Research On Precoding Technologies For Multiuser MIMO System

Multi-input multi-output (MIMO) system, a system implemented with multiple transmit antennas and multiple receive antennas, which can exponentially increase wireless channel capacity without extra frequency band and transmit power, is proved to be a key technique in wireless communication system. Multiuser MIMO precoding is an important technique in MIMO system, which is developed to eliminate the multiuser interference (MUI), decrease the bit error rate (BER) or increase the capacity through processing at the transmitter.This dissertation researches on the precoding technologies for multiuser MIMO system through three aspects of linear precoding, nonlinear precoding and the combination of them. Firstly, the linear, nonlinear and the combining system model are constructed, on which some classical precoding schemes are studied. Secondly, based on the concept of SLNR (signal-to-leakage-and-noise ratio), an iterative SLNR algorithm suitable for any antenna configuration is proposed. With the conventional matrix decomposition replaced by Schmidt Orthogonalization method, a CO (channel orthogonalization) algorithm and its improved algorithm CON (CO with Noise) are proposed latter. Then, to eliminate the residual interference in CO, the combination of CO and THP (CO-THP) is proposed. Finally, simulation results are given to compare the proposed algorithms with the other algorithms in the literature to verify their effectiveness.