The Research And Experiment On Improving The Quality Of Services Of WLAN In Wireless Heterogeneous Network

In the recent years, with the development of wireless technology andpopularity of Internet, wireless heterogeneous network is becoming maininfrastructure network providing wireless Internet access service. In thewireless heterogeneous network, the RF interference and the disparity ofthe media transmission capability challenge the quality of services (QoS)in wireless Internet. More and more research focus on the assurancemechanisms and algorithms for Quality of Services. This thesis chooses3GPP&WLAN inter-network as background, which is the typical modelof wireless heterogeneous network, and WLAN as the research object,then we proceed the research and experiment in following two aspects:the RF interference in physical layer and the service consecutiveness inapplication layer. The primary works in the thesis are:1) At present, WLAN devices that base on the IEEE802.11b protocol aremost popular. But since they work at 2.4GHz ISM frequency, which islicense free, the WLAN devices may suffer the interference from theneighboring WLAN device, or the White Gaussian Noise from nature,burst noise and some interference that comes from other RFtransmitter. But no matter which type of interference, wheninterference exceeds the bearing threshold, the network performanceof WLAN could decline significantly, even be unavailable. So at first,this thesis focuses on the RF characteristics of WLAN, and considersavoiding the interference. The research bases on the theory ofAdaptive Channel Allocation Mechanism in IEEE802.11b, realizesthe prototype of the mechanism in LINUX, and tests and evaluates themechanism through experiment. The research proves that the...