- Signals Research Group (SRG) visited T-Mobile’s headquarters in the middle of the night
- The goal was to test some of Nokia’s pre-commercial 5G features when commercial traffic on T-Mobile's network was low
- Tests showed meaningful double-digit throughput gains and better spectral efficiency by reducing interference between nearby smartphones in a 5G TDD network
Signals Research Group (SRG) likes to joke that it went all “Sleepless in Seattle” for its 60th benchmark study, testing Nokia’s technology in the middle of the night near T-Mobile’s campus in Bellevue, Washington.
Missing a good night’s rest was well worth it, according to SRG Research President Michael Thelander. He and SRG Technology VP Emil Olbrich used the wee hours of a night in late April to test multi-user MIMO (MU-MIMO) and single-user MIMO (SU-MIMO) with Nokia’s zero forcing technology. Zero forcing isn't new, but it's new in this 5G Advanced implementation.
T-Mobile was sort of an instigator in all of this, as it was the one that tipped Thelander off that it has this technology working on a pre-commercial basis. The carrier assigned two teams of T-Mobile engineers to help SRG collect the data and provide network support during the tests.
However, Thelander said T-Mobile had no influence on where or how they conducted the tests.
SRG Research gave a short pre-brief to T-Mobile prior to publishing its report last week, but otherwise, SRG had sole responsibility for analyzing the data and providing commentary on the results, he told Fierce.
Thelander shared photos of the set-up shortly after conducting the tests. The report is available via SRG’s website or through this post on LinkedIn.
T-Mobile’s throughput increase
Simply put, the results show that T-Mobile is getting significant benefits from the additional Nokia technology. Who would’ve thought?
Well, SRG wanted to see it for themselves, so they ended up testing four different network configurations using four Samsung Galaxy S25 Ultra devices: SU-MIMO (legacy), MU-MIMO (legacy), MU-MIMO with zero forcing and SU-MIMO with sub-band beamforming. The latter feature is an inherent part of the zero forcing capability, but with MU-MIMO pairing disabled, according to Thelander.
“What that means is it allows multi-user MIMO to work better in a 5G network by minimizing interference that can occur with smartphones that are located in proximity to each other. That’s kind of the big thing here. It's basically improving downlink performance in a 5G TDD network,” he said.
Specifically, MU-MIMO with zero forcing cancels out inter-user interference, meaning MU-MIMO performs much better than the legacy implementation, especially when smartphones are close to one another.
“The ‘aha’ moments are that when we tested with these new features, we saw improvements in throughput for all the smartphones,” he said. “There was a meaningful double-digit increase in total throughput, which also means increased spectral efficiency,” translating into the network being able to support more downlink data traffic.
Typically, SRG saves a lot of the juicy details for subscribers who buy its full reports, but Fierce asked if Thelander could give any hints as to the “double-digit percentage gains” they documented.
“I would say generally, at a minimum, it’s greater than 20 [percent], and that’s comparing SU-MIMO to SU-MIMO or MU-MIMO to MU-MIMO,” he said. However, if you compare the legacy SU-MIMO to the enhanced multi-user MIMO, it’s even greater than that.
Thelander saw this technology when he did a Nokia booth tour during Mobile World Congress 2026 in Barcelona this past March. However, SRG had no interaction with Nokia until after they had done their testing.
“We did have a call with the vendor prior to releasing this report since we had some questions regarding their solution that we felt they could best answer,” SRG said in an executive summary of its report.
Again, the features are not yet commercial in the T-Mobile network, but “we expect they will be commercial later this year,” SRG said. “We also understand that the Nokia roadmap will include future enhancements to sub-band beamforming, MU-MIMO and Sound Referencing Signals (SRS), which will both improve performance while also increasing the effective coverage area of the capabilities.”
The SRG test results are well aligned with T-Mobile’s internal test results of this 5G Advanced technology, according to a T-Mobile spokesperson, who confirmed T-Mobile will deploy this technology in areas with compatible Nokia infrastructure. A timeline wasn’t provided.
It’s all Nokia
It’s worth noting that the features are specific to Nokia; T-Mobile is the only one of the three big U.S. carriers using Nokia infrastructure in its 5G network.
SRG has tested MU-MIMO on Ericsson and Samsung equipment. However, “I really can’t compare the best of Nokia to the best of Samsung and Ericsson because there’s so many variables in the test set-up and everything that it’s hard to say what’s best,” Thelander said.
Bottom line: “If you have Nokia in your network, this is kind of a no-brainer upgrade,” he concluded. “It’s pretty meaningful in terms of the performance gains you can get.”