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提出了一种多径衰落信道下多输入多输出正交频分复用(MIMO OFDM)系统的定时同步算法.算法将恒幅零自相关码作为训练序列,每根发射天线采用修正的循环延迟序列,在接收端分别计算本地序列和接收信号的互相关和接收信号的对称自相关,再将二者结合起来以确定定时位置.为了对抗多径信道中第1径不是最强径的情况,还采用了多径后向搜索技术,并利用可变阈值进行判决,以改善同步性能.通过仿真对算法在加性高斯白噪声信道和多径信道下的性能进行了验证和比较.
A multi-input multi-output orthogonal frequency division multiplexing (MIMO OFDM) system timing synchronization algorithm is proposed in multi-path fading channel.The algorithm uses constant amplitude zero auto-correlation code as training sequence, and each transmitting antenna adopts a modified cyclic delay Sequence, respectively, at the receiving end of the local sequence and received signal correlation and received signal symmetric autocorrelation, and then combine the two to determine the timing position.In order to combat multipath channel diameter is not the first diameter of the case, The multi-path backward search technique is also adopted and the decision is made by using the variable threshold to improve the synchronization performance.The performance of the algorithm under additive white Gaussian noise channel and multipath channel is verified through simulation.