Beam combination scheme for multi-user massive MIMO systems

• Published in: Electronics letters 2017-07, Vol.53 (14), p.966-968
• Main Authors: Zhang, Fangchao, Sun, Shaohui, Gao, Qiubin
• Format: Article
• Language: English
• Subjects: array signal processing; base station; beam combination scheme; beam selection principle; beamforming vector; channel estimation; channel state information; CSI acquisition scheme; downlink channel estimation; frequency division duplexing systems; frequency division multiplexing; massive MIMO systems; massive multiple‐input multiple‐output systems; MIMO communication; multiuser channels; multiuser interference; subband combination coefficients acquisition; uplink CSI feedback; user equipments; wideband beam group construction; Wireless communications
• ISSN: 0013-5194; 1350-911X; 1350-911X
• DOI: 10.1049/el.2016.4704

Channel state information (CSI) at the base station (BS) is crucial to fully exploit the advantages of massive multiple-input multiple-output (MIMO) systems. In frequency division duplexing systems, CSI is obtained through downlink channel estimation and uplink CSI feedback. The conventional CSI acquisition scheme, which has been designed based on the beam selection principle, suffers from severe multi-user interference when same beamforming vector is selected for different user equipments (UEs), and the spatial richness of the channel cannot be captured by the selected beamforming vector for the rich scattering environment. To address such issues, a beam combination scheme is proposed by combining multiple selected beamforming vectors for each UE, where the beam combination process is divided into wideband beam group construction and subband combination coefficients acquisition. Simulation results demonstrate that the proposed scheme could achieve considerable increase in the system throughput while maintaining acceptable feedback overhead.