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5G

Sluggish lowband 5G from AT&T, T-Mobile raises the question: Why bother?

A new report from Signals Research Group offers a very clear and detailed look at the decidedly mediocre performance of lowband 5G from AT&T and T-Mobile.

"To summarize, LTE network performance was at least as good as if not better than 5G NR @ 850MHz," the analyst firm wrote of AT&T's lowband 5G network in Indianapolis, Ind. The firm conducted extensive tests of both operators' 5G and LTE networks in two different cities using professional RF testing equipment from Rohde & Schwarz. Such results are mostly impossible to obtain from standard, consumer-focused network testing apps like Ookla's Speedtest or OpenSignal.

The firm found the current performance of 5G in lowband spectrum so uninspiring that it raised the obvious question: Why not just stick with LTE?

"After all, the 5G NR lowband coverage is no better than LTE in Band 2 or Band 66, the upgrade cost is higher than LTE, the performance gains are nominal, the smartphones are more expensive," the firm wrote, explaining that today's "non-standalone" 5G networks cannot work without an "anchor" channel in an LTE band like 2 or 66. Most US operators hope to move to "standalone" 5G in the coming months in order to sidestep that problem.

Unimpressive results
To underscore its argument, Signals Research Group reported that AT&T's lowband 5G accounted for just 7.8% of the operator's total network throughput in Indianapolis. Specifically, the firm's Rohde & Schwarz testing equipment found AT&T's median 5G NR speeds were just 19 Mbit/s, compared with 108 Mbit/s for LTE. (It's important to note that most 5G transmissions today actually involve a mix of 5G and LTE connections.)

The reason for the poor results, the firm explained, is because AT&T has so far only deployed 5G NR in just 5MHz of spectrum in its 850MHz holdings in Indianapolis. LTE, meantime, stretches across more than 100MHz of AT&T spectrum holdings in the city ranging from the 700MHz band to the 2300MHz band, and that total doesn't even include the 60MHz of unlicensed spectrum AT&T is using in the city via LAA (licence assisted access). (Wireless network speeds are often directly related to the amount of spectrum a carrier is using for its transmissions.)

"We observed a peak data rate of 494Mbit/s during our drive tests, due entirely to LTE since 5G NR was not active at the time," the firm said.

It's worth noting that both AT&T and T-Mobile have downplayed the speeds customers should expect on initial lowband 5G deployments.

5G is the future
The reason AT&T, T-Mobile and others are moving to 5G is because LTE is a mature technology while 5G is in its infancy, the firm explained. These initial lowband 5G networks from AT&T and T-Mobile represent just a first, tentative step on a long 5G journey that ought to take each of the operators years to complete, and should eventually include a wide range of technologies like edge computing and spectrum bands like the C-Band.

"There isn't a valid argument for why everyone would not be better off right now with an LTE-only strategy. However, this view is a bit short-sighted since it ignores the 5G NR migration path," the firm wrote. "Operators will eventually be able to leverage the SA (standalone) network architecture, meaning they will be able to take full advantage of the RF propagation characteristics of the low frequency spectrum allocations. Additionally, with SA and 5G NR, operators will be able to offer true 5G NR services that benefit from low latency and/or high reliability."

The firm added that, as 5G technology improves, operators will be able to use a technology called "carrier aggregation" to essentially glue together 5G transmissions across various spectrum bands.

"A lowband 5G NR channel could, for example, be paired with millimeter wave, thereby improving the millimeter wave coverage by moving the control channel... to the lowband," the firm explained in its report. "This strategy would also allow the operator to dedicate the entire millimeter wave TDD channel to the downlink, which would improve downlink data speeds. The uplink traffic would go over the low-band or midband 5G NR channels."

Finally, the analysts at Signals Research Group explained that AT&T is replacing aging UMTS hardware with its new lowband 5G network. "AT&T needs to replace this equipment anyway so it might as well deploy 5G NR," the firm noted.

Future expansions
Both AT&T and T-Mobile are working to expand their 5G networks across the nation using lowband spectrum. For example, AT&T just this week announced 13 more cities with lowband 5G, bringing its total number of states covered with the technology to 25. Both operators are also working to expand their 5G networks using highband, millimeter wave (mmWave) spectrum in parts of some big cities.

Verizon too is widely expected to expand its 5G network to its lowband holdings; the operator so far has focused its energies on its mmWave 5G network.

Sprint meantime covers 16 million people across nine cities with its midband 5G offering.

All of the operators have promised to expand 5G offerings into additional locations and spectrum bands in the future, actions that will likely raise 5G speeds and performance.

Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano

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