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Test & Measurement

T-Mobile's standalone 5G proves sporadic in initial tests

While most of the US tech press was digesting the latest 5G gadgets from Samsung this week, a few dedicated wireless industry observers were setting their sights on another major technological unveiling: T-Mobile's standalone 5G network, one of the very first such commercial networks in the world.

Indeed, Mike Thelander of Signals Research Group said he specifically bought a new Samsung Galaxy S20 Ultra this week in order to test out the new network.

And after unwrapping his shiny new device, downloading the software update to enable T-Mobile's standalone 5G connection, "I was up and running," Thelander said. (Thelander, a longtime wireless analyst with deep networking experience, also connected his new phone to wireless testing equipment from Accuver Americas and Spirent in order to properly evaluate T-Mobile's network.)

And what did Thelander discover during a day of network testing in Minnesota?

"The S20 Ultra would frequently fall back to non-standalone mode," he said. "The phone is not staying in standalone mode."

Thus, any benefits Thelander might have derived from T-Mobile's new standalone 5G offering "are hard to achieve," he said dryly.

Thelander said he conducted a series of detailed network assessments, including stationary tests and a drive test, and discovered that the phone spent virtually no time connected to standalone (SA) 5G. Instead, it spent the vast majority of time connected to the non-standalone (NSA) 5G network T-Mobile launched at the end of last year.

He said he was able to push the phone back into SA 5G by switching it in and out of airplane mode, but said that it would quickly drop into NSA mode afterward. "I don't know what causes it to stay in SA mode," he said.

Interestingly, Thelander said that he spoke with T-Mobile engineers about the situation after he conducted his tests. He said they explained that the company is specifically pushing its 5G phones off of SA mode and into NSA mode in areas where it operates offers speedy and reliable 4G LTE connections. However, Thelander said that, in his tests, T-Mobile's 5G phones didn't necessarily exactly align with those parameters – for example, he said his tests showed a 5G phone retaining a SA connection even in an area where the operator's 4G LTE network was stout. He attributed the situation to the fact that the network is relatively new and still requires tweaking and modification.

Quick connection
However, Thelander said that, in the relatively limited amount of results he derived from his tests of the Samsung Galaxy S20 Ultra when it was connected to standalone 5G, he found a significant reduction in the amount of time the phone spent connecting to T-Mobile's 5G signal. He explained that, in the 5G testing conducted by Signals Research Group, the firm has found that non-standalone 5G requires a lengthy setup time in order to establish a 5G connection. T-Mobile's standalone 5G, on the other hand, establishes a connection much more quickly.

Thelander cautioned that his testing only includes the results from one location on one day. Depending on the configuration of T-Mobile's network, its spectrum resources, the equipment vendors involved and the location of a customer and the device they are using, the results could be much different. And it's likely a temporary issue anyway – the networking equivalent to breaking the window on the new truck you're unveiling.

Nonetheless, Thelander's tests offer a very first glimpse at what most in the industry agree is the future of 5G. After all, the NSA version of 5G was in part designed to allow existing 4G LTE operators to more quickly launch 5G services. Indeed, the NSA version of 5G requires a concurrent 4G LTE network connection to handle things like authentication.

A step toward 'pure' 5G
Standalone 5G, on the other hand, is viewed as "pure" 5G that needs no other connection and can support advanced technologies like network slicing. That's partly why operators ranging from Verizon to Vodafone are racing to launch SA 5G.

T-Mobile's launch of standalone 5G is noteworthy considering the 3GPP – the global technology standards association charged with developing 5G – released the final specifications for standalone 5G just last month.

Finally, it's worth noting that T-Mobile's engineers are undoubtedly working to tweak the operator's network around the country on a daily if not hourly basis. For example, Thelander said that, in Minnesota, the operator launched 5G in its 600MHz spectrum band with 10MHz, but recently increased that allocation to 15MHz. Such tweaks likely reflect T-Mobile's efforts to increase the amount of spectrum devoted to 5G in order to improve customers' 5G experience.

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

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