Aiming at the problem of modulation recognition in OFDM signals under multi-path channel, a new algorithm based on wavelet decomposition geting detail feature is proposed. According to the different signal types have different detail component in the same decomposition level, the detail component of signals can be separated after the wavelet decomposition of signals. Because detail component contains almost all the signal' s detail information, the detail information can directly reflect the change of different signal types. The theory and simulation demonstrate that the amplitude values corresponding to detail component change differently after OFDM signals and single carrier digital signals making wavelet decomposition. Then the amplitude difference is regarded as a feature value, and the rule of Nearest Neighbor is used to recognize of OFDM signals and single carrier digital signals. Computer simulation results show that the feature value is immune to multi-path channel, and the algorithm is both feasibility and correctness in low SNR environment.%针对多径信道下OFDM信号的识别问题,提出了一种基于小波分解获得细节特征的信号识别方法.由于不同调制方式信号的细节分量在同一分解水平下存在较大差异,而细节分量几乎包含了信号的全部细节信息,从而直接反应信号的变化情况.通过理论推导和仿真测试证明单载波和OFDM信号在进行多层小波分解后,每层对应细节分量的幅度值具有不同的变化,然后利用其幅度差作为特征参数,并基于最近邻法判决规则实现单载波信号和OFDM信号的有效识别.仿真结果证实了该方法在较低信噪比下识别的正确性和可行性.
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