The Cognitive Radio (CR) networks have the capability to be aware of the licensed spectrum and to solve the inefficient usage of the vacant bands in an opportunistic manner. Thus, a spectrum awareness framework must be designed by considering the spectrum availability, the Primary User (PU) interference avoidance and the heterogeneous Quality of Service (QoS) requirements of CR users (CrUs). Considering these challenges, the main contribution of this paper is to design a complete framework for the spectral awareness in CR networks achieving higher spectrum utilization and fairness. Specifically, a PU Presence Map (PuM) is built for the PU interference avoidance. The QoS requirements of CR users are classified using a Request Map, ReM. An admission control is proposed to stabilize the heterogeneous QoS requirements according to PuM and ReM. Moreover, the adaptiveness of the framework is provided by continuous monitoring of the spectrum against dynamic variations. The simulations demonstrate that the proposed spectrum awareness framework maximizes the available spectrum utilization while maintaining the fairness. (C) 2012 Elsevier B.V. All rights reserved.