Transmit Beam Selection Scheme for Massive MIMO Using Expected Beam Responses

Yoshihito KUBO  Yukitoshi SANADA  

IEICE TRANSACTIONS on Communications   Vol.E102-B   No.4   pp.913-920
Publication Date: 2019/04/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2018EBP3086
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
5G,  massive MIMO,  beamforming,  transmit beam selection,  

Full Text: PDF(1.5MB)>>
Buy this Article

Massive multiple-input multiple-output (MIMO) realizes simultaneous transmission to a large number of mobile stations (MSs) and improves frequency utilization efficiency. It is drawing attention as the key technology of the fifth-generation (5G) mobile communication systems. The 5G system is going to be implemented in a high frequency band and massive MIMO beamforming (BF) is applied to compensate propagation loss. In the conventional BF scheme, a transmit beam is selected based on the power of received signals over subcarriers. The signal on a different subcarrier is transmitted with a different directivity. To improve the accuracy of beam selection, this paper proposes a transmit beam selection scheme for massive MIMO. The proposed scheme calculates the expected responses of the signals over the subcarriers based on the relative directivity between a base station (BS) and a MS. The MS calculates the correlation between the received signals and each of the expected response sequences. It then selects the beam with the highest correlation value. It is shown in this paper that the proposed scheme can improve the average signal-to-noise ratio of a received signal by about 1.5dB as compared with that of the power based search scheme. It is also shown that the proposed scheme with limited response coefficients can reduce the computational complexity by a factor of 1/100 while it still increases the average SNR by about 1.0dB.