SRG(Signal Research Group) did this study with the support of Accuver Americas (XCAL5 and XCAP). 

They just completed the industry's first independent benchmark study of 8-layer 5G MU-MIMO (Multi-User MIMO) in a commercial network (T-Mobile Band n41) while using a mix of commercial and precommercial devices.

This report contains results and analysis from a single test that we conducted at the T-Mobile facilities in Irvine, CA prior to doing more extensive testing in a number of commercial cell sites.