Millimeter wave beamforming for multiuser dual-polarized MIMO systems

Fifth generation wireless communication systems can achieve massive throughput increases from multi-user, multiple-input multiple-output systems combined with the emerging use of millimeter wavelengths in small heterogeneous cells. In this paper, we propose a beamforming algorithm for an outdoor millimeter wave, multiuser network, which exploits polarization diversity. First, we propose an adaptive channel sampling algorithm that estimates the beam-alignment vectors for multiple users. The proposed subspace sampling algorithm reduces the beam search time by sounding the channels for multiple users in parallel. With the beam-alignment vectors, we propose an algorithm for jointly estimating the optimal beamformers and combiners that minimize inter-user interference among serviced users while increasing the sum-rate of the system.