Networking Technology Research Of WLAN Based On SDN Architecture

With the rapid spread of mobile smart devices,people's demand for wireless networks is increasing.Traditional WLAN networks have been widely deployed because of their simple deployment,low cost,and greatly reduced the pressure of traditional cellular networks.However,due to defects such as vendor lock-in,poor compatibility,and long deployment period of new functions,traditional WLAN networks are difficult to meet the needs of future networks.SDN decouples the control plane from the data plane,implements logical centralized control,and provides many programmable interfaces.It is considered to be a powerful technology to replace traditional networks.Obviously,the introduction of SDN into the WLAN network can solve the problems in the traditional WLAN network.Therefore,this thesis studies the networking technology of WLAN based on SDN architecture.The main research work is as follows:(1)For existing SDWN networking architectures,there is only one controller in the control plane.When the network scale is large or the network state changes dramatically,a single controller is easy to become the performance bottleneck.In this thesis,a multi-controller SDWN networking architecture is proposed.It divides the data plane into different domains.All network forwarding devices in the domain are connected to each other through a wired network.Each domain has one or more domain border switches.These domain border switches are connected to the inter-domain switches.Thereby achieving connectivity between domains.In the control plane,there is a master controller and multiple slave controllers,Each slave controller is responsible for controlling one domain in the data plane,and the master controller is connected to all inter-domain switches in the data plane through the southbound interface.Control the flow of traffic flowing from the external network and the traffic flowing to the external network to ensure the security of the network.At present,the most influential southbound protocols are developed for wired networks,and lack of support for wireless features in WLAN networks.Therefore,this thesis extends OpenFlow1.0 protocol.At the same time,in order to ensure the consistency of control information in the network,a wireless east-west protocol was developed for the interaction between controllers.(2)Aiming at the low bandwidth utilization of traditional channel allocation algorithms,an inspiring channel allocation algorithm is proposed.The algorithm maintains a channel bitmap for each AP,and the channel assigned to the AP must be a channel marked as available in its channel bitmap.Once a channel is assigned to an AP,the corresponding channel is marked as unavailable in the channel bitmap of all APs adjacent to it,so that adjacent APs work on different channels,Avoiding co-channel interference between adjacent APs.Furthermore,the algorithm also introduces channel bonding technology.Periodically allocate channels of different bandwidth according to the band utilization of the AP.The simulation test results show that the algorithm can effectively improve the overall throughput of the network when the channel allocation period is set properly.