Network virtualization is a promising technology that enables the deployment of multiple virtual networks over a single physical network. These virtual networks are allowed to share the set of available resources in order to provide different services to their intended users. Although many projects are studying different aspects of network virtualization, the field of wireless network virtualization is not well investigated. In this work, we propose a dynamic cognitive radio virtualization framework in which several virtual networks are built over a set of physical nodes managed and controlled by a Base Station (BS). This framework is proposed to virtualize Cognitive Radio Networks (CRNs) in order to reduce the control overhead on the BS side by delegating some of its responsibilities to the node side. The proposed framework is applied to a network with multiple overlapping cells. To cope with the self-coexistence problem, we use a resource allocation algorithm to distribute the available channels over the overlapping cells based on their traffic loads with the goal of avoiding harmful interference, enhancing blocking rates and increasing throughput.