Wireless Lan Service Quality Assurance Mechanism

Wireless LAN which is the result of combining computer network technology with mobile communication techniques in the 1990s, has raised new wave of mobile computing, and has been widely applied in the real world. It satisfies people's demands for broadband wireless access network. Wireless users are increasing which brings a series of problems of Quality of Service, Next-generation wireless network environment is required more and more wide range for supporting real-time multimedia applications, and can meet the needs of people accessing the mobile Internet in anytime. Therefore, how to guarantee WLAN QoS is a hot research topic at present.Based on the analysis of the current situation of WLAN QoS support and EEEE802.11 MAC protocol, we take the IEEE802.11 supporting QoS in WLAN MAC layer as the research target, and focus on the research on the mechanism of competition EDCF and AP switch security mechanism. WLAN service quality guarantee mechanism for increasing the reliability of the data transmission based on real-time and saving resources to improve spectrum availability ratio, reduce the delay is of great significance.This paper, firstly, makes a detailed theoretical analysis and derivation of p value in p-persistent CSMA/CA of enhancement distributed cooperation function. The optimal value of the probability of node successfully visiting channel is 1/n theoretically and points out that the probability of the node having not successfully visited channel at any time from 1 to[en]time slots is 1/e which is maximum. Within t= 2[en]ln n time slots, all nodes with not less than the probability of 1-n-1 successfully visit channel one time at least. Through getting the probability of a node and all successfully visiting channel, it provides sufficient theoretical basis for further research WLAN QoS guarantee mechanism.Secondly, in the WLAN expansion service set mode, when the node has a few APs to be selected, the users of AP are more leading network traffic load excessive weight because of some signal of AP are too strong, both thinking over each AP signal intensity and actual utilization of channel in the process of reconnecting, we put forward uninterrupted slide switch AP access control mechanism, and use link resources according to the AP maximum load balancing. Based on these, we improve the neighbors graph reconnecting algorithm, put forward the optimized neighbors graph algorithm.Finally, through the neighbors graph reconnecting algorithm and optimized neighbors graph algorithm NS2 simulation, according to the experimental data, we make a analysis and comparison between two. Compared with two, we can learn that optimized neighbors graph algorithm reduces delays and increases the system throughput, thereby, it guarantees WLAN quality of service.