Classification of linear modulations by a combination of different orders cyclic cumulants

The search for discriminating features is a crucial point when a modulation classification task is aimed. This paper introduces new features based on a combination of fourth- and second-order temporal cyclic cumulants. Such a combination enhances the theoretical discrimination that can be achieved by a single stationary cumulant, and moreover, the cyclic parameters become discriminating whereas it is not the case when they are considered at pure orders. As an application, we propose a process to classify 4-PSK vs. 16-QAM modulations. The classification is achieved by estimating the feature for the received signal, and comparing it with theoretical ones by a matched filter technique. Simulations show that though the cyclic parameters are a priori more discriminating than their stationary counterparts, the variance of their estimates may overcome this advantage.