QoS Research Of 802.11 MAC And Embeded System Application

Recently, WLAN technology has developed quickly in communication field. WLAN has been developed into one of the most important parts of the computer network with the increasing demands for broadband wireless communication. It is the successful establishment and consecutive development of IEEE802.11 protocol that causes WLAN become the reliable and flexible network connection scheme in the places which can not be accessed by wired network. The establishment of 802. 11g draft protocol provides a large space for farther development of WLAN.In order to provide the QoS support, the Group of IEEE 802. 11 is establishingthe enhanced mechanism of IEEE 802. 11, which is also called IEEE 802.11. It hasintroduced two mechanisms , which are Enhanced DCF and HCF. The Mobile Terminal (MT)having the function of IEEE 802. 11 will be called Enhanced MT. The Enhanced MT whichprovides the concentrated control for other MTs will be called HC, which id is usuallysubstituted by Access Point(AP). The IEEE 802.11 has combined the super frame CPand the circulate period of CFP. EDCF can only be used in the period of CP. HCF canbe used during the period of CP and CFP , which is the reason why it is called HCF.Combined with the national high technology project named "Key techniques ofthe wireless module in field bus facilities" , this paper focuses on the maintechnologies of IEEE802. 11 physical and MAC layers, which includes the backgroundof WLAN , the spread of the protocol of MAC layer in WLAN and QoS mechanism of IEEE802.11, etc.