Research On Channel Assignment In WLAN Under Co-channel Deployment

In recent years,WLAN(Wireless Local Area Network)has been developed and widespreaded rapidly as its high data rates,low cost and other characteristics.With the increasing of APs(Access Point)and clients,wireless network becomes more and more intensive,which makes the co-channel interference problem more serious.Therefore,how to utilize the limited spectrum resources reasonably to reduce the co-channel interference is extraordinary necessary and urgent.In this paper,we study the network performance with the influence of inter-AP under dense WLANs and propose a channel assignment algorithm based on PCF(Point Coordination Function),whick can provide effective strategy for large-scale and highdensity WLAN deployment.The specific work is as follows.First,we study the co-channel interference problem in dense WLAN deployments.At the beginning,the interference conflict graph is constructed based on the dynamic network topology.And then analyse and compute the conflict matrix by using point coloring model.After that,the channel assignment algorithm is proposed,which includes two steps.The first step is the basic channel assignment algorithm which divides the superframe period of PCF into several time slots and utilize the time slots scheme to schedule APs.The second step is reserving the time slots by combining with the polling list of neighboring APs.Thus,the idle time slots will be reduced and the network performance will be improved.Second,we study the PCF polling algorithm.As the problem of polling overhead,empty polling and polling scheduling algorithm,the priority channel access strategy is present based on the existing polling algorithm under the co-channel deployment.The strategy classifies the clients and adjustes the priority of clients dynamically according to the requirements of clients,which can realize priority polling for the high priority clients and achieve high network throughput.Finnally,we simulate our algorithm on OPNET network simulation platform.The simulation results show that our proposed algorithm can improve the network throughput by 10% and reduce the transmission delay and packet loss rate by 15% and 8% respectively compared with the TMCA scheme.