T-Mobile clocks 1.2 Gbps in NYC thanks to ‘layer cake’: report

T-Mobile went live with its 5G spectrum “layer cake” in New York City last month and new analysis by Ookla provides some morsels of what performance on the 5G network could look like.

T-Mobile activated the new mid-band frequencies in Philadelphia in April, but NYC is the first market where T-Mobile now has all three of its New Radio (NR) layers: foundational 600 MHz spectrum for broad coverage; mid-band 2.5 GHz for both coverage and speed; and high-band millimeter wave spectrum for faster speeds in small pockets.

“Two weeks of testing T-Mobile’s 5G in New York City delivered an impressive user experience, and it was just an early taste of a 5G layer cake that could continue to improve,” concluded the analysis by Ookla’s Milan Milanovic.

Ookla graph TMobile 5G NYC 2020

Across the three layers in NYC, mean download speeds increased 25% since January, going from 79.18 Mbps to 98.96 Mbps by May 15.

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The analysis shows that T-Mobile’s new 2.5 GHz 5G NR layer is flexing its strength in terms of contribution to download speeds. This calculation carves out the portion of the download speed that that comes only from 5G NR, with LTE contributing the rest of the end-user’s download speed. 

In field tests conducted in the eastern part of Manhattan between May 5 and 19, T-Mobile’s activation of 40 MHz of 2.5 GHz, using Ericsson radio gear, delivered a peak NR downlink of 541 Mbps. To be clear, Milanovic’s report emphasized results only represent a snapshot of T-Mobile’s 5G network potential, as there are presently very few 5G users on the network and tests were done outdoors with good signal conditions.

T-Mobile is also making more efficient use of the coveted mid-band frequencies than the legacy Sprint network did, with Ookla measuring a 47% improvement in spectral efficiency. Peak results on Sprint’s now decommissioned network were 367 Mbps in August 2019, according to the analysis. The results were based on the same amount of spectrum and performed in similar conditions; T-Mobile’s new deployment used Ericsson radio gear, while Sprint originally used Nokia.

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The analysis points to better use of 256 QAM and MIMO by T-Mobile as one possible reason for the improvement.

Spectral efficiency of the 2.5 GHz was also clear compared to T-Mobile’s limited 28 GHz millimeter wave layer, which it deployed in NYC in the summer of 2019. With 100 MHz of 28 GHz spectrum, tests resulted in 5G peak speed contribution above 520 Mbps. That’s fast, but Milanovic wrote: “T-Mobile’s mid-band 2.5 GHz NR layer is able to deliver similar capacity out of just 40 MHz of spectrum.”

The increased efficiency was attributed to the mid-band using four data streams and 256 QAM, which mmWave chipsets aren’t capable of yet.

Wider channels bring benefits

As T-Mobile increased bandwidth at certain sites, 5G speeds increased as well.   

In three locations in New York’s East Village, the report observed T-Mobile increased the amount of 2.5 GHz allocated for 5G from 40 MHz to 60 MHz, after which 5G NR contributed close to 900 Mbps downlink.

When combined with LTE and License Assisted Access (LAA) technology, it resulted in peak speeds of more than 1.2 Gbps, observed on May 19. Again, the tests are meant to show “the full potential” of T-Mobile’s new network deployment, and not likely typical performance.

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The operator’s base 5G layer, using spectrum in the 600 MHz band, also notched improvements after increasing from 5 MHz to 10 MHz in March. With the wider channel, T-Mobile’s 600 MHz delivered 5G peak downlink of about 100 Mbps, up from 42 Mbps previously.

In terms of mmWave, Milanovic noted T-Mobile could tap the full potential of its high-band frequencies by deploying significantly wider channels than its current 100 MHz channel – moving up to 400 MHz or 800 MHz.

“Leveraging the existing macro grid, T-Mobile’s Manhattan mmWave overlay, in terms of cell site density, is one of the most impressive in the world,” wrote Milanovic.

T-Mobile controls 1,160 MHz of millimeter wave spectrum across the U.S, Ookla noted. The operator previously scooped up 24 GHz spectrum and at the most recent FCC mmWave auction won licenses in the 39 GHz and 47 GHz band. It's unclear when 47 GHz might be deployed, as there still isn't infrastructure or device support for that band. 

In May, T-Mobile asked the FCC for Special Temporary Authority (STA) to test base stations and handsets using 39 GHz spectrum it won in markets including Dallas/Fort Worth, Texas; and Irvine and San Diego, California. The operator needs permission because the FCC still has to process applications related to the auction spectrum purchases, which is expected to take several months.