Software defined network (SDN) is an emerging network paradigm and has been deployed to a wide range of networking systems. It can significantly simplify the network management and offer a programmable and flexible network architecture. Originally, SDN is designed for wired networks, such as data center network and campus LAN. Fortunately, the architecture is general enough to be applied to wireless networks as well. Due to the popularity and generality, the software defined concept has now been employed to many forms of wireless networks. Similar to wired implementations, Software Defined Wireless Networks (SDWN) can also bring flexibility, programmability, and scalability into mobile networks.
 In the meantime, applying software defined wireless networks also entails several distinct challenges that need to be solved. On one hand, to decouple the control/data plane and establish centralized control of the entire wireless network is not easy. Wireless signals travel through unguided media in the air, and broadcast is the nature of wireless signals. Hence, the probability of transmission error tends to be higher than wired networks. In addition, the heterogeneity of physical layer standard makes the network integration more difficult. Moreover, the mobility of nodes can also cause frequent topology change of the entire networks. On the other hand, the requirement of wireless applications is more complicated. Conventional SDN is generally designed for Ethernet with IP-based protocols. However, many wireless specific features can also impact the performance of the networks, such as the bandwidth, wireless spectrum, and geographical location of wireless nodes. It is necessary to redesign the standards and flow rules for software defined wireless networks.