On spatio-temporal Tomlinson Harashima Precoding in IIR channels: MMSE solution, properties, and fast computation

We consider spatio-temporal Tomlinson Harashima Precoding where the feedforward filter is located at the transmitter and an additional scalar gain is employed as receive filter. In contrast to other works, we allow channel, feedforward, and feedbackward filters to have one-sided but infinite impulse responses. The optimal filters with respect to a minimum mean square error criterion are derived. We elaborate several interesting properties of our solution and discuss a fast implementation with only quadratic complexity in the latency time.