Frequency domain equalization with tomlinson-harashima precoding for single carrier broadband MIMO systems

In this paper, we combine the transmit Tomlinson-Harashima precoding (THP) technique with single carrier frequency domain equalization (SC-FDE) and propose two new FDE multi-input multi-output (MIMO) schemes, which we refer to as parallel THP-FDE and successive THP-FDE, based on the minimum mean square error (MMSE) criterion. For the successive THP-FDE scheme, where all transmit streams are subsequently preceded, we propose an optimal MMSE ordering algorithm. Since the feedback processing is performed at the transmitter, no error propagation problem exists in the proposed THP-FDE MEMO schemes. Numerical results will demonstrate the significant performance improvement of our proposed schemes compared to the conventional FDE MIMO schemes. We will also analyze the error probability, and investigate the channel estimation errors and channel variation effects on the proposed THP-FDE MIMO systems. It will be shown that by applying channel prediction and THP compensation techniques such detrimental effects can be greatly reduced.