一种低复杂度的多用户MIMO THP排序算法

Low complexity ordering algorithm for multiuser MIMO Tomlinson-Harashima precoding

Tomlinson-Harashima预编码算法是一种有效的多用户多输入多输出下行链路算法,但是它的性能严重依赖于预编码符号的顺序.为了有效地衡量Tomlinson-Harashima预编码排序算法的性能,定义了一种排序增益因子.在此基础上为了最大化排序增益,提出了一种基于近似等对角QR分解的低复杂度Tomlinson-Harashima预编码排序算法.该算法通过对信道矩阵的行向量排序,使信道分解后的三角阵具有近似相等的对角元素值,改善了排序性能.仿真表明,与优化的Tomlinson-Harashima预编码排序算法相比,该算法大大降低了计算复杂度,而误码率性能几乎没有损失.

The nonlinear Tomlinson-Harashima precoding（THP） algorithm is an effective solution for MIMO broadcast. However, the performance of the THP strongly depends on the ordering of precoding symbols. To compare different ordering THP algorithms effectively, an ordering gain factor is defined in this paper. And we propose a low complexity ordering THP algorithm based on the approximate equal-diagonal QR decomposition. The proposed algorithm obtains a triangle matrix with approximate equal diagonal elements by rearranging the order of the channel matrix＇s rows to maximize the ordering gain. Simulation results reveal that the proposed algorithm has a significant reduction of computational complexity at the expense of only slight performance degradation compared to the optimal ordering THP algorithm.