Abstract: Concerning the problem of modulation identification in the Rayleigh channel, a new algorithm based on cumulants was proposed. The method was efficient and could easily classify seven kinds of signals of BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 4ASK (4-ary Amplitude Shift Keying), 16QAM (16-ary Quadrature Amplitude Modulation), 32QAM (32-ary Quadrature Amplitude Modulation), 64QAM (64-ary Quadrature Amplitude Modulation) and OFDM (Orthogonal Frequency Division Multiplexing) by using the decision tree classifier and the feature parameters that were extracted from combination of four-order cumulant and six-order cumulant. Through theoretical derivation and analysis, the algorithm is insensitive to Rayleigh fading and AWGN (Additive White Gaussian Noise). The computer simulation results show that the successful rates are over 90% when SNR (Signal-to-Noise Ratio) is higher than 4dB in Rayleigh channel, which demonstrates the feasibility and effectiveness of the proposed algorithm.

Key words: modulation recognition, Rayleigh channel, high-order cumulant, Orthogonal Frequency Division Multiplexing (OFDM), single carrier signal

摘要： 针对瑞利信道下调制方式分类的问题，提出了一种基于累积量的识别方法。该方法利用四阶累积量和六阶累积量的组合作为特征参数，采用决策树分类器，能够实现二相相移键控(BPSK)、四相相移键控(QPSK)、四进制幅移键控(4ASK)、四阶正交幅度调制（16QAM）、五阶正交幅度调制（32QAM）、六阶正交幅度调制（64QAM）和正交频分复用（OFDM）七种调制方式的识别分类，且计算量小，易于实现。从理论上进行推导与分析，所提方法对瑞利衰落和加性高斯白噪声干扰不敏感。计算机仿真结果表明：信噪比大于4dB时，正确识别率达到90%以上，说明了所提方法的可行性及有效性。

关键词: 调制识别, 瑞利信道, 高阶累积量, 正交频分复用, 单载波信号