T-Mobile expands 5G voice, fetes 5G 4-CA data call

BARCELONA—The “un-carrier” announced two significant achievements on Wednesday: the expansion of Voice over 5G, or VoNR, to four additional U.S. cities and the completion of a four-carrier aggregation data call on a commercial device.

With the expansion of VoNR, T-Mobile now covers six cities, with plans to cover 100 million people with VoNR in the coming months. The new cities are Cincinnati, New Orleans, New York and Seattle. Previously, T-Mobile announced Portland, Oregon, and Salt Lake City, Utah, as VoNR cities.

“We’re going market by market,” said T-Mobile President of Technology Neville Ray on the sidelines of MWC 2023. “We’re never going to take anything away from voice, so that’s got to be VoLTE or better quality.”

Getting voice over 5G to work has been a challenge throughout the industry. Some carriers say they’re in no hurry because LTE does a good job providing voice service through VoLTE, but the end game is to get all the voice traffic on 5G standalone (SA) where and when it’s possible.

The first with a nationwide 5G SA network, T-Mobile is ahead of the pack. In the near term, customers connected to VoNR may notice slightly faster call set-up times, meaning less delay between the time they dial a number and when the phone starts ringing, the company said in a press release.

“We went through this with LTE,” where voice came later than data, Ray said. The same thing is happening with 5G, but now T-Mobile is the one leading the OEMs and chip manufacturers to come to the table and deliver the goods.

“5G is a way more complex technology. There’s a lot of layers and banding,” and you can’t just copy and paste what was done in 4G LTE and apply it to 5G voice. “A lot of it is we’re harnessing and leveraging a lot more different spectrum sources,” he said.

“For us, we want to move everything on that 5G highway,” he said. “Are we going to bring a whole new level of voice quality? No. I think it will sound pretty much the same, maybe marginally better. But I do think we can combine voice services with messaging services and other data applications and services in a 5G way,” including video.

As for devices getting on board to support VoNR, “we think we’ll get most devices on” by the end of 2023, he said. Including the iPhone? “We’ll see.”

Aggregation of 4 channels

While there’s plenty to grouse about when it comes to 5G disappointments, especially in the monetization realm, 5G is definitely upping the game when it comes to aggregation, according to Ray.

T-Mobile said it was able to aggregate four channels of mid-band spectrum on its 5G standalone network with the Samsung Galaxy S23 device, working with Ericsson, Nokia, Qualcomm Technologies and Samsung. In the test run, they were able to reach speeds of 3.3 Gbps.

The ability to do four-carrier aggregation in 5G means they’re able to combine two FDD and two TDD carriers and they couldn’t do that in LTE. It didn’t have the bandwidth capability, for one thing.

Historically, most spectrum in the U.S. was FDD, and it was just paired, he said. Then came time division duplexing, or TDD, which is what Sprint brought with 2.5 GHz, and that enabled something other than a 50-50 split on the uplink and downlink, he said.

TDD includes 2.5 GHz, all of the C-band at 3.7 GHz and recently auctioned 3.45 GHz. Right now, there’s a lot more downlink usage but in the future, uplink demands will increase. “Now you can combine the spectrum in ways that you could never do in LTE,” he said.

In T-Mobile’s four-carrier aggregation demonstration, it merged two channels of 2.5 GHz and two channels of 1.9 GHz to effectively create a 225 MHz-wide 5G channel.

It’s not quite at the commercial stage yet. T-Mobile said customers with the Samsung Galaxy S23 will be among the first to experience four-carrier aggregation later this year, with more devices to follow.  

“The best place to run a wireless network today is 5G,” because it’s far more efficient, Ray said, noting that 70% of T-Mobile’s network traffic today is on 5G.

Fixed wireless access is also a use case that benefits from 5G in a big way. “5G is a powerful home broadband play,” and it wouldn’t be possible to get the same horse power with LTE. “You wouldn’t have the capacity or the efficiency to do it,” he said.