Research On Optimal Control Of Virtual Wireless Access Network

Wireless local area network(WLAN)gets widespread popularization in daily life because of its low cost,easy installation and so on,meanwhile the wirelss data traffic is showing a rapid rising tendency,so there is no doubt that WLAN possesses tremendous development potencial,however it is also exposed with some problems.Firstly,the traditional distribute network architecture of WLAN is not competent to the construction of large network,and the centralized architecture is subject to devices seriously.Secondly,the users' QoE is not well considered in present WLAN,it is difficult for manager to control the network for particular users.Thirdly,the default algorithm of STA accesses to AP is likely to cause the imbanlance of network.Therefor,the existing problems of WLAN mentioned before are carefully analyzed and studied in this thesis,and some optimal control strategies is designed and implemented based under the same logic centralized architecture for management and control.First of all,this thesis studies the problem of virtualized wireless access network under this architecture.The author designes and implements an access management subsystem aimed at VAP,including front-end pages of portal,validating logic and process control of back-end,database storage,and conversation between controller and back-end,which can achieve several main capabilities as follows: the first is the portal authentication for users,it differentiates users to do authenticate,and the relevant information is stored only when the users are proved to be legal,also,it communicates with controller so that the operation of PVAP can be done collaboratively;the second is the information maintenance of users,viewing and modifying of personal account and equipment information is allowed;the last is visualization of WLAN's network status,combined with the location information,subsystem provides network administrator with connection status and other information of Aps and STAs on Baidu map.Then,the thesis studies the optimal control algorithm of STA's association under this architecture.Aimed at banlancing the throughput of each STA and improving the throughput of the whole network at the same time,the author designed a global access control algorithm(GACA)at first,which establishes a mixed integer non-linear programming problem with maxing the total network throughput as the objective function,and then the hybrid self-adaptive genetic algorithm is used as the solving method to get the optimization of the association shceme among STAs and APs,the controller should run the algorithm periodically to adjust network;then the author puts forward an incremental access control algorithm(IACA),the algorithm takes the influence that caused by STA connects to different AP into account,and finally selects the most suitable AP for the STA and let STA connect to the selected AP,the controller can run the algorithm when new STA arrives and wants to join in the network.Through a large number of simulation experiments on NS-3,it is proved that the designed algorithms are effivtive.