Research And Improvement On Enhanced Distributed Channel Access

In recent years, as the development of wireless communication and computer networks,the growing demand for portable, mobile computers, wlan has been widely used as it's advantages such as moved flexibly, maintain and set up easily, privacy strong. WLAN that is one of the key technologies of wireless networks establishs the communication between computers through a wireless connection means. IEEE802.11 standard is widely recognized as wireless LAN standard, accounting for a large market share. It can only ensure the common data transmission, but can't satisfy the quality of service of advanced businesses. As the rapid growth of the demand for multimedia businesses, it has become a matter to be concerned and resolved to realize the quality of service of multimedia applications in the wireless LAN.IEEE802.11e group was set up for the purpose, and was committed to the research and standardization work in order to support the quality of service for different businesses. It includes two kinds of EDCA and HCCA access mode and also introduces the concept of priority. Different priority businesses have different access parameters in order to make the high priority business will be given priority access to channel.However, due to the competitive characteristics of EDCA access mode, particularly in the case of network saturation, conflicts adversely affect quality of service. Through the study and summarized about the EDCA access mechanism, this paper presents a adaptive algorithm that is more reasonable and can improve network performance based on the current network load between the nodes. In a node, this paper introduces a concept of priority threshold, and improves the working principle of virtual processor. Within the various businesses in a node, not only ensure the high-priority business to use the channel, but also increase probability to low-priority business to use the channel. So the improved EDCA access mechanism can improve the equity. By the improvement of nodes and the internal node, EDCA access mechanism meets better the requirement of the quality of service. Finally, complete the relevant simulation, and verify the feasibility and effectiveness of the improved mechanism.