Understanding real many-antenna MU-MIMO channels

We conducted one of the most comprehensive many-antenna MU-MIMO channel measurement campaigns ever reported. Our measurement system supports full mobility with very high time-frequency resolution. We report channel traces in the UHF, 2.4 GHz, and 5 GHz bands, in diverse environments, with up to 104 base-station antennas serving 8 users. We characterize channel stability and capacity across these bands and environments with varying mobility. Our results show that channels exhibit large capacity fluctuations on the order of milliseconds, even with just pedestrian mobility. However in stationary environments, MU-MIMO channels are long-term stable regardless of frequency, and are only ephemerally affected by environmental mobility. Furthermore, these traces and measurement system are made openly available online, enabling future research on many-antenna wireless systems.