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针对多径衰落信道下正交频分复用(OFDM)信号调制识别难题,提出一种基于循环自相关的OFDM信号调制识别算法.通过对多径衰落信道下具有循环前缀的OFDM信号循环自相关特性的数学推导,验证了在一定延时处,OFDM信号的循环自相关会出现峰值,而单载波信号无此峰值,据此特性可以实现多径衰落信道下OFDM信号和单载波信号的调制识别.该算法消除了如符号时间估计、载波估计、波形恢复、信噪比估计等预处理过程,计算复杂度低,识别率较高.理论分析及仿真结果均验证了该算法的正确性和有效性.
Aiming at the problem of Orthogonal Frequency Division Multiplexing (OFDM) signal modulation recognition in multi-path fading channels, an OFDM signal modulation recognition algorithm based on cyclic autocorrelation is proposed. By cyclic autocorrelation of OFDM signals with cyclic prefix in multipath fading channels, The mathematical deduction verifies that at certain delay, the cyclic autocorrelation of OFDM signal will peak, while the single-carrier signal does not have such peak, so the modulation recognition of OFDM signal and single-carrier signal under multi-path fading channel can be achieved The algorithm eliminates the preprocessing such as symbol time estimation, carrier estimation, waveform recovery and signal to noise ratio estimation with low computational complexity and high recognition rate.The theoretical analysis and simulation results verify that the algorithm is correct and effective Sex.