Modulation classification by Hilbert-Huang Transform

The problem of identifying the modulation type of the signals at the receiver, is very helpful intermediate step for spectrum sensing which the cognitive radio systems are commonly used today. In this study, Hilbert-Huang Transform is proposed for identifying the modulation type of digitally modulated signals in the noisy environments. Hilbert-Huang Transform obtains the instantaneous features of the signals, like time-frequency and time-amplitude information, and the obtained data are used to determine the type of modulation. The most important feature of the proposed method is there is no need for any a priori knowledge about the signal. Computer simulations demonstrate the accuracy and the superiority of the method in a comparative manner.