Adaptive Parameter Adaptation in 802.11e

Abstract

IEEE 802.11e is an extension for media access control in wireless network. It is used for different Quality of Service requirement for different transmission application. But it assumes that all terminals operate in the same transmission speed. But when terminals use different transmission speeds, the access mechanism, EDCA, can not perform to its design purposes. Because the parameters designed for the four different categories can not be adapted according to the transmission speed. For high priority application, it is given a fixed transmission time, this will make the terminal with low speed difficult to achieve the required QoS due to insufficient time to transmit large packet. However, for low priority application, the system will be occupied by terminal with slow transmission speed when transmitting a long packet. This will affect the real time requirement of the QoS service and eventually reduce the total system performance. This paper will address the above two issues and try to purpose methods to improve it. First, a method is used to reduce the time that a low speed terminal will take when transmitting low priority data. Secondly, another method is used to enhance the QoS for all terminals with different transmission speed. With those two methods, we can obtain better throughput and better QoS for the WiFi system.