There are many research papers published in modulation classification, and most of them have a common framework. In this paper we will give an overview, and the paper contains four topics: 1) Some fundamental principles, 2) features used for classification, 3) the algorithm structure, and finally 4) a literature survey.
We study n dimensional Riemanniann manifolds with harmonic forms of constant length and first Betti number equal to n−1 showing that they are 2-steps nilmanifolds with some special metrics. We also characterise, in terms of properties on the product of harmonic forms, the left invariant metrics among them. This allows us to clarify the case of equality in… (More)