Lattice-reduction-aided Tomlinson-Harashima precoding based on MMSE criteria in multiuser MIMO downlink system

In this paper, two kinds of lattice-reduction-aided (LRA) Tomlinson-Harashima precoding (THP) will be proposed. THP is a nonlinear precoding technique which uses modulo operation and successive interference cancellation (SIC). Lattice reduction methods have been proved to be powerful tools in solving the closest lattice point search problem. The lattice reduction methods which implement to the THP can improve the performance obviously. The LLL algorithm is a common used method for the lattice reduction, and the lattice reduction that based on LLL algorithm can transform the channel matrix into a more orthogonal one. Simulation results show the proposed schemes significantly outperform the traditional MMSE based THP.