Angle-based beamforming in mmWave massive MIMO systems with low feedback overhead using multi-pattern codebooks

The integration of millimeter-wave (mmWave) communications and massive multiple input multiple output (MIMO) techniques is a promising solution to dramatically increase the 5G network throughput. By using large antenna arrays, beamforming can be adopted to improve the 5G capacity by employing spatial domain resources. In a frequency division duplexing (FDD) based 5G mmWave MIMO system, beamforming operation requires timely downlink channel state information (CSI) feedback. However, the rapid channel variations caused by short wavelength of mmWave band, and the high-level feedback information required due to the large number of antennas in massive MIMO system lead to the significantly increased beamforming overhead. In this paper, by exploiting the higher angular stability of such channels, we propose an angle-based beamforming scheme to reduce the feedback frequency and the number of feedback bits. To facilitate this approach users are initially selected to reduce the intra-zone interference before beamforming. Besides, location related feedback, which is not affected by the number of antennas, is adopted to reduce overhead. The simulation results show that two proposed user selection algorithms can adapt to scenarios with diverse requirements, while the feedback overhead of proposed angle-based beamforming algorithm is sharply reduce compared with that of CSI-based beamforming algorithm.