Block diagonalization using FFT beams at user terminal for implicit beamforming

Multiuser MIMO (MU-MIMO) improves the system channel capacity by employing the transmission between a base station (BS) and multiple user terminals (UTs). Block Diagonalization (BD) has been proposed as a practical algorithm in MU-MIMO broadcast channel. However, when the number of transmit antennas is equals to the total number of received antennas, the transmission rate by the BD algorithm is decreased. In this paper, FFT based orthogonal beam selection method at the UT, in order to apply the implicit beamforming (IBF) which can eliminate the channel state information (CSI) feedback from the UT to BS. Moreover, the BER performance is compared by the proposed method and conventional BD algorithm.