基于格规约辅助的MIMO系统GMD-TH预编码方案

现有的GMD-TH(Geometric Mean Decomposition-Tomlison Harashima)预编码方案在发射 端未对获得MIMO（Multiple-Input-Multiple-Output）信道增益矩阵优化，因而 其误码率和分集增益无法获得令人满意的效果。为此，在原有MIMO系统GMD-TH预编码的基础 上，提出一种基于格规约辅助的GMD-TH预编码方案。该方案采用基于格规约的算法对信道 矩阵进行优化，经过优化的信道矩阵其列向量之间具有更好的正交性并且向量的长度更短， 并且采用优化的信道矩阵提高了GMD-TH预编码MIMO系统的分集增益。仿真结果表明：相比于 传统的线性预编码方案，该预编码方案有效地提高了MIMO分集增益，相同误码率下，信噪 比降低3 dB以上，具有实用价值。

A GMD-TH precoding scheme based on lattice reduction for MIMO systems

In the exiting GMD-TH (Geometric Mean Decomposition-Tomlison Harashima) preco ding schemes, the obtained channel gain matrix is not optimized and so its bit e rror rate(BER) and diversity order are not satisfactory. In this paper, a new GM D-TH precoding scheme is proposed. The lattice reduction algorithm is applied in this scheme to optimize the channe l at the transmitter to make the orthogonality of the sub-channels better and t heir length shorter. The diversity order of the MIMO system is also improved wi th optimized sub-channels. The simulation results show that the precoding sch eme can effectively improve the diversity gain of MIMO system in comparison with the traditional linear precoding scheme, and at the same BER, the SNR is reduce d more than 3 dB. So the proposed scheme is applicable.