#### Abstract

Tomlinson-harashima precoding (THP) is one kinds schemes which is widely used to improve system performance or alleviate the complexity at receiver side with the assumption full channel state information known at transmitter. In THP precoding scheme bit error rate performance is always determined by the minimum square value of the diagonal elements of matrix R over the noise ratio where R is the triangle matrix of QR decomposition to the channel matrix. In this paper we propose a scheme in which number of data streams is reduced so as to obtain a larger minimum absolute diagonal elements of R , hence we obtain better bit error rate performance with even higher order modulation applied. In addition, the bit error rate formula of THP precoding is derived in this paper which is close to the simulation results. It can be applied for assessment of the THP precoding schemes with different data streams and modulation orders. Numerical simulation results verify the feasibility of the proposed scheme.