Wireless network security has become a strong requirement for effective deployment of wireless communication applications. There are obviously some reasons for users who like to use wireless technology because of its various benefits. However, as the attacks against WLANs are easier than LAN, the security architectures in WLANs have been discussed frequently. In this paper, the vulnerabilities and weakness of WEP protocol which is used in IEEE 802.11b have been analyzed. A new dynamic key generation scheme that surely enhances the security of WEP (Wired Equivalent Privacy) has been proposed. The proposed method found to be more effective than conventional system.