Tight Lower Bounds on Achievable Information Rates for Regularized Tomlinson-Harashima Precoding in Multi-User MIMO Systems

Tomlinson-Harashima precoding (THP) is considered to be a prominent precoding scheme due to its ability to efficiently cancel out the known interference at the transmitter side. Therefore, the information rates achieved by THP are superior to those achieved by conventional linear precoding schemes. In this paper, new lower bounds on the achievable information rates for the regularized THP scheme are derived. Analytical results show that the lower bounds derived in this paper are tighter than the original lower bounds particularly for the low SNR range, while all lower bounds converge to $\\log _{2}(t)-\\log _{2}\\sqrt{2\\pi e}\\sigma$ as SNR → ∞.