Researching On WLAN Channel Allocation Algorithm And Designing Of Hierarchical Network

The Wireless Local Area Network(WLAN)adopts the IEEE 802.11 standard,which has strict requirements on the transmit power and the transmit frequency of devices,causing the transmission distance and the coverage area of WLAN are limited.In some scenarios,such as airport helipads,access points(APs)establishing the first hop of communication with stations can not directly access the wired network due to the lacking of wired communication infrastructure.Therefore,it is necessary to establish communication between workstation and data center by using of WLAN relay communication.In the airport,the electromagnetic environment is complex around the relay nodes located in terminal buildings,so the channel interference between the relay node and the surrounding communication devices is more serious.The WLAN relay communication working on one channel can reduce the probability of channel collision between the access node and the surrounding communication devices,therefore it is more appropriate in the airport.The network may be divided into an access layer,a convergence layer and a center layer by introducing a convergence AP as a relay node for connecting the WLAN and the wired network.Considering only the performance of the hierarchical WLAN network,in addition to the limite of available channels and the overlap of adjacent channel in WLAN networks,because of the introduction of the convergence AP,only one channel is used when convergence AP and access AP establishing communication,which leading to channel resources in the access layer being tense and having serious system interference,and that may easily lead to the reduction of the throughput of the stations and the reduction of the service rate.Therefore,it is important to design an appropriate channel allocation algorithm to reduce system interference and improve network performance for the hierarchical WLAN.This article focuses on the design of suitable hierarchical WLAN network such as the airport and the researching of the channel assignment problem in this network.The main work and results in this article are list as follows:1)The design of a hierarchical WLAN network.Aiming at the scenario of the airport,a hierarchical WLAN network is designed.By analyzing the network model of the network,the importance of channel allocation for hierarchical WLAN is pointed out.2)The design of a channel assignment algorithm based on recursive channel elimination.Aiming at the NP-hard problem of channel assignment in hierarchical WLAN network,a channel assignment algorithm based on recursive channel elimination is given from the perspective of minimum system interference.The simulation results show that this algorithm can reduce interference and improve throughput for stations.3)The design of the channel allocation method jointing power control.By discussing the impact of power control on hierarchical WLAN system interference,basing on the recursive channel elimination algorithm,combining with the power control and channel selection strategy from the perspective of avoiding interference,a comprehensive channel allocation method is given.The simulation results show that the method is effective in improving network performance.