Abstract
Massive multiple-input multiple-output (MIMO) systems operating in the
centimeter-wave (cmWave) and millimeter-wave (mmWave) region offer huge
spectral efficiencies, which enable to satisfy the urgent need for
higher data rates in mobile communication networks. However, the proper
design of those massive MIMO systems first requires a deep understanding
of the underlying wireless propagation channel. Therefore, we present a
fully-digital MIMO measurement system operating around 28 GHz. The
system enables to take fast subsequent snapshots of the complex MIMO
channel matrix. Based on this method we statistically analyze the
time-dependent channel behavior, the achievable signal quality and
spectral efficiency, as well as the channel eigenvalue profile.
Furthermore, the presented calibration approach for the receiver enables
an estimation of the dominant absolute angle of arrival (AoA) and allows
us to draw conclusions about the line-of-sight (LOS) dominance of the
scenario. In total, 159 uplink communication measurements over 20
seconds are conducted in three different small cell site scenarios to
investigate the wireless propagation behavior. The measurements reveal
the existence of several spatial propagation paths between the mobile
transmitter and the base station. Furthermore, an insight into their
likelihood in different propagation scenarios is also given.