5G massive MIMO, Gangnam-style: SRG puts Samsung radios to the test in Seoul
One of the defining characteristics of 5G networks has been the integration of massive multiple-input-multiple-output (MIMO) radios into the macro network, in order to increase spectral efficiency and provide faster throughput in spectrum from the midband on up.
MIMO systems have shifted from simple two-transmit, two-receive (2T2R) systems to an increasing number of elements. Signals Research Group recently took the opportunity after the close of 3GPP’s meeting in Seoul, South Korea, to do some comparative testing of MIMO systems in the form of 32T32R and 64T64R radios from Samsung Networks in Korea Telecom’s 5G Standalone network.
SRG wanted to know whether there were performance differences between the 64-element radio and a 32-element radio, and what any gains would look like. KT is in the process of migrating its 5G SA network from 32T32R to 64T64R radios, and its network in the Gangnam district of Seoul offered the chance to drive-test both radios in an apples-to-apples, urban scenario. Clearly the carrier sees the upgrade as investment-worthy—and the SRG testing shows why.
“We easily identified an obvious gain in downlink performance with the 64T64R radios,” SRG reported, going on to say that “there was a clear double-digit percentage gain with the use of more antenna elements.”
On an intriguing note, SRG also found that the relative performance gain for the 64T64R radios increased as network loading increased. The gains were “far more obvious during the midafternoon drive tests than the nighttime drive tests,” the benchmarking and analysis firm concluded.
“From an operator’s perspective, the performance gains translate into higher spectral efficiency, meaning the ability to support more voice and data traffic. This outcome was also very evident in the results we analyzed,” SRG said.
SRG also found that the relative gains increased with distances further away from the cell site.
Early last year, SRG had also benchmarked Samsung Networks’ 64T64R massive MIMO radios in Verizon’s network. Read more details from that testing here.
For SRG, the Seoul testing was also a chance for reflection on how far the 5G ecosystem has come, given that it had tested the same area of the city in 2019, back when 5G was first emerging and, of course, pre-Covid-19. That testing was plagued with link failures due to overheating handsets, and LTE was the anchor carrier because 5G SA networks simply didn’t exist at the time.
This time? No overheating smartphones, and SRG said that “the 5G data speeds stomped all over what we obtained back in 2019,” when LTE was frequently faster than 5G. 5G uplink speeds were “rarely” below 75 Mbps and downlink speeds exceeded 1 Gbps more than 50% of the time, according to SRG’s summary of its testing. And it wasn’t due to an increase in available bandwidth, SRG noted—each Korean operator uses (then and now) one 100-megahertz channel of 3.5 GHz for their 5G traffic. But the downlink speeds achieved in 2025 were 3x faster than what SRG saw in 2019, with a delta that SRG called “startling to say the least.”
“The only thing that has changed is the maturity of the 5G ecosystem on the part of the operator, network infrastructure, device and chipset,” SRG said.
SRG used a Galaxy S23 Ultra smartphone for the testing, plus logging and analysis tools from Accuver. The testing was conducted in mid-March, before KT implemented MIMO in the uplink—a whole other side of performance improvements that KT is in the process of rolling out.
Read more details from SRG here.
