Lattice-reduction aided Successive Optimization Tomlinson-Harashima Precoding strategies for physical-layer security in wireless networks

In this paper, we investigate precoding techniques for physical-layer security in multi-user MIMO systems under various conditions of channel state information (CSI). A Lattice Reduction (LR) aided non-linear precoding technique based on Successive Optimization Tomlinson-Harashima Precoding (SO-THP) and Simplified Generalized Matrix Inversion (S-GMI) technique is proposed along with a strategy for injecting artificial noise prior to transmission. Simulation results show that the proposed LR-SO-THP+S-GMI precoding technique outperforms existing non-linear and linear precoding algorithms in terms of BER and secrecy rate performances.