After Wired Equivalent Privacy (WEP) was found to be be inherently flawed and thus, not adequate for protecting wireless data transmission over Wi-Fi networks, some extensions were made onto WEP to enhance security. Agere Systems made one attempt known as WEPplus, or WEP+, which addressed concerns over weak IV values that were more prone to attack. Basically, the system worked to avoid the use of weak IVs altogether. A major limitation to WEPplus however, is that it will only work if WEPplus is used at both ends of the wireless connection, which might be impossible to enforce depending on the circumstances.
WEPplus should not be considered a solution to the WEP security vulnerabilities, and either WPA or WPA2 (recommended) should be used whenever possible to protect the data transmission within a wireless network. Another attempt to address WEP concerns was WEP2, which was unsuccessful in its goal.
More information: Wired Equivalent Privacy (WEP)