding that the software is working well.

“The capability that comes with dynamic spectrum sharing enables us to share the spectrum between 4G and 5G, and adjust and adapt the allocation of spectrum based on the actual presence or customer demand that's being generated by 4G devices and 5G devices,” he said. 

“It's a very elegant way for us to give both our 4G and 5G customers the best possible experience. And it enables us to continue to adapt really on a near real-time basis the amount of spectrum that's allocated to 5G as customers move around,” Stone added. “It's also going to make it that much easier for us to continue to deploy 5G in additional frequency bands as the device penetration does increase over time.”

T-Mobile US has been among the most vocal critics of DSS, focusing its belittlement largely on Verizon but AT&T also relies on DSS for its “nationwide” 5G footprint. T-Mobile US has greater flexibility and room to criticize the technology in that regard because it’s nationwide 5G network runs on previously unused spectrum.

Neville Ray, president of technology at T-Mobile US, earlier this year called DSS a capacity hog with “corrosive” impacts on network performance. 

“T-Mobile likes to throw shade at Verizon about its use of DSS technology, and for good reason,” analysts at Lightshed Partners wrote in a new report. “DSS likely erodes capacity that Verizon needs for its 120 million subscribers.”

Verizon consistently refutes those claims, but recent speed tests have effectively emboldened concerns about DSS, the analysts wrote. The firm questioned Verizon’s long-term strategy on DSS and wonders if the operator already determined that “the capacity reducing impact of DSS on its mid-band spectrum was not worth the impact it would have on existing customers.”

Stone said Verizon plans to use DSS in all of its spectrum bands currently used for 4G LTE, but the extent to which that effort will reach Verizon’s mid-band spectrum holdings remains unclear. 

Finally, a separate but more all-encompassing effort for Verizon revolves around its 5G standalone core. This network component delivers true 5G, unencumbered by the legacy 4G LTE network cores that most 5G networks, including Verizon’s, rely on today. 

Verizon’s 5G standalone core is still under development. The operator shared some advancements on that effort in July, and it’s still on pace to have some network traffic hitting that new core before the end of the year with full commercialization slated to occur in 2021, according to Stone.

“We’re moving forward relatively quickly,” he said. Verizon has yet to name its 5G core vendors, but Stone said it’s “pretty far advanced with each of the vendors selected” for that effort.

That 5G core, according to Stone, will support all of the frequency bands that Verizon is using for 5G.