- SRG just completed a benchmark study of new 5G uplink features
- We’re talking really new – because the features aren’t prevalent in a lot of handsets outside of China
- Until recently, the uplink in 5G networks has taken a backseat to the downlink
A new study by Signals Research Group (SRG) gives operators more reasons to hasten their transition to 5G standalone (SA) networks. That's because the study shines a light on new 5G SA uplink features that can drastically improve throughput, coverage and/or spectral efficiency – all big deals when it comes to social media and AI applications.
In the study, SRG focused on features that amplify the uplink data transfer. Usually, it’s the downlink that gets all the attention and rightfully so, because the majority of mobile data traffic resides in the downlink.
However, “the times, they are a changin’,” wrote SRG President Michael Thelander, quoting a fellow Minnesotan.
Thelander, a 20-year wireless industry veteran who last year famously chronicled how he turned off 5G on his phone, said AI is an oft-cited use case that’s driving interest in the uplink channel. But perhaps a more prevalent driver right now is plain old social media – with or without the AI.
Thelander cites his favorite walleye fisherman who on YouTube is now streaming his adventures from remote lakes in Wisconsin where there isn’t a reliable Wi-Fi hotspot for miles.
“We’re thinking his mobile operator should sponsor him and display their logo on his fishing boat,” Thelander quipped in his latest report.
Infrastructure vendors like Ericsson and Nokia might also want to jump on board. Both of them emphasized the importance of uplink at their recent analyst events, Thelander noted.
UP MIMO requires 5G SA
One of the features that figures prominently in SRG’s report is 5G uplink MIMO, or UL-MIMO. Outside of China, it’s a feature that remains mostly on the sidelines from a device perspective, but it’s now available in bands 1.9 GHz and 2.5 GHz. Like other features SRG tested, UP MIMO shows promise for extending the phone's battery life.
UL-MIMO can double the speed/spectral efficiency of a data session. Like it sounds, it’s very similar to downlink MIMO but in the opposite direction.
“It basically means that over a given radio channel, you’re sending essentially two data streams, so in theory, you can double your capacity,” he told Fierce. “You can get twice the data speeds in an individual phone and you can double the efficiency of your radio channel.”
UL-CA might be easier
The other up-and-coming feature is UL-Carrier Aggregation, or UL-CA, which serves as a nice complement to UL-MIMO, he said.
UL-CA delivers higher throughput by using two uplink channels, and it proves very effective in increasing the uplink data speeds, especially when the smartphone doesn’t support UL-MIMO.
UL-CA might be easier to implement in a device, probably because it’s been done with LTE, he said. UL-CA is somewhat comparable to Evolved Non-standalone Dual Connectivity (EN-DC), which involves a combination of data traffic on a 5G radio bearer and LTE radio bearer.
SRG’s executive summary doesn’t include exact data speeds achieved in the tests. But earlier this year, T-Mobile boasted about the record uplink speed of 345 Mbps it achieved on its 5G SA network using a new feature called UL Tx switching. SRG’s report mentions that feature, which Thelander said is right around the corner but wasn’t available when he conducted his tests.
Testing, testing
SRG’s tests focused on 5G handset features that are designed to improve throughput, coverage and/or spectral efficiency, but generally require a 5G SA network, which are few and far between.
In the U.S., T-Mobile is the sole incumbent wireless operator with a nationwide commercial 5G SA network. Verizon and AT&T are lagging but working toward nationwide 5G SA status. The financially strapped Dish Network also boasts a 5G SA network, albeit with far fewer customers.
So, SRG conducted its tests in early July using T-Mobile’s network in the Seattle area, which uses radio access network (RAN) gear provided by Nokia. The devices– the razr 2024 and razr+ 2024 – were provided by Motorola.
Neither T-Mobile nor Motorola company had any direct involvement in SRG’s tests or analysis, although they were given a heads up just before the July 31 report was published, Thelander said.
Advantages of not being first
The upshot for the other two incumbent U.S. carriers that haven’t yet launched nationwide 5G SA is that by the time they’re ready to introduce these new features, it’s probably going to be a lot easier than it was for T-Mobile, Thelander said.
“All the heavy lifting has been done,” such as interop testing between chipsets and infrastructure, he said. “There was probably a lot of pain that was felt to get to this point,” so when a vendor wants to install UL-CA, for example, the learning curve is much better than it was when T-Mobile started.
All of this begs the question of whether we’re ever going to see handsets more closely aligned to networks. In the past, operators like AT&T and Verizon have said they’re in no hurry to widely deploy 5G SA until there’s a sizable number of compatible devices in customers’ hands that can take advantage of the new features.
“I guess you have to build the house before you put the roof on it,” Thelander said, noting that if you take the most advanced network solution and most advanced chipset, the network in most cases is still going to be ahead of the handsets.