  In this paper, we propose successive optimization non-linear precoding
strategies for physical-layer security in wireless networks. We also
investigate different precoding techniques for multi-user MIMO systems under
various conditions of channel state information (CSI) between the access point
and the users and the eavesdroppers. A 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 SO-THP+S-GMI precoding technique outperforms
existing non-linear and linear precoding algorithms in terms of BER and secrecy
rate performances.
