Low complexity hybrid beamforming and precoding for 2D planar antenna array mmWave systems

The massive multiple-input multiple-output (MIMO) system utilizes a large number of antennas to enhance the throughput and reliability of 5G systems. Millimeter wave (mmWave) system is one of the important massive MIMO systems because its small wavelength allows the tightly package of large antenna array. This paper presents a low-complexity algorithm that can jointly determine the RF beamforming array vector and baseband precoding matrix for 2D planar antenna array in mmWave systems. The proposed antenna selection before the beamforming can reduce the dimension of the baseband precoding matrix. This study also proposes a sliding-window-based index selection for RF beamforming array vector. This index selection scheme not only reduces the baseband complexity but also enable highly paralleled hardware architecture. The antenna selection technique can reduce about 93% complexity of the SVD computation and the proposed precoding algorithm can reduce about 20-26% complexity of the previous work in a 16×8 2D planar antenna array MIMO systems.