摘要
在无线时变衰落信道环境下,提出一种用于多输入、多输出(MIMO)天线系统的自适应信道跟踪方法.在空时分组码(space-time block code,STBC)的MIMO系统中,用导频进行信道估计后,采用基于最小均方(least mean square,LMS)的改进自适应算法对时变信道进行跟踪.该方法分别跟踪信道矩阵经正交分解(QR)后的参数,定义了度量时变衰落大小的信道矩阵“对角非零因子(diagonal nonzero factor,DNF)”,并利用它来调整LMS的步长以提高对信道的跟踪能力.仿真结果表明,该方法在相同的导频开销下,与传统的用LMS算法直接跟踪信道相比,性能有所提高.
An LMS-based adaptive channel tracking method for space-time block code MIMO system over time-varying wireless channels was proposed. Channel estimation after the training period was achieved by tracking the parameters from QR decomposition on the predicted channel matrix, by which noise was effectively reduced. Furthermore, in order to track more precisely, the step size of LMS algorithm was adjusted by the defined diagonal-nonzero-factor, which reflected the degree of channel fading. Computer simulation results show an improvement over traditional LMS tracking, in terms of MSE and SER. In the meantime this method retains the low complexity of LMS algorithm compared with RLS.
基金
国家自然科学基金(60496314)
国家"863"计划(2003AA12331003)资助
