Impact of Reconfigurable Antennas on MU-MIMO Over Measurements in a Reverberation Chamber

While the theoretical multiplexing gains of multiuser (MU) MIMO are substantial, the performance gains in practical systems such as IEEE 802.11ac and LTE/LTE-Advanced have been limited. One of the key limiting factors are spatially correlated user channels. In this paper, we evaluate the impact of pattern reconfigurable antennas (PRA) on downlink MU-MIMO transmission. PRAs are capable of dynamically adjusting their radiation pattern, providing an additional degree of freedom that can be leveraged to improve MU-MIMO performance by treating the array configuration and radiation characteristics as additional components in the joint optimization of adaptive system parameters. We conduct measurements in a statistically repeatable environment and demonstrate the gains provided by pattern diversity in decorrelating user channels. Our experimental results show significant gains in SINR and achievable sum rates of MU-MIMO linear precoders when appropriate directional beams are used to decorrelate the channel matrices and provide directional gain.