MQAM信号调制方式盲识别

该文提出了一种MQAM信号调试方式的盲识别算法。算法首先通过信号频谱粗略估计信号载频和带宽，从而进行下变频和低通滤波。然后通过信号包络平方的频谱估算出波特率，结合符号定时完成信号的波特率采样。最终计算MQAM信号矢量图中最小环带的方差，完成调制方式的识别。该MQAM信号调制识别算法无需载频和波特率等先验信息，对载波残余不敏感，没有复杂的迭代过程，可以应用于实际信号的调制识别。仿真表明信噪比在16 dB，码元数目为2400时，对5种QAM信号的识别率达到99%以上，证明了其有效性。

Blind Modulation Recognition Algorithm for MQAM Signals

A blind modulation recognition algorithm for MQAM signals is proposed. The method firstly estimates the signal carrier frequency and bandwidth from its spectrum to complete the frequency conversion and the low-pass filtering. Then the baud rate is estimated by calculating the frequency spectrum of the square envelope, and the baud rate sampling is done according the symbol timing. Finally the modulation type is identified by comparing the variance of sequences in the minimum ring of vectogram. It does not require prior information about carrier frequency and baud rate, and is not sensitive to the carrier offset. Moreover, there is no complex iterative process. So it is suitable for signal recognition of practical applications. Computer simulations show that the correct recognition probability is larger than 99% if SNR is greater than 16dB and using 2400 symbols. It verifies the validity of the algorithm.