Design And Implementation Of Software-Defined And Virtual WLAN

With the presentation of the "smart city", a national strategic plan, the mobile networks has grown from providing simple data service to full interconnection and smart networks, which combines some state-of-the-art technologies, like the internet of things, cloud computing and big data to achieve comprehensive perception, ubiquitous connectivity and computing. As a typical representative of wireless networks, wireless local area network(WLAN) has many advantages, like high transmission speed, flexible architecture, low system costs and better scalability, etc. Thus, WLAN has been widely deployed, and it is the indispensable infrastructure for building a "smart city".However, with the explosive growth of user scale, as well as the mobile data, the current WLANs are facing serious challenges. Firstly, the network devices' hardware and software are closely related, while the control plane and data plane are tightly coupled. when the devices are outage or need to be upgraded, the operators can only replace them, which results high operation and maintenance expenditure. Secondly, currently large-scale deployed WLANs often adopt centralized architecture, although they can achieve centralized management of all access points(APs) effectively, there is a lack of unified, flexible control interface. Finally, heterogeneous networks integration is now the trend, while the WLAN lacks of mechanisms for integration with other networks, which also hinders the development of WLANs. Therefore, the current WLAN architecture needs to be changed, to address the underlying difficulties of upgrade and integration, in order to keep up to the currently rapid development of the mobile internet.Software defined networking(SDN) is now the most remarkable technology in the field of network, it separates the control and forwarding plane, centralizes the control plane, thus developing a programmable network. Inspired by the idea of SDN, we propose the software defined and virtual wireless local area network(SD-WLAN) in this paper. SD-WLAN is composed of three layers, i.e., infrastructure, network controller and application layer. Firstly, network control plane is decoupled from forwarding plane, and the only work of soft-defined access points(SD-APs), the main entity at the infrastructure layer is forwarding the packages according to the instructions from network controller. Secondly, with a global view of the network, network controller could abstract, encapsulate,and virtualize the physical resources(e.g., computing, storage, and radio resources) in networks. Finally, by binding all the resources at the infrastructure and access control layers, isolated virtual resource chains are built up and mapped to northbound interface(NBI). By invoking the interface of the virtual resource chain, any network application could be easily implemented only by coding at the application layer, which facilitates the scheduling of network resource, so as the management of network.Based on the proposed framework, we employ common hardware devices and standard interfaces to design and implement a SD-WLAN experimental platform. The remarkable feature of our platform is that, we extend the Open Flow protocol to implement the abstraction and centralized management of network resources, thus, we achieve a unified management of wired and wireless devices in wireless local area networks. What's more, by calling the interface of virtual resource chain in network controller, we developed an application of load balance on our experimental platform, and we verified the reliability of it through experiments. Experiment results demonstrate the flexibility and extensibility afforded by the proposed framework, which can be easily deployed and managed, and various network applications can be developed quickly based on the SD-WLAN.