Signals Flash!

Signals Flash!

Stop the Presses: MU-MIMO

09/27/2022 | 20 pages

SRG did some preliminary testing of MU-MIMO, based on testing that we did in the Verizon Band n77 network in the western suburbs of Minneapolis. Although the contents of this report do not reflect a full-fledged benchmark study, they do show that MU-MIMO is alive and well, and potentially heading to a 5G network near you soon

Our Thanks.  We did this study with the support of Accuver Americas (XCAL-M, XCAL-Solo and XCAP) and Spirent Communications (Umetrix Data). SRG is fully responsible for the data collection and all analysis and commentary provided in this report.

The Background.  While collecting data for a forthcoming Signals Ahead report that benchmarks multiple phones and chipsets (Qualcomm, MediaTek and Samsung) in 5G FR1 (sub 6 GHz) and FR2 (mmWave), we came across some performance characteristics that resembled MU-MIMO. After confirming its presence, we shifted gears and collected some preliminary data that we are sharing in this Signals Flash report.

Our Testing Methodology.  We leveraged [only] two Galaxy S22 smartphones – one phone was stationary in our test vehicle while we used XCAL-Solo to walk around the cell sector. We used Umetrix Data to generate full buffer downlink data transfers.

Our Data Analysis.  We looked at PDSCH resource block utilization, downlink MIMO layers, MCS values, CQI reports and total throughput. With perfect MU-MIMO pairing mobile devices should use the maximum number of resource blocks (no sharing) and retain the use of all MIMO layers with little or no impact to MCS / CQI reports, meaning an effective doubling of sector throughput with two smartphones.

Great Opportunity for Backhaul Expansion.  Although all results looked very promising, we were hampered by the lack of sufficient backhaul to see a benefit in total throughput. The upside is that there is an obvious opportunity for backhaul service providers and equipment vendors.

Enhances the FWA Business Case.  At one of the sites where we tested it was located in a very rural area and clearly without any need for additional capacity for mobile broadband. The availability of MU-MIMO at this site reflects the relative ease associated with deploying the technology widespread, plus it significantly increases the business case for fixed wireless access, which involves high bandwidth consumption with stationary devices.