Driven by the requirements from traffic volume versatile services and spectrum scarcity, the concept of cloud network and cognitive radio could become new features in the next generation mobile and wireless access networks. For example, to deploy LTE femtocells and Wi-Fi networks in the TV white spaces provides a new way for traffic offloading and enables spectrum sharing as a cognitive radio network. In this paper, we propose and prototype a software defined network architecture with the OpenFlow protocols for heterogeneous network spectrum sharing in the TV white space. Then, we analyze the controller architecture for cognitive radio and the OpenFlow enabled infrastructure architecture. We implement a prototype of software defined cognitive radio network with this SDN controller and LTE/Wi-Fi network simulator. Some essential control functions of cognitive radio are implemented and new potential scenarios based cognitive radio networks are given.