一种改进的块对角化预编码算法

An Improved Block Diagonalization Precoding Algorithm

为进一步提高块对角化预编码算法的性能,提出一种多用户多输入多输出下行链路中基于Givens变换的正交三角(QR)分解改进块对角化算法(QR-Givens-BD)。在块对角化预编码算法中,首先需要求出预编码矩阵的前半部分来解决多用户干扰问题,然后求出预编码矩阵的后半部分来降低用户自身天线间的数据干扰。在求解预编码矩阵的前半部分时,使用的核心算法是矩阵的正交化算法,矩阵的正交性的强弱将直接影响块对角化预编码算法的误码率性能的好坏。因此,针对块对角化预编码算法中的矩阵正交化算法,使用基于Givens变换的QR分解正交化算法替换原有正交化算法,求解预编码矩阵的前半部分,从而获得信道干扰矩阵零空间的正交基。通过对矩阵采用本方法进行正交分解,可以获得正交性更好的正交矩阵,从而进一步降低系统误码率。仿真结果表明,本文所提出的算法与传统的块对角化算法相比,在降低了计算复杂度的同时大幅提高了系统的误码率性能;与基于Gram-schmidt正交化的改进块对角化算法相比,在略微增加复杂度的前提下可以提高3~5 dB的误码率性能。

In order to improve the performance of block diagonalization preeoding algorithm,an improved algorithm was proposed for multiuser multiple-input multiple-output （MIMO） downlink systems,which employs QR decomposition based on Givens transformation.In the block diagonalization precoding algorithm,the first half of the precoding matrix is required to solve the problem of multiuser interference,and the latter one to reduce the interference between the antennas of each user.The core algorithm of the first half matrix is orthogonalization algorithm,which will directly affect the bit error rate （BER） performance of the block diagonalization pre- coding algorithm.Therefore,the original orthogonalization algorithm was replaced by QR decomposition algorithm based on Givens transformation.Using this algorithm to solve the first half of the precoding matrix,the orthogonal basis of the interference matrix＇s zero space can be obtained.By using the Givens transformation,the matrix with better orthogonality can be obtained,so as to further re- duce the BER of the system.The simulation results showed that compared with the traditional block diagonalization algorithms,the complexity of the system was decreased and the BER performance can be improvedgreatly.Compared with the block diagonalization algorithms based on Gram-Schmidt orthogonalization,the BER performance can be improved by 3-5 dB,with a slight increase in the algorithm complexity.