Several sensing techniques are commonly used to detect PU signals. It has to be noticed that OFDM signals exhibit periodicities embedded in equally spaced sinusoidal carriers, cyclic prefix (CP) and pilot patterns that can be exploited not only to detect but also to classify heterogeneous PUs. Following this reasoning, a better knowledge of the environment is available. We also exploit the ability of classifying heterogeneous PUs to improve the CR adaptability in terms of throughput and interference protection towards PUs, and to design a flexible Cognitive Radio Resource Management (RRM).