Hierarchical digital modulation classification using cumulants

A simple method, based on elementary fourth-order cumulants, is proposed fo r the classification of digital modulation schemes. These statistics are na tural in this setting as they characterize the shape of the distribution of the noisy baseband I and Q samples. It is shown that cumulant-based classi fication is particularly effective when used in a hierarchical scheme, enab ling separation into subclasses at low signal-to-noise ratio with small sam ple size. Thus, the method can be used as a preliminary classifier if desir ed. Computational complexity is order N, where N is the number of complex b aseband data samples. This method is robust in the presence of carrier phas e and frequency offsets and can be implemented recursively. Theoretical arg uments are verified via extensive simulations and comparisons with existing approaches.