Interference-Nulling Time-Reversal Beamforming for mm-Wave Massive MIMO Systems

We present a novel beamforming technique for multi-user frequency-selective indoor channels called interference-nulling time-reversal (INTR). The beamformer is implemented with a pre-filter designed to minimize the inter-user interference present in conventional time-reversal (TR). Moreover, our technique relies on a large number of antennas at the transmitter to mitigate inter-symbol interference, enabling low computational complexity receivers. We demonstrate that INTR outperforms previous TR techniques with respect to average bit error rate per user and achievable sum rate. Thus, INTR can be used for space division multiple access in no-line-of-sight mm-wave massive MIMO, providing remarkable diversity and multiplexing gains.