基于星座图恢复的MQAM信号调制方式识别算法*

针对MQAM信号调制方式的识别问题,提出了一种基于星座图恢复的算法。该算法首先估计信号载频及信噪比等参数,并依据波特率和符号定时完成对接收信号的波特率采样。随后采用一种非判决辅助载频偏差估计方法,以消除载频偏差及相位偏移对星座图恢复的影响。最后利用平均似然比检测的方法,完成MQAM信号调制方式的识别。仿真结果表明,与仅考虑信号幅值分布的极大似然算法相比,该算法具有更优的识别性能。

Modulation recognition of MQAM signals based onconstellation recovery

An algorithm for modulation recognition of MQAM signals based on constellation recovery is proposed. This algorithm firstly estimates the carrier frequency and signal to noise ratio from its spectrum, and subsequently the baud rate sampling is done according the symbol timing. Then non-decision-aided carrier frequency offset estimator is used to mitigate the effect of frequency offset and phase offset in constellation recovery. Finally, the modulation type is recognized by the average likelihood ratio test method. Simulation results demonstrate that the proposed algorithm have the better recognition performance, compared with the amplitude-based maximum likelihood algorithm.