多径衰落信道下OFDM信号盲识别

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.

Blind Recognition of OFDM Signals in Multi-Path Fading Channels

Based on cyclic autocorrelation,an algorithm of blind recognition of orthogonal frequency division multiplexing(OFDM) signals in the multi-path fading channels is proposed.Derivation of the cyclic autocorrelation characteristics for OFDM signals with a cyclic prefix in the multipath fading channels is done,it verifies that the cyclic autocorrelation of OFDM signals will appear peaks at a certain time delay,while single-carrier signals is without peaks.So,OFDM signals can be recognized from single-carrier signals in multi-path fading channels.The new recognition algorithm eliminates the preprocessing tasks,such as symbol timing estimation,carrier and waveform recovery,and signal to noise ratio estimation as well.Also,the proposed algorithm is with low computational complexity and high recognition rate.Simulation verifies that the proposed recognition algorithm is correct and efficient.