Research Of WLAN Load Balancing Diffusion Algorithm Based On SDN

In recent years,with the rapid development of mobile Internet,the surging number of intelligent terminals has brought great pressure to the wireless network.Many applications,especially multimedia services,need to occupy a large number of wireless bandwidth.If you can't choose appropriate access points for the application,there will be a number of nodes overloaded,while some other nodes have a lot of resources that are not being used properly,and the network congestion appears to affect the use quality for users.Therefore,this thesis introduces the Software Defined Networking(SDN)to solve this problem.SDN is proposed by the clean slate project group of Stanford University,which is facing more and more problems in the traditional network.SDN draws the control plane out of the traditional data plane,concentrates the control level together to realize the unified and flexible management of the network resources.The open interface completes the programmable control and realizes the ability to call the network on demand.The idea of SDN is applied to load sensing in wireless network,and centralized management of all wireless access points is done by load balancer.When the wireless node has mobile terminal access,the node reports the access message to the load equalizer in the control layer in time.The load balancer runs the load balancing algorithm.It calculates the optimal migration scheme according to the load information of the current global network,and then sends it to the OpenFlow switch in the control layer to complete the phase.The action that should be done.In this thesis,the traditional FOS(First Order Scheme)diffusion algorithm is introduced into it.In the process of load balancing using the traditional FOS diffusion algorithm,some problems are found.After the analysis of the problem,an improved scheme is proposed.This thesis first introduces the theoretical knowledge of SDN,and learns the controller of SDN,the north and South interface protocol and the related technologies,which provides a theoretical basis for the introduction of load balancing technology in the SDN architecture.Secondly,we learn a variety of load balancing technologies.In the process of load balancing using traditional FOS diffusion algorithm in SDN,it is found that there are the following problems and corresponding solutions are put forward:(1)In the process of load updating,the traditional FOS diffusion algorithm combines the nodes of the network with all the adjacent nodes at the same time,which makes the load migration overhead.Aiming at this problem,the thesis proposes a start node,which reduces the load migration cost by setting the threshold;(2)The traditional FOS diffusion algorithm does not take into account the actual situation of the node in the global network when carrying out the load balancing,so that the algorithm can't converge to the effective direction.In this thesis,by establishing the method of migration group,a diffusion algorithm that can realize the load perception between adjacent nodes is proposed,which enables the load to converge in the process of migration according to the load distribution in the current node;(3)In the load updating formula of the traditional FOS diffusion algorithm,the influence factor of the load exchange is only related to the degree of the node and its neighbor nodes.When the node degree is determined,the influence factor is a fixed value,and it can't be updated according to the real-time condition of the node load.This thesis is based on the water pressure knowledge point of the connector to improve it,so that the node can be updated according to the current load distribution in a certain proportion.Finally,the simulation experiment is carried out to verify the proposed improvement plan.First,the load migration and convergence are verified by the matlab simulation experiment.The experimental results show that the improved algorithm reduces the load migration and effectively improves the convergence.Then,a reasonable system model is built on the wireless network simulation platform Mininet-Wifi that can support SDN thought,and the network transmission performance is tested.Compared with the traditional FOS diffusion algorithm,the improved algorithm reduces the packet loss rate,shortens the round-trip delay and increases the network throughput in the process of network transmission,and achieves the desired goal.