On the sensitivity of the MIMO Tomlinson-Harashima precoder with respect to channel uncertainties
IEEE Transactions on Signal Processing
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This paper investigates the joint Tx-Rx design of a multicarrier multiple-input multiple-output (MIMO) system employing Tomlinson-Harashima precoding (THP). The optimality criterion is the minimization of the mean-square-error (MSE) at the receiver side under a constraint on the overall transmitted power. Theoretical analysis and computer simulations are used to assess the performance of the proposed scheme in terms of bit-error-rate (BER) and minimum achievable MSE. It is shown that non-linear precoding may provide much better results than linear pre-filtering, especially when the number of parallel data streams is close to the number of transmitting and receiving antennas. Compared with other existing methods based on THP, our scheme is different in that the preceded symbols are linearly prefiltered before being launched over the MIMO channel. This results into a power loading operation over the channel eigenmodes, which leads to a remarkable improvement of the error-rate performance.