Ieee802.11b Access And Security Studies

With the combination of wireless technology and Internet, WLAN has a rapid progress. As the primary technique of WLAN, IEEE 802.11b has been widely used in many fields. At the time of the widespread application of WLAN, the capability of the network, especially, the security and throughput of WLAN, need better requirement. At present, IEEE 802.11b mostly adopts the default method: basic access control method, which is not with eye on the actual condition. With the increase of WLAN users, large numbers of conflicts in WLAN will appear, which will bring rapid decrease of the saturation throughput and badly affect the capability of WLAN. For the limitation of not taking the security problems into consideration when WEP was designed in IEEE 802.11b, the development of WLAN urges the exposure of the security flaws, which result in that WEP cannot meet the requirement now.According to the problems mentioned above, the access control and security in IEEE 802.11b are explored and investigated deeply in this dissertation. And the application of the technology of Virtual Private Network in 802.11b is also investigated.The main work of the dissertation is as follows:1. The MAC protocols and Media Access Control protocols of WLAN IEEE 802.11b are studied.2. The effects of various access methods of IEEE 802.11b are investigated in detail and the related mechanisms are discussed, especially, the basic access method and the RTS/CTS method are compared with in theory and with OPNET.3. The security setting and limitation are analyzed, and the main technniques of defense are compared. To improve the security performance of IEEE 802.11b, a new security project based on VPN is designed and investigated.With the theoretical analysis and simulation experiment, it is found that using RTS/CTS access method in actual WLAN, the capability of WLAN will be improved greatly, where the throughput is increased and the delay is decreased at the same time. In addition, the security performance of WLAN is enhanced when VPN technique is...