T-Mobile isn’t sitting still now that AT&T and Verizon have launched their new C-band 5G networks. The carrier is turning on a new technology that’s focused not on speed, but on range—hoping to leapfrog its competitors’ C-band buildout by taking “ultra-capacity” 5G to more places, faster.
5G carrier aggregation (5G CA, or NR CA for New Radio carrier aggregation) lets T-Mobile combine two 5G channels for better speed, or better range. T-Mobile has said the capability is out there, but has been frustratingly coy as to exactly where. In three days of wandering around three boroughs of New York City with a compatible phone, I found it on seven blocks of Brooklyn.
The capability requires a Samsung Galaxy S21, S21+, S21 Ultra, or iPhone 13 series, with relatively recent (but not the absolute latest) firmware update. T-Mobile says it’ll be available on more phones “in the coming months.”
While testing Verizon’s C-band in Brooklyn, my T-Mobile Samsung Galaxy S21+ picked up the first evidence I’ve seen of 5G CA in the wild. Along a stretch of Throop Avenue in Bedford-Stuyvesant, my phone started reporting that it was no longer using 80MHz of band 41 5G; it was now combining it with 10MHz of band 71, or even with another 80MHz of band 41.
That widened the bandwidth I was using to a total of 200MHz: 40MHz of 4G LTE and 160MHz of 5G. That’s far more than AT&T and Verizon have available to them outside of their very limited millimeter-wave 5G coverage, even with C-band.
I’m getting these details because I’m running Ookla’s new Wind software, which gives highly detailed data on cellular connections. (Note: Ookla is owned by Ziff Davis, PCMag.com’s parent company.)
Here’s where I saw T-Mobile’s 5G carrier aggregation in Brooklyn.
(Image: Sascha Segan)
Room to Grow
The average speeds I saw with 5G CA—340Mbps down and 82Mbps up—weren’t any better than I got with regular “ultra-capacity” 5G. My 5G CA speeds peaked at 425Mbps down; I had just gotten a regular UC speed of 642Mbps a few minutes before.
Looking at how my traffic divided between frequencies, I found that some of my transmissions didn’t send any data over the second carrier. Two speed tests sent a little bit of data over the second carrier.
That might be the usual configuration issues, but it might also just be the fact that my tests weren’t even saturating the first 5G channel; I’m pretty sure my speed was being limited by the capacity of the tower, not of the airwaves.
In other words, the second channel was just hanging out in case I needed it. I didn’t; that’s cool. Freezing cold, actually—it was 15 degrees and there was no one out on the streets. On a busy summer’s day with the streets full of life, there might have been enough phones uploading to Instagram to need that second channel.
All of this just confirms that T-Mobile’s UC network has room to grow—and if the carrier can build it, it’ll be able to match or beat AT&T’s and Verizon’s performance over the next few years.
These two charts show how many megahertz of spectrum the LTE and 5G networks were using. Where the LTE line is missing, it was a standalone, 5G-only connection.
(Images: Sascha Segan)
It’s About Range
Using 200MHz of spectrum, with two band 41 channels, gives T-Mobile room to expand in terms of capacity. It’ll let the company offer home internet service to more people, for instance.
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But I’ve mostly heard NR CA described in terms of improving range. By combining low-band 600MHz (band 71) 5G with mid-band “ultra capacity” 5G, T-Mobile should be able to stretch its high-speed 5G range farther, and have it handle going indoors better.
Ironically, it’s very difficult to test T-Mobile’s range in New York City because the carrier has so many sites here. There’s a T-Mobile cell site every few blocks, which means the sites aren’t operating at their maximum volume; they’re being good neighbors rather than trying to shout to faraway phones.
T-Mobile’s 5G covers the areas I tested very well, so I couldn’t see any range advantage that the NR CA gave me. It’ll be more useful in suburbs and exurbs where T-Mobile doesn’t have as many towers.
The Competition Continues
There’s going to be a lot of change in 5G this year. AT&T’s and Verizon’s networks will get faster for people in 46 cities, with the new C-band. T-Mobile’s network will be able to cover more area, and penetrate better indoors, with NR CA. Later in the year, AT&T and T-Mobile will get another boost with the new 3.45GHz airwaves they just purchased, and Dish might even launch its own network.
We’ll keep covering it all here, so make sure to check back for more 5G news.
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