A Loading Balance Mechanism Based On Virtual Access Points For High-density WLAN Environment

Wireless local area networks (WLAN)have been rapidly developed and extensivelywelcomed in the recent decade. In the high density wireless network environment, dueto the access and handoff criteria from the IEEE802.11standard, the load between theaccess points (AP) will become imbalanced with high probability in the metric of thenumber of users, degrading the overall performance and wasting the resources of theWLAN.In response to the above problems, we propose a load balancing strategy based onthe migration of virtual access points instead of user stations residing in one physical AP.Whenever load imbalance occurs in a high-density wireless network, a virtual AP,together with all its associated user stations, can be scheduled by one AP controller (AC)to emigrate to one adjacent, light load physical AP, thereby adjusting the loaddistribution in the network quickly and efficiently. We design the load balancing methodbased on the above ideology and do an initial test. The works we have done andpresented in this thesis include:1.analyze the open source driver codes in Linux environment, and have a goodcommand of the basic architecture of the NIC driver and related workflows. The newload balancing algorithm is proposed on the basis of the NIC virtualization technology.2.Designs and implementations of the various functional modules which areintroduced in the load balancing system. First we use PACMAP to develop and achievethe virtual access points and the centralized controller, after that realize thecommunication of management frames between them to support the load balancingsystem; And then through the Linux wireless network card management tool whichnamed wireless tool, we call the APIs which provided by wNIC driver to implement thevirtual station, so as to simulate the high-density user scenarios.3.Experiments to verify the validity and correctness of the load balancing strategy.Ultimately our experimental results show that the proposed load balancing strategyin this paper has the advantage of adjusting the user load imbalance between Apsrapidly without affecting the existing communication of the terminals, which deservesfurther study combined with the practical application scenarios.