Linear Precoding for Channel Orthogonalization with Reduced Restriction about Antenna Assignment in Multiuser MIMO-OFDM

Abstract

In downlink multiuser multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems, a base station (BS) communicates with multiple user terminals (UTs) simultaneously using MIMO transmission. Since UTs each receive signals intended for other UTs in addition to those intended for themselves, they suffer from multiuser interference (MUI). To eliminate MUI, the use of block diagonalization (BD) has been proposed. BD is a scheme of channel inversion that divides a multiuser MIMO channel into multiple single-user MIMO channels by transmitter-side linear precoding. However, BD has two restrictions about the antenna assignment to be able to calculate the precoding weight matrix. In this paper, we propose another linear precoding scheme for MUI elimination. Our proposed scheme is released from one of two restrictions in calculating the precoding weight matrix for MUI elimination. Simulation results show that the proposed scheme and BD achieve the same bit error rate (BER) performance under the same antenna assignment. Furthermore, we can show that the proposed precoding scheme eliminates MUI even under antenna assignments which are impracticable with BD and that the principle of the proposed scheme is applied to uplink multiuser MIMO-OFDM systems.