基于循环稳定特性的空时分组码MC-CDMA信号盲识别算法

空时码应用最广泛的是空时分组码(space-time block code,STBC)和垂直分层空时码(vertical bell layered space-time code, VBLAST),因为STBC信号具有时间上的相关特性,所以在求高阶循环累积量时,该信号有一个特殊的循环频率,而VBLAST信号没有此特性。提出了一种基于循环稳定特性的STBC多载波码分多址（multicarrier code division multiple access,MC-CDMA）信号识别算法。该方法先根据信号系统的基带物理结构和信号模型来建立信号相关函数的选择标准,然后估计出这些相关函数对应的四阶累积量,接着把四阶循环累积量跟信道的参数结合起来建立一个循环统计量,最后把这个循环统计量与检测门限进行比较,实现信号识别。计算机模拟仿真表明,该算法能在较低的输入信噪比条件下良好地工作。

Blind recognition for STBC MC-CDMA signal based on cyclic stability

Space-time block code (STBC) and vertical bell layered space-time code (VBLAST) signals are used most widely in space-time code. With STBC the transmitted signals are correlated in time, while with VBLAST scheme the transmitted signals do not have such correlation. So the STBC signal has a specific cyclic frequency in the higher-order cyclic cumulant, the VBLAST signal emitted from different antennas are uncorrelated. The blind recognition for the STBC multicarrier code division multiple access (MC CDMA) signal based on the cyclic stability method is proposed in this paper. This algorithm first establishes the correlation choosing criteria, then obtains the fourth order cyclic cumulants of these corresponding correlation functions. The cyclic statistics after that is estimated by combining fourth-order cyclic cumulants with channel parameters. Finally, the cyclic statistics is compared with detection threshold, which is obtained by given a probability of false alarms. The simulation results and theoretical analysis indicate that the proposed method can work well on the lower signal noise ratio (SNR) input signals.