Based On The Ieee802.11e Edca Channel Access Algorithm Improvements And Simulation

In order to provide service quality of multimedia transmission services, IEEE 802.11 Group proposed 802.11e. The agreement enhances the existing 802.11MAC channel access, and support priority QoS and parameterized QoS .Hybrid Coordination Function (Hybrid Coordination Function, HCF)is propsed in IEEE802.11e. polling-based HCF channel access mechanism (HCCA) and spread the competition-based EDCA channel access mechanism (EDCA) are included in HCF. in this papers ,we only talk about the improving performance in the EDCA.In this paper, based on AEDCF method to design a new approach.that is before sending the packet, back timer does not fall back to zero time, if the channel is detected busy, we increase the value of the competition window. In this paper, NS2 network simulation software is used to construct a wireless network infrastructure for the EDCA, AEDCF and the proposed algorithm .Under the constant rate and variable rate , the simulation results show that this design approach is better than AEDCF and EDCA for network throughput, delay, channel utilization has increased obviously. Especially in high load conditions the channel,this improvement is more evident. Because the simulation assumes that node location is fixed, the final discussion in this article occurs when the mobile node is sending data the transmission rate will change, this change affects the entire network performance. According to the relevant academic research, changing the packet size and competition window can improve the situation, in the paper these two methods are simulated.