Sprint's 5G Gives T-Mobile a Major Boost

T-Mobile's use of Sprint 5G airwaves in Philadelphia has led to a doubling of speeds on the carrier's network there, according to a new report from Ookla Speedtest's Milan Milanovic.

The company's activation of 2.5GHz 5G in Philly led average 5G speeds to rise from 60Mbps to 120Mbps, the report says. T-Mobile's smaller 5G rollout in New York City, which only affects small parts of the city, led to a 25 percent rise in speeds, from 79Mbps to 99Mbps.

T-Mobile is making 47 percent better use of the spectrum than Sprint did, the report says. While Sprint was able to show 367Mbps downloads using 40MHz of spectrum, T-Mobile transmits 541Mbps on the same airwaves.

5G appears to get more efficient as the channel sizes grow. This is an advantage for carriers that have bigger-than-50MHz channels, like T-Mobile in 2.5GHz or Verizon in mmWave, and a disadvantage for carriers using narrow channels, like AT&T's and T-Mobile's low-band systems. By increasing from 40MHz to 60MHz, the system also gets more bits per hertz, the report shows.

Milanovic attributes T-Mobile's better performance compared to Sprint to more advanced 256QAM encoding, better use of 3x3 and 4x4 MIMO, and possibly the radios not having to split duties between 4G and 5G on 2.5GHz, as T-Mobile doesn't intend to run any 4G at that frequency.

We're Still Not Sure What's Up With mmWave

What the heck is T-Mobile's millimeter-wave strategy? The company has left it extremely unclear. T-Mobile launched six millimeter-wave cities last year and hasn't expanded much since then. It refers to millimeter-wave as the smallest part of its "layer cake," but as Milanovic notes, it has bought up more than a GHz of millimeter-wave spectrum nationwide.

T-Mobile's New York network "is one of the most impressive in the world" in terms of coverage, although its 100MHz of spectrum only delivers up to 520Mbps of speed, less than AT&T and Verizon are doing with their much bigger spectrum allotments.

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T-Mobile Busts Gigabit Barrier With Mid-Band New York City 5G

Mid-band 5G technology is more advanced and more efficient than mmWave right now, Milanovic notes, pointing out that T-Mobile can get the same speeds on 40MHz of mid-band that it does with 100MHz of mmWave. That's because mid-band supports 256QAM encoding and 4x4 MIMO, while mmWave devices don't currently support those efficiency features.

Milanovic has much more detail on T-Mobile's new network performance in his full report.

Disclosure: Ookla is owned by PCMag's parent company, Ziff Davis.