5G: THE GREATEST SHOW ON EARTH!

Throw the Switch! A benchmark study of UL Transmit Switching along with a Smorgasbord of other 5G Uplink Features

07/23/2025 | 58 pages
Price: $1,995.00

SRG just completed its 52nd 5G benchmark study. For this endeavor we collaborated with Accuver Americas and Spirent Communications to conduct a benchmark study of Uplink Transmit Switching (UL Tx Switching) and how it performs relative to FDD-TDD CA. We also included UL-MIMO (FDD and TDD) as well as higher power class amplifiers (PC1.5 in TDD and PC2 in FDD). We tested in T-Mobile’s network north of Seattle where Nokia is the infrastructure supplier.

Highlights of the Report include the following:

Our Thanks. We did this study with the support of Accuver Americas and Spirent Communications. Accuver provided us with its XCAL5 drive test software and XCAP post-processing software. We used XCAL5 to collect the chipset diagnostic messages and we used XCAP for the post processing of the data and subsequent analysis. We used Umetrix Data from Spirent Communications to generate the high bandwidth data transfers. Both companies have been trusted partners with us for nearly two decades. SRG is responsible for all analysis and commentary provided in this report.

The Background. UL Tx switching is a critical feature that builds on top of FDD-TDD CA to further enhance uplink performance. T-Mobile provided us with the location of cell sites that supported UL Tx switching. All other uplink features that we tested were commercially available at all the sites in the market. We used two Motorola razr Ultra 2025 smartphones, a Galaxy S25 Ultra and a Galaxy S25 smartphone as part of the study.

The Methodology. We had the ability to lock all smartphones to any 5G band combination (Band n41, Band n71 and Band n25). With the Motorola smartphones we also had the ability to enable / disable all features that we tested. We did drive tests and stationary tests to cover the full range of radio conditions. We compared UL Tx switching versus FDD-TDD CA, UL-MIMO versus UL SISO (FDD and TDD), as well as the relative impact of PC1.5 (Band n41) and PC2 (Band n25) on uplink performance.

The Analysis. We analyzed multiple uplink metrics, including PUSCH throughput, Mbps/RB, MCS, UL-MIMO, RB allocations, and PUSCH/SRS transmit power. We looked at cumulative data as well as relative to RSRP.

The Results. We observed meaningful gains in uplink throughput with UL Tx switching versus FDD-TDD CA. The gains were driven by the ability of the smartphones to leverage UL-MIMO in the TDD band when the TDD band was supporting uplink data traffic. UL-MIMO continues to significantly outperform SISO (single layer) with PC1.5 and PC2 helping to further improve the performance of UL-MIMO and edge-of-cell performance.

What Happens Next? UL-MIMO (FDD and TDD) will become a key/mandatory feature in 5G smartphones – it is just too compelling to exclude. UL Tx switching will also become mainstream with higher power class amplifiers helping to further enhance performance. Most of these features are contingent on operators first deploying 5G SA.