Position-aware Uplink Beamwidth Adjustment Scheme of Massive MIMO for High-Speed Railway Communications

Massive multiple-input multiple-output (MIMO) technology is one of the candidate technologies for the future communication systems which can improve data transmission rate and increase link reliability by configuring a large number of antennas on the base station (BS). But it will cause inter-beam interference. Using the beamforming technology can reduce inter-beam interference and further improve the performance of the communication system. Massive MIMO can narrow the beamwidth and obtain high beam directivity. However, narrowing the beamwidth will reduce the effective beamforming probability. Therefore, it is necessary to select the appropriate beamwidth to transmit information. In this paper, an optimal position-aware beamwidth adjustment strategy is proposed for HSR communications. We consider the relationship between beamwidth and beam directivity under the condition of certain position error. And an optimal beamwidth expression is presented by maximize the beam directivity under the condition of guaranteeing quality of service (QoS). The simulation results show that the proposed scheme can reduce the computational complexity and improve the total service capacity.