Novel THP algorithms with minimum BER criterion for MIMO broadcast communications

In this article, two novel Tomlinson-Harashima precoding (THP) algorithms are proposed at the downlink broadcast channel of multi-user multiple-input multiple-output (MIMO) systems. The optimality criterion is the minimization of the bit error rate (BER) at the receiver with a constraint on the overall transmitted power. In these algorithms, transmit power allocation (TPA) matrix is introduced to the traditional THP algorithms as part of the precoding matrix. This leads to a power loading operation based on substreams signal to interference-plus-noise ratio (SINR) and results in improvement of the error rate performance compared with traditional THP algorithms. When the precoding loss factor is considered, further performance improvement is achieved by the enhanced algorithm.