Polynomial Eigen-Beamformer in Time Domain for MIMO-OFDM Systems

Co-space interference (CSI) mitigation is one of the main challenging issues in multiple input multiple output (MIMO) systems. Using beamformer in both transmit and receive sides is an approach to mitigate the CSI. In the MIMO systems employing orthogonal frequency division multiplexing (OFDM) technique, frequency domain or time domain beamforming can be used. In this paper, we propose a new time domain broadband beamforming (TBBF) for MIMO-OFDM systems based on a SVD type of block circular channel matrix. TBBF is attained by polynomial eigen-beamformer when the right and the left polynomial eigenvectors are utilized at the transmitter and the receiver sides, respectively. The new proposed TBBF is able to completely mitigate the CSI due to shaping the multiple beams in orthogonal directions. Performance of the proposed polynomial eigen-based TBBF is evaluated by computer simulations and compared with the previously proposed TBBF scheme based on the SBR2 algorithm. The results show that the proposed time domain beamforming method outperforms the SBR2-based scheme.