Design And Implementation Of WiFi-based Ultra-dense Software Defined Network

With the development of communication technology,intelligent mobile terminals are undergoing explosive growth and people's lives are becoming more and more inseparable from WiFi.However,in some high-density environments,such as shopping malls,hospitals,conference sites and other wireless sites,home WiFi routers or enterprise-class AC AP(Thin AP)architectures are usually adopted.However,there are still many problems to be solved in this architecture,such as: 1)Time-consuming network management and maintenance can't achieve real-time monitoring of network operations;2)inadequate management and control capabilities to allocate resources to the entire network in a timely and effective manner;and 3)that data planes and control planes are not separated and that local data The flow needs to be forwarded by the AC;4)the terminal selects the associated AP,it is difficult to achieve seamless switching between APs and load balancing;5)poor expandability,ordinary home WiFi router or enterprise AP+AC router products are not perfect,For the upper application development.In view of the above problems,this thesis introduces the idea of SDN,proposes centralized control WiFi architecture based on SDN,AP is responsible for small management functions such as data forwarding and sta discovery.The SDN controller is responsible for quasi-access management and is responsible for obtaining the status of the whole network and storage,power,channel and other wireless resources,the rational allocation of user rights management and access to some of the parameters of the link.Using the design of the router and custom protocol based on OpenWrt operating system,the software and hardware development and function testing of the system are realized.The detailed work done in this thesis is as follows:(1)Propose a new scheme of wireless AP system.The idea of SDN is introduced.The AP periodically reports all resource information of itself and sta to the SDN controller management platform.According to the AP real-time reporting of resource dynamic information,the SDN controller can realize the real-time monitoring of the global network.Meanwhile,Based on the effective distribution of the global network,flexible scheduling control,but also reduce the network's energy consumption and reduce interference,and ultimately improve the user's experience.(2)SDN switches southbound interface protocol design.AP and controller through a custom communication protocol OpenAP message exchange and instruction transfer.Based on the OpenFlow protocol,this thesis completes the design of the southbound interface protocol suitable for this system.The main work includes the design of the protocol header of the southbound interface of AP and SDN controller,and the design of the data blocks of AP and SDN controller.(3)Hardware and software development of nodes and controllers in ultra-dense wireless WiFi system.Mainly use the C/C++/Java programming language,while using the JavaEE technology SSH framework and some middleware,such as: Echarts,EasyUI,Qunee-H5-v2.6.04.Achieve system networking,terminal access,associated certification,load balancing.Complete the system to build,test and analysis.The test results show that the wireless AP network system designed in this thesis can effectively utilize the network resources and guarantee the QoS of users,meeting the expected requirements.Finally,this article summarizes the content of the work,and prospects for future work.