Aiming at the channel fading characteristics in the wireless physical layer security technol-ogy, two common channel feature extraction methods, i.e, the power detection method and the channel impulse response ( CIR) method, are investigated and the corresponding mathematics mod-els are established.The relationship of these two methods is analyzed and their characteristics are al-so clarified.On this basis, the average mutual information of the extracted feature measurements of two communication parties is calculated using these two methods.And by taking the mutual informa-tion as metrics, their key extraction efficiencies are compared.The simulation results show that the received waveforms obtained by the power detection method reflect the channel fading feature effec-tively and is independent of the carrier frequency offset, but the key extraction efficiency is lower than CIR method.Besides, the simulation results in the long term evolution ( LTE) wireless channel environments indicate that the channel mobility has a close relation with the key extraction rate and the effects on these two methods are different.%针对无线物理层安全技术中的信道衰落特性，研究了功率检测法和信道冲激响应法2种常见的信道特征提取方法，分别建立了数学模型，并分析了2种方法之间的关系，阐明各自的特点。在此基础上，采用这2种方法计算了通信双方提取特征量的平均互信息，并将此作为度量，对比了两者的密钥提取效率。仿真结果表明，功率检测法得到的接收波形有效反映了信道的衰落特性，且与载波频偏无关，但其密钥提取效率较低。此外，在LTE无线信道环境中对2种方法进行了仿真比较。结果表明，信道的移动性与可提取的密钥速率有关，且对2种方法的影响程度存在差异。
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